The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
T J T P Van Den Berg - One of the best experts on this subject based on the ideXlab platform.
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measurement of Stray Light and glare comparison of nyktotest mesotest Stray Light meter and computer implemented Stray Light meter
British Journal of Ophthalmology, 2005Co-Authors: L J Van Rijn, C Nischler, D Gamer, L Franssen, R Kaper, D J Vonhoff, G Grabner, Helmut Wilhelm, H J Volkerdieben, T J T P Van Den BergAbstract:Aim: To evaluate the properties of devices for measuring Stray Light and glare: the Nyktotest, Mesotest, “conventional” Stray Light meter and a new, computer implemented version of the Stray Light meter. Methods: 112 subjects, divided in three groups: (1) young subjects without any eye disease; (2) elderly subjects without any eye disease, and (3) subjects with (early) cataract in at least one eye. All subjects underwent a battery of glare and Stray Light tests, measurement of visual acuity, contrast sensitivity, refraction, and LOCS III cataract classification. Subjects answered a questionnaire on perceived disability during driving. Results: Repeatability values were similar for all glare/Stray Light tests. Validity (correlation with LOCS III and questionnaire scores), discriminative ability (ability to discriminate between the three groups), and added value (to measurement of visual acuity and contrast sensitivity) were all superior for both Stray Light meters. Results of successive measurements are interrelated for the conventional but not the new Stray Light meter. This indicates a better resistance to fraud for the latter device. Conclusions: The new computer implemented Stray Light meter is the most promising device for future Stray Light measurements.
Steven W. Brown - One of the best experts on this subject based on the ideXlab platform.
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simple spectral Stray Light correction method for array spectroradiometers
Applied Optics, 2006Co-Authors: Yuqin Zong, Steven W. Brown, Keith R. Lykke, Carol B Johnson, Yoshi OhnoAbstract:A simple, practical method has been developed to correct a spectroradiometer's response for measurement errors arising from the instrument's spectral Stray Light. By characterizing the instrument's response to a set of monochromatic laser sources that cover the instrument's spectral range, one obtains a spectral Stray Light signal distribution matrix that quantifies the magnitude of the spectral Stray Light signal within the instrument. By use of these data, a spectral Stray Light correction matrix is derived and the instrument's response can be corrected with a simple matrix multiplication. The method has been implemented and validated with a commercial CCD-array spectrograph. Spectral Stray Light errors after the correction was applied were reduced by 1-2 orders of magnitude to a level of approximately 10(-5) for a broadband source measurement, equivalent to less than one count of the 15-bit-resolution instrument. This method is fast enough to be integrated into an instrument's software to perform real-time corrections with minimal effect on acquisition speed. Using instruments that have been corrected for spectral Stray Light, we expect significant reductions in overall measurement uncertainties in many applications in which spectrometers are commonly used, including radiometry, colorimetry, photometry, and biotechnology.
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Correction of Stray Light in spectrographs: implications for remote sensing
Proceedings of SPIE, 2005Co-Authors: Yuqin Zong, Steven W. Brown, Keith R. Lykke, Bettye C. Johnson, Yoshihiro OhnoAbstract:ABSTRACT Spectrographs are used in a variety of ap plications in the field of remote sensing for radiometric measurements due to the benefits of measurement speed, sensitivity, and portability. However, spectrographs are single grating instruments that are susceptible to systematic errors arising from Stray radiation within the instrument. In the application of measurements of ocean color, Stray Light of the spectrographs has led to significan t measurement errors. In this work, a simple method to correct Stray-Light erro rs in a spectrograph is described. By measuring a set of monochromatic laser sources that cover the instrume nts spectral range, the instruments Stray-Light property is characterized and a Stray-Light correction matrix is derived. The matrix is then used to co rrect the Stray-Light error in me asured raw signals by a simple matrix multiplication, which is fast enough to be implemented in the spectrographs firmware or software to perform real-time corrections: an important feature for remote sensing applications. The results of corrections on real instruments demonstrated that the Stray-Light errors were reduced by one to two orders of magnitude, to a level of approximately 10
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Stray Light correction algorithm for spectrographs
Metrologia, 2003Co-Authors: Steven W. Brown, Michael Feinholz, M A Yarbrough, Stephanie J Flora, Keith R. Lykke, Carol B Johnson, Dennis K ClarkAbstract:In this paper, we describe an algorithm to correct a spectrograph's response for Stray Light. Two recursion relations are developed:?one to correct the system response when measuring broad-band calibration sources, and a second to correct the response when measuring sources of unknown radiance. The algorithm requires a detailed understanding of the effect of Stray Light in the spectrograph on the instrument's response. Using tunable laser sources, a dual spectrograph instrument designed to measure the up-welling radiance in the ocean was characterized for Stray Light. A?Stray-Light correction algorithm was developed, based on the results of these measurements. The instrument's response was corrected for Stray Light, and the effects on measured up-welling in-water radiance were evaluated.
L J Van Rijn - One of the best experts on this subject based on the ideXlab platform.
