Articles de revues : « Wavelength dependency »

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Schmeissner, J., et A. N. Tyulyusov. « ROCKING CURVE OF A DOUBLE-CRYSTAL SPECTROMETER IN THE BRAGG-BRAGG GEOMETRY INCLUDING THE ABSORPTION COEFFICIENT DEPENDENCY FROM THE NEUTRON WAVELENGTH ». Кристаллография 68, n^o 4 (1 juillet 2023) : 531–35. http://dx.doi.org/10.31857/s0023476123600180.

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An analytical expression is obtained for the rocking curve of a double-crystal spectrometer, which does not require restrictions on the absorption cross section dependency on the wavelength. A modeled rocking curve (instrumental line) for the Bragg–Bragg spectrometric scheme is calculated using the example of an InSb crystal in the region of weak dependency between the absorption cross section and the wavelength and in the region of wavelengths close to the absorption resonance.

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Nakamura, S. « Wavelength dependency of diarylethene derivatives ». Journal of Molecular Graphics 8, n^o 1 (mars 1990) : 58. http://dx.doi.org/10.1016/0263-7855(90)80077-s.

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Schmailzl, Wolfgang, Claudio Piemonte, Stefan Schelhase et Walter Hansch. « Characterization of the photo-detection efficiency temperature dependence of silicon photomultipliers from -30°C to 70°C ». Journal of Instrumentation 17, n^o 12 (1 décembre 2022) : P12009. http://dx.doi.org/10.1088/1748-0221/17/12/p12009.

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Abstract We present photon detection efficiency (PDE) measurements of three different silicon photomultipliers (SiPM) and report the temperature coefficient of this parameter using a direct measurement method. This study provides first results in such a wide temperature and wavelength range, from -30°C to 70°C and from 365 nm to 900 nm respectively. To carry out this study we developed a setup providing stable illumination of the device under test in temperature. The PDE is evaluated using a photon-counting method and the wavelength-dependent PDE temperature coefficients of all devices are determined. The different designs are compared and the individual contributors to the temperature dependence of the PDE are discussed. The PDE is shown to be linearly dependent on temperature for all designs and the temperature coefficient depends on wavelength and bias voltage. At shorter wavelengths, the temperature dependency approaches values close to zero for one design whereas all devices show increasing temperature coefficients for increasing wavelengths. This study shows that despite the more complex designs of SiPMs, compared to silicon photodiodes, similar factors contribute to the temperature dependence of the PDE.

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Welch, John. « Demonstrating Wavelength Dependency on Medium Density ». Physics Teacher 47, n^o 7 (octobre 2009) : 476. http://dx.doi.org/10.1119/1.3225516.

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Zauner, Johannes, Herbert Plischke et Hans Strasburger. « Spectral dependency of the human pupillary light reflex. Influences of pre-adaptation and chronotype ». PLOS ONE 17, n^o 1 (12 janvier 2022) : e0253030. http://dx.doi.org/10.1371/journal.pone.0253030.

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Non-visual photoreceptors (ipRGCs) and rods both exert a strong influence on the human pupil, yet pupil models regularly use cone-derived sensitivity as their basis. This inconsistency is further exacerbated by the fact that circadian effects can modulate the wavelength sensitivity. We assessed the pupillary reaction to narrowband light stimuli in the mesopic range. Pupil size for eighty-three healthy participants with normal color vision was measured in nine experimental protocols with varying series of continuous or discontinuous light stimuli under Ganzfeld conditions, presented after 90 seconds of dark adaptation. One hundred and fifty series of stimulation were conducted across three experiments, and were analyzed for wavelength-dependency on the normalized pupillary constriction (nPC), conditional on experimental settings and individual traits. Traits were surveyed by questionnaire; color vision was tested by Ishihara plates or the Lanthony D15 test. Data were analyzed with generalized additive mixed models (GAMM). The normalized pupillary constriction response is consistent with L+M-cone derived sensitivity when the series of light stimuli is continuous, i.e., is not interrupted by periods of darkness, but not otherwise. The results also show that a mesopic illuminance weighing led to an overall best prediction of pupillary constriction compared to other types of illuminance measures. IpRGC influence on nPC is not readily apparent from the results. When we explored the interaction of chronotype and time of day on the wavelength dependency, differences consistent with ipRGC influence became apparent. The models indicate that subjects of differing chronotype show a heightened or lowered sensitivity to short wavelengths, depending on their time of preference. IpRGC influence is also seen in the post-illumination pupil reflex if the prior light-stimulus duration is one second. However, shorter wavelengths than expected become more important if the light-stimulus duration is fifteen or thirty seconds. The influence of sex on nPC was present, but showed no interaction with wavelength. Our results help to define the conditions, under which the different wavelength sensitivities in the literature hold up for narrowband light settings. The chronotype effect might signify a mechanism for strengthening the individual´s chronotype. It could also be the result of the participant’s prior exposure to light (light history). Our explorative findings for this effect demand replication in a controlled study.

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Agekyan, V., N. Filosofov, G. Karczewski, A. Serov, I. Shtrom et A. Reznitsky. « Spectroscopic evidence of tunnel coupling between CdTe quantum wells in the CdTe/ZnTe heterostructures ». Journal of Physics : Conference Series 2103, n^o 1 (1 novembre 2021) : 012102. http://dx.doi.org/10.1088/1742-6596/2103/1/012102.

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Abstract The photoluminescence (PL) spectra of CdTe/ZnTe double quantum wells (QWs) are studied on a series of samples containing two CdTe layers with nominal thicknesses of 2 and 4 monolayers (ML) in the ZnTe matrix. The QWs were grown in atomic-layer epitaxy and separated by ZnTe spacers with the thicknesses dsp =40−160 ML. The dependences of the relative intensity of shallow QW1 and deep QW2 PL bands (I1 and I2 , respectively) on the pump intensity (J) when excited by the lasers with different radiation wavelengths are investigated. It is found that in the sample with dsp=40 ML, the ratio Y(J)=I1/I2 depends on J and the shape of the Y(J) dependency changes with the excitation wavelength. In the samples with dsp > 70 ML Y(J) also changes with the excitation intensity J, but the shape of this dependence is the same for various excitation wavelengths. It is concluded that the energy relaxation in these samples is influenced not only by the tunneling of charge carriers from QW1 to QW2, but also by carrier relaxation at the nonradiative centers, for which the recombination rate is different for shallow and deep QWs.

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Virkkula, A., X. Chi, A. Ding, Y. Shen, W. Nie, X. Qi, L. Zheng et al. « On the interpretation of the loading correction of the aethalometer ». Atmospheric Measurement Techniques Discussions 8, n^o 7 (17 juillet 2015) : 7373–411. http://dx.doi.org/10.5194/amtd-8-7373-2015.

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Abstract. Aerosol optical properties were measured with a 7-wavelength aethalometer and a 3-wavelength nephelometer at the suburban site SORPES in Nanjing, China, in September 2013–January 2015. The aethalometer compensation parameter k, calculated with the Virkkula et al. (2007) method depended on the backscatter fraction, measured with the independent method, the integrating nephelometer. At λ = 660 nm the daily-averaged compensation parameter k ≈ 0.0017 ± 0.0002 and 0.0042 ± 0.0013 when backscatter fraction at λ = 635 nm was in the ranges of 0.100 ± 0.005 and 0.160 ± 0.005, respectively. Also the wavelength dependency of the compensation parameter depended on the backscatter fraction: when b(λ = 525 nm) was less than approximately 0.13 the compensation parameter decreased with wavelength and at larger b it increased with wavelength. This dependency has not been considered in any of the algorithms that are currently used for processing aethalometer data. The compensation parameter also depended on single-scattering albedo ω0 so that k decreased with increasing ω0. For the green light (λ = 520 nm) in the ω0 range 0.870 ± 0.005 the average (± standard deviation) k ≈ 0.0047 ± 0.006 and in the ω0 range 0.960 ± 0.005 k ≈ 0.0028 ± 0.0007. This difference was larger for the near-infrared light (λ = 880 nm): in the ω0 range 0.860 ± 0.005 k ≈ 0.0055 ± 0.0023 and in the ω0 range 0.960 ± 0.005 k ≈ 0.0019 ± 0.0011. The negative dependence of k on ω0 was also shown with a simple theoretical analysis.

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Lang, Philipp, Robin Giereth, Stefanie Tschierlei et Matthias Schwalbe. « Unexpected wavelength dependency of the photocatalytic CO2 reduction performance of the well-known (bpy)Re(CO)3Cl complex ». Chemical Communications 55, n^o 5 (2019) : 600–603. http://dx.doi.org/10.1039/c8cc08742c.

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The photocatalytic activity of bpyRe(CO)₃Cl is highest when wavelengths larger than 450 nm are used – even if the compound hardly absorbs in this region. Mechanistic investigations suggest the wavelength-dependent involvement of different intermediates and reaction pathways.

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Virkkula, A., X. Chi, A. Ding, Y. Shen, W. Nie, X. Qi, L. Zheng et al. « On the interpretation of the loading correction of the aethalometer ». Atmospheric Measurement Techniques 8, n^o 10 (21 octobre 2015) : 4415–27. http://dx.doi.org/10.5194/amt-8-4415-2015.

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Abstract. Aerosol optical properties were measured with a seven-wavelength aethalometer and a three-wavelength nephelometer at the suburban site SORPES in Nanjing, China, in September 2013–January 2015. The aethalometer compensation parameter k, calculated with the Virkkula et al. (2007) method depended on the backscatter fraction, measured with an independent method, the integrating nephelometer. At λ = 660 nm the daily averaged compensation parameter k &approx; 0.0017 ± 0.0002 and 0.0042 ± 0.0013 when backscatter fraction at λ = 635 nm was in the ranges of 0.100 ± 0.005 and 0.160 ± 0.005, respectively. Also, the wavelength dependency of the compensation parameter depended on the backscatter fraction: when b(λ = 525 nm) was less than approximately 0.13 the compensation parameter decreased with wavelength and at larger b it increased with wavelength. This dependency has not been considered in any of the algorithms that are currently used for processing aethalometer data. The compensation parameter also depended on the single-scattering albedo ω0 so that k decreased with increasing ω0. For the green light (λ = 520 nm) in the ω0 range 0.870 ± 0.005, the average (± standard deviation) k &approx; 0.0047 ± 0.006 and in the ω0 range 0.960 ± 0.005, k &approx; 0.0028 ± 0.0007. This difference was larger for the near-infrared light (λ = 880 nm): in the ω0 range 0.860 ± 0.005, k &approx; 0.0055 ± 0.0023 and in the ω0 range 0.960 ± 0.005, k &approx; 0.0019 ± 0.0011. The negative dependence of k on ω0 was also shown with a simple theoretical analysis.

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Sassu, Lorenzo, Laura Perezzani, William A. Ivancic, Russell H. Barnes et Busolo Wa Wabuyele. « Oxygen Quenching Measurements for the S1 and S2 Fluorescence of Gas-Phase Fluoranthene ». Applied Spectroscopy 55, n^o 3 (mars 2001) : 307–10. http://dx.doi.org/10.1366/0003702011951704.

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The fluorescence emission of the fluoranthene molecule has been investigated at excitation wavelengths varying from 240 to 360 nm, and conducted from near collision-free conditions to atmosphericpressure conditions. The oxygen quenching rate for the fluorescence of the F1 band (S1 → S0 transition) of fluoranthene at 340 nm excitation wavelength was found to be 1 × 109 L mol−1 s−1. The quenching rate for the F2 band (S2 → S0 transition) was found to be 100-fold greater for the wavelength region investigated. The wavelength dependency of the oxygen-quenching constants of the two transitions was also established in the excitation range from 240 to 332 nm. The influence of oxygen and nitrogen pressure on the spectral fluorescence bandwidth of fluoranthene and the oxygen-quenching constants for the S1 and S2 bands are reported. The results shed some light on fluoranthene's unusual inertness to oxygen quenching.

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Becerra, Raimundo, Cesar A. Azurdia-Meza, Pablo Palacios Játiva, Ismael Soto, Jorge Sandoval, Muhammad Ijaz et Diego Fernando Carrera. « A Wavelength-Dependent Visible Light Communication Channel Model for Underground Environments and Its Performance Using a Color-Shift Keying Modulation Scheme ». Electronics 12, n^o 3 (23 janvier 2023) : 577. http://dx.doi.org/10.3390/electronics12030577.

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Reliable wireless communications are crucial for ensuring workers’ safety in underground tunnels and mines. Visible light communications (VLC) have been proposed as auxiliary systems for short-range wireless communications in underground environments due to their seamless availability, immunity to electromagnetic interference, and illumination capabilities. Although multiple VLC channel models have been proposed for underground mines (UM) so far, none of these models have considered the wavelength dependence of the underground mining VLC channel (UM-VLC). In this paper, we propose a single-input, single-output (SISO), wavelength-dependent UM-VLC channel model considering the wavelength dependence of the light source, reflections, light scattering, and the attenuation due to dust and the photodetector. Since wavelength dependence allows us to model VLC systems more accurately with color-based modulation, such as color-shift keying (CSK), we also propose a wavelength-dependent CSK-based UM-VLC channel model. We define a simulation scenario in an underground mine roadway and calculate the received power, channel impulse response (CIR), signal-to-noise ratio (SNR), signal-to-interference ratio (SIR), root mean square (RMS) delay, and bit error rate (BER). For comparison, we also calculate these parameters for a monochromatic state-of-the-art UM-VLC channel and use it as a reference channel. We find that the inclusion of wavelength-dependency in CSK-based UM-VLC systems plays a significant role in their performance, introducing color distortion that the color calibration algorithm defined in the IEEE 802.15.7 VLC standard finds harder to revert than the linear color distortion induced by monochromatic CSK channels.

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Takahashi, Yukitoshi, Tateki Fujiwara, Kazuichi Yagi et Masakazu Seino. « Wavelength Dependency of Photoparoxysmal Responses in Photosensitive Nonepileptic Subjects. » Tohoku Journal of Experimental Medicine 181, n^o 2 (1997) : 311–19. http://dx.doi.org/10.1620/tjem.181.311.

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Hou, Wen-Che, Lingjun Kong, Kevin A. Wepasnick, Richard G. Zepp, D. Howard Fairbrother et Chad T. Jafvert. « Photochemistry of Aqueous C60Clusters : Wavelength Dependency and Product Characterization ». Environmental Science & ; Technology 44, n^o 21 (novembre 2010) : 8121–27. http://dx.doi.org/10.1021/es101230q.

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Díaz-Soriano, Antonio, Antonio Ortiz-Mora, David Martínez-Muñoz et Pedro Rodríguez. « On the Impact of Wavelength Dependency on Supercontinuum Generation in Photonic Crystal Fibers ». Applied Sciences 14, n^o 4 (9 février 2024) : 1429. http://dx.doi.org/10.3390/app14041429.

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It is common practice when simulating propagation through an optical fiber to assume that its characteristic parameters are constant and determined solely by the central wavelength of the input pulse. In this paper, we propose a study of the impact that the actual wavelength dependence of these parameters has on the propagation results. To this end, simulations were carried out considering both the constant model and the wavelength-dependent model, applying them to the case of the especially sensitive effect of supercontinuous generation in a photonic crystal fiber. The results showed differences of up to 20% of the spectrum and, hence, the importance of taking into account the wavelength dependence of the dispersion fiber parameters to obtain more-realistic results in the simulations.

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Matsuyama, Tetsuya, Noboru Osaka, Mikiya Yamaguchi, Naohiro Kanamaru, Kenji Wada, Ai Kawakita, Kaori Murata, Kenji Sugimoto et Koichi Okamoto. « Evaluation of Phototoxicity of Short-Wavelength Laser Light Utilizing PCNA Accumulation ». Micromachines 15, n^o 5 (13 mai 2024) : 646. http://dx.doi.org/10.3390/mi15050646.

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In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at the irradiation site was investigated using live cell imaging techniques to irradiate individual living cells with short-wavelength laser light. By examining the dependency of PCNA accumulation on the irradiation site within the cells and their cell cycle, it was observed that PCNA accumulation occurred only when the cell nucleus of cells in the S phase of the cell cycle was irradiated. We investigated the accumulation of PCNA at the laser irradiation site using laser light at wavelengths of 405 nm and 375 nm, with intensities ranging from 0.5 μW to 9.0 μW. The results confirmed an increase in PCNA accumulation with increasing intensity, and a higher accumulation was observed with laser light irradiation at a wavelength of 375 nm compared to 405 nm. By comparing the PCNA accumulation and 24 h cell viability, we demonstrated the feasibility of quantitatively assessing laser light toxicity through the measurement of PCNA accumulation.

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Vakkari, Ville, Holger Baars, Stephanie Bohlmann, Johannes Bühl, Mika Komppula, Rodanthi-Elisavet Mamouri et Ewan James O'Connor. « Aerosol particle depolarization ratio at 1565 nm measured with a Halo Doppler lidar ». Atmospheric Chemistry and Physics 21, n^o 8 (19 avril 2021) : 5807–20. http://dx.doi.org/10.5194/acp-21-5807-2021.

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Abstract. The depolarization ratio is a valuable parameter for lidar-based aerosol categorization. Usually, the aerosol particle depolarization ratio is determined at relatively short wavelengths of 355 nm and/or 532 nm, but some multi-wavelength studies including longer wavelengths indicate strong spectral dependency. Here, we investigate the capabilities of Halo Photonics StreamLine Doppler lidars to retrieve the particle linear depolarization ratio at the 1565 nm wavelength. We utilize collocated measurements with another lidar system, PollyXT at Limassol, Cyprus, and at Kuopio, Finland, to compare the depolarization ratio observed by the two systems. For mineral-dust-dominated cases we find typically a slightly lower depolarization ratio at 1565 nm than at 355 and 532 nm. However, for dust mixed with other aerosol we find a higher depolarization ratio at 1565 nm. For polluted marine aerosol we find a marginally lower depolarization ratio at 1565 nm compared to 355 and 532 nm. For mixed spruce and birch pollen we find a slightly higher depolarization ratio at 1565 nm compared to 532 nm. Overall, we conclude that Halo Doppler lidars can provide a particle linear depolarization ratio at the 1565 nm wavelength at least in the lowest 2–3 km above ground.

