Validation of spectral radiance assignments to integrating sphere radiance standards for the Advanced Baseline Imager

2014 ◽  
Author(s):  
B. C. Johnson ◽  
Stephen Maxwell ◽  
Eric Shirley ◽  
Kim Slack ◽  
Gary D. Graham
Keyword(s):  
Spectral Radiance ◽  
Integrating Sphere

scholarly journals Adjustable light source for low light level with nearly constant correlated color temperature

2022 ◽  
Vol 2149 (1) ◽  
pp. 012016
Author(s):  
Z F Wu ◽  
L Li ◽  
C H Dai ◽  
Y F Wang ◽  
Q T Cheng ◽  
...  
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Light Level ◽  
Color Temperature ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Spectral Difference ◽  
Low Light ◽  
Light Levels ◽  
Variable Aperture

Abstract Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

Remote Raman Efficiencies and Cross-Sections of Organic and Inorganic Chemicals

2016 ◽  
Vol 71 (5) ◽  
pp. 1025-1038 ◽  
Author(s):  
Tayro E. Acosta-Maeda ◽  
Anupam K. Misra ◽  
John N. Porter ◽  
David E. Bates ◽  
Shiv K. Sharma
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Fused Silica ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Organic Liquids ◽  
Experimental Conditions ◽  
Phosphate Ions ◽  
The University ◽  
532 Nm

We determined Raman cross-sections of various organic liquids and inorganic polyatomic ions in aqueous solutions with a 532 nm pulsed laser using remote Raman systems developed at the University of Hawaii. Using a calibrated integrating sphere as a light source, we converted the intensity counts in the spectrum of the light from the integrating sphere measured with UH remote Raman instrument to spectral radiance. From these data, a response function of the remote Raman instrument was obtained. With the intensity-calibrated instrument, we collected remote Raman data from a standard 1 mm path length fused silica spectrophotometer cell filled with cyclohexane. The measured value of the differential Raman cross-section for the 801 cm−1 vibrational mode of cyclohexane is 4.55 × 10−30 cm2 sr−1 molecule−1 when excited by a 532 nm laser, in good agreement with the values reported in the literature. Using the measured cyclohexane Raman cross-section as a reference and relative Raman mode intensities of the various ions and organic liquids, we calculated the Raman cross-sections of the strongest Raman lines of nitrate, sulfate, carbonate, phosphate ions, and organic liquids by maintaining same experimental conditions for remote Raman detection. These relative Raman cross-section values will be useful for estimating detection capabilities of remote Raman systems for planetary exploration.

A New Kind of Integrating Sphere Radiation Calibration System for Satellite Remote Sensors

2012 ◽  
Vol 500 ◽  
pp. 569-573
Author(s):  
Ting Liang Guo ◽  
Guo Jin Feng ◽  
Yu Wang ◽  
Ying Wei He
Keyword(s):  
Light Exposure ◽  
Field Of View ◽  
Flash Lamp ◽  
Large Field ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Wave Band ◽  
Calibration System ◽  
Remote Sensors ◽  
Remote Sensor

A new kind of half integrating sphere radiation system that has the adjustable area of radiating surface in the 380nm-2500nm wave band is introduced in this paper. The opening diameter of the integrating sphere reaches to Φ600mm. Half Integrating sphere radiation system is mainly composed of a half sphere, extension part, cyclic annular baffles and other components. The diameter of half-integrating sphere is Φ1800mm. The radiance uniformity through opening reaches up to 98%. Systems can now be used for all types of large field of view of satellite remote sensor for the calibration of spectral radiance; in addition, it can also be applied for various types of light exposure calibration such as flash lamp and so on.

scholarly journals ESTIMATION OF THE SPECTRAL SENSITIVITY FUNCTIONS OF UN-MODIFIED AND MODIFIED COMMERCIAL OFF-THE-SHELF DIGITAL CAMERAS TO ENABLE THEIR USE AS A MULTISPECTRAL IMAGING SYSTEM FOR UAVS

2015 ◽  
Vol XL-1/W4 ◽  
pp. 207-214 ◽  
Author(s):  
E. Berra ◽  
S. Gibson-Poole ◽  
A. MacArthur ◽  
R. Gaulton ◽  
A. Hamilton
Keyword(s):  
Open Source ◽  
Spectral Sensitivity ◽  
Multispectral Imaging ◽  
Spectral Response ◽  
Monochromatic Light ◽  
Imaging Systems ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Digital Cameras ◽  
Commercial Off The Shelf

Commercial off-the-shelf (COTS) digital cameras on-board unmanned aerial vehicles (UAVs) have the potential to be used as multispectral imaging systems; however, their spectral sensitivity is usually unknown and needs to be either measured or estimated. This paper details a step by step methodology for identifying the spectral sensitivity of modified (to be response to near infra-red wavelengths) and un-modified COTS digital cameras, showing the results of its application for three different models of camera. Six digital still cameras, which are being used as imaging systems on-board different UAVs, were selected to have their spectral sensitivities measured by a monochromator. Each camera was exposed to monochromatic light ranging from 370 nm to 1100 nm in 10 nm steps, with images of each step recorded in RAW format. The RAW images were converted linearly into TIFF images using DCRaw, an open-source program, before being batch processed through ImageJ (also open-source), which calculated the mean and standard deviation values from each of the red-green-blue (RGB) channels over a fixed central region within each image. These mean values were then related to the relative spectral radiance from the monochromator and its integrating sphere, in order to obtain the relative spectral response (RSR) for each of the cameras colour channels. It was found that different un-modified camera models present very different RSR in some channels, and one of the modified cameras showed a response that was unexpected. This highlights the need to determine the RSR of a camera before using it for any quantitative studies.

Research of UV Spectral Radiance Characteristics of the Integrating Sphere Based on Calibration by the Absolute Radiance Radiometer

2011 ◽  
Vol 38 (10) ◽  
pp. 1008007 ◽  
Author(s):  
杨小虎 Yang Xiaohu ◽  
王淑荣 Wang Shurong ◽  
曲艺 Qu Yi ◽  
黄煜 Huang Yu ◽  
林冠宇 Lin Guanyu
Keyword(s):  
Spectral Radiance ◽  
Integrating Sphere ◽  
The Absolute

scholarly journals Realization of the Radiance Scale Using Transfer Function of the Laser-Based Optical System

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
M. Kilin ◽  
H. Tutunculer ◽  
O. Bazkir ◽  
S. Meric
Keyword(s):  
Focal Length ◽  
Laser Wavelength ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Current Response ◽  
Silicon Photodiode ◽  
Yag Lasers ◽  
Radiation Sources ◽  
Measurement Results ◽  
Low Uncertainty

This work aims to determine the radiance responsivity to be used in the calibration of polychromatic radiation sources with low uncertainty. To realize the radiance, Ar-ion, He-Ne, and Nd-YAG lasers as well as an integrating sphere with a 0.15 m diameter are used to obtain radiation sources having Lambertian distributions. Then, a silicon photodiode-based reflection-type trap detector with calibrated precision aperture, which is traceable to a liquid helium cooled laser-based cryogenic radiometer, is used to measure the photocurrent corresponding to each wavelength and thereby to obtain radiance. The proposed system, which measures the spectral current response of this laser-based radiance, is a double-grating monochromator with a 2 × 300 mm focal length and triple gratings in each of its turrets. First, the radiance of the laser beam that emerged from the integrating sphere is calculated, and then the radiance responsivity of the system is obtained by measuring the photocurrent outputted from the exit slit of the monochromator at each laser wavelength. Finally, the spectral radiance values of the polychromatic lamps are obtained using the radiance responsivity of the system. Consequently, the study aims to develop the derivation and better understand traceability of the other radiometric and photometric quantities with low uncertainty from the fundamental radiometric radiance unit. Measurement results obtained in the expanded measurement uncertainty scale are determined using both classical and Monte Carlo methods.

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