US 4,275,454 A · Optical system phase error compensator

Abstract

A method for compensating for phase errors in an optical data processing system for performing a Fourier transformation analysis of a data source. The aberrations of the system are holographically recorded by passing an object beam through the system and the optical data source in a direction opposite to that of the DC read beam used in the transformation analysis. The object beam and a reference beam derived from a common coherent light source are generated by the system and directed to an optical memory wherein the interference pattern between the object and reference beam is recorded. The data source is analyzed by providing a read beam incident the optical memory along a path in the reverse direction of the reference beam. In such manner, a reconstruction beam emanating from the hologram is directed back through the data source to display the Fourier transform of the data in the data source. The reconstruction beam thus serves to automatically compensate for phase errors introduced into the system by thickness variations of the data source as well as from the lenses in the system.

Claims12

Dependent claims

A method of compensating for phase errors in an optical data processing system having a plurality of lenses for displaying the Fourier transformation of optical data contained in a data source, said method comprising:

generating a reference and object beam from a coherent light source;
passing the object beam in a given direction through the lenses and data source of the data processing system;
using a low frequency spatial filter to pass only low frequency components of the object beam incident said data source;
directing the filtered object beam and reference beam to an optical memory;
storing the interference pattern between the object beam and the reference beam in the optical memory as a hologram whereby low spatial frequency phase errors of the system are recorded;
and
reading the data from the data source by providing a read beam incident said memory along a path in the reverse direction of the reference beam, with the hologram stored in the memory providing a reconstruction beam which passes back through the same lenses and through the data source opposite to said given direction to a plane at which the Fourier transformation of the data is displayed, thereby compensating for the phase errors in the system data source and lenses.

4 more elements

Dependencies are inferred from the claim text.

Optical system phase error compensator

Life of this patent

Optical system phase error compensator

Life of this patent

Abstract

Claims12