Accession Number : ADA305562

Title :   Maximum Likelihood Estimation of Wave Front Slopes using a Hartmann-type Sensor.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Sallberg, Scott A.

PDF Url : ADA305562

Report Date : DEC 1995

Pagination or Media Count : 72

Abstract : Current methods for estimating the wave front slope at the pupil of a telescope equipped with a Hartmann-type wave front sensor (H-WFS) are based on a simple centroid calculation of the intensity distributions (spots) recorded in each subaperture of the H-WFS. The centroid method does not include any knowledge concerning correlation properties of the slopes over the subapertures or the amount of light collected by the telescope and diverted to the H-WFS for wave front reconstruction purposes. This thesis devises a maximum likelihood (ML) estimation of the spot centroids by incorporating statistical knowledge of the spot shifts. The light level in each subaperture and the relative spot size is also employed by the shift estimator. The shift estimator is found to be unbiased and is upper bounded by the mean squared error performance exhibited by the classical centroid technique.

Descriptors :   *ATMOSPHERIC DISTURBANCES, *COMPENSATION, *TELESCOPES, *ADAPTIVE OPTICS, COMPUTATIONS, DISTRIBUTION, MAXIMUM LIKELIHOOD ESTIMATION, THESES, ESTIMATES, CORRELATION, WAVEFRONTS.

Subject Categories : Optical Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE