Accession Number : ADA138056

Title :   Analysis of Laser Spot Quality.

Descriptive Note : Master's thesis,


Personal Author(s) : Pitts,W. D.

Report Date : DEC 1983

Pagination or Media Count : 92

Abstract : A four-moment method is presented to analyze the quality of laser beam spots. The first four central moments are calculated on two-dimensional transverse intensity distributions of several laser spots. The four moments represent the center, spread, skewness, and peakness, respectively of the spot. A pure Gaussian and uniform intensity spot were included as controls. A photograph of each laser spot was scanned by a TV camera and digitized. Each spot generated 31K (31744) pixel elments of data. Each pixel was weighted by the intensity at that point. The data were then processed by a computer to get the moments. The first moment was reported as a pair of numbers, representing the coordinates of the center of the spot. The second, third and fourth moments were reported as four, eight and sixteen element tensors, respectively. An eigenvalue problem was formed from the second moment, yielding an angle of general spread from the center. Symmetric distributions, such as the Gaussian and uniform, showed near-zero third moments, as expected. The position of a spot only affected the first moment, as expected. The Gaussian and uniform distributions are ideals against which to compare other laser spots.

Descriptors :   *Laser spots, Quality, Laser beams, Pattern recognition, Statistical distributions, Eigenvalues, Method of moments, Computer programs, Collecting methods, Theses

Subject Categories : Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE