Dr. Earl Spillar (AFRL), Marjorie Shoemake (AFRL and The Boeing Corporation), Ann Slavin (AFRL and The Boeing Corporation)
Keywords: Instrumentation, Sensors & Systems
Abstract:
The Starfire Optical Range has developed an atmospheric turbulence monitor (Starfire Atmospheric Monitor, or SAM), which uses wave front distortions to measure the Fried parameter, the Greenwood parameter and scintillation parameter simultaneously. SAM differs from Differential Image Motion Monitor (DIMM) instruments in that it measures the atmosphere with a Shack Hartman wavefront sensor. Shack Hartman wavefront sensors have been used to monitor the atmosphere in the past; however SAM enables these measurements to be made with a dedicated instrument that can sample at higher spatial frequencies than most adaptive optics systems. Compared to DIMM instruments, rapid statistically accurate measurements of the Fried parameter (r0) can be made with SAM because it measures and calculates many differential tilts simultaneously. Furthermore, because SAM utilizes a 4-by-4 set of detector elements for each subaperture instead of a quad cell it can measure r0 values down to 1cm.
This paper provides a basic overview and operation of the instrument. We discuss the construction of SAM including the telescope, optics, camera, and electronics. We then will discuss the data reduction and calculation of the Fried parameter (r0) from differential tilt data. The basic capabilities of SAM, including day/night operation, limiting star magnitudes, and the validation of SAM will also be discussed. We present initial measurements of r0 measured by SAM. Finally, we discuss other measurements SAM will be able to make.
Date of Conference: September 1-4. 2009
Track: Instrumentation, Sensors & Systems