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Jose, Jule Griebrok, et Donald G. Pitts. « Wavelength dependency of cataracts in albino mice following chronic exposure ». Experimental Eye Research 41, n^o 4 (octobre 1985) : 545–63. http://dx.doi.org/10.1016/s0014-4835(85)80011-7.

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Lim, Seungyoung, Tae-Soo Kim, Jaesang Kang, Jaesun Kim, Minhyup Song, Hyun Deok Kim et Jung-Hoon Song. « Anomalous Photocurrent Reversal Due to Hole Traps in AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes ». Micromachines 13, n^o 8 (31 juillet 2022) : 1233. http://dx.doi.org/10.3390/mi13081233.

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The trap states and defects near the active region in deep-ultraviolet (DUV) light-emitting diodes (LED) were investigated through wavelength-dependent photocurrent spectroscopy. We observed anomalous photocurrent reversal and its temporal recovery in AlGaN-based DUV LEDs as the wavelength of illuminating light varied from DUV to visible. The wavelength-dependent photocurrent measurements were performed on 265 nm-emitting DUV LEDs under zero-bias conditions. Sharp near-band-edge (~265 nm) absorption was observed in addition to broad (300–800 nm) visible-range absorption peaks in the photocurrent spectrum, while the current direction of these two peaks were opposite to each other. In addition, the current direction of the photocurrent in the visible wavelength range was reversed when a certain forward bias was applied. This bias-induced current reversal displayed a slow recovery time (~6 h) when the applied forward voltage was removed. Furthermore, the recovery time showed strong temperature dependency and was faster as the sample temperature increased. This result can be consistently explained by the presence of hole traps at the electron-blocking layer and the band bending caused by piezoelectric polarization fields. The activation energy of the defect state was calculated to be 279 meV using the temperature dependency of the recovery time.

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Taniguchi, Masaharu, et Yasumasa Nishiura. « Stability and characteristic wavelength of planar interfaces in the large diffusion limit of the inhibitor ». Proceedings of the Royal Society of Edinburgh : Section A Mathematics 126, n^o 1 (1996) : 117–45. http://dx.doi.org/10.1017/s0308210500030638.

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A characteristic wavelength and its parametric dependency are studied for planar interfaces of activator-inhibitor systems as well as their stability in two-dimensional space. When an unstable planar interface is slightly perturbed in a random way, it develops with a characteristic wavelength, that is, the fastest-growing one. A natural question is to ask under what conditions this characteristic wavelength remains finite and approaches a positive definite value as the width of interface, say ε, tends to zero. In this paper, we show that the fastest-growing wavelength has a positive limit value as ε tends to zero for the system:This is a fundamental fact for stuyding the domain size of patterns in higher-space dimensions.

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TWIG, GILAD, HANNA LEVY, ELITE WEINER et IDO PERLMAN. « Light adaptation and color opponency of horizontal cells in the turtle retina ». Visual Neuroscience 20, n^o 4 (juillet 2003) : 437–52. http://dx.doi.org/10.1017/s0952523803204090.

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Chromaticity-type (C-type) horizontal cells of the turtle retina receive antagonistic inputs from cones of different spectral types, and therefore their response to background illumination is expected to reflect light adaptation of the cones and the interactions between their antagonistic inputs. Our goal was to study the behavior of C-type horizontal cells during background illumination and to evaluate the role of wavelength in background adaptation. The photoresponses of C-type horizontal cells were recorded intracellularly in the everted eyecup preparation of the turtleMauremys caspicaduring chromatic background illuminations. The voltage range of operation was either reduced or augmented, depending upon the wavelengths of the background and of the light stimuli, while the sensitivity to light was decreased by any background. The response–intensity curves were shifted to brighter intensities and became steeper as the background lights were made brighter regardless of wavelength. Comparing the effects of cone iso-luminant backgrounds on the Red/Green C-type horizontal cells indicated that background desensitization in these cells could not solely reflect background adaptation of cones but also depend upon response compression/expansion and changes in synaptic transmission. This leads to wavelength dependency of background adaptation in C-type horizontal cells, that is expressed as increased light sensitivity (smaller threshold elevation) and improved suprathreshold contrast detection when the wavelengths of the background and light stimuli were chosen to exert opponent effects on membrane potential.

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Chaen, Yutaka, Kazuhiro Tanabe, Haisong Jiang et Kiichi Hamamoto. « Low wavelength dependency design for MMI (multi-mode interference) mode converter ». IEICE Electronics Express 12, n^o 20 (2015) : 20150727. http://dx.doi.org/10.1587/elex.12.20150727.

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Colditz, H. J. O., R. Kurt et M. Büchel. « Photodegradation and wavelength dependency of blue polymer light-emitting diode devices ». Applied Physics Letters 87, n^o 25 (19 décembre 2005) : 253505. http://dx.doi.org/10.1063/1.2149184.

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Matthews, Yasmin J., Gary M. Halliday, Tai A. Phan et Diona L. Damian. « Wavelength dependency for UVA-induced suppression of recall immunity in humans ». Journal of Dermatological Science 59, n^o 3 (septembre 2010) : 192–97. http://dx.doi.org/10.1016/j.jdermsci.2010.07.005.

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Liebschner, Dorothee, Yusuke Yamada, Naohiro Matsugaki, Miki Senda et Toshiya Senda. « On the influence of crystal size and wavelength on native SAD phasing ». Acta Crystallographica Section D Structural Biology 72, n^o 6 (25 mai 2016) : 728–41. http://dx.doi.org/10.1107/s2059798316005349.

