Relevant bibliographies by topics / Partial transmittance optics

Academic literature on the topic 'Partial transmittance optics'

Author: Grafiati
Published: 10 December 2022
Last updated: 19 February 2023

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Journal articles on the topic "Partial transmittance optics"

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Segtnan, V. H., and T. Isaksson. "Evaluating near Infrared Techniques for Quantitative Analysis of Carbohydrates in Fruit Juice Model Systems." Journal of Near Infrared Spectroscopy 8, no. 2 (March 2000): 109–16. http://dx.doi.org/10.1255/jnirs.270.

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Several techniques for measuring quality parameters in foods by the use of near infrared (NIR) technology have been reported. The aim of this experiment is to evaluate the main techniques in order to find the optimal measurement conditions for NIR analysis of carbohydrates in fluid food systems. Two different model systems were studied, each system containing 61 designed samples. The first system was designed to give scatter, and was based on a commercial orange juice. The other system was designed to be scatter-free, and was based on distilled water. To all samples were added the same total amounts of glucose, fructose and sucrose, and measured using the following NIR techniques: transmittance measurements in cuvettes, dry extract diffuse reflectance (DESIR), fibre-optic transflectance and fibre-optic transmittance. Calibration models were made by partial least squares regression in the spectral regions 780–2500nm for DESIR measurements, 1100–1315nm for 10mm pathlengths and 1100–1880+2130–2350nm for 1mm pathlengths. The models were fully cross-validated. Optimal prediction errors (Root Mean Square Error of Prediction, Cross-Validated) for DESIR measurements ranged from 0.020 to 0.030% (w/w), while 1mm cuvette values ranged from 0.008 to 0.012%. For these techniques there were only small differences between juice and water samples. Using fibre-optics, 1mm transmittance gave values in the range 0.068–0.081% for juice samples and 0.022–0.066% for water samples, while 1mm transflectance gave 0.044–0.051% for juice samples and 0.045–0.078% for water samples. 10mm pathlengths provided substantially higher prediction errors than 1mm for all techniques investigated. From these results, two main conclusions can be drawn. First, when measuring off-line, direct transmittance measurements in cuvettes gave better prediction results than DESIR. Second, when using fibre-optics, transflectance gave lower prediction errors than transmittance for scattering samples, while transmittance performed better than transflectance for non-scattering samples.
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Chen, G., and C. L. Tien. "Partial Coherence Theory of Thin Film Radiative Properties." Journal of Heat Transfer 114, no. 3 (August 1, 1992): 636–43. http://dx.doi.org/10.1115/1.2911328.

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A new approach based on the partial coherent theory of light is introduced to predict the radiative properties of a thin film. General expressions obtained for the normal reflectance and transmittance of a thin film not only degenerate into the limiting results of the wave and the geometric optics in the coherent and incoherent cases, but also apply for all partial coherent states between the limits. The key element in the formulation is the complex degree of coherence, for which a general integral expression is obtained and further approximated algebraically for nearly monochromatic radiation. Limiting criteria and regime maps are established to demonstrate the range of applications for the various methods.
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Li, Shijie, Chen Yang, Jin Zhang, Linpeng Dong, Changlong Cai, Haifeng Liang, and Weiguo Liu. "Tunable Optical Properties of Amorphous-Like Ga2O3 Thin Films Deposited by Electron-Beam Evaporation with Varying Oxygen Partial Pressures." Nanomaterials 10, no. 9 (September 6, 2020): 1760. http://dx.doi.org/10.3390/nano10091760.

