Surface Reflection Models For Stray-Light Calculations

1977 ◽  
Author(s):  
Robert J. Noll
Keyword(s):  
Stray Light ◽  
Surface Reflection ◽  
Reflection Models

scholarly journals Characterization of in band stray light in SBUV/2 instruments

2014 ◽  
Vol 7 (1) ◽  
pp. 267-278
Author(s):  
L. K. Huang ◽  
M. T. DeLand ◽  
S. L. Taylor ◽  
L. E. Flynn
Keyword(s):  
Zenith Angle ◽  
Empirical Model ◽  
Solar Zenith Angle ◽  
Stray Light ◽  
Surface Reflection

Abstract. Significant in-band stray light (IBSL) error at solar zenith angle (SZA) values larger than 77° near sunset in 4 SBUV/2 (Solar Backscattered Ultraviolet) instruments, on board the NOAA-14, 17, 18 and 19 satellites, has been characterized. The IBSL error is caused by large surface reflection and scattering of the air-gapped depolarizer in front of the instrument's monochromator aperture. The source of the IBSL error is direct solar illumination of instrument components near the aperture rather than from earth shine. The IBSL contamination at 273 nm can reach 40% of earth radiance near sunset, which results in as much as a 50% error in the retrieved ozone from the upper stratosphere. We have analyzed SBUV/2 albedo measurements on both the dayside and nightside to develop an empirical model for the IBSL error. This error has been corrected in the V8.6 SBUV/2 ozone retrieval.

scholarly journals Characterization of In Band Stray Light in SBUV/2 Instruments

2013 ◽  
Vol 6 (4) ◽  
pp. 7911-7943
Author(s):  
L.-K. Huang ◽  
M. T. DeLand ◽  
S. L. Taylor ◽  
L. E. Flynn
Keyword(s):  
Zenith Angle ◽  
Empirical Model ◽  
Solar Zenith Angle ◽  
Stray Light ◽  
Surface Reflection ◽  
Night Side

Abstract. Significant In-Band Stray Light (IBSL) error at solar zenith angle (SZA) values larger than 77° near sunset in 4 SBUV/2 instruments has been characterized. The IBSL error is caused by large surface reflection and scattering of the air-gapped depolarizer in front of the instrument's monochromator aperture. The source of the IBSL error is direct solar illumination of instrument components near the aperture rather than from earth shine. We have analyzed SBUV/2 albedo measurements on both dayside and night side to develop an empirical model for the IBSL error. This error has been corrected in the V8.6 SBUV/2 ozone retrieval.

Optimal Absorbance for Transmission or Reflection Spectra Measured under Conditions of Constant Detector Noise in the Presence of Stray Radiation

2002 ◽  
Vol 56 (7) ◽  
pp. 916-919 ◽  
Author(s):  
Tomas Isaksson ◽  
Peter R. Griffiths
Keyword(s):  
Diffuse Reflection ◽  
Signal To Noise Ratio ◽  
Front Surface ◽  
Stray Light ◽  
Reference Spectrum ◽  
Surface Reflection ◽  
Fourier Transform Spectrometry ◽  
Maximum Value ◽  
Stray Radiation ◽  
Ft Ir

The signal-to-noise ratio ( S/N) for absorption spectrometers can be expressed as absorbance/absorbance noise ( Am/ SAm), where Am is the measured absorbance and Smm is the standard deviation in Am, or as concentration/concentration noise ( c/sc) calculated from Beer's law. For measurements made under ideal conditions, Am/ SAm. However, when stray radiation, or an analogous phenomenon, such as detector nonlinearity in FT-IR measurements or surface reflection in diffuse reflection spectrometry, contributes to the spectrum, C/ Sc ≠ Am/ SAm. It is known that the optimum value of Am/ SAm in the absence of stray light is found at an absorbance of 0.4816 when noise from the reference spectrum is taken into account and 0.4343 when noise from the reference spectrum is excluded from the calculations. In the present paper we discuss the effect of stray light on the absorbance and concentration S/N. The maximum value of c/sc is found at lower absorbance than is the case if stray light is absent. While this effect is negligibly small for the typical levels of stray light found with most contemporary monochromators, it can be significant when, for example, the response of a detector used in Fourier transform spectrometry is nonlinear or when the front-surface reflection in diffuse reflection measurements is large. For effective stray light levels of 10%, the maximum value of c/sc is found at an absorbance that is 22% lower than when no source of stray light is present.