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Native SAD is an emerging phasing technique that uses the anomalous signal of native heavy atoms to obtain crystallographic phases. The method does not require specific sample preparation to add anomalous scatterers, as the light atoms contained in the native sample are used as marker atoms. The most abundant anomalous scatterer used for native SAD, which is present in almost all proteins, is sulfur. However, the absorption edge of sulfur is at low energy (2.472 keV = 5.016 Å), which makes it challenging to carry out native SAD phasing experiments as most synchrotron beamlines are optimized for shorter wavelength ranges where the anomalous signal of sulfur is weak; for longer wavelengths, which produce larger anomalous differences, the absorption of X-rays by the sample, solvent, loop and surrounding medium (e.g.air) increases tremendously. Therefore, a compromise has to be found between measuring strong anomalous signal and minimizing absorption. It was thus hypothesized that shorter wavelengths should be used for large crystals and longer wavelengths for small crystals, but no thorough experimental analyses have been reported to date. To study the influence of crystal size and wavelength, native SAD experiments were carried out at different wavelengths (1.9 and 2.7 Å with a helium cone; 3.0 and 3.3 Å with a helium chamber) using lysozyme and ferredoxin reductase crystals of various sizes. For the tested crystals, the results suggest that larger sample sizes do not have a detrimental effect on native SAD data and that long wavelengths give a clear advantage with small samples compared with short wavelengths. The resolution dependency of substructure determination was analyzed and showed that high-symmetry crystals with small unit cells require higher resolution for the successful placement of heavy atoms.

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Basyir Rodhuan, Mirza, Rosmila Abdul-Kahar, Hajar Najihah Mohd Yazid, Amirah Nabilah Mohd Rapi, Nur Hidayu Baharin et Nanang Burhan. « Size dependency of CdSe for light harvesting in quantum dots solar cell using COMSOL Multiphysics ». International Journal of Application on Sciences, Technology and Engineering 1, n^o 1 (28 février 2023) : 232–40. http://dx.doi.org/10.24912/ijaste.v1.i1.232-240.

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A solar cell (SC) can increase its performance by applying a semiconductor nanoparticle into it, and the name became quantum dots solar cell (QDSC). A nanotube of titanium dioxide (TiO2) with various sizes of cadmium selenide (CdSe) quantum dots (QDs) was designed and simulated using COMSOL Multiphysics. This study is to identify the size of CdSe QDs that can harvest more light energy at 550 nm of wavelength through electric field distribution simulation. Following the result for CdSe QD that harvested highest at 550 nm of diameter size 3.0 nm, which matched the result of previous research, further study was done to look at the absorption percentage of this size. With the different structures of amorphous silicon SC, the maximum absorption value was 50.664% at 657 nm of wavelength and will increase to 52.819 % at 617 nm of wavelength when the 3 nm diameter size of CdSe is inserted. The presence of a certain size CdSe within an SC structure does improved the performance of SC.

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Sakai, Takaomi, Kunio Isono, Masatoshi Tomaru, Akishi Fukatami et Yuzuru Oguma. « Light wavelength dependency of mating activity in the Drosophila melanogaster species subgroup ». Genes & ; Genetic Systems 77, n^o 3 (2002) : 187. http://dx.doi.org/10.1266/ggs.77.187.

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EL Sherbini, Ashraf M., et Christian G. Parigger. « Wavelength dependency and threshold measurements for nanoparticle-enhanced laser-induced breakdown spectroscopy ». Spectrochimica Acta Part B : Atomic Spectroscopy 116 (février 2016) : 8–15. http://dx.doi.org/10.1016/j.sab.2015.11.006.

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Preusser, S., U. Stimming et S. Tokunaga. « The Wavelength and Potential Dependency of Spatially Resolved Photoelectrochemical Measurements on TiO2 ». Journal of The Electrochemical Society 142, n^o 1 (1 janvier 1995) : 102–11. http://dx.doi.org/10.1149/1.2043847.

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Neckel, Heinz. « On the wavelength dependency of solar limb darkening (??303 to 1099 nm) ». Solar Physics 167, n^o 1-2 (août 1996) : 9–23. http://dx.doi.org/10.1007/bf00146325.

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Chowdhury, Prosenjit Roy. « Study on Coupling of Step and Graded Index Single Mode Optical Fiber Considering the Transverse Misalignment ». Science & ; Technology Journal 8, n^o 2 (1 juillet 2020) : 78–82. http://dx.doi.org/10.22232/stj.2020.08.02.12.

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"Advance design and day to day up-gradation of communication system is the requirement of international telecommunication. The optical communication systems involve the effective fiber coupling or splicing to meet the need of long communication channel. When the studies on both the intensive and extensive properties of optical fiber are exploring new research horizons, the effectiveness of such systems can be calibrated with transmission parameters like transmitted fractional power, which is a function of ‘spot size’ as well. Our study of fiber junctions based on fundamental parameters like wavelength, fiber profile index etc. has touched some unrevealed areas and explored some interesting results. The profile index of optical fiber has received less attention compared to other structural parameters of optical fiber but our study at important wavelengths for different profiles has shown that the less-used fiber profiles has some interesting premier outcomes, which can introduce some significant impact on optical fiber based system design and engineering. We have observed almost frequency or wavelength independent transmitted fractional power around the most used 1.55 micrometer wavelengths at some rarely used fiber profile index. Our study predicts the best and worst fiber profiles for transmitted fractional power (T ), at the same time, we have observed the fiber profile index independent region for a band of ‘T’ values. The reporting and its approach are found to be premier in this field. So, our work is reporting a comparison of effective fiber-to-fiber coupling, based on fiber profile index of different fibers. It is also giving a clear view of the wavelength dependency of effective fiber coupling for different fibers having wide range of graded fiber profiles."

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Prokop, Vit, Lukas Strizik, Jiri Oswald, Milan Vlcek, Ludvik Benes, Spyros N. Yannopoulos, Bozena Frumarova et Tomas Wagner. « 1.5 μm photoluminescence and upconversion photoluminescence in GeGaAsS:Er chalcogenide glass ». Pure and Applied Chemistry 91, n^o 11 (26 novembre 2019) : 1757–67. http://dx.doi.org/10.1515/pac-2018-1231.

