US 4,937,786 A · Binary hologram transducer using magnetic bubbles

Abstract

A hologram transducer using the Faraday effect in magnetic bubble devices for recording and reproducing the amplitude and phase distributions over a section of a beam of coherent light is disclosed. The transducer spatially modulates the intensity, by using linear polarization, and the phase, by using circular polarization, of light transmitted through a magnetic bubble device. Using linear polarization and a single magnetic bubble domain to traverse in a sequence the possible storage positions in the magnetic bubble device, the transducer samples at each of these positions the intensity of the transmitted light. Using in addition a coherent reference beam of light to interfere with the light being measured, the transducer samples the phase in the half range of 0 through .pi. radians at these positions. Further, using a quarter cycle phase shift in the reference beam, the transducer resolves the phase values over the full range of 0 through 2.pi. radians. Because of the localization of the sample values by the magnetic bubbles to the order of the wavelength of the light, optical holograms may be directly recorded as electrical signals by the transducer and the corresponding images reconstructed by the transducer from the electrical signals.

Claims14

Dependent claims

An optical sampling and modulating device for sampling the amplitude and the phase of a beam of light from a coherent source at a set of sampling points over a cross-section of the said beam, with localization approaching the wavelength of the said light, comprising

a magnetic bubble array layer placed at the said cross-section so that the said light tends to pass through the layer,
a polarizer means located in the path of the said light to polarize the said light before the said light reaches the said layer,
a second polarizer means located in the path of the said light after the said layer, to selectively transmit one of the two portions of the said light, the portion which passed through magnetic bubbles in the said layer and the portion which did not,
a photodetector means to measure the light emerging from the second polarizer means,
a reference beam of light coherent with the said source and interfering with the first beam at the said cross-section,
a phase-shifting means located in the path of the said reference beam before the reference beam reaches the said layer, to shift the phase of the said reference beam,
and a bubble layer control means to position a single magnetic bubble successively at each of the said sampling points to measure the amplitude and the phase of the said first beam at that sampling point,
in which the said reference beam is turned off to measure the amplitude of the said first beam,
in which the said reference beam is turned on to determine the phase of the said first beam in the half range of 0 through .pi. radians, and in which the phase of the said reference beam is shifted by the said phase-shifting means by a quarter cycle to further resolve the phase of the said first beam over the full range 0 through 2.pi. radians at each of the said sampling points.

6 more elements

Dependencies are inferred from the claim text.

Binary hologram transducer using magnetic bubbles

Life of this patent

Binary hologram transducer using magnetic bubbles

Life of this patent

Abstract

Claims14