Light modulator by gated interferometry

Claim 2

A light modulator for collimated radiation comprising means for dividing an incident beam of collimated quasi-monochromatic radiation along two beam paths, means for recombining the divided beam in such a nonparallel manner as to cause them to interfere with one another producing a spatial fringe pattern exhibiting plural radiation maxima and radiation minima, fixed means having optically opaque and optically transparent areas regularly spaced in such a manner as to enable either the opaque or the transparent ares to be aligned with the fringe maxima or fringe minima, and means in at least one of the divided beam paths and responsive to electrical signals for controllably changing the length of said optical path and thereby spatially shifting the said interfering fringe pattern relative to the fixed optical means thereby changing the light output therethrough.

Claim 3

A light modulator as set forth in claim 1 wherein the optical path length changing means comprises an electro-optic material in said optical path and means for applying an electric field in the megacycle or higher range to said electro-optic material to change its index of refraction to modify the length of the optical path by approximately one-half a wavelength.

Claim 4

A light modulator as set forth in claim 1 wherein the optically opaque and transparent means comprises a slotted mask.

Claim 5

A light modulator as set forth in claim 1 wherein the two beams are recombined at a small angle to produce the spatial fringe pattern.

Claim 6

A light modulator as set forth in claim 9 wherein the electric field applying means comprises electrodes applied to both reflecting surfaces, one of said reflecting surfaces being slightly off-parallel with respect to said other reflecting surface.

Claim 7

A light modulator as set forth in claim 5 wherein the optically opaque and optically transparent means comprises a slotted mask provided on the exiting surface of the other body.

Claim 8

A light modulator for collimated radiation comprising means for dividing an incident plane polarized beam of collimated quasi-monochromatic radiation along two beam paths, means for recombining the divided beam in nonparallel relationship so as to cause them to interfere with one another producing a spatial fringe pattern exhibiting radiation maxima and radiation minima, means having plural optically opaque and plural optically transparent areas regularly spaced in such a manner as to enable the opaque areas to be aligned with the fringe maxima, and means in at least one of the divided beam paths and responsive to electrical signals for rotation the plane of polarization of the beam in said optical path up to 90* and thereby destroy the said interfering fringe pattern thereby increasing the light output through the output means.

Claim 9

A light modulator for collimated radiation comprising means for dividing an incident plane polarized beam of collimated quasi-monochromatic radiation along two beam paths, means for recombining the divided beam in nonparallel relationship so as to cause them to interfere with one another producing a spatial fringe pattern exhibiting radiation maxima and radiation minima, means having plural optically opaque and plural optically transparent areas regularly spaced in such a manner as to enable the opaque areas to be aligned with the fringe maxima, and means in at least one of the divided beam paths and responsive to electrical signals for rotation the plane of polarization of the beam in said optical path up to 90* and thereby destroy the said interfering fringe pattern thereby increasing the light output through the output means.

Claim 10

A light modulator as set forth in claim 7 wherein the last-named means comprises a Faraday rotator.

Claim 11

A light modulator for collimated radiation comprising a first body of substantially optically transparent electro-optic material, a second body of substantially optically transparent material, a beam-splitting mirrored surface on one of said fist and second bodies, the other of said first and second bodies being joined to said one body at said beam-splitting mirrored surface, said one body also having a beam-receiving surface and an adjacent reflecting surface, said other body having a beam-exiting surface and an adjacent reflecting surface, said surfaces being oriented in such manner that an incident beam entering said one body at said receiving surface will impinge upon the beam-splitting surface dividing the incident beam into two beams, the first of which will be reflected by the beam-splitting surface towards the one-body reflecting surface from which it is reflected towards the beam-splitting surface where a portion of it will enter the other body, and the second of which after entering the other body will reflect off the other body reflecting surface and recombine with said portion of the first beam at a small angle and the recombined beam then exits from the other body at the exiting surface, said recombined beam producing an interference spatial fringe pattern having radiation maxima and minima, means in the path of the exiting beam and having optically opaque and optically transparent areas regularly spaced in such manner as to enable either the opaque or the transparent areas to be aligned with the fringe maxima or fringe minima, and means for applying an electric field to at least the first electro-optic body to change the optical path length for a beam therein and thereby spatially shift the said interfering fringe pattern relative to the optically opaque and transparent means thereby changing the light output therethrough.

Claim 12

A light modulator for collimated radiation comprising a first body of substantially optically transparent electro-optic material, a second body of substantially optically transparent material, a beam-splitting mirrored surface on one of said fist and second bodies, the other of said first and second bodies being joined to said one body at said beam-splitting mirrored surface, said one body also having a beam-receiving surface and an adjacent reflecting surface, said other body having a beam-exiting surface and an adjacent reflecting surface, said surfaces being oriented in such manner that an incident beam entering said one body at said receiving surface will impinge upon the beam-splitting surface dividing the incident beam into two beams, the first of which will be reflected by the beam-splitting surface towards the one-body reflecting surface from which it is reflected towards the beam-splitting surface where a portion of it will enter the other body, and the second of which after entering the other body will reflect off the other body reflecting surface and recombine with said portion of the first beam at a small angle and the recombined beam then exits from the other body at the exiting surface, said recombined beam producing an interference spatial fringe pattern having radiation maxima and minima, means in the path of the exiting beam and having optically opaque and optically transparent areas regularly spaced in such manner as to enable either the opaque or the transparent areas to be aligned with the fringe maxima or fringe minima, and means for applying an electric field to at least the first electro-optic body to change the optical path length for a beam therein and thereby spatially shift the said interfering fringe pattern relative to the optically opaque and transparent means thereby changing the light output therethrough.