Fourier transform holography using pseudo-random phase shifting of object illuminating beams and apodization
US4013338A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 1976 |
| Grant date | Mar 22, 1977 |
| Priority date | — |
| Expiry date | Jan 26, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase mask comprised of a square array of phase shifting areas arranged in pseudo-random pattern is illuminated with a beam of electromagnetic radiation, as a result of which an array of pseudo-randomly phase shifted beams emerges from the phase mask and impinges upon an object transparency to be intensity-modulated thereby and come to a focus on a Fourier transform plane. The power spectrum of the beams distributes in orthogonal directions on the Fourier transform plane from its center maxima in a distinct pattern of series of fringes. The technique of apodization is employed to suppress the fringes to thereby reduce the coherent noise of a hologram to a minimum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.