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measurement of Stray Light and glare comparison of nyktotest mesotest Stray Light meter and computer implemented Stray Light meter
British Journal of Ophthalmology, 2005Co-Authors: L J Van Rijn, C Nischler, D Gamer, L Franssen, R Kaper, D J Vonhoff, G Grabner, Helmut Wilhelm, H J Volkerdieben, T J T P Van Den BergAbstract:Aim: To evaluate the properties of devices for measuring Stray Light and glare: the Nyktotest, Mesotest, “conventional” Stray Light meter and a new, computer implemented version of the Stray Light meter. Methods: 112 subjects, divided in three groups: (1) young subjects without any eye disease; (2) elderly subjects without any eye disease, and (3) subjects with (early) cataract in at least one eye. All subjects underwent a battery of glare and Stray Light tests, measurement of visual acuity, contrast sensitivity, refraction, and LOCS III cataract classification. Subjects answered a questionnaire on perceived disability during driving. Results: Repeatability values were similar for all glare/Stray Light tests. Validity (correlation with LOCS III and questionnaire scores), discriminative ability (ability to discriminate between the three groups), and added value (to measurement of visual acuity and contrast sensitivity) were all superior for both Stray Light meters. Results of successive measurements are interrelated for the conventional but not the new Stray Light meter. This indicates a better resistance to fraud for the latter device. Conclusions: The new computer implemented Stray Light meter is the most promising device for future Stray Light measurements.
Dennis K Clark - One of the best experts on this subject based on the ideXlab platform.
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Stray Light correction algorithm for spectrographs
Metrologia, 2003Co-Authors: Steven W. Brown, Michael Feinholz, M A Yarbrough, Stephanie J Flora, Keith R. Lykke, Carol B Johnson, Dennis K ClarkAbstract:In this paper, we describe an algorithm to correct a spectrograph's response for Stray Light. Two recursion relations are developed:?one to correct the system response when measuring broad-band calibration sources, and a second to correct the response when measuring sources of unknown radiance. The algorithm requires a detailed understanding of the effect of Stray Light in the spectrograph on the instrument's response. Using tunable laser sources, a dual spectrograph instrument designed to measure the up-welling radiance in the ocean was characterized for Stray Light. A?Stray-Light correction algorithm was developed, based on the results of these measurements. The instrument's response was corrected for Stray Light, and the effects on measured up-welling in-water radiance were evaluated.
Keith R. Lykke - One of the best experts on this subject based on the ideXlab platform.
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simple spectral Stray Light correction method for array spectroradiometers
Applied Optics, 2006Co-Authors: Yuqin Zong, Steven W. Brown, Keith R. Lykke, Carol B Johnson, Yoshi OhnoAbstract:A simple, practical method has been developed to correct a spectroradiometer's response for measurement errors arising from the instrument's spectral Stray Light. By characterizing the instrument's response to a set of monochromatic laser sources that cover the instrument's spectral range, one obtains a spectral Stray Light signal distribution matrix that quantifies the magnitude of the spectral Stray Light signal within the instrument. By use of these data, a spectral Stray Light correction matrix is derived and the instrument's response can be corrected with a simple matrix multiplication. The method has been implemented and validated with a commercial CCD-array spectrograph. Spectral Stray Light errors after the correction was applied were reduced by 1-2 orders of magnitude to a level of approximately 10(-5) for a broadband source measurement, equivalent to less than one count of the 15-bit-resolution instrument. This method is fast enough to be integrated into an instrument's software to perform real-time corrections with minimal effect on acquisition speed. Using instruments that have been corrected for spectral Stray Light, we expect significant reductions in overall measurement uncertainties in many applications in which spectrometers are commonly used, including radiometry, colorimetry, photometry, and biotechnology.
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Correction of Stray Light in spectrographs: implications for remote sensing
Proceedings of SPIE, 2005Co-Authors: Yuqin Zong, Steven W. Brown, Keith R. Lykke, Bettye C. Johnson, Yoshihiro OhnoAbstract:ABSTRACT Spectrographs are used in a variety of ap plications in the field of remote sensing for radiometric measurements due to the benefits of measurement speed, sensitivity, and portability. However, spectrographs are single grating instruments that are susceptible to systematic errors arising from Stray radiation within the instrument. In the application of measurements of ocean color, Stray Light of the spectrographs has led to significan t measurement errors. In this work, a simple method to correct Stray-Light erro rs in a spectrograph is described. By measuring a set of monochromatic laser sources that cover the instrume nts spectral range, the instruments Stray-Light property is characterized and a Stray-Light correction matrix is derived. The matrix is then used to co rrect the Stray-Light error in me asured raw signals by a simple matrix multiplication, which is fast enough to be implemented in the spectrographs firmware or software to perform real-time corrections: an important feature for remote sensing applications. The results of corrections on real instruments demonstrated that the Stray-Light errors were reduced by one to two orders of magnitude, to a level of approximately 10
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Stray Light correction algorithm for spectrographs
Metrologia, 2003Co-Authors: Steven W. Brown, Michael Feinholz, M A Yarbrough, Stephanie J Flora, Keith R. Lykke, Carol B Johnson, Dennis K ClarkAbstract:In this paper, we describe an algorithm to correct a spectrograph's response for Stray Light. Two recursion relations are developed:?one to correct the system response when measuring broad-band calibration sources, and a second to correct the response when measuring sources of unknown radiance. The algorithm requires a detailed understanding of the effect of Stray Light in the spectrograph on the instrument's response. Using tunable laser sources, a dual spectrograph instrument designed to measure the up-welling radiance in the ocean was characterized for Stray Light. A?Stray-Light correction algorithm was developed, based on the results of these measurements. The instrument's response was corrected for Stray Light, and the effects on measured up-welling in-water radiance were evaluated.