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Abstract The paper reports on ≈1.5 μm Stokes photoluminescence (PL) emission and upconversion photoluminescence (UCPL) emission in the visible and near-infrared spectral region in Er3+-doped Ge25Ga8As2S65 chalcogenide glasses at pumping wavelengths of 980 and 1550 nm. The ≈1.5 μm PL emission spectra are broadened with increasing concentration of Er ions which is discussed in terms of radiation trapping and UCPL dynamics affecting the Er3+: 4I13/2 level lifetime. The UCPL emission was observed at ≈530, ≈550, ≈660, ≈810 and ≈990 nm and its overall intensity as well as red-to-green UCPL emission intensity ratio increases with increasing Er concentration. To explore the UCPL dynamics we measured double logarithmic dependency of green (≈550 nm) and red (≈660 nm) UCPL emission versus pump power at pumping wavelength of 975 nm. Moreover, we measured quadrature frequency resolved spectroscopy (QFRS) on green UCPL emission (≈550 nm) using 975 nm pumping wavelength and various excitation powers. The QFRS spectra on green UCPL were analyzed in term of QFRS transfer function for three-level model from which we deduced energy transfer upconversion rate w11 (s−1) originating from Er3+: 4I11/2, 4I11/2→4F7/2, 4I15/2 transitions.

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Baumgartner, Nick R., et Paul E. Blatz. « WAVELENGTH DEPENDENCY OF THE RATE OF IODINE CATALYZED PHOTOISOMERIZATION OF RETINOL and RETINAL ». Photochemistry and Photobiology 54, n^o 5 (novembre 1991) : 805–10. http://dx.doi.org/10.1111/j.1751-1097.1991.tb02094.x.

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PREUSSER, S., U. STIMMING et S. TOKUNAGA. « ChemInform Abstract : Wavelength and Potential Dependency of Spatially Resolved Photoelectrochemical Measurements on TiO2. » ChemInform 26, n^o 13 (18 août 2010) : no. http://dx.doi.org/10.1002/chin.199513297.

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Deeg, Hans J., Roi Alonso, David Nespral et Tabetha S. Boyajian. « Non-grey dimming events of KIC 8462852 from GTC spectrophotometry ». Astronomy & ; Astrophysics 610 (février 2018) : L12. http://dx.doi.org/10.1051/0004-6361/201732453.

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We report ground-based spectrophotometry of KIC 8462852 obtained during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour signature and are deeper in visual blue than in red wavelengths. The wavelength dependency of the flux loss can be described with an absorption Ångström coefficient of 2.19 ± 0.45, which is compatible with absorption by optically thin dust with particle sizes of the order of 0.0015 to 0.15 μm. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished from a comoving body on time-scales of days. If dust is indeed the source of the dimming events of KIC 8462852, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers.

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Egli, Luca, Julian Gröbner, Herbert Schill et Eliane Maillard Barras. « Total column ozone retrieval from a novel array spectroradiometer ». Atmospheric Measurement Techniques 16, n^o 11 (13 juin 2023) : 2889–902. http://dx.doi.org/10.5194/amt-16-2889-2023.

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Abstract. This study presents a new total column ozone (TCO) retrieval from the Koherent system, developed at the Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC). The instrument is based on a small, cost-effective, robust, low-maintenance and state-of-the-art-technology array spectroradiometer. It consists of a BTS-2048-UV-S-F array spectroradiometer from Gigahertz-Optik GmbH, coupled with an optical fibre to a lens-based telescope mounted on a sun tracker for measuring direct UV irradiance in the ultraviolet wavelength band between 305 to 345 nm. Two different algorithms are developed for retrieving TCO from these spectral measurements: (1) TCO retrieved by a least-squares-fit algorithm (LSF) and (2) a custom-double-ratio (CDR) technique using four specifically selected wavelengths from the spectral measurements. The double-ratio technique is analogous to the retrieval algorithm applied for the Dobson instruments and the Brewer instruments but is adopted here for TCO retrieval with Koherent. The instrument was calibrated in two different ways: (a) absolute calibration of the spectra using the portable reference for ultraviolet radiation QASUME for the LSF retrieval and (b) relative calibration of the extraterrestrial constant (ETC) of the CDR retrieval by minimising the slope between air mass and the relative differences of TCO from QASUME and Koherent. This adjustment of the ETC allows the instrument to be calibrated with standard TCO reference instruments during calibration campaigns, such as a double-monochromator Brewer. A 2-year comparison in Davos, Switzerland, between Koherent and the Brewer 156 (double monochromator) shows that TCO derived from Koherent and the Brewer 156 agree, on average, over the entire period within 0.7 % for all retrievals in terms of offset. The performance in terms of slant path depends on the selected retrieval and the applied corrections. The stray-light-corrected LSF retrieval exhibits a smaller slant path dependency than the CDR retrieval and performs almost as well as a double-monochromator system. The slant path dependency of the CDR is comparable to the slant path dependency of a single Brewer monochromator. The combination of both retrievals leads to performance with an offset close to zero compared to Brewer 156, a seasonal amplitude of the relative difference of 0.08 % and a slant path dependency of maximum 1.64 %, which is similar to other standard TCO instruments such as single Brewer or Dobson. Applying the double-ratio technique by selecting the wavelengths and slit functions from Brewer and Dobson, respectively, allows for the determination of the effective ozone temperature with an uncertainty of 3 K in terms of daily averages. With the improved TCO retrieval, Koherent serves as a new low-maintenance instrument which could also be used to monitor TCO at remote sites. The TCO retrieval presented here may be applied to other array-based spectroradiometers, providing direct spectral measurements in the ultraviolet wavelength band.

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Beirle, Steffen, Johannes Lampel, Christophe Lerot, Holger Sihler et Thomas Wagner. « Parameterizing the instrumental spectral response function and its changes by a super-Gaussian and its derivatives ». Atmospheric Measurement Techniques 10, n^o 2 (23 février 2017) : 581–98. http://dx.doi.org/10.5194/amt-10-581-2017.

