Journal articles on the topic 'Cone gratings'
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VICTOR, JONATHAN D., KEITH P. PURPURA, and MARY M. CONTE. "Chromatic and luminance interactions in spatial contrast signals." Visual Neuroscience 15, no. 4 (April 1998): 607–24. http://dx.doi.org/10.1017/s0952523898154032.
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We report VEP studies which delineate interactions between chromatic and luminance contrast signals. We examined responses to sinusoidal luminance gratings undergoing 4-Hz square-wave contrast reversal, upon which standing gratings with various admixtures of luminance and chromatic contrast were alternately superimposed and withdrawn. The presence of the standing grating induced a VEP component at the fundamental frequency of the contrast-reversal grating. This VEP component appeared without any appreciable lag, and did not vary in amplitude over the 4 s during which the standing grating was present. The observed fundamental response differed from the fundamental component that would be expected from the known interaction between the luminance component of the standing grating with the modulated grating (Bodis-Wollner et al., 1972; Bobak et al., 1988), in three ways: (1) The fundamental response was not nulled for standing gratings that were isoluminant or near-isoluminant. (2) The chromatic dependence of the fundamental response implied an S-cone input to the interaction. (3) No single mechanism (driven by a linear combination of cone signals) could account quantitatively for the size of this response, particularly when the standing grating strongly modulated two cones in phase.
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ORGER, MICHAEL B., and HERWIG BAIER. "Channeling of red and green cone inputs to the zebrafish optomotor response." Visual Neuroscience 22, no. 3 (May 2005): 275–81. http://dx.doi.org/10.1017/s0952523805223039.
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Visual systems break scenes down into individual features, processed in distinct channels, and then selectively recombine those features according to the demands of particular behavioral tasks. In primates, for example, there are distinct pathways for motion and form processing. While form vision utilizes color information, motion pathways receive input from only a subset of cone photoreceptors and are generally colorblind. To explore the link between early channeling of visual information and behavioral output across vertebrate species, we measured the chromatic inputs to the optomotor response of larval zebrafish. Using cone-isolating gratings, we found that there is a strong input from both red and green cones but not short-wavelength cones, which nevertheless do contribute to another behavior, phototaxis. Using a motion-nulling method, we measured precisely the input strength of gratings that stimulated cones in combination. The fish do not respond to gratings that stimulate different cone types out of phase, but have an enhanced response when the cones are stimulated together. This shows that red and green cone signals are pooled at a stage before motion detection. Since the two cone inputs are combined into a single ‘luminance’ channel, the response to sinusoidal gratings is colorblind. However, we also find that the relative contributions of the two cones at isoluminance varies with spatial frequency. Therefore, natural stimuli, which contain a mixture of spatial frequencies, are likely to be visible regardless of their chromatic composition.
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Jirigalantu, Bayanheshig, and Xiang Dong Qi. "The Research of Rigid Lapping Technique on Diamond Grating Ruling Tool." Advanced Materials Research 179-180 (January 2011): 641–45. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.641.
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One of the effective method of improving diamond tool life on rulling large diffraction gratings is developing precise double-cone edged on line edge transfering tool.But traditional died weight or manual lapping technique couldn't meet the precision requirement of on line edge transfering tool.So preliminary studied rigid lapping of diamond grating ruling tool.Choosing traditional BC6063 shaping machine and made a series of alteration on it, achieved the automation of lapping process of diamond grating ruling tool. Through lapping grating ruling tool and AFM measurement find that the surface roughness of tool is 1.51nm,the radius of tool edge is 160nm, edge quality is good enough,this verified the feasibility of rigid lapping of diamond grating ruling tool and lay the foundation for developing precision lapping machine.
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NORTHMORE, D. P. M., D. J. OH, and M. A. CELENZA. "Acuity and contrast sensitivity of the bluegill sunfish and how they change during optic nerve regeneration." Visual Neuroscience 24, no. 3 (May 2007): 319–31. http://dx.doi.org/10.1017/s0952523807070307.
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Spatial vision was studied in the bluegill sunfish, Lepomis macrochirus (9.5–14 cm standard length) to assess the limitations imposed by the optics of the eye, the retinal receptor spacing and the retinotectal projection during regeneration. Examination of images formed by the dioptric elements of the eye showed that spatial frequencies up to 29 c/° could be imaged on the retina. Cone spacing was measured in the retina of fresh, intact eyes. The spacing of rows of double cones predicted 3.4 c/° as the cutoff spatial frequency; the spacing between rows of single and double cones predicted 6.7 c/°. Contrast sensitivity functions were obtained psychophysically in normals and fish with one regenerating optic nerve. Fish were trained to orient to gratings (mean luminance = 25 cd/m2) presented to either eye. In normals, contrast sensitivity functions were similar in shape and bandwidth to those of other species, peaking at 0.4 c/° with a minimum contrast threshold of 0.03 and a cutoff at about 5 c/°, which was within the range predicted by cone spacing. Given that the optical cutoff frequency exceeds that predicted by cone spacing, it is possible that gratings could be detected by aliasing with the bluegill's regular cone mosaic. However, tests with high contrast gratings up to 15 c/° found no evidence of such detection. After crushing one optic nerve in three trained sunfish, recovery of visual avoidance, dorsal light reflex and orienting to gratings, were monitored over 315 days. At 64–69 days postcrush, responses to gratings reappeared, and within 2–5 days contrast sensitivity at low (0.15 c/°) and medium (1.0 c/°) spatial frequencies had returned to normal. At a high spatial frequency (2.93 c/°) recovery was much slower, and complete only in one fish.
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Johnson, Elizabeth N., Michael J. Hawken, and Robert Shapley. "Cone Inputs in Macaque Primary Visual Cortex." Journal of Neurophysiology 91, no. 6 (June 2004): 2501–14. http://dx.doi.org/10.1152/jn.01043.2003.
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To understand the role of primary visual cortex (V1) in color vision, we measured directly the input from the 3 cone types in macaque V1 neurons. Cells were classified as luminance-preferring, color-luminance, or color-preferring from the ratio of the peak amplitudes of spatial frequency responses to red/green equiluminant and to black/white (luminance) grating patterns, respectively. In this study we used L-, M-, and S-cone–isolating gratings to measure spatial frequency response functions for each cone type separately. From peak responses to cone-isolating stimuli we estimated relative cone weights and whether cone inputs were the same or opposite sign. For most V1 cells the relative S-cone weight was <0.1. All color-preferring cells were cone opponent and their L/M cone weight ratio was clustered around a value of –1, which is roughly equal and opposite L and M cone signals. Almost all cells (88%) classified as luminance cells were cone nonopponent, with a broad distribution of cone weights. Most cells (73%) classified as color-luminance cells were cone opponent. This result supports our conclusion that V1 color-luminance cells are double-opponent. Such neurons are more sensitive to color boundaries than to areas of color and thereby could play an important role in color perception. The color-luminance population had a broad distribution of L/M cone weight ratios, implying a broad distribution of preferred colors for the double-opponent cells.
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Lee, Barry B., Robert M. Shapley, Michael J. Hawken, and Hao Sun. "Spatial distributions of cone inputs to cells of the parvocellular pathway investigated with cone-isolating gratings." Journal of the Optical Society of America A 29, no. 2 (January 26, 2012): A223. http://dx.doi.org/10.1364/josaa.29.00a223.
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HONG, SANG WOOK, and STEVEN K. SHEVELL. "Binocular rivalry between identical retinal stimuli with an induced color difference." Visual Neuroscience 25, no. 3 (March 6, 2008): 361–64. http://dx.doi.org/10.1017/s0952523808080139.
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An open question in color rivalry is whether alternation between two colors is caused by a difference in receptoral stimulation or a difference in the neural representation of color appearance. This question was examined with binocular rivalry between physically identical lights that differed in appearance due to chromatic induction. Perceptual alternation was measured between gratings of the same chromaticity; each one was presented within a different patterned surround that caused the gratings, one to each eye, to appear unequal in hue because of chromatic induction. The gratings were presented dichoptically with binocular disparity so the rivalrous gratings appeared in front of the surround. Perceptual alternation in hue was found for the two physically identical chromaticities. Stereoscopic depth also was perceived, corroborating binocular neural combination despite color rivalry (Treisman, 1962). The results show that color rivalry is resolved after color-appearance shifts caused by chromatic context, and that color rivalry does not require competing unequal cone excitations from the rivalrous stimuli.
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Kremers, Jan, Luiz Carlos L. Silveira, and Bjørg E. Kilavik. "Influence of Contrast on the Responses of Marmoset Lateral Geniculate Cells to Drifting Gratings." Journal of Neurophysiology 85, no. 1 (January 1, 2001): 235–46. http://dx.doi.org/10.1152/jn.2001.85.1.235.
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The responses of lateral geniculate nucleus (LGN) cells in the common marmoset ( Callithrix jacchus) to drifting luminance or cone isolating gratings of different spatial frequencies and contrasts were measured. The response noise, defined as the variability of the responses to single sweeps in the complex plane, was independent of stimulus contrast and spatial frequency but increased with increasing overall responsiveness of the cell. The signal-to-noise ratio of parvocellular (PC) cells was smaller than of magnocellular (MC) cells. At each contrast, the response amplitude as a function of spatial frequency could be described with a difference of Gaussians model. With this model, the sizes and the peak sensitivities of the receptive field centers and surrounds were estimated. It was found that receptive field center and surround sizes of LGN cells decrease slightly with increasing contrast. Further, the peak sensitivity decreases with increasing contrast. The two factors are involved in a decrease in responsivity (the response per unit contrast) with increasing contrast which is compatible to response saturation for low spatial frequency stimuli. PC cells did not saturate as much to luminance stimuli although some saturation was found with cone isolating gratings. We found that the response phase lag of both PC and MC cells decreased with increasing contrast, which cannot be explained on the basis of linear response behavior. Apparently the phase of LGN cell responses to drifting gratings is altered in comparison with the retinal inputs by additional nonlinearities.
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Heimel, J. Alexander, Stephen D. Van Hooser, and Sacha B. Nelson. "Laminar Organization of Response Properties in Primary Visual Cortex of the Gray Squirrel(Sciurus carolinensis)." Journal of Neurophysiology 94, no. 5 (November 2005): 3538–54. http://dx.doi.org/10.1152/jn.00106.2005.
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The gray squirrel ( Sciurus carolinensis) is a diurnal highly visual rodent with a cone-rich retina. To determine which features of visual cortex are common to highly visual mammals and which are restricted to non-rodent species, we studied the laminar organization of response properties in primary visual area V1 of isoflurane-anesthetized squirrels using extra-cellular single-unit recording and sinusoidal grating stimuli. Of the responsive cells, 75% were tuned for orientation. Only 10% were directionally selective, almost all in layer 6, a layer receiving direct input from the dorsal lateral geniculate nucleus (LGN). Cone opponency was widespread but almost absent from layer 6. Median optimal spatial frequency tuning was 0.21 cycles/°. Median optimal temporal frequency a high 5.3 Hz. Layer 4 had the highest percentage of simple cells and shortest latency (26 ms). Layers 2/3 had the lowest spontaneous activity and highest temporal frequency tuning. Layer 5 had the broadest spatial frequency tuning and most spontaneous activity. At the layer 4/5 border were sustained cells with high cone opponency. Simple cells, determined by modulation to drifting sinusoidal gratings, responded with shorter latencies, were more selective for orientation and direction, and were tuned to lower spatial frequencies. A comparison with other mammals shows that although the laminar organization of orientation selectivity is variable, the cortical input layers contain more linear cells in most mammals. Nocturnal mammals appear to have more orientation-selective neurons in V1 than diurnal mammals of similar size.
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RUDVIN, INGER. "Visual evoked potentials for reversals of red–green gratings with different chromatic contrasts: Asymmetries with respect to isoluminance." Visual Neuroscience 22, no. 6 (November 2005): 749–58. http://dx.doi.org/10.1017/s0952523805226068.
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Human visual evoked potentials (VEPs) were recorded for abrupt 6.25-Hz reversals of 2 c/deg square-wave gratings combining red–green contrast with different levels of luminance contrast. Response characteristics— amplitudes and peak latencies as a function of luminance contrast—were compared for four different pairs of red–green colors and an isochromatic yellow grating. For each of the red–green color pairs, the plots of VEP amplitudes and latencies were nonsymmetrical with respect to isoluminance. The amplitude dropped to a minimum within a region of rapid phase change, at a different contrast for each color pair but always at a luminance contrast for which the greener color had the higher luminance. When the contrast-response curve for each of the four red–green pairs was modeled by a simple |CL − CM| opponency of L- and M-cone contrast using a fixed CL/CM weighting ratio of about two, there was a close correspondence between the contrast giving a null in the modeled response and that giving a minimum in the VEP amplitude. So for the stimulus parameters applied here, the reversal VEP appeared to be dominated by L/M-opponent response contributions for which the signed CL/CM-cone weighting ratio was close to a value of minus two rather than to a value of minus one, which is characteristic of the psychophysical red–green detection mechanism and representative of CL/CM weighting ratios for precortical cells in the parvocellular pathway.
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Kiper, Daniel C., Suzanne B. Fenstemaker, and Karl R. Gegenfurtner. "Chromatic properties of neurons in macaque area V2." Visual Neuroscience 14, no. 6 (November 1997): 1061–72. http://dx.doi.org/10.1017/s0952523800011779.
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AbstractWe recorded from single cells in area V2 of cynomolgus monkeys using standard acute recording techniques. After measuring each cell's spatial and temporal properties, we performed several tests of its chromatic properties using sine-wave gratings modulated around a mean gray background. Most cells behaved like neurons in area V1 and their responses were adequately described by a model that assumes a linear combination of cone signals. Unlike in V1, we found a subpopulation of cells whose activity was increased or inhibited by stimuli within a narrow range of color combinations. No particular color directions were preferentially represented. V2 cells showing color specificity, including cells showing narrow chromatic tuning, were present in any of the stripe compartments, as defined by cytochrome-oxidase (CO) staining. An addition of chromatic contrast facilitated the responses of most neurons to gratings with various luminance contrasts. Neurons in all three CO compartments gave significant responses to isoluminant gratings. Receptive-field properties of cells were generally similar for luminance and chromatically defined stimuli. We found only a small number of cells with a clearly identifiable double-opponent receptive-field organization.
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Brückner, Jean-Baptiste, Judikaël Le Rouzo, Ludovic Escoubas, Gérard Berginc, Cécile Gourgon, Olivier Desplats, and Jean-Jacques Simon. "Flat-top and patterned-topped cone gratings for visible and mid-infrared antireflective properties." Optics Express 21, no. 13 (June 27, 2013): 16043. http://dx.doi.org/10.1364/oe.21.016043.
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Zlatkova, Margarita B., Angel Vassilev, and Roger S. Anderson. "Resolution acuity for equiluminant gratings of S-cone positive or negative contrast in human vision." Journal of Vision 8, no. 3 (March 12, 2008): 9. http://dx.doi.org/10.1167/8.3.9.
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Reisbeck, T. E., and K. R. Gegenfurtner. "Orientation Discrimination at Isoluminance." Perception 25, no. 1_suppl (August 1996): 127. http://dx.doi.org/10.1068/v96l1202.
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Colour and form are important attributes of the objects in our visual environment. We tested the hypothesis that colour and orientation are processed independently in the visual system. Orientation perception for stimuli defined by luminance is characterised by a decrease in thresholds with increasing stimulus contrast, and by a strong oblique effect: stimuli along the horizontal or vertical axes are discriminated more easily. We determined orientation discrimination thresholds for stationary, slow (1 Hz) or fast (8 Hz) moving sine-wave gratings (1 cycle deg−1) defined by luminance or isoluminant (red — green) contrast. In a 4AFC paradigm, three of four stimulus patches were identical and the fourth differed in orientation, contrast, or in both. When we measured orientation discrimination thresholds as a function of stimulus contrast, thresholds decreased for all stimuli with increasing contrast. At all temporal frequencies the functions relating orientation thresholds to stimulus contrast had similar shapes for luminance and isoluminant gratings. On a cone-contrast metric, thresholds for stationary and slowly moving stimuli were consistently lower for isoluminant compared to luminance stimuli. For fast-moving stimuli orientation thresholds were similar for both kinds of gratings. For both types of stimuli a marked oblique effect was observed. To characterise processing of contrast and orientation completely, we measured simultaneous thresholds for contrast and orientation. The shapes of the resulting two-dimensional threshold contours were similar for luminance and isoluminant gratings, indicating similar rules for combining differences in contrast and orientation. We conclude that processing of isoluminant and luminance stimuli undergoes the same neural processing at least for the low spatial frequencies used here.
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Drezet, A., F. Przybilla, E. Laux, O. Mahboub, C. Genet, T. W. Ebbesen, J. S. Bouillard, et al. "Opening the light extraction cone of high index substrates with plasmonic gratings: Light emitting diode applications." Applied Physics Letters 95, no. 2 (July 13, 2009): 021101. http://dx.doi.org/10.1063/1.3176435.
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Tonazzini, Ilaria, Monica Pellegrini, Mario Pellegrino, and Marco Cecchini. "Interaction of leech neurons with topographical gratings: comparison with rodent and human neuronal lines and primary cells." Interface Focus 4, no. 1 (February 6, 2014): 20130047. http://dx.doi.org/10.1098/rsfs.2013.0047.
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Controlling and improving neuronal cell migration and neurite outgrowth are critical elements of tissue engineering applications and development of artificial neuronal interfaces. To this end, a promising approach exploits nano/microstructured surfaces, which have been demonstrated to be capable of tuning neuronal differentiation, polarity, migration and neurite orientation. Here, we investigate the neurite contact guidance of leech neurons on plastic gratings (GRs; anisotropic topographies composed of alternating lines of grooves and ridges). By high-resolution microscopy, we quantitatively evaluate the changes in tubulin cytoskeleton organization and cell morphology and in the neurite and growth cone development. The topography-reading process of leech neurons on GRs is mediated by filopodia and is more responsive to 4-µm-period GRs than to smaller period GRs. Leech neuron behaviour on GRs is finally compared and validated with several other neuronal cells, from murine differentiated embryonic stem cells and primary hippocampal neurons to differentiated human neuroblastoma cells.
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Shirhatti, Vinay, and Supratim Ray. "Long-wavelength (reddish) hues induce unusually large gamma oscillations in the primate primary visual cortex." Proceedings of the National Academy of Sciences 115, no. 17 (April 9, 2018): 4489–94. http://dx.doi.org/10.1073/pnas.1717334115.
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Gamma oscillations (∼30–80 Hz) are a prominent signature of electrophysiological signals, with a purported role in natural vision. Previous studies in the primary visual cortex (area V1) have shown that achromatic gratings or gabor stimuli generate salient gamma oscillations, whose strength and frequency depend on stimulus properties such as their size, contrast, and orientation. Surprisingly, although natural images are rarely achromatic, the effect of chromatic input on gamma has not been thoroughly investigated. Recording from primate V1, we show that gamma oscillations of extremely high magnitude (peak increase of ∼300-fold in some cases), far exceeding the gamma generated by optimally tuned achromatic gratings, are induced in the local field potentials by full-field color stimuli of different hues. Furthermore, gamma oscillations are sensitive to the hue of the chromatic input, with the strongest oscillations for long-wavelength (reddish) hues and another, smaller gamma response peak for hues in the short-wavelength (bluish) range, which lie approximately on the two cardinal chromatic response axes of the upstream lateral geniculate nucleus neurons. These oscillations depended critically on the purity of the hue, decreasing with hue desaturation, but remained robust for pure hue stimuli even at reduced luminance. Importantly, the magnitude of gamma oscillations was highly correlated with positive L−M cone contrast produced by the stimuli, suggesting that gamma could be a marker of the specific mechanisms underlying this computation. These findings provide insights into the generation of gamma oscillations, as well as the processing of color along the visual pathway.
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Bedat, L., A. Saadane, and D. Barba. "Masking Effects Induced by Perceptual Colour Components." Perception 26, no. 1_suppl (August 1997): 85. http://dx.doi.org/10.1068/v970317.
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Signals from the three types of cone photoreceptors are generally thought to be combined into two opponent-colour components and an achromatic component. Here we have chosen the cardinal directions Ach (achromatic axis), Cr1 (reddish - greenish axis) and Cr2 (bluish - yellowish axis) defined by Krauskopf to build a colour image coding scheme based on features of the human visual system. In order to design the optimal perceptual quantisers, we studied the perception of colour at different spatial frequencies, measuring the effect of a colour masking signal on the perception threshold for achromatic or chromatic sine-wave gratings. Three cases were considered to describe these interactions. First, we measured the masking effect of each colour component by itself. For the two chromatic components, we observed a pedestal effect for low masking contrasts and threshold rises for higher masking contrasts. Second, we studied interactions between the two colour axes. With colour masking signals composed of Cr1 and Cr2 components, thresholds for Cr1 stimuli dropped at low contrasts of the Cr2 component of the masking signal. This effect disappeared for high Cr2 masking contrasts. This was true at all contrasts of the Cr1 component of the masking signal. Thresholds for Cr2 stimuli were not modified by Cr1 masking. Finally, interactions between the chromatic and achromatic components were more complex. We observed a strong modification of the achromatic contrast-sensitivity function when a Cr1 masking sine-wave grating was added. When the achromatic frequency was lower than the colour masking frequency, the threshold rose. However, when the achromatic frequency was higher than the colour masking frequency, there was a significant pedestal effect. The global effect is a shift of the achromatic contrast sensitivity function. With a Cr2 masking signal, no significant modification of the achromatic contrast-sensitivity function was observed.
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Drezet, A., F. Przybilla, E. Laux, O. Mahboub, C. Genet, T. W. Ebbesen, J. S. Bouillard, et al. "Publisher's Note: “Opening the light extraction cone of high index substrates with plasmonic gratings: Light emitting diode applications” [Appl. Phys. Lett. 95, 021101 (2009)]." Applied Physics Letters 95, no. 6 (August 10, 2009): 069903. http://dx.doi.org/10.1063/1.3202553.