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Ga2O3 thin films were fabricated by the electron-beam evaporation technique at a varying oxygen partial pressure from 0 to 2.0 × 10−2 Pa. The effect of oxygen partial pressure on the crystalline structure and optical properties of the Ga2O3 films was analyzed using sophisticated techniques including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, spectroscopic ellipsometry, ultraviolet-visible spectroscopy and a laser-induced damage test system. The correlation between the oxygen partial pressure and the film’s properties in optics and materials were investigated. XRD and Raman revealed that all films were amorphous in spite of applying a varying oxygen partial pressure. With the change of oxygen partial pressure, XPS data indicated that the content of oxygen in the Ga2O3 films could be broadly modulable. As a result, a changeable refractive index of the Ga2O3 film is realizable and a variable blue-shift of absorption edges in transmittance spectra of the films is achievable. Moreover, the damage threshold value varied from 0.41 to 7.51 J/cm2 according to the rise of oxygen partial pressure. These results demonstrated that the optical properties of Ga2O3 film can be broadly tunable by controlling the oxygen content in the film.
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Lazarova, Katerina, Silvia Bozhilova, Sijka Ivanova, Darinka Christova, and Tsvetanka Babeva. "Flexible and Transparent Polymer-Based Optical Humidity Sensor." Sensors 21, no. 11 (May 25, 2021): 3674. http://dx.doi.org/10.3390/s21113674.

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Thin spin-coated polymer films of amphiphilic copolymer obtained by partial acetalization of poly (vinyl alcohol) are used as humidity-sensitive media. They are deposited on polymer substrate (PET) in order to obtain a flexible humidity sensor. Pre-metallization of substrate is implemented for increasing the optical contrast of the sensor, thus improving the sensitivity. The morphology of the sensors is studied by surface profiling, while the transparency of the sensor is controlled by transmittance measurements. The sensing behavior is evaluated through monitoring of transmittance values at different levels of relative humidity gradually changing in the range 5–95% and the influence of up to 1000 bending deformations is estimated by determining the hysteresis and sensitivity of the flexible sensor after each set of deformations. The successful development of a flexible sensor for optical monitoring of humidity in a wide humidity range is demonstrated and discussed.
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Hamdy, Omnia, Zienab Abdel-Salam, and Mohamed Abdel-Harith. "Optical Characterization of Biological Tissues Based on Fluorescence, Absorption, and Scattering Properties." Diagnostics 12, no. 11 (November 17, 2022): 2846. http://dx.doi.org/10.3390/diagnostics12112846.

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Optical diagnostics methods are significantly appealing in biological applications since they are non-destructive, safe, and minimally invasive. Laser-induced fluorescence is a promising optical spectrochemical analytical technique widely employed for tissue classification through molecular analysis of the studied samples after excitation with appropriate short-wavelength laser light. On the other hand, diffuse optics techniques are used for tissue monitoring and differentiation based on their absorption and scattering characteristics in the red to the near-infrared spectra. Therefore, it is strongly foreseen to obtain promising results by combining these techniques. In the present work, tissues under different conditions (hydrated/dry skin and native/boiled adipose fat) were distinguished according to their fluorescence emission, absorption, and scattering properties. The selected tissues’ optical absorption and scattering parameters were determined via Kubelka–Munk mathematical model according to the experimental tissue reflectance and transmittance measurements. Such measurements were obtained using an optical configuration of integrating sphere and spectrometer at different laser wavelengths (808, 830, and 980 nm). Moreover, the diffusion equation was solved for the fluence rate at the sample surface using the finite element method. Furthermore, the accuracy of the obtained spectroscopic measurements was evaluated using partial least squares regression statistical analysis with 0.87 and 0.89 R-squared values for skin and adipose fat, respectively.
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Hong, Suk-Ju, Shin-Joung Rho, Ah-Yeong Lee, Heesoo Park, Jinshi Cui, Jongmin Park, Soon-Jung Hong, Yong-Ro Kim, and Ghiseok Kim. "Rancidity Estimation of Perilla Seed Oil by Using Near-Infrared Spectroscopy and Multivariate Analysis Techniques." Journal of Spectroscopy 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/1082612.