Perceived Glossiness: Beyond Surface Properties

2019 ◽  
Vol 2019 (1) ◽  
pp. 37-42
Author(s):  
Davit Gigilashvili ◽  
Jean-Baptiste Thomas ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg
Keyword(s):  
Surface Properties ◽  
Human Subjects ◽  
Surface Geometry ◽  
Surface Reflection ◽  
Different Color

Gloss is widely accepted as a surface- and illuminationbased property, both by definition and by means of metrology. However, mechanisms of gloss perception are yet to be fully understood. Potential cues generating gloss perception can be a product of phenomena other than surface reflection and can vary from person to person. While human observers are less likely to be capable of inverting optics, they might also fail predicting the origin of the cues. Therefore, we hypothesize that color and translucency could also impact perceived glossiness. In order to validate our hypothesis, we conducted series of psychophysical experiments asking observers to rank objects by their glossiness. The objects had the identical surface geometry and shape but different color and translucency. The experiments have demonstrated that people do not perceive objects with identical surface equally glossy. Human subjects are usually able to rank objects of identical surface by their glossiness. However, the strategy used for ranking varies across the groups of people.

A low stray light, high current, low energy electron source

1999 ◽  
Vol 70 (10) ◽  
pp. 3886-3888 ◽  
Author(s):  
M. Adelt ◽  
R. Körber ◽  
W. Drachsel ◽  
H.-J. Freund
Keyword(s):  
Electron Source ◽  
Low Energy ◽  
Energy Electron ◽  
Stray Light ◽  
High Current ◽  
Low Energy Electron

scholarly journals Remote Reflectivity Sensor for Industrial Applications

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1301
Author(s):  
Federico Cavedo ◽  
Parisa Esmaili ◽  
Michele Norgia
Keyword(s):  
Low Cost ◽  
Cost Effective ◽  
Industrial Applications ◽  
Interference Immunity ◽  
Surface Reflection ◽  
Measurement Systems ◽  
Digital Detector ◽  
Reflected Light ◽  
Surface Optical ◽  
Diffused Light

A low-cost optical reflectivity sensor is proposed in this paper, able to detect the presence of objects or surface optical properties variations, at a distance of up to 20 m. A collimated laser beam is pulsed at 10 kHz, and a synchronous digital detector coherently measures the back-diffused light collected through a 1-inch biconvex lens. The sensor is a cost-effective solution for punctual measurement of the surface reflection at different distances. To enhance the interference immunity, an algorithm based on a double-side digital baseline restorer is proposed and implemented to accurately detect the amplitude of the reflected light. As results show, the sensor is robust against ambient light and shows a strong sensitivity on a wide reflection range. The capability of the proposed sensor was evaluated experimentally for object detection and recognition, in addition to dedicated measurement systems, like remote encoders or keyphasors, realized far from the object to be measured.

scholarly journals Stray light characterization with ultrafast time-of-flight imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
L. Clermont ◽  
W. Uhring ◽  
M. Georges
Keyword(s):  
Path Length ◽  
Imaging System ◽  
Time Of Flight ◽  
Optical Path Length ◽  
Optical Path ◽  
Stray Light ◽  
Laser Source ◽  
Space Telescopes ◽  
Characterization Methods ◽  
Instance Space

AbstractUnderstanding stray light (SL) is a crucial aspect in the development of high-end optical instruments, for instance space telescopes. As it drives image quality, SL must be controlled by design and characterized experimentally. However, conventional SL characterization methods are limited as they do not provide information on its origins. The problem is complex due to the diversity of light interaction processes with surfaces, creating various SL contributors. Therefore, when SL level is higher than expected, it can be difficult to determine how to improve the system. We demonstrate a new approach, ultrafast time-of-flight SL characterization, where a pulsed laser source and a streak camera are used to record individually SL contributors which travel with a specific optical path length. Furthermore, the optical path length offers a means of identification to determine its origin. We demonstrate this method in an imaging system, measuring and identifying individual ghosts and scattering components. We then show how it can be used to reverse-engineer the instrument SL origins.

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