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Jark, Werner, and Diane Eichert. "On amplitude beam splitting of tender X-rays (2–8 keV photon energy) using conical diffraction from reflection gratings with laminar profile." Journal of Synchrotron Radiation 23, no. 1 (January 1, 2016): 91–97. http://dx.doi.org/10.1107/s1600577515019761.
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Conical diffraction is obtained when a radiation beam impinges onto a periodically ruled surface structure parallel or almost parallel to the ruling. In this condition the incident intensity is diffracted through an arc, away from the plane of incidence. The diffracted intensity thus lies on a cone, which leads to the name `conical diffraction'. In this configuration almost no part of the ruled structure will produce any shadowing effect for the incident or the diffracted beam. Then, compared with a grating in the classical orientation, relatively higher diffraction efficiencies will be observed for fewer diffraction orders. When the incident beam is perfectly parallel to the grooves of a rectangular grating profile, the symmetry of the setup causes diffraction of the intensity symmetrically around the plane of incidence. This situation was previously tested experimentally in the VUV spectral range for the amplitude beam splitting of a radiation beam with a photon energy of 25 eV. In this case the ideally expected beam splitting efficiency of about 80% for the diffraction into the two first orders was confirmed for the optimum combination of groove depth and angle of grazing incidence. The feasibility of the amplitude beam splitting for hard X-rays with 12 keV photon energy by use of the same concept was theoretically confirmed. However, no related experimental data are presented yet, not even for lower energy soft X-rays. The present study reports the first experimental data for the conical diffraction from a rectangular grating profile in the tender X-ray range for photon energies of 4 keV and 6 keV. The expected symmetries are observed. The maximum absolute efficiency for beam splitting was measured to be only about 30%. As the reflectivity of the grating coating at the corresponding angle of grazing incidence was found to be only of the order of 50%, the relative beam splitting efficiency was thus 60%. This is to be compared also here with an ideally expected relative efficiency of 80%. It is predicted that a beam splitting efficiency exceeding 50% should be possible by use of more appropriate materials.
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Горай, Л. И., Т. Н. Березовская, Д. В. Мохов, В. А. Шаров, К. Ю. Шубина, Е. В. Пирогов, and А. С. Дашков. "Дифракционные решетки с блеском, получаемые на пластинах Si --- первые результаты." Журнал технической физики 91, no. 10 (2021): 1538. http://dx.doi.org/10.21883/jtf.2021.10.51368.81-21.
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Using direct laser lithography and liquid etching of polished vicinal Si(111) wafers, a technology was developed and diffraction gratings 500 /mm with a blaze angle of 4° were fabricated. The manufacturing process of a reflective Si-grating of a triangular profile (sawtooth) can be divided into four main steps: (1) obtaining a pattern of a protective mask for etching grooves; (2) anisotropic etching of grooves in KOH solution; (3) etching to smooth the grating profile and polish the surface of working facets; (4) coating to increase reflectivity. The samples obtained were characterized using scanning electron microscopy and atomic force microscopy methods to determine the shape of the groove profile and roughness: the shape turned out to be close to the ideal triangular, and the root-mean square roughness was less than 0.3 nm. With the help of the PCGrate™ code, taking into account the measured real groove profile, the diffraction efficiency of gratings operating in classical and conical mounts in soft-X-ray and extreme ultraviolet radiation has been simulated. The obtained efficiency values are close to the record ones for the corresponding spectral range and the Au-coating of the grating.
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Chen, Jin, Li Xin Tang, and Hui Long Chen. "A Novel Structured Light Pattern for One-Shot Shape Acquisition." Applied Mechanics and Materials 401-403 (September 2013): 1191–94. http://dx.doi.org/10.4028/www.scientific.net/amm.401-403.1191.
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This paper proposes a new one-shot grayscale structured lighting scheme to obtain depth data fast. Its key idea is to code the pattern using modulated sinusoidal gratings along two axes. The features used for matching are the fringe central lines of the vertical grating. The correlation of the intensity profiles is used to measure the similarity of features. Experimental results using a vision system with two cameras and a projector show that the proposed scheme is effective and efficient.
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Donner, Kristian, and Simo Hemilä. "Modelling the spatio-temporal modulation response of ganglion cells with difference-of-Gaussians receptive fields: Relation to photoreceptor response kinetics." Visual Neuroscience 13, no. 1 (January 1996): 173–86. http://dx.doi.org/10.1017/s0952523800007215.
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AbstractDifference-of-Gaussians (DOG) models for the receptive fields of retinal ganglion cells accurately predict linear responses to both periodic stimuli (typically moving sinusoidal gratings) and aperiodic stimuli (typically circular fields presented as square-wave pulses). While the relation of spatial organization to retinal anatomy has received considerable attention, temporal characteristics have been only loosely connected to retinal physiology. Here we integrate realistic photoreceptor response waveforms into the DOG model to clarify how far a single set of physiological parameters predict temporal aspects of linear responses to both periodic and aperiodic stimuli. Traditional filter-cascade models provide a useful first-order approximation of the single-photon response in photoreceptors. The absolute time scale of these, plus a time for retinal transmission, here construed as a fixed delay, are obtained from flash/step data. Using these values, we find that the DOG model predicts the main features of both the amplitude and phase response of linear cat ganglion cells to sinusoidal flicker. Where the simplest model formulation fails, it serves to reveal additional mechanisms. Unforeseen facts are the attenuation of low temporal frequencies even in pure center-type responses, and the phase advance of the response relative to the stimulus at low frequencies. Neither can be explained by any experimentally documented cone response waveform, but both would be explained by signal differentiation, e.g. in the retinal transmission pathway, as demonstrated at least in turtle retina.
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Ahmed, Hassan Yousif, Medien Zeghid, Belgacem Bouallegue, Abdellah Chehri, and Somia A. Abd El-Mottaleb. "Reduction of Complexity Design of SAC OCDMA Systems by Utilizing Diagonal Permutation Shift (DPS) Codes with Single Photodiode (SPD) Detection Technique." Electronics 11, no. 8 (April 12, 2022): 1224. http://dx.doi.org/10.3390/electronics11081224.
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In this paper, a diagonal permutation code is presented for spectral amplitude coding optical code division multiple access (SAC-OCDMA) employing a single photodiode (SPD) detection technique. It is characterized by practical code length and ideal in-phase cross correlation (CC) that results in multiple access interference (MAI) suppression. A diagonal permutation shift (DPS) code can be constructed using both prime codes and some matrix operations. In addition, it can be easily implemented as it exists for prime numbers P, which limits the addressing probability of codes to P2. Fiber Bragg gratings (FBGs) are used for code encoding and decoding. Simulation analysis that calibrates with BER, Q-factor, and eye diagram proves that DPS code using SPD technique is able to maintain error free transmission compared to the complementary detection scheme (CDS) technique. It is reported that a reduction of fiber Bragg grating (FBG) sets by 41.6% was achieved for SPD over CDS techniques.
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Gegenfurtner, Karl R., Daniel C. Kiper, and Jonathan B. Levitt. "Functional Properties of Neurons in Macaque Area V3." Journal of Neurophysiology 77, no. 4 (April 1, 1997): 1906–23. http://dx.doi.org/10.1152/jn.1997.77.4.1906.
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Gegenfurtner, Karl R., Daniel C. Kiper, and Jonathan B. Levitt. Functional properties of neurons in macaque area V3. J. Neurophysiol. 77: 1906–1923, 1997. We investigated the functional properties of neurons in extrastriate area V3. V3 receives inputs from both magno- and parvocellular pathways and has prominent projections to both the middle temporal area (area MT) and V4. It may therefore represent an important site for integration and transformation of visual signals. We recorded the activity of single units representing the central 10° in anesthetized, paralyzed macaque monkeys. We measured each cell's spatial, temporal, chromatic, and motion properties with the use of a variety of stimuli. Results were compared with measurements made in V2 neurons at similar eccentricities. Similar to area V2, most of the neurons in our sample (80%) were orientation selective, and the distribution of orientation bandwidths was similar to that found in V2. Neurons in V3 preferred lower spatial and higher temporal frequencies than V2 neurons. Contrast thresholds of V3 neurons were extremely low. Achromatic contrast sensitivity was much higher than in V2, and similar to that found in MT. About 40% of all neurons showed strong directional selectivity. We did not find strongly directional cells in layer 4 of V3, the layer in which the bulk of V1 and V2 inputs terminate. This property seems to be developed within area V3. An analysis of the responses of directionally selective cells to plaid patterns showed that in area V3, as in MT and unlike in V1 and V2, there exist cells sensitive to the motion of the plaid pattern rather than to that of the components. The exact proportion of cells classified as being selective to color depended to a large degree on the experiment and on the criteria used for classification. With the use of the same conditions as in a previous study of V2 cells, we found as many (54%) color-selective cells as in V2 (50%). Furthermore, the responses of V3 cells to colored sinusoidal gratings were well described by a linear combination of cone inputs. The two subpopulations of cells responsive to color and to motion overlapped to a large extent, and we found a significant proportion of cells that gave reliable and directional responses to drifting isoluminant gratings. Our results show that there is a significant interaction between color and motion processing in area V3, and that V3 cells exhibit the more complex motion properties typically observed at later stages of visual processing.
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Goray, Leonid, Werner Jark, and Diane Eichert. "Rigorous calculations and synchrotron radiation measurements of diffraction efficiencies for tender X-ray lamellar gratings: conical versus classical diffraction." Journal of Synchrotron Radiation 25, no. 6 (October 8, 2018): 1683–93. http://dx.doi.org/10.1107/s1600577518012419.
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When reflection gratings are operated at grazing incidence in the extreme off-plane configuration and the incident beam trajectory is parallel to the grooves, the diffraction into the first order can be more efficient than in the classical orientation. This situation is referred to as the conical diffraction case. In the classical configuration the grooves are perpendicular to the incident beam and thus an efficiency-reducing shadowing effect will be observed at very grazing angles. It was recently shown that a laminar grating could provide symmetric and relatively high efficiencies in conical diffraction for diffraction even of photons with large energies of the order of 4 and 6 keV. For photon energies in the tender X-ray range, accurate computing tools for the calculation of diffraction efficiencies from gratings with simple coatings have not been available. Promising results for this spectral range now require the development of tools for modelling the diffraction efficiency expected in optical instrumentation, in which the provision of high efficiency in the indicated spectral range is mandatory. This is the case when weak sources are to be investigated, like in space science. In this study it will be shown that scalar calculations are not appropriate for this purpose, while newly introduced rigorous calculations based on the boundary integral equation method, implemented in the PCGrate ® code, can provide predictions that are in agreement with observed diffraction efficiencies. The agreement is achieved by modelling the exact surface profile. This applies for both the conical diffraction configuration and for the classical in-plane configuration, in which a significantly lower efficiency was obtained. Even though the profile of the presented grating was not perfect, but significantly distorted, the calculations show that efficiency-wise the structure provided already more than 75% of the ideally expected efficiency for conical diffraction. This is a very promising result for further optimization of diffraction gratings for use in the tender X-ray range.
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TROY, J. B., D. L. BOHNSACK, and L. C. DILLER. "Spatial properties of the cat X-cell receptive field as a function of mean light level." Visual Neuroscience 16, no. 6 (November 1999): 1089–104. http://dx.doi.org/10.1017/s0952523899166094.
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Our objective with this study was to provide a near complete characterization of how mean light level changes the spatial receptive-field properties of X-cells. Single X-cells were recorded extracellularly either from cell bodies in the retina or from their axons in the optic tract. Frequency responses of the cells at 2 Hz were measured for a set of gratings of different spatial frequencies and for a stimulus designed to probe the spatial properties of the receptive-field surround. Predicted frequency responses of a Gaussian center-surround model for the receptive field were fit simultaneously to both sets of measurements and the parameters of the model that best fit the data used to characterize the spatial properties of the receptive field. Measurements were made at a number of mean light levels for each cell and changes in receptive-field properties were characterized by changes in the parameters of the Gaussian center-surround model. The range of illuminances studied covered the bulk of the range encountered by a cat naturally and three distinct functional ranges appeared to express themselves in the data. One range corresponded to the cat's photopic range of vision. The other two ranges were where signals originating in rods dominate X-cell responses. We argue that one corresponds to the range that rod signals pass predominantly through rod bipolars en route to the X-cell, while the other is where rod signals flow predominantly through cones via gap junctions and then follow the path of cone signals to the X-cell. Among the major findings are that Weber's Law is followed throughout the photopic but not the scotopic range, that center radius expands under scotopic conditions, and that the surround is present even at the lowest scotopic levels we studied.
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O'Keefe, Lawrence P., Jonathan B. Levitt, Daniel C. Kiper, Robert M. Shapley, and J. Anthony Movshon. "Functional Organization of Owl Monkey Lateral Geniculate Nucleus and Visual Cortex." Journal of Neurophysiology 80, no. 2 (August 1, 1998): 594–609. http://dx.doi.org/10.1152/jn.1998.80.2.594.
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O'Keefe, Lawrence P., Jonathan B. Levitt, Daniel C. Kiper, Robert M. Shapley, and J. Anthony Movshon. Functional organization of owl monkey lateral geniculate nucleus and visual cortex. J. Neurophysiol. 80: 594–609, 1998. The nocturnal, New World owl monkey ( Aotus trivirgatus) has a rod-dominated retina containing only a single cone type, supporting only the most rudimentary color vision. However, it does have well-developed magnocellular (M) and parvocellular (P) retinostriate pathways and striate cortical architecture [as defined by the pattern of staining for the activity-dependent marker cytochrome oxidase (CO)] similar to that seen in diurnal primates. We recorded from single neurons in anesthetized, paralyzed owl monkeys using drifting, luminance-modulated sinusoidal gratings, comparing receptive field properties of M and P neurons in the lateral geniculate nucleus and in V1 neurons assigned to CO “blob,” “edge,” and “interblob” regions and across layers. Tested with achromatic stimuli, the receptive field properties of M and P neurons resembled those reported for other primates. The contrast sensitivity of P cells in the owl monkey was similar to that of P cells in the macaque, but the contrast sensitivities of M cells in the owl monkey were markedly lower than those in the macaque. We found no differences in eye dominance, orientation, or spatial frequency tuning, temporal frequency tuning, or contrast response for V1 neurons assigned to different CO compartments; we did find fewer direction-selective cells in blobs than in other compartments. We noticed laminar differences in some receptive field properties. Cells in the supragranular layers preferred higher spatial and lower temporal frequencies and had lower contrast sensitivity than did cells in the granular and infragranular layers. Our data suggest that the receptive field properties across functional compartments in V1 are quite homogeneous, inconsistent with the notion that CO blobs anatomically segregate signals from different functional “streams.”
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Schubert, Martin, Burkhard Plaum, Jörg Stober, Albrecht Herrmann, Walter Kasparek, Carsten Lechte, Fritz Leuterer, et al. "Beam tracing study for design and operation of two-pass electron cyclotron heating at ASDEX Upgrade." EPJ Web of Conferences 203 (2019): 02009. http://dx.doi.org/10.1051/epjconf/201920302009.
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The electron cyclotron resonance heating system at ASDEX Upgrade (AUG) is currently being extended to eight similar Gyrotrons in total. Each Gyrotron operates at 105 and 140 GHz and is designed for up to 1 MW millimetre wave output power. A substantial part of the AUG program will focus on experimental conditions, where the plasma density may be above the X-2 cut-off density at 140 GHz. In order to cope with the high density, the heating system will operate in the O-2 mode scheme with potentially incomplete absorption in the first pass. Reflecting gratings installed into the heat shield on AUG’s inner column allow for a controlled second pass of the beam’s unabsorbed fraction. Thermocouple measurements serve to control the beam position on the grating. The beam geometry is being finalized for the launchers #1-4. Beam propagation is simulated with the TORBEAM code and previous high density experiments are used as a database. The geometry is optimized using three criteria: central deposition, high absorption and robustness of the beam dump after the second pass. The experimental conditions, and the plasma electron density in particular, may vary such that the Gaussian beam parameters of the incoming beam on the grating deviate from the design values. It is proposed to model the effect of the grating with an equivalent ellipsoidal mirror. Laboratory measurements are shown, which support this model.
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Zhu, Dan Dan, Jian Song, Xiu Zhen Hu, and Yuan Yuan Zhang. "Design of Sampled Fiber Bragg Grating Comb Filter." Applied Mechanics and Materials 397-400 (September 2013): 1850–53. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1850.
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This article based on the theoretical basis of sampled fiber grating, using transfer matrix method to analyse sampled fiber grating, and the analysed the spectrum of sampled fiber grating, and studied sampled fiber grating filter properties. by adjusting the parameters of sampling grating such as: the length of the grating, grating period, duty ratio ( sampling rate) and other parameters, to construct 6 comb filter, and finally come to sampled fiber grating filter preparation method and process in the theory, analysed the application of sampled fiber grating filter in some optical fiber communication fields.
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Levitt, J. B., D. C. Kiper, and J. A. Movshon. "Receptive fields and functional architecture of macaque V2." Journal of Neurophysiology 71, no. 6 (June 1, 1994): 2517–42. http://dx.doi.org/10.1152/jn.1994.71.6.2517.
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1. Visual area V2 of macaque monkey cerebral cortex is the largest of the extrastriate visual areas, yet surprisingly little is known of its neuronal properties. We have made a quantitative analysis of V2 receptive field properties. Our set of measurements was chosen to distinguish neuronal responses reflecting parvocellular (P) or magnocellular (M) inputs and to permit comparison with similar measurements made in other visual areas; we further describe the relationship of those properties to the laminar and cytochrome oxidase (CO) architecture of V2. 2. We recorded the activity of single units representing the central 5 degrees in all laminae and CO divisions of V2 in anesthetized, paralyzed macaque monkeys. We studied responses to geometric targets and to drifting sinusoidal gratings that varied in orientation, spatial frequency, drift rate, contrast, and color. 3. The orientation selectivity and spatial and temporal tuning of V2 neurons differed little from those in V1. As in V1, spatial and temporal tuning in V2 appeared separable, and we identified a population of simple cells (more common within the central 3 degrees) similar to those found in V1. Contrast sensitivity of V2 neurons was greater on average than in V1, perhaps reflecting the summation of inputs in V2's larger receptive fields. Many V2 neurons exhibited some degree of chromatic opponency, responding to isoluminant color variations, but these neurons differed from V1 in the linearity with which they summate cone signals. 4. In agreement with others, we found that neurons with selective responses to color, size, and motion did seem to cluster in different CO compartments. However, this segregation of qualitatively different response selectivities was not absolute, and response properties also seemed to depend on laminar position within each compartment. As others also have noted, we found that CO stripe widths in the macaque (unlike in the squirrel monkey) did not consistently appear different. We relied on the segregation of qualitatively distinct cell types, and in some cases the pattern of Cat-301 staining as well, to distinguish CO stripes when the staining pattern of CO alone was ambiguous. Although all cell types were found in all CO compartments and laminae, unoriented cells were more prominent in layers 2–4 of “thin” stripes, direction-selective cells in layers 3B/4 of “thick” stripes, color-selective cells in the upper layers of thin and pale stripes, and end-stopped cells mainly outside of layer 4 in thin stripes.(ABSTRACT TRUNCATED AT 400 WORDS)
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Li, Wei, Yong Jia Zhang, and Hong Qiao Wen. "A Multiple Fiber Grating Sensor System Using Code Division Multiple Access." Advanced Materials Research 765-767 (September 2013): 2444–47. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.2444.
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In order to increase the multiplying density of Fiber Bragg Grating (FBG) sensors, a novel FBG Sensing System based on CDMA technology has been developed. Simulation experiment indicates the CDMA technology combine with optical fiber grating sensing system together successfully. Furthermore, the system can distinguishes the FBG and enhance the FBG network band utilization.
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Ghabara, Taoufik. "Electric Transverse Emissivity of Sinusoidal Surfaces Determined by a Differential Method: Comparison with Approximation of Geometric Optics." International Journal of Differential Equations 2021 (November 29, 2021): 1–10. http://dx.doi.org/10.1155/2021/1506485.
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We present in this paper a numerical study of the validity limit of the optics geometrical approximation in comparison with a differential method which is established according to rigorous formalisms based on the electromagnetic theory. The precedent studies show that this method is adopted to the study of diffraction by periodic rough surfaces. For periods much larger than the wavelength, the mechanism is analog to what happens in a cavity where a ray is trapped and undergoes a large number of reflections. For gratings with a period much smaller than the wavelength, the roughness essentially behaves as a transition layer with a gradient of the optical index. Such a layer reduces the reflection there by increasing the absorption. The code has been implemented for TE polarization. We determine by the two methods such as differential method and the optics geometrical approximation the emissivity of gold and tungsten cylindrical surfaces with a sinusoidal profile, for a wavelength equal to 0.55 microns. The obtained results for a fixed height of the grating allowed us to delimit the validity domain of the optic geometrical approximation for the treated cases. The emissivity calculated by the differential method and that given on the basis of the homogenization theory are satisfactory when the period is much smaller than the wavelength.
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Gai, Shao Yan, and Fei Peng Da. "Material Surface Reconstruction Based on Light Projection." Advanced Materials Research 143-144 (October 2010): 768–72. http://dx.doi.org/10.4028/www.scientific.net/amr.143-144.768.
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A surface reconstruction method for material shape analysis is presented. The three-dimensional shape reconstruction system detects object surface based on optical principle. A series of gratings are projected to the object, and the projected gratings are deformed by the object surface. From images of the deformed gratings, three-dimensional profile of the material surface can be obtained. The basic aspects of the method are discussed, including the vision geometry, the light projection and code principle. The proposed method can deal with objects with various discontinuities on the material surface, thus increasing the flexibility and robustness of shape reconstruction process. The experimental results show the efficiency of the method, the material surface can be reconstructed with high precision in various applications.
