Dual-domain point diffraction interferometer

Patent · Fri Dec 31 23:00:00 EST 1999

OSTI ID:873147

Naulleau, Patrick P ^[1]; Goldberg, Kenneth Alan ^[2]

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1. 5239 Miles Ave., Apt. A, Oakland, CA 94618
2. 1195 Keeler Ave., Berkeley, CA 94708

A hybrid spatial/temporal-domain point diffraction interferometer (referred to as the dual-domain PS/PDI) that is capable of suppressing the scattered-reference-light noise that hinders the conventional PS/PDI is provided. The dual-domain PS/PDI combines the separate noise-suppression capabilities of the widely-used phase-shifting and Fourier-transform fringe pattern analysis methods. The dual-domain PS/PDI relies on both a more restrictive implementation of the image plane PS/PDI mask and a new analysis method to be applied to the interferograms generated and recorded by the modified PS/PDI. The more restrictive PS/PDI mask guarantees the elimination of spatial-frequency crosstalk between the signal and the scattered-light noise arising from scattered-reference-light interfering with the test beam. The new dual-domain analysis method is then used to eliminate scattered-light noise arising from both the scattered-reference-light interfering with the test beam and the scattered-reference-light interfering with the "true" pinhole-diffracted reference light. The dual-domain analysis method has also been demonstrated to provide performance enhancement when using the non-optimized standard PS/PDI design. The dual-domain PS/PDI is essentially a three-tiered filtering system composed of lowpass spatial-filtering the test-beam electric field using the more restrictive PS/PDI mask, bandpass spatial-filtering the individual interferogram irradiance frames making up the phase-shifting series, and bandpass temporal-filtering the phase-shifting series as a whole.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
• DOE Contract Number: AC03-76SF00098
• Assignee: Naulleau, Patrick P. (5239 Miles Ave., Apt. A, Oakland, CA 94618);Goldberg, Kenneth Alan (1195 Keeler Ave., Berkeley, CA 94708)
• Patent Number(s): US 6100978
• OSTI ID: 873147
• Country of Publication: United States
• Language: English

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