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Abstract. The instrumental spectral response function (ISRF) is a key quantity in DOAS analysis, as it is needed for wavelength calibration and for the convolution of trace gas cross sections to instrumental resolution. While it can generally be measured using monochromatic stimuli, it is often parameterized in order to merge different calibration measurements and to plainly account for its wavelength dependency. For some instruments, the ISRF can be described appropriately by a Gaussian function, while for others, dedicated, complex parameterizations with several parameters have been developed.Here we propose to parameterize the ISRF as a super-Gaussian, which can reproduce a variety of shapes, from point-hat to boxcar shape, by just adding one parameter to the classical Gaussian. The super-Gaussian turned out to describe the ISRF of various DOAS instruments well, including the satellite instruments GOME-2, OMI, and TROPOMI.In addition, the super-Gaussian allows for a straightforward parameterization of the effect of ISRF changes, which can occur on long-term scales as well as, for example, during one satellite orbit and impair the spectral analysis if ignored. In order to account for such changes, spectral structures are derived from the derivatives of the super-Gaussian, which are afterwards just scaled during spectral calibration or DOAS analysis. This approach significantly improves the fit quality compared to setups with fixed ISRF, without drawbacks on computation time due to the applied linearization. In addition, the wavelength dependency of the ISRF can be accounted for by accordingly derived spectral structures in an easy, fast, and robust way.

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Malek, Samaneh, et Reza Poursalehi. « Nanosecond Pulsed Laser Heating of Colloidal Copper Nanoparticles in Water ». Advanced Materials Research 829 (novembre 2013) : 263–67. http://dx.doi.org/10.4028/www.scientific.net/amr.829.263.

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In this study, localized heating of homogenous spherical copper nanoparticles surrounded by water on exposure to short laser pulses is investigated. We are intended to estimate the maximum temperatures of nanoparticles by calculating the absorption efficiency and absorbed energy with some radii in the range 1-50 nm at the laser wavelengths of 248 and 633 nm using Mie theory. The dependency of the melting temperature of nanoparticles upon the particle size is also considered. Our calculations show the appropriate laser wavelength and nanoparticle size which are preferred for large area heating, localized heating without thermal damage or completely localized destroying of small amount of species and polymeric materials modification. The significant temperature rising and the heat transfer to the immediate vicinity is of exceptional interest in selective cell targeting, diagnosis and therapeutic applications, surface modification, and particle removing below damage threshold energy of surrounding media.

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Vega, Fidel, Miguel Faria-Ribeiro, Jesús Armengol et María S. Millán. « Pitfalls of Using NIR-Based Clinical Instruments to Test Eyes Implanted with Diffractive Intraocular Lenses ». Diagnostics 13, n^o 7 (27 mars 2023) : 1259. http://dx.doi.org/10.3390/diagnostics13071259.

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The strong wavelength dependency of diffractive elements casts reasonable doubts on the reliability of near-infrared- (NIR)-based clinical instruments, such as aberrometers and double-pass systems, for assessing, post-surgery, the visual quality of eyes implanted with diffractive multifocal intraocular lenses (DMIOLs). The results obtained for such patients when using NIR light can be misleading. Ordinary compensation for the refractive error bound to chromatic aberration is not enough because it only considers the best focus shift but does not take into account the distribution of light energy among the foci which strongly depends on the wavelength-dependent energy efficiency of the diffractive orders used in the DMIOL design. In this paper, we consider three commercial DMIOL designs with the far focus falling within the range of (−1, 0, +1)-diffractive orders. We prove theoretically the differences existing in the physical performance of the studied lenses when using either the design wavelength in the visible spectrum or a NIR wavelength (780 to 850 nm). Based on numerical simulation and on-bench experimental results, we show that such differences cannot be neglected and may affect all the foci of a DMIOL, including the far focus.

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Rapp, Lutz, et João Ferreira. « Dynamics of Spectral Hole Burning in EDFAs : Dependency on Pump Wavelength and Pump Power ». IEEE Photonics Technology Letters 22, n^o 16 (août 2010) : 1256–58. http://dx.doi.org/10.1109/lpt.2010.2052798.

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WHITAKER, DAVID, RICHARD STEEN et DAVID B. ELLIOTT. « Light Scatter in the Normal Young, Elderly, and Cataractous Eye Demonstrates Little Wavelength Dependency ». Optometry and Vision Science 70, n^o 11 (novembre 1993) : 963–68. http://dx.doi.org/10.1097/00006324-199311000-00014.

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Torii, Kan, Akira Maeda, Chiyo Saito, Takuya Furuhashi, Yoichi Shintani, Yuji Shirakata et Akimichi Morita. « UVB wavelength dependency of antimicrobial peptide induction for innate immunity in normal human keratinocytes ». Journal of Dermatological Science 56, n^o 3 (décembre 2009) : 214–16. http://dx.doi.org/10.1016/j.jdermsci.2009.07.011.

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Nakabayashi, Takakazu, Hiromi Okamoto et Mitsuo Tasumi. « Probe-Wavelength Dependency of Picosecond Anti-Stokes Raman Spectra oftrans-Stilbene in the S1State ». Journal of Physical Chemistry A 101, n^o 39 (septembre 1997) : 7189–93. http://dx.doi.org/10.1021/jp971495q.

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Yamada, Hirotaka, Kengo Moriyasu, Hiroto Sato et Hidekazu Hatanaka. « Dependency of speckle reduction by wavelength diversity on angular diversity in laser projection system ». Journal of the Society for Information Display 26, n^o 4 (avril 2018) : 237–45. http://dx.doi.org/10.1002/jsid.652.

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Zhang, Hanqing, Wei Duan, Ting Wei, Chunting Xu et Wei Hu. « Broadband Multichannel Optical Vortex Generators via Patterned Double-Layer Reverse-Twist Liquid Crystal Polymer ». Crystals 10, n^o 10 (29 septembre 2020) : 882. http://dx.doi.org/10.3390/cryst10100882.

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The capacity of an optical communication system can be greatly increased by using separate orbital angular momentum (OAM) modes as independent channels for signal transmission and encryption. At present, a transmissive OAM mode generator compatible with wavelength division multiplexing is being highly pursued. Here, we introduce a specific double-layer reverse-twist configuration into liquid crystal polymer (LCP) to overcome wavelength dependency. With this design, broadband-applicable OAM array generators are proposed and demonstrated. A Damman vortex grating and a Damman q-plate were encoded via photopatterning two subsequent LCP layers adopted with oppositely handed chiral dopants. Rectangular and hexagonal OAM arrays with mode conversion efficiencies exceeding 40.1% and 51.0% in the ranges of 530 to 930 nm, respectively, are presented. This provides a simple and broadband efficient strategy for beam shaping.