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Near-infrared spectroscopy and multivariate analysis techniques were employed to nondestructively evaluate the rancidity of perilla seed oil by developing prediction models for the acid and peroxide values. The acid, peroxide value, and transmittance spectra of perilla seed oil stored in two different environments for 96 and 144 h were obtained and used to develop prediction models for different storage conditions and time periods. Preprocessing methods were applied to the transmittance spectra of perilla seed oil, and multivariate analysis techniques, such as principal component regression (PCR), partial least squares regression (PLSR), and artificial neural network (ANN) modeling, were employed to develop the models. Titration analysis shows that the free fatty acids in an oil oxidation process were more affected by relative humidity than temperature, whereas peroxides in an oil oxidation process were more significantly affected by temperature than relative humidity for the two different environments in this study. Also, the prediction results of ANN models for both acid and peroxide values were the highest among the developed models. These results suggest that the proposed near-infrared spectroscopy technique with multivariate analysis can be used for the nondestructive evaluation of the rancidity of perilla seed oil, especially the acid and peroxide values.
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Zhang, Chu, Chang Wang, Fei Liu, and Yong He. "Mid-Infrared Spectroscopy for Coffee Variety Identification: Comparison of Pattern Recognition Methods." Journal of Spectroscopy 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/7927286.

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The potential of using mid-infrared transmittance spectroscopy combined with pattern recognition algorithm to identify coffee variety was investigated. Four coffee varieties in China were studied, including Typica Arabica coffee from Yunnan Province, Catimor Arabica coffee from Yunnan Province, Fushan Robusta coffee from Hainan Province, and Xinglong Robusta coffee from Hainan Province. Ten different pattern recognition methods were applied on the optimal wavenumbers selected by principal component analysis loadings. These methods were classified as highly effective methods (soft independent modelling of class analogy, support vector machine, back propagation neural network, radial basis function neural network, extreme learning machine, and relevance vector machine), methods of medium effectiveness (partial least squares-discrimination analysis,Knearest neighbors, and random forest), and methods of low effectiveness (Naive Bayes classifier) according to the classification accuracy for coffee variety identification.
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Xiong, Yating, Shintaroh Ohashi, Kazuhiro Nakano, Weizhong Jiang, Kenichi Takizawa, Kazuyuki Iijima, and Phonkrit Maniwara. "Quantification of potassium concentration with Vis–SWNIR spectroscopy in fresh lettuce." Journal of Innovative Optical Health Sciences 13, no. 06 (October 28, 2020): 2050029. http://dx.doi.org/10.1142/s1793545820500297.

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Chronic kidney disease (CKD) is becoming a major public health problem worldwide, and excessive potassium intake is a health threat to patients with CKD. In this study, visible–short-wave near-infrared (Vis–SWNIR) spectroscopy and chemometric algorithms were investigated as nondestructive methods for assessing the potassium concentration in fresh lettuce to benefit the CKD patients’ health. Interactance and transmittance measurements were performed and the competencies were compared based on the multivariate methods of partial least-square regression (PLS) and support vector machine regression (SVR). Meanwhile, several preprocessing methods [first- and second-order derivatives in combination with standard normal variate (SNV)] and wavelength selection method of competitive adaptive reweighted sampling (CARS) were applied to eliminate noise and highlight the spectral characteristics. The PLS models yielded better prediction than the SVR models with higher correlation coefficients ([Formula: see text]) and residual predictive deviation (RPD), and lower root-mean-square error of prediction (RMSEP). Excellent prediction of green leaves was obtained by the interactance measurement with [Formula: see text], [Formula: see text][Formula: see text]mg/100[Formula: see text]g, and [Formula: see text]; while the transmittance spectra of petioles provided optimal prediction with [Formula: see text], [Formula: see text][Formula: see text]mg/100[Formula: see text]g, and RPD[Formula: see text]=[Formula: see text]3.34, respectively. Therefore, the results indicated that Vis–SWNIR spectroscopy is capable of intelligently detecting potassium concentration in fresh lettuce to benefit CKD patients around the world in maintaining and enhancing their health.
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Hakobyan, Armen V. "Aperture shapes and the effectiveness of ground-based large and extremely large telescopes." Monthly Notices of the Royal Astronomical Society 496, no. 4 (July 21, 2020): 5414–22. http://dx.doi.org/10.1093/mnras/staa1792.

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ABSTRACT Aperture shapes in modern large and forthcoming extremely large telescopes (ELTs), with effective light-gathering sizes more than D ∼ 10 m, differ significantly from the desirable circular one. They deliver specific point spread functions, which may also differ notably from that of the fine structure of the classical Airy pattern. The optical power of such a telescope can be changed notably compared with a circular aperture with the same area. The presence of atmospheric optical turbulence complicates the effect additionally and makes it seeing- and wavelength-dependent. So, what is the impact of a non-circular pupil on telescope exploitation? It concerns the efficiency, which is an important point, especially for instruments of such a class. In this research an attempt is made to assess the values of these changes in the context of the Keck, HDRT, GMT, TMT and ELT telescopes. Relative performance characteristics (integral contrast and signal-to-noise ratio, S/N) of the telescopes, working in the seeing-limited regime, under a range of plausible turbulence conditions, for a wide (from UV to mid-IR) spectral region are obtained. The partial role of central obscuration is assessed. The effect of adaptive optics implementation in this context is also analysed. It is shown that, for instance, maximal S/N degradation due to the non-circularity of the pupil shape can be as much as $\sim 6~{{\ \rm per\ cent}}$ (TMT) to $30~{{\ \rm per\ cent}}$ (HDRT), depending on the telescope and observational mode. The numbers are comparable with or may even substantially exceed the losses that could be caused by the other parameters (e.g. residual wave-front error, optical transmittance) relevant to the quality of the optical system.
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Hsu, Jin-Cherng, and Yu-Yun Chen. "Comparison of the Optical and Electrical Properties of Al-Doped ZnO Films Using a Lorentz Model." Coatings 9, no. 1 (December 21, 2018): 4. http://dx.doi.org/10.3390/coatings9010004.

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In this research, zinc oxide (ZnO) films are doped with various amounts of Al dopants, from 0 to 13 at.%, using ion-beam co-sputtering for Zn and Al metallic targets at room temperature. The Al-doped ZnO (AZO) films appear to have lower transmittances in the UV and near-IR ranges. The electrical and optical properties of each film are successfully analyzed by using the spectroscopic ellipsometry of two Lorentz oscillators for the two lower transmittances. The optimal AZO film is deposited with an Al-dopant of 1.5 at.% at an oxygen partial pressure of 0.12 mTorr; it has the smallest resistivity of 7.8 × 10−4 Ω cm and high transmittance of > 80% in the visible regions. The free carrier concentration and mobility evaluated using ellipsometry are different from those measured using the Hall effect. This phenomenon was the result of the grain boundary scattering due to the small ~20-nm grain size of the AZO film used in this study.
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Dissertations / Theses on the topic "Partial transmittance optics"

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ATKURI, HARI MUKUNDA. "METHODS TO ADJUST THE PHYSICAL PROPERTIES OF LIQUID CRYSTALS AND RELATED DEVICES." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1343078114.

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(12271705), John Austin Guthrie. "Robustness of NIR calibrations for assessing fruit quality." Thesis, 2005. https://figshare.com/articles/thesis/Robustness_of_NIR_calibrations_for_assessing_fruit_quality/21454485.

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Predictive models based on near infra-red spectroscopy for the assessment of fruit internal quality attributes must exhibit a degree of robustness across the parameters of variety, district and time to be of practical use in fruit grading. At the time this thesis was initiated, while there were a number of published reports on the development of near infra-red based calibration models for the assessment of internal quality attributes of intact fruit, there were no reports of the reliability ("robustness") of such models across time, cultivars or growing regions. As existing published reports varied in instrumentation employed, a re-analysis of existing data was not possible.

