Wavefront Estimation for Adaptive Optics.
Abstract
The first step in obtaining maximum irradiance on an object or for image compensation is that of wavefront diagnostics. This report considers the use of estimation theory techniques in order to diagnose the required wavefront changes for wavefront control. The control elements can be the adjustment of the focal length of a Cassegrain telescope by changing the distance between the primary and secondary mirrors, the control of a tilt mirror, and the control of a deformable mirror. This paper considers the use of an extended Kalman filter in order to obtain estimates of the diffraction focus position and the target range from a measurement of the reflected irradiance. The measurement is obtained by a detector with a wide field of view located near the location of the Cassegrain telescope. As the detector gain of an irradiance measurement is a function of certain target characteristics and as these characteristics may only be nominally known, a scale factor error in the detector gain is introduced and estimated. The laser system considered transmits a focused, truncated Gaussian beam at 10.6 micrometer wavelength. However the filter can be used for other wavelengths.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1976
- Accession Number
- ADA028586
Entities
People
- Robert B. Asher
Organizations
- United States Air Force Academy