US 7,576,837 B2
Micro-mirror optical tracking and ranging system
Jony Jiang Liu, Olney, Md. (US); and Christian von der Lippe, Columbia, Md. (US)
Assigned to The United States of America as represented by the Secretary of the Army, Washington, D.C. (US)
Filed on Aug. 27, 2007, as Appl. No. 11/845,214.
Claims priority of provisional application 60/840790, filed on Aug. 29, 2006.
Prior Publication US 2008/0174762 A1, Jul. 24, 2008
Int. Cl. G01C 3/08 (2006.01)
U.S. Cl. 356—5.15 12 Claims
OG exemplary drawing
 
1. An optical tracking and ranging device comprising:
a pseudo-monolithic optical transmitter for outputting a substantially collimated laser beam at a predetermined frequency and modulation;
a micro-electro-optical mechanical system (MEOMS) laser beam steering device disposed to receive the substantially collimated laser beam from said pseudo-monolithic optical transmitter for steering the modulated laser beam; the MEOMS laser steering device comprising a plurality of planar micro-mirrors each of which is mounted perpendicular to a central axis upon which the mirrors rotates, the MEOMS laser steering device being controlled by electronic control so that they spin and tilt to form an adjustable conical shaped scanning pattern;
at least one optical receiver modulated synchronously with the collimated laser beam at the predetermined modulation frequency for detecting a modulated laser beam reflected off of a scanned object present within the conically shaped scan pattern;
a high-frequency chirp modulator operatively connected to the pseudo-monolithic optical transmitter and at least one receiver; the high-frequency chirp modulator generating at least one output signal that synchronously modulