# US 4,391,515 A · Optical transmitter/receiver apparatus sharing common optics

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- Number: US 4,391,515 A
- Document ID: US4391515A
- Status: Granted
- Kind: A
- Application number: 06/261,341
- Filed: 1981-05-07
- Granted: 1983-07-05
- Earliest claimed: 1981-05-07
- Assignees: The United States of America as represented by the Secretary of the Navy
- Inventors: Howard M. Forrester; John R. Crisler
- Web page: https://patentgrep.com/patent/US4391515A

## CPC

- G01S 7/499: using polarisation effects
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

Optical detection apparatus is provided which includes a coherent light sce for generating a beam of coherent light. The apparatus further includes a unitized or discrete optical component which receives the generated beam, and projects light thereof which has a particular polarization characteristic into a specified environment. The optical component also functions to receive or absorb light from the environment which has the particular polarization characteristic, and to directably reflect light from the environment which does not have the polarization characteristic. A lens or other light collecting device focuses light reflected by the discrete optical component upon a light detection element. A light conducting path is provided between the coherent light source and the light detecting element to enable generated coherent light to be mixed with the reflected light upon the light detecting element to provide data signals which indicate the presence of an object in the environment.

## Claims

### Claim 1

Optical detection apparatus comprising:
means for generating a beam of coherent light;
a discrete optical polarizing component including a plurality of wedge shaped light transmissive plates arranged in two groups each group being arranged in a spaced apart stack,
one surface of one of said wedge shaped plates from one of said groups being positioned to intercept the light from said coherent light generating means at a predetermined angle of incidence,
another surface of another of said wedge shaped plates being arranged to receive incoming light reflected from an object in an ambiant environment having particular polarization characteristics;
a light detection element;
a lens positioned between said discrete optical component upon said light detection element; and
means for transmitting light from said coherent light generating means to said light detecting element, whereby it is mixed with the coherent light from said discrete optical component to produce a data signal.