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Liu, Shu Gui, Li Shuan Ji, Shu Jian Han, Xiao Jie Zhang, and Hong Wei Zhang. "An Improved Composite Grating for Phase Unwrapping in 3-D Measurement of Specular Objects." Advanced Materials Research 468-471 (February 2012): 753–57. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.753.
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The paper proposes a novel method of improving the traditional composite grating in 3-D measurement of the specular objects. The traditional composite grating is improved by altering the intensity of the center stripe in one of the fringes. The improved composite grating not only includes the primary phase information, which is modulated by the object's surface, but also includes the code information, which is necessary for the phase unwrapping. The paper introduces the formation of the improved composite grating, demodulating the composite grating and computing the unwrapped phase based on the altered fringe. Simulated and actual experiments prove that this method is valid. Because of projecting a single composite grating, the method is suitable for dynamical measurement.
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METHA, ANDREW B., and PETER LENNIE. "Transmission of spatial information in S-cone pathways." Visual Neuroscience 18, no. 6 (November 2001): 961–72. http://dx.doi.org/10.1017/s095252380118613x.
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The mosaics of S-cones and the neurons to which they are connected are relatively well characterized, so the S-cone system is a good vehicle for exploring how the sampling of the retinal image controls visual performance. We used an interferometer to measure the grating acuity of the S-cone system in the fovea and at a range of eccentricities out to 20 deg. We also developed a simple model observer that, by assuming only that cone pathways are noisy and that signals are subject to eccentricity-dependent postreceptoral pooling, predicts the measured acuities from the sampling properties of the S-cone mosaic. The amount of pooling required to explain performance is consistent with that suggested by anatomical and physiological measurements.
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Shao, Ting, Feng Tang, Laixi Sun, Xin Ye, Junhui He, Liming Yang, and Wanguo Zheng. "Fabrication of Antireflective Nanostructures on a Transmission Grating Surface Using a One-Step Self-Masking Method." Nanomaterials 9, no. 2 (February 1, 2019): 180. http://dx.doi.org/10.3390/nano9020180.
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Suppression of Fresnel reflection from diffraction grating surfaces is very important for many optical configurations. In this work, we propose a simple method to fabricate subwavelength structures on fused-silica transmission grating for optical antireflection. The fabrication is a one-step self-masking reaction ion etching (RIE) process without using any masks. According to effective medium theory, random cone-shaped nanopillars which are integrated on the grating surface can act as an antireflective layer. Effects of the nanostructures on the reflection and transmission properties of the grating were investigated through experiments and simulations. The nanostructure surface exhibited excellent antireflection performance, where the reflection of the grating surface was suppressed to zero over a wide range of incident angles. Results also revealed that the etching process can change the duty cycle of the grating, and thus the diffraction orders if there are oblique lateral walls. The simulation results were in good agreement with the experimental ones, which verified our physical comprehension and the corresponding numerical model. The proposed method would offer a low-cost and convenient way to improve the antireflective performance of transmission-diffractive elements.
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Wei Li, Wei Li. "Fiber Bragg grating sensing system based on code division multiple access." Chinese Optics Letters 11, s2 (2013): S20602–320604. http://dx.doi.org/10.3788/col201311.s20602.
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Qin, Rui Rui, Wen Cai Xu, and Shi Yong Luo. "Analysis of the Columnar Lens Grating Used for Auto-Stereoscopic Three Dimensional Printing with Different Sizes." Applied Mechanics and Materials 200 (October 2012): 757–60. http://dx.doi.org/10.4028/www.scientific.net/amm.200.757.
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Columnar lens grating is the most frequently-used grating in modern auto-stereoscopic three dimensional (3D) printing. It has a very important impact on the auto-stereoscopic 3D presswork. Micro-analysis about columnar lens grating of auto-stereoscopic 3d presswork with different sizes is given in this work. The formula is obtained in which micro-parameters of the columnar lens grating come into contact. A practical analysis about the columnar lens grating used for auto-stereoscopic 3D presswork with same visual effect but different sizes is given with the aid of a scanning electron microscope (SEM). Moreover, the reason for different sizes of columnar lens grating used for auto-stereoscopic 3D presswork is presented, and the formula is proved practical by practical analysis. Various microcosmic parameters of columnar lens grating will be suitable for different sizes of the auto-stereoscopic 3D presswork.
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Chen, Lawrence R., and Peter W. E. Smith. "Fiber Bragg Gratings Enable Optical Code-Division Multiple Access." Optics and Photonics News 11, no. 12 (December 1, 2000): 17. http://dx.doi.org/10.1364/opn.11.12.000017.
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Araujo de Oliveira, Lelis, Fabio De Sousa, Jackson Moreira Oliveria, Hudson Afonso Batista da Silva, Jorge Everaldo de Oliveira, Fabrício Pinho da Luz, Fabio Souza de Araújo, Alan Dos Reis Silva, and Marcos Benedito Caldas Costa. "Analysis of the performance of an All-optical Network using Arrayed Waveguide and Fiber Bragg Grating Demultiplexers." Conjecturas 22, no. 2 (March 3, 2022): 442–59. http://dx.doi.org/10.53660/conj-682-816.
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This work aims to discuss a study of numerical simulations of the performance of arrayed waveguide grating (AWG) and fiber Bragg grating (FBG) demultiplexers in a fiber optical network in a special class of fiber denominated fiber of photonic crystal (PCF) considering the dispersive and non-linear effects. The proposed method is based on numerical simulations in a wavelength division multiplexing (WDM) network configuration in PCF. For the simulation and analysis, the commercial OptiGrating software was used, a versatile numerical tool used to model integrated devices that incorporate FBG and OptiSystem software to simulate fiber propagation with non-linear and dispersive characteristics. The analysis of the performance of the systems was done through a comparison between the values obtained in terms of Bit Error Rate (BER) and Quality Factor (Q Factor) in a dense WDM system with spacing between 50 GHz channels, and 12 Gbit/s transmission rate. The results show that the FBG demultiplexer in terms of the BER and the Q factor for the PCF was the one that obtained the best performance, when compared the FBG demultiplexer with SMF and the AWG demultiplexer obtained excellent results for both fibers.
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Laurenty, F., H. Sulsilah, A. M. Amin, A. Samsudin, and D. Rusdiana. "Enhancing conceptual understanding via Diffraction Grating Innovative Media (DIAGRAM)." Journal of Physics: Conference Series 2098, no. 1 (November 1, 2021): 012013. http://dx.doi.org/10.1088/1742-6596/2098/1/012013.
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Abstract Diffraction grating innovative media (DIAGRAM) is a physics experimental tool that can be implemented in the learning of diffraction grating material. This research endeavored to analyse students’ conceptual understanding on diffraction grating material after using the diffraction grating innovative media (DIAGRAM). Pre-experimental design was used as the method in this research with one-group pretest-posttest as the design and 10 female students and 1 male students from three schools in Indonesia which are in Banjaran, Pamarayan and Makassar participated. Starting from interpretation test using multiple choices test consisting of 8 questions and using google form, the stage then carried out learning activity utilizing the DIAGRAM and given a posttest in the end of the class. At the last data had been analysed by N-Gain. The come about of this consider were gotten by students’ increment in high category which is 0,73. To sum up, diffraction grating innovative media (DIAGRAM) can make enhancement of senior high school students’ conceptual understanding in diffraction grating material.
