Fourier-transform holography by pseudo-random phase shifting
US4037918A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1975 |
| Grant date | Jul 26, 1977 |
| Priority date | — |
| Expiry date | Jul 31, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/1871
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase mask comprised of a rectangular array of phase shifting areas arranged in a pseudo-random pattern is illuminated with a beam of electromagnetic radiation. The array of pseudo-randomly phase shifted beams is focused on a Fourier transform plane on which the power spectrum of the beams distributes in two orthogonal directions from its center maxima. The phase shifting areas are arranged in such a manner that there is an approximately equal number of phase shifts for each of the different phase shifting areas with a constant phase relation between orthogonally adjacent phase shifting areas. The center maxima of the spectrum is confined to a rectangular-shaped area and uniformly distributed by suitably selecting the number of different phase shifts. Coherent noise on the reconstructed image is effectively eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.