Out Of Field Of View Rejection Measurements Of The ZIP Telescope #2

Recent re-measurement of the Out-of Filed-of View-Rejection (OFVR) characteristics of the ZIP telescope #2 indicated that the Point Source Power Transmittance (PSPT) was increased by as much as a factor of 400 at one off-axis source orientation in comparison with the OFVR measurement of the identical telescope three years ago. The OFVR degradation was caused by particulate contamination of the telescope optical surfaces. After cleaning of the primary mirror, the OFVR performance was restored for off-axis angles of 2 degrees to 7 degrees, but the OFVR was still degraded by a factor of 2 to 20 for off-axis angles between 8 degrees to 15 degrees. This remaining degradation was also restored after cleaning of the secondary mirror. Since the original OFVR measurement, the telescope package was opened about 10 times in a Class 100 clean room environment for intergration and testing and was exposed to Class 100 environment 3 to 4 days at a time. Subsequently, the telescope was sealed and stored in an evacuated vessel at room temperature for two years.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.