Advanced Multidither Coat Studies.
Abstract
Multidither adaptive optics systems are vulnerable to interference caused by the motion of a speckle pattern across the receiver aperture. This program investigated various techniques for reducing or canceling this interference. Several concepts were studied. A very promising one, which we call ASPECT II, was demonstrated with an experimental laboratory COAT system. Computer simulations and experimental data show that with ASPECT-II it is possible to almost completely restore speckle degraded performance of multidither COAT systems. An extensive analysis that explicitly illustrates how speckle effects interfere with COAT operations has been developed. It shows that the primary effect is to amplitude modulate the usual point source intensity distribution reflected from a target glint. With large targets, there is also an additive noise contribution from the receiver spatial intensity variations associated with reflections from the area surrounding the target focal spot. This analysis is also used to explain the operations of the ASPECT-I and ASPECT-II speckle cancelation schemes. Experimental data showing ASPECT cancelation of simulated speckle modulations is presented. The experiments show that the laboratory ASPECT system can cancel single-frequency and broadband modulations within the COAT dither band.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1979
- Accession Number
- ADA068005
Entities
People
- R. C. Lind
- S. A. Kokorowski
- T. Calderone
- T. R. O'meara
Organizations
- HRL Laboratories