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Chang, Yao Tang, and Chung Wei Tsailin. "Enhanced Design for AWG-Based Dynamic Reconfigurable Free-Spectral-Range Group Hopping Coder/Decoders to Protect against Eavesdropping." Applied Mechanics and Materials 764-765 (May 2015): 1240–44. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.1240.
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To further robust confidentiality protecting against eavesdropping over optical code-division multiple-access (OCDMA) networks, this study improves the robustness of the network toward eavesdropping for encryption/decryption mechanism by using a specified storage register controller controlling optical switches approach in which Free-spectral-range group hopping code is used to generate a specific signature address. This paper presents an enhanced security mechanism to protect spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) networks against eavesdropping. This study proposes an alternative to huge code-space size techniques such as wavelength hopping and exchange-encode for network protection against eavesdropping by exploiting the cyclic properties of arrayed-waveguide-grating routers and maximal-length sequence code (M-sequence code). In addition, the network is protected using a wavelength hopping based on optical switches and exchange the encode assignment scheme implemented using the exchange switches before import to arrayed-waveguide-grating routers (AWG).In this scheme, eavesdropper is difficult to solute correct user data bit , whatever there is using brute-force searching or simple energy detector..
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Jalil, Muhammad Arif Bin. "Simulation of Fiber Bragg Grating Characteristics and Behaviors as Strain and Temperature Sensor." International Journal for Research in Applied Science and Engineering Technology 9, no. 11 (November 30, 2021): 1154–61. http://dx.doi.org/10.22214/ijraset.2021.38883.
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Abstract: Optical Fiber Sensor (OFS) has come quite considerable and famous in world of sensor technology where it has been used widely to detect for a changeable environment and responds to some output on other system such as in industrial, chemical analysis and monitoring. A Fiber Bragg Grating (Fiber Bragg Grating) is a kind of appropriated where the short fragment of optical fiber which certain and specific wavelength is reflected with light and the Bragg reflector started developed and transmits all others. The current project is concerned with the development characteristics and behaviors of strain and temperature sensors acting on Fiber Bragg Grating by a computer simulation. This study focuses on analyzing the performance of the characteristics and behavior of strain and temperature sensors acting on Fiber Bragg Grating. A strain sensor is used to measure strain on an object of which the resistance varies range with applied force. Meanwhile,for the temperature sensor is used to measure and detect any abnormality of temperature acting on Fiber Bragg Grating such as can lead into fire and accidents. This will found out on how Fiber Bragg Grating can demonstrate strain and temperature sensors. A simulation of the computer program (MATLAB) will be carried out to simulate due to the strain and temperature sensor of Fiber Bragg Grating. Keywords Fiber Bragg Grating, sensors; Strain; Temperature; Simulation; MATLAB
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Iwasaka, Masakazu. "On-chip light scattering imaging of the guanine platelet." Japanese Journal of Applied Physics 61, no. 2 (January 24, 2022): 027002. http://dx.doi.org/10.35848/1347-4065/ac439b.
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Abstract A guanine platelet is a very thin optical component that plays a role in light reflection control in the narrow space within the body of a fish. However, the details of this light control mechanism have not been revealed to date. In this work, guanine micro-platelets floating in water are visualized via light projection near an image sensor. These guanine platelets demonstrate light scattering in specific directions. By setting a thin water layer on top of the image sensor’s cover glass, each platelet in the water layer forms column- or bar-code-shaped images on the screen. The existence of nanohole gratings in these platelets was confirmed by high-resolution optical microscopy. Numerical electromagnetic simulations indicated that the nanohole gratings contributed to the formation of unique light projection spots.
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Lubina, A., and A. Sorokin. "FEATURES OF THERMAL HYDRAULICS OF ACTIVE ZONES OF FAST LOW-POWER AND HIGH-POWER SODIUM PRODUCTION REACTORS FOR A CLOSED FUEL CYCLE SYSTEM." PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2021, no. 4 (December 26, 2021): 162–71. http://dx.doi.org/10.55176/2414-1038-2021-4-162-171.
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The paper considered the features of heat transfer of two fast sodium reactors of large and low power (1000 and 190 MW(e.)), which are developed for use in the production of secondary nuclear fuel. The design of a case fuel assembly for a higher power reactor is a combination of thin fuel elements (6.1 mm) with U-Pu fuel and a wide grating (relative pitch 1.39) with spacing of the gratings. For a low-power reactor, in this paper, three fuel assemblies (diameter of fuel rod 8.1 mm, relative pitch 1.16) were considered: without a cover, with a cover 1 mm apart from the peripheral row of fuel rods and with a cover spaced 0,5 mm from the peripheral row of fuel rods. Calculations were carried out using the COBRA-IV-I code. Data were obtained on the azimuthal temperature distributions on the claddings of the corner, peripheral and central fuel rods, temperatures on the surfaces of the covers, and calculations were performed to optimize the designs of fuel assemblies in order to reduce the temperature difference on the claddings of the peripheral fuel rods. For a large-power reactor, optimization of the configuration of the corner cell was proposed in order to reduce the azimuthal temperature difference at the corner and peripheral fuel rods. For a low-power reactor, optimization of the fuel assembly design is recommended by replacing the spacer grids with wire spacing and equalizing the temperature field by mixing the coolant, as well as increasing the relative pitch of the fuel element grid from 1.16 to 1.19.
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Feldman, Eliot. "A reflection grating that nullifies the specular reflection: A cone of silence." Journal of the Acoustical Society of America 98, no. 1 (July 1995): 623–34. http://dx.doi.org/10.1121/1.413656.
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LEE, BARRY B., JAN KREMERS, and TSAIYAO YEH. "Receptive fields of primate retinal ganglion cells studied with a novel technique." Visual Neuroscience 15, no. 1 (January 1998): 161–75. http://dx.doi.org/10.1017/s095252389815112x.
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We have reinvestigated receptive-field structure of ganglion cells of the macaque parafovea using counterphase modulation of a bipartite field. Receptive fields were mapped with luminance, chromatic, and cone-isolating stimuli. Center sizes of middle (M) and long (L) wavelength cone opponent cells of the parvocellular (PC) pathway were consistent with previous estimates (Gaussian radii of 2–4 min of arc, corresponding to center diameters of 6–12 min of arc). We calculate that a large factor of the enlargement relative to cone radius could be blur due to the eye's natural optics. Maps were consistent with cone selectivity in surround mechanisms, which had radii of 5–8 min of arc. For magnocellular (MC) cells, center size estimates were also consistent with grating measurements from the literature (also Gaussian radii of 2–4 min of arc). The surround mechanism contributing the MC-cell frequency-doubled response to chromatic modulation appears to possess a subunit structure, and we speculate it derives from nonlinear summation of signals from M,L-cone opponent subunits, such as midget bipolar cells.
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Meng Yunqing, 蒙云清, 董贤 Dong Xian, 武创 Wu Chuang, 李杰 Li Jie, and 关柏鸥 Guan Baiou. "裸露纤芯边孔光纤布拉格光栅制备及其折射率传感特性研究." Laser & Optoelectronics Progress 59, no. 1 (2022): 0106003. http://dx.doi.org/10.3788/lop202259.0106003.
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Min, Seong-Sik. "Back-propagation based nonbinary optical code for OCDMA with fiber gratings." Microwave and Optical Technology Letters 49, no. 3 (January 26, 2007): 632–36. http://dx.doi.org/10.1002/mop.22213.
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