1、Lessons Learned Entry: 1595Lesson Info:a71 Lesson Number: 1595a71 Lesson Date: 2005-02-10a71 Submitting Organization: LARCa71 Submitted by: Kimberly Graupnera71 Authored by: Ron HuppiSubject: Interferometer Design Abstract: The Focal Plane Arrays (FPAs)-to-Read-Only Integrated Circuits (ROICs) timin
2、g and frame synchronization for imaging interferometers are significantly different than those typically used in radiometric cameras and other similar FPA applications. Because the Michelson interferometer used on GIFTS utilizes a translating end mirror to change and continuously scan the optical pa
3、th, the frames of FPA are collected at constant Optical Path Difference (OPD) intervals over the entire scan. The interferometer mirrors translation rate and its corresponding OPD change rate are not perfectly linear. Thus, the FPA collection frame rate will vary with time. Description of Driving Ev
4、ent: A metrology laser is used within the interferometer to measure the interferometers OPD position and change rate so that the FPA collection frames and the corresponding integrations times can be controlled. However, the frames coming out of the ROICs are typically resynchronized with time. Imagi
5、ng interferometer sensor systems are offering broader capabilities and performance characteristics through the use of large field of view and data throughput. But system performance can easily be compromised by FPAs and ROICs that are not fully compatible with operational capabilities and performanc
6、e requirements of the interferometer. The FPAs and ROICs should be designed, fabricated, and tested to meet the spectral, spatial, temporal, radiometric, control, and stability requirements needed to achieve the specified performance of the interferometer. FPA technologies can be overstressed by ove
7、r-extending the longwave spectral cutoff point. This is especially true of long wave FPAs. Keeping the cutoff as short as possible can significantly improve FPA yield and performance and can reduce the cooling requirements for currently available technologies. Thus, the recommendation is to choose F
8、PAs with the shortest cutoff wavelength that will still accomplish the desired science measurements. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) Learned: Fully understand the spectral, spatial, temporal, radiometric, control, and stabil
9、ity requirements of the interferometer before committing to the FPA and ROIC designs. Ensure that the FPA, ROICs, and their interactions will not compromise system performance. Measured ROIC noise is currently predicted to be the largest contributor to total system noise for the Geosynchronous Imagi
10、ng Fourier Transform Spectrometer (GIFTS) sensor. Make all attempts to limit the ROIC noise to values close to the theoretically predicted limits. ROICs are not off-the-shelf devices and additional runs may be needed to refine the designs to meet the customized FPA-to-ROIC requirements of the interf
11、erometer. Project funding and scheduling should take ROICs reworks into account. Recommendation(s): Make attempts to limit the ROIC noise to values close to the theoretically predicted limits. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a7
12、1 ScienceAdditional Key Phrase(s): a71 Research & DevelopmentAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2007-04-20a71 Approval Name: ghendersona71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