An instrument platform, based on partial transmittance optics, a halogen light source and a (Zeiss MMS1) detector operating in the short wavelength near infra-red region was developed for use in the assessment of intact fruit. This platform was used to assess populations of macadamia kernels, melons and mandarin fruit for total soluble solids, dry matter and oil concentration. Calibration procedures were optimised and robustness assessed across growing areas, time of harvest, season and variety. In general, global modified partial least squares regression (MPLS) calibration models based on derivatised absorbance data were better than either multiple linear regression or 'local' MPLS models in the prediction of independent validation populations. Robustness was most affected by growing season, relative to the growing district or variety. Various calibration updating procedures were evaluated in terms of calibration robustness. Random selection of samples from the validation population for addition to the calibration population was equivalent to or better than other methods of sample addition (methods based on the Mahalanobis distance of samples from either the centroid of the population or neighbourhood samples). In these exercises the global Mahalanobis distance (GH) was calculated using the scores and loadings from the calibration population on the independent validation population. In practice, it is recommended that model predictive performance be monitored in terms of predicted sample GH, with model updating using as few as 10 samples from the new population undertaken when the average GH value exceeds 1.0.

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Conference papers on the topic "Partial transmittance optics"

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Gladen, Adam C., Susan C. Mantell, and Jane H. Davidson. "A Parametric Numerical Study of Radiative Transfer in Thermotropic Materials." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17183.

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A thermotropic material is modeled as an absorbing, thin slab containing anisotropic scattering, monodisperse, spherical particles. Monte Carlo ray tracing is used to solve the governing equation of radiative transfer. Predicted results are validated by comparison to the measured normal-hemispherical reflectance and transmittance of samples with various volume fraction and relative index of refraction. A parametric study elucidates the effects of particle size parameter, scattering albedo, and optical thickness on the normal-hemispherical transmittance, reflectance, and absorptance. The results are interpreted for a thermotropic material used for overheat protection of a polymer solar absorber. For the preferred particle size parameter of 2, the optical thickness should be less than 0.3 to ensure high transmittance in the clear state. To significantly reduce the transmittance and increase the reflectance in the translucent state, the optical thickness should be greater than 2.5 and the scattering albedo should be greater than 0.995. For optical thickness greater than 5, the reflectance is asymptotic and any further reduction in transmittance is through increased absorptance. A case study is used to illustrate how the parametric study can be used to guide the design of thermotropic materials. Low molecular weighted polyethylene in poly(methyl methacrylate) is identified as a potential thermotropic material. For this material and a particle radius of 200 nm, it is determined that the volume fraction and thickness should equal 10% and 1 mm, respectively.
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Zhao, Xinying, Yihua Hu, Youlin Gu, and Le Li. "The infrared spectral transmittance of Aspergillus niger spore aggregated particle swarm." In Applied Optics and Photonics China (AOPC2015), edited by Bin Xiangli, Dae Wook Kim, and Suijian Xue. SPIE, 2015. http://dx.doi.org/10.1117/12.2202894.

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Yellowhair, Julius, and Clifford K. Ho. "Optical Ray-Tracing Performance Modeling of Quartz Half-Shell Tubes Aperture Cover for Falling Particle Receiver." In ASME 2019 13th International Conference on Energy Sustainability collocated with the ASME 2019 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/es2019-3927.

