Abstract

This method of optical image subtraction makes use of the extremely high demagnification and the large image densities involved in the multiple-imaging effect obtained with photographic diffusers. A coarse grid of period equal to 25 mm is multiply imaged by the diffuser, which represents a photographic recording of a fine-grain speckle distribution. An in-plane displacement of the coarse grid produces an equivalent motion in each of the multiple-image gratings that modulate the input transparencies. This means that the π-rad phase shift between them can be obtained by operating on the coarse grid, thus increasing the accuracy of phase shifting by a factor equal to the demagnification of the imaging process. A description of the method, supported by experimental results, is given.

© 1984 Optical Society of America

Observation of a phase object using a multipinhole camera

A. G. Apostolidis and E. D. Vanidhis
Appl. Opt. 25(23) 4321-4324 (1986)

Spectral and imaging properties of uniform diffusers

Marek Kowalczyk
J. Opt. Soc. Am. A 1(2) 192-200 (1984)

Imaging with photographic diffusers

C. P. Grover and R. Tremblay
Appl. Opt. 21(24) 4500-4504 (1982)

Generation of optimum random pinhole arrays for multiple imaging

A. Senthil Kumar and R. M. Vasu
Appl. Opt. 26(18) 3858-3861 (1987)

Detection of gratings hidden by diffusers using intensity interferometry

D. Newman and J. C. Dainty
J. Opt. Soc. Am. A 1(4) 403-411 (1984)