1 June 1996 New technique for ray aberration detection in Hartmanngrams based on regularized bandpass filters
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Optical Engineering, 35(6), (1996). doi:10.1117/1.600743
Abstract
The Hartmann test is a well-known technique for testing large telescopes mirrors. The Hartmann technique samples the wavefront under analysis using a screen of a uniformly spaced array of holes located at the pupil’s plane. The traditional technique used to gather quantitative data requires the measurement of the centroid of these holes as imaged near the paraxial focus. The deviation from its unaberrated uniform position is proportional to the slope of the wavefront’s asphericity. The centroid estimation is normally done manually with the aid of a microscope or a densitometer. Traditional techniques for carrier frequency fringe analysis cannot be used to analyze Hartmanngrams because this pattern contains many spatial frequencies hard to eliminate using standard linear filters. Also due to the finite extent of the pupils, Fourier transform methods and convolution filters with large support are not well suited for the analysis. We propose a new technique based on regularized bandpass filters to detect the transverse aberration in Hartmanngrams. These filters are used to transform the distorted 2-D dot pattern of the Hartmanngram into two orthogonal linear-carrier phase-modulated cosinusoidal gratings. The resulting cosinusoidal fringe patterns are then well suited for the analysis using highly sensitive 2-D carrier frequency phase estimation techniques such as direct interferometry.
Manuel Servin Guirado, Daniel Malacara-Hernandez, Jose Luis Marroquin Zaleta, Francisco J. Cuevas-de-la-Rosa, "New technique for ray aberration detection in Hartmanngrams based on regularized bandpass filters," Optical Engineering 35(6), (1 June 1996). http://dx.doi.org/10.1117/1.600743
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KEYWORDS
Wavefronts

Fringe analysis

Bandpass filters

Linear filtering

Photography

Monochromatic aberrations

Chromatic aberrations

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