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Xiaoxiong Xiong - One of the best experts on this subject based on the ideXlab platform.
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pre launch characterization of aqua modis scan mirror response versus scan angle for thermal emissive bands
Proceedings of SPIE, 2007Co-Authors: Kwofu Chiang, Xiaoxiong XiongAbstract:The double-sided paddle wheel scan mirror is the Key Optical Component of the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the NASA EOS Terra and Aqua satellites. At a constant rotating speed, the scan mirror continuously reflects the Earth's top-of-atmosphere radiances through the instrument nadir aperture door and onto four focal plane assemblies (FPA), which consist of 36 spectral bands. Of those 36 bands, 16 are thermal emissive bands (TEB) with wavelengths ranging from 3.7 to 14.4μm. While this cross-track scanning system provides the Earth scene observations over a range of ±55° viewing angles from the nadir, the on-orbit calibration for TEB is performed by an On-Board Calibrator Blackbody (OBC BB) at a fixed viewing angle. The response versus scan angle (RVS) of the scan mirror is sensitive to the MODIS radiometric calibration. This paper describes how the pre-launch TEB RVS of the Aqua MODIS was characterized at the instrument system level by using ground support equipment, a Blackbody Calibration Source (BCS). The RVS test setup, test procedure, data analysis, derivation of RVS, and the fitting uncertainty are discussed in the paper. A separate paper that gives similar RVS analysis for the MODIS Reflective Solar Bands (RSB) is presented in this proceeding.
Kwofu Chiang - One of the best experts on this subject based on the ideXlab platform.
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pre launch characterization of aqua modis scan mirror response versus scan angle for thermal emissive bands
Proceedings of SPIE, 2007Co-Authors: Kwofu Chiang, Xiaoxiong XiongAbstract:The double-sided paddle wheel scan mirror is the Key Optical Component of the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the NASA EOS Terra and Aqua satellites. At a constant rotating speed, the scan mirror continuously reflects the Earth's top-of-atmosphere radiances through the instrument nadir aperture door and onto four focal plane assemblies (FPA), which consist of 36 spectral bands. Of those 36 bands, 16 are thermal emissive bands (TEB) with wavelengths ranging from 3.7 to 14.4μm. While this cross-track scanning system provides the Earth scene observations over a range of ±55° viewing angles from the nadir, the on-orbit calibration for TEB is performed by an On-Board Calibrator Blackbody (OBC BB) at a fixed viewing angle. The response versus scan angle (RVS) of the scan mirror is sensitive to the MODIS radiometric calibration. This paper describes how the pre-launch TEB RVS of the Aqua MODIS was characterized at the instrument system level by using ground support equipment, a Blackbody Calibration Source (BCS). The RVS test setup, test procedure, data analysis, derivation of RVS, and the fitting uncertainty are discussed in the paper. A separate paper that gives similar RVS analysis for the MODIS Reflective Solar Bands (RSB) is presented in this proceeding.
Lianxiang Yang - One of the best experts on this subject based on the ideXlab platform.
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unified approach for holography and shearography in surface deformation measurement and nondestructive testing
Optical Engineering, 2003Co-Authors: M Y Y Hung, H.m. Shang, Lianxiang YangAbstract:Holography and shearography are two useful whole-field non- contacting Optical tools for nondestructive flaw detection and precision measurements. Holography serves as a displacement transducer since it gives direct measurements on displacements whereas shearography serves as a strain gage since it gives direct measurements on displace- ment gradients. This paper views holography and shearography and their variations as a single Optical technique having the same basic mathematical formulation and instrumentation. A Key Optical Component used in both techniques is a doubly-refractive prism that combines two angularly separated laser rays to interfere at near collinearity, thereby permitting the use of a low-resolution CCD camera for recording the interference pattern. Shearography uses a doubly-refractive prism with small image shearing so that two neighboring points on the test surface are brought to interfere at the image plane of the camera, whereas ho- lography, on the other hand, uses a doubly-refractive prism with large image shearing so that light scattered from two different objects—a test object and a reference surface (serving as a reference beam)—are brought to interfere at the image plane of the camera. Hence, testing and measurements made using holography may also be made using shearography, and vice versa. © 2003 Society of Photo-Optical Instrumentation
M Y Y Hung - One of the best experts on this subject based on the ideXlab platform.
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unified approach for holography and shearography in surface deformation measurement and nondestructive testing
Optical Engineering, 2003Co-Authors: M Y Y Hung, H.m. Shang, Lianxiang YangAbstract:Holography and shearography are two useful whole-field non- contacting Optical tools for nondestructive flaw detection and precision measurements. Holography serves as a displacement transducer since it gives direct measurements on displacements whereas shearography serves as a strain gage since it gives direct measurements on displace- ment gradients. This paper views holography and shearography and their variations as a single Optical technique having the same basic mathematical formulation and instrumentation. A Key Optical Component used in both techniques is a doubly-refractive prism that combines two angularly separated laser rays to interfere at near collinearity, thereby permitting the use of a low-resolution CCD camera for recording the interference pattern. Shearography uses a doubly-refractive prism with small image shearing so that two neighboring points on the test surface are brought to interfere at the image plane of the camera, whereas ho- lography, on the other hand, uses a doubly-refractive prism with large image shearing so that light scattered from two different objects—a test object and a reference surface (serving as a reference beam)—are brought to interfere at the image plane of the camera. Hence, testing and measurements made using holography may also be made using shearography, and vice versa. © 2003 Society of Photo-Optical Instrumentation
H.m. Shang - One of the best experts on this subject based on the ideXlab platform.
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unified approach for holography and shearography in surface deformation measurement and nondestructive testing
Optical Engineering, 2003Co-Authors: M Y Y Hung, H.m. Shang, Lianxiang YangAbstract:Holography and shearography are two useful whole-field non- contacting Optical tools for nondestructive flaw detection and precision measurements. Holography serves as a displacement transducer since it gives direct measurements on displacements whereas shearography serves as a strain gage since it gives direct measurements on displace- ment gradients. This paper views holography and shearography and their variations as a single Optical technique having the same basic mathematical formulation and instrumentation. A Key Optical Component used in both techniques is a doubly-refractive prism that combines two angularly separated laser rays to interfere at near collinearity, thereby permitting the use of a low-resolution CCD camera for recording the interference pattern. Shearography uses a doubly-refractive prism with small image shearing so that two neighboring points on the test surface are brought to interfere at the image plane of the camera, whereas ho- lography, on the other hand, uses a doubly-refractive prism with large image shearing so that light scattered from two different objects—a test object and a reference surface (serving as a reference beam)—are brought to interfere at the image plane of the camera. Hence, testing and measurements made using holography may also be made using shearography, and vice versa. © 2003 Society of Photo-Optical Instrumentation