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Abstract A 1 MWt falling particle receiver prototype was designed, built and is being evaluated at Sandia National Laboratories, National Solar Thermal Test Facility (NSTTF). The current prototype has a 1 m2 aperture facing the north field. The current aperture configuration is susceptible to heat and particle losses through the receiver aperture. Several options are being considered for the next design iteration to reduce the risk of heat and particle losses, in addition to improving the receiver efficiency to target levels of ∼90%. One option is to cover the receiver aperture with a highly durable and transmissive material such as quartz glass. Quartz glass has high transmittance for wavelengths less than 2.5 microns and low transmittance for wavelengths greater than 2.5 microns to help trap the heat inside the receiver. To evaluate the receiver optical performance, ray-tracing models were set up for several different aperture cover configurations. The falling particle receiver is modeled as a box with a 1 m2 aperture on the north side wall. The box dimensions are 1.57 m wide × 1.77 m tall × 1.67 m deep. The walls are composed of RSLE material modeled as Lambertian surfaces with reflectance of either 0.9 for the pristine condition or 0.5 for soiled walls. The quartz half-shell tubes are 1.46 m long with 105 mm and 110 mm inner and outer diameters, respectively. The half-shell tubes are arranged vertically and slant forward at the top by 30 degrees. Four configurations were considered: concave side of the half-shells facing away from the receiver aperture with (1) no spacing and (2) high spacing between the tubes, and concave side of the half-shells facing the aperture with (3) no spacing and (4) high spacing between the tubes. The particle curtain, in the first modeling approach, is modeled as a diffuse surface with transmittance, reflectance, and absorptance values, which are based on estimates from previous experiments for varying particle flow rates. The incident radiation is from the full NSTTF heliostat field with a single aimpoint at the center of the receiver aperture. The direct incident rays and reflected and scattered rays off the internal receiver surfaces are recorded on the internal walls and particle curtain surfaces as net incident irradiance. The net incident irradiances on the internal walls and particle curtain for the different aperture cover configuration are compared to the baseline configuration. In all cases, just from optical performance alone, the net incident irradiance is reduced from the baseline. However, it is expected that the quartz half-shells will reduce the convective and thermal radiation losses through the aperture. These ray-tracing results will be used as boundary conditions in computational fluid dynamics (CFD) analyses to determine the net receiver efficiency and optimal configuration for the quartz half-shells that minimize heat losses and maximize thermal efficiency.
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Van Der Gracht, Joseph. "Partially coherent image enhancement by source modification." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.thgg1.

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We introduce a partially coherent optical image enhancement system capable of eliminating unwanted sinusoidal signals that are additive in object amplitude transmittance. The spatial distribution of the pupil mask in a Koehler illumination imaging system remains fixed while the source distribution is changed to block sinusoids of different spatial frequencies. The operating principle is a variation of dark field imaging. In dark field imaging, the pupil is chosen to block all bright regions of the source so that no undiffracted light is passed by the pupil. A similar principle can be employed to block sinusoids of different spatial frequencies. For a single sinusoid object, two spatially shifted images of the source are incident on the pupil. The source is chosen so that these shifted versions are completely blocked by the pupil to prevent that particular sinusoid from reaching the output image plane. The choice of a pseudorandom pupil distribution combined with the appropriate source distribution leads to good rejection of unwanted sinusoids while preserving image detail.
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Kaßner, H., A. Stuke, R. Vaßen, and D. Stöver. "Influence of Microstructure on Thermal and Optical Properties of Suspension Plasma Sprayed (SPS) and Atmospheric Plasma Sprayed (APS) Coatings." In ITSC2008, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0573.

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Abstract Normally the conventional thermal spray processes as the atmospheric plasma spraying (APS) have to use easily flowable powders in a size range between 10 and 100 µm. In contrast the suspension plasma spraying (SPS) makes it possible to process nano sized particles directly. Due to the use of nano materials new microstructures and properties could be generated. One point is the possibility to influence the porosity level, its size range and micro crack densities in a wide band. Microstructure features like the porosity and cracks serve as scattering centres and lead to changes of optical properties. Furthermore the thermal conductivity is affected by the porosity level. In this work yttria partially stabilized zirconia coatings were generated by the SPS and APS process. The influence of the different microstructures on the thermal conductivity, the hemispherical reflectance and transmittance for wavelengths between 0.3 to 2.5 µm has been investigated. Due to the higher porosity and crack level of the SPS coatings the thermal conductivity and hemispherical transmittance was significant reduced.
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Pilewskie, Peter. "Radiative properties of liquid-water and ice clouds." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.mf1.