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Qi, Xue, Kay Schaarschmidt, Guangrui Li, Saher Junaid, Ramona Scheibinger, Tilman Lühder et Markus A. Schmidt. « Understanding Nonlinear Pulse Propagation in Liquid Strand-Based Photonic Bandgap Fibers ». Crystals 11, n^o 3 (19 mars 2021) : 305. http://dx.doi.org/10.3390/cryst11030305.

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Ultrafast supercontinuum generation crucially depends on the dispersive properties of the underlying waveguide. This strong dependency allows for tailoring nonlinear frequency conversion and is particularly relevant in the context of waveguides that include geometry-induced resonances. Here, we experimentally uncovered the impact of the relative spectral distance between the pump and the bandgap edge on the supercontinuum generation and in particular on the dispersive wave formation on the example of a liquid strand-based photonic bandgap fiber. In contrast to its air-hole-based counterpart, a bandgap fiber shows a dispersion landscape that varies greatly with wavelength. Particularly due to the strong dispersion variation close to the bandgap edges, nanometer adjustments of the pump wavelength result in a dramatic change of the dispersive wave generation (wavelength and threshold). Phase-matching considerations confirm these observations, additionally revealing the relevance of third order dispersion for interband energy transfer. The present study provides additional insights into the nonlinear frequency conversion of resonance-enhanced waveguide systems which will be relevant for both understanding nonlinear processes as well as for tailoring the spectral output of nonlinear fiber sources.

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Kol, R., E. Ben-Hur, R. Marko et I. Rosenthal. « Inhibition of Human Lymphocyte Stimulation by Visible Light and Phthalocyanine Photosensitization : Mitogen and Wavelength Dependency ». International Journal of Radiation Biology 55, n^o 6 (janvier 1989) : 1015–22. http://dx.doi.org/10.1080/09553008914551041.

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Kravets, Viktor, Volodymyr Samusia, Dmytro Kolosov, Kostiantyn Bas et Serhii Onyshchenko. « Discrete mathematical model of travelling wave of conveyor transport ». E3S Web of Conferences 168 (2020) : 00030. http://dx.doi.org/10.1051/e3sconf/202016800030.

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A mathematical model of a travelling wave in a matrix form is constructed. A degree of discreteness of the travelling wave and corresponding steps in phase and length are introduced. Asymmetric, unified matrices are compiled, which represent a generalized travelling wave, depending on a degree of discreteness. A generalized, dimensionless travelling wave is transformed into a required one with dimensions by specified technical parameters: amplitude and wavelength that is realized. A dependency of coordinates of points of a plane discrete travelling wave and discrete phase angles is established. A dependency of angular (phase) velocity and velocity of the travelling wave, which corresponds to the known results, is established. The presented matrix mathematical model is considered as an initial stage of technical possibility to realize a continuous travelling wave in a discrete form when developing a new type of transportation – wave transport.

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Skupin, A., A. Ansmann, R. Engelmann, P. Seifert et T. Müller. « Four-year long-path monitoring of ambient aerosol extinction at a central European urban site : dependence on relative humidity ». Atmospheric Chemistry and Physics Discussions 15, n^o 8 (29 avril 2015) : 12583–616. http://dx.doi.org/10.5194/acpd-15-12583-2015.

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Abstract. The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30–50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300–1000 nm) on relative humidity up to almost 100% was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80%. The respective four-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidty increase from 40 to 95%. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.463 for the 2009–2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yield good agreement. Also, time series of the particle extinction coefficient computed from in-situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40% relative humidity) were found in good overall consistency, which corroborates the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390–881 nm Ångström exponent from, on average, 0.3 (at 30% relative humidity) to 1.3 (at 95% relative humidity) for the four-year period.

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Skupin, A., A. Ansmann, R. Engelmann, P. Seifert et T. Müller. « Four-year long-path monitoring of ambient aerosol extinction at a central European urban site : dependence on relative humidity ». Atmospheric Chemistry and Physics 16, n^o 4 (18 février 2016) : 1863–76. http://dx.doi.org/10.5194/acp-16-1863-2016.

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Abstract. The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30–50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300 to 1000 nm) on relative humidity up to almost 100 % was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80 %. The respective 4-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidity increase from 40 to 95 %. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.46 for the 2009–2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found, indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yields good agreement. Also, time series of the particle extinction coefficient computed from in situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40 % relative humidity) were found in good overall consistency, which verifies the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390–881 nm Ångström exponent from, on average, 0.3 (at 30 % relative humidity) to 1.3 (at 95 % relative humidity) for the 4-year period.

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Kaasalainen, Sanna, Markku Åkerblom, Olli Nevalainen, Teemu Hakala et Mikko Kaasalainen. « Uncertainty in multispectral lidar signals caused by incidence angle effects ». Interface Focus 8, n^o 2 (16 février 2018) : 20170033. http://dx.doi.org/10.1098/rsfs.2017.0033.

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Multispectral terrestrial laser scanning (TLS) is an emerging technology. Several manufacturers already offer commercial dual or three wavelength airborne laser scanners, while multispectral TLS is still carried out mainly with research instruments. Many of these research efforts have focused on the study of vegetation. The aim of this paper is to study the uncertainty of the measurement of spectral indices of vegetation with multispectral lidar. Using two spectral indices as examples, we find that the uncertainty is due to systematic errors caused by the wavelength dependency of laser incidence angle effects. This finding is empirical, and the error cannot be removed by modelling or instrument modification. The discovery and study of these effects has been enabled by hyperspectral and multispectral TLS, and it has become a subject of active research within the past few years. We summarize the most recent studies on multi-wavelength incidence angle effects and present new results on the effect of specular reflection from the leaf surface, and the surface structure, which have been suggested to play a key role. We also discuss the consequences to the measurement of spectral indices with multispectral TLS, and a possible correction scheme using a synthetic laser footprint.

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