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Most clouds in the lower and middle troposphere are optically thick to the extent that their pattern of scattered radiation bears little resemblance to the scattering pattern from a single water droplet or ice crystal. Photons at visible and near-infrared wavelengths that emerge from a thick cloud have been, on average, scattered several times and retain little memory of the angular dependence or even particle-shape dependence of scattering from a single particle. Indeed, single-scattering phenomena, such as the halo and corona, are not visible from optically thick clouds. However, even though most of the angular and wavelength dependencies of single scattering are washed away, radiation reflected by and transmitted through a thick cloud still holds clues to the cloud's physical makeup. Cloud particle thermodynamic phase and size, cloud optical depth, and water path can, at least in principle, be derived from the measurement of near-infrared spectral reflectance or transmittance because of the dependence of absorption in clouds on particle size and bulk water absorption coefficient. Thus far, efforts to infer cloud properties by means of near-infrared remote sensing have had only limited success.
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George, Nicholas, and Shen-Ge Wang. "Particulate sizing and the use of wavelength dependence to measure axial dispersion." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.turr2.

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Particle measurements are of importance in the study of aerosols, combustion processes, and pharmaceuticals. In this report, first we briefly review a simple derivation of an inversion formula from basic principles. We describe a modification to the usual form based upon intensity superposition so that one has a form that is accurate at tiny scattering angles. Then, we present the results of a new study of the wavelength dependence of the optical transform of a particulate distribution. Starting with the idealized amplitude transmittance, p(x−x m ,y−y m )for a particle at spatial position (x m ,y m ) and taking the Fourier transform, one finds immediately the exponential term given by exp [−i2π(f x x m + fY m )] in which the transform frequencies are f x = ξν/(Fc) and f y = ην/(Fc). We show how this exponent contains the essence of the temporal frequency dependence of the speckle pattern for the particulate cloud. We calculate the second moment of the intensity in the optical transform. We prove theoretically that it is possible to measure the axial distribution of a particulate sample simply by gathering optical transform data by using illumination by a tunable laser. This novel technique is then demonstrated with (1) computer simulations and (2) masks with various axial distributions. Some concluding remarks will also be made about the use of neural network software in re mote sensing of particulate sizing and spatial distributions.
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Ohkubo, Toshifumi, Nobuyuki Terada, and Yoshikazu Yoshida. "Lock-In Detection of Directivity of Fluorescence From a Minute Particle Using TAS Chip Incorporated With Radially Arranged Light Waveguides." In ASME 2017 Conference on Information Storage and Processing Systems collocated with the ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/isps2017-5402.

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It has long been thought that an optical sensor, such as a light waveguide implemented total analysis system (TAS), is one of the most functional components that will be needed to realize a “ubiquitous human healthcare system”. A transparent resin-based TAS chip incorporated with a light waveguide [1] is quite preferable in such a cost-effective and disposal use. In line with the technical demand, we have already proposed a specially fabricated structure for an epoxy resin-based monolithic light waveguide capable of illuminating a cell or particle running along a microfluidic channel [2], as well as of obtaining directivity of fluorescence with a radially arranged waveguide structure (as shown in Figure 1) and a sequential light scanning mechanism based on a forced vibrated optical fiber [3]. Utilizing this TAS system, we have successfully detected preliminary results of fluorescence directivity of a 5-μm-diameter polystyrene particle with scanning angle range of 180 degrees, at illuminating light scanning frequency of approximately 1.7 kHz [4]. However, the transmittance of the trial-manufactured light waveguides was slightly lower owing mainly to its smaller cross section size, and, as a result, signal-to-noise ratio of detected fluorescence signal waveform was not as good as we have expected. To improve the S/N ratio, it is necessary to increase illuminating power of a laser source, and, at the same time, to increase multiplication factor of a photo-electron multiplier sensor to beyond its performance limit. Unfortunately, with the capability of the current equipment, it is difficult to drastically improve the S/N ratio. In this paper, we attempted to apply AC detection method to measure extremely weak fluorescence with a high frequency modulated laser source of its wavelength of 488 nm, and with a high speed lock-in-amplifier having both higher reference frequency up to 3MHz and smaller time constant.
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Wang, Yao, Pei-feng Hsu, and Yingsang Wu. "Near Infrared Radiative Properties of Thermal Barrier Coatings." In ASME 2021 Heat Transfer Summer Conference collocated with the ASME 2021 15th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/ht2021-61258.

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Abstract Thermal barrier coatings are widely used in gas turbines to protect the gas turbine metal components against very high combustion product temperature. To improve energy efficiency, higher combustion temperatures are needed. A limiting factor at present is the stability under extreme and prolonged heating of thermal barrier coatings. The coatings are typically made by the air plasma sprayed process in which fine particles of yttria-stabilized zirconia (YSZ) are melted or partially melted and ejected from plasma jet at high speed onto the bond coated substrate metal. With increasing combustion temperature and pressure in the modern gas turbine engines radiative heat transfer is becoming an important portion of the overall heat transfer in the thermal barrier coating. This study has demonstrated that the commonly used Kubelka-Munk method in the radiative property reduction from the measured transmittance and reflectance spectra of YSZ coatings will incur inaccurate result when the coating optical thickness is not sufficiently large. An alternative method — the discrete ordinates method with the asymmetric spherical ring angular quadrature — is used instead. The absorption and scattering coefficients of air plasma sprayed YSZ films are determined over the wavelength range from 1 to 2.6 μm at room temperature. Over this near infrared wavelength range, the scattering coefficient decreases with the increasing wavelength and the absorption coefficient is very small overall. The pore size distributions before and after the 50-hr temperature gradient, thermal cycling are compared. The sintering effect as well as the crack growth will impact the coating radiative properties. These results point to a clear need for better understanding of the radiative heat transfer process, which includes the microstructure-property relationship, progressive changes of the radiative properties with the operation condition and time.
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10

Wang, Yao, Pei-feng Hsu, and Mary Helen McCay. "The Pore Size Dependence of the Radiative Scattering Coefficient in Yttria-Stabilized Zirconia Films." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-80853.

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Abstract The yttria-stabilized zirconia (YSZ) top coat provides a thermal resistance function in the thermal barrier coatings used in gas turbines and Diesel engines. Besides the thermal conductivity, the thermal radiative properties, especially their dependence on the coating microstructure, under the high temperature combustion temperature are critically needed to the design and operation of the thermal barrier coating (TBC) systems. In this study ceramic oxide films made of thermally sprayed YSZ powder are prepared with three average porosities 5.9%, 14.5%, and 23.3% at film thickness from 283 to 955 μm. These films are fabricated with the air plasma spray (APS) deposition on the aluminum surface. The porosity changes are accomplished by varying the spraying parameters or ceramic oxide powder particle size. The room-temperature, spectral directional-hemispherical transmittance and reflectance are measured over the wavelength range from 1.35 to 2.5 μm. The radiative properties of absorption and scattering coefficients are reduced by using a hybrid method of the discrete ordinate method and the Kubelka-Munk four-flux method, depending on the film’s optical thickness. The films are then mounted, sectioned, and polished for SEM imaging. Using the image processing tools developed in-house, the porosity and pore size distribution (PSD) are obtained for each film. A numerical algorithm is used to convert the two-dimensional PSD into a three-dimensional PSD assuming all pores are spheriod. The absorption and scattering coefficients can be computed directly by the Mie theory based on the electromagnetic wave scattering from a distribution of sphere sizes. The new approach provides a predictive model of radiative properties based on the pore size distribution and pore number density, which are dependent on the APS spraying parameters, powder size and morphology. Comparison of radiative properties obtain by direct Mie theory computation and those obtained by reduction from spectral measurement is made and discrepancy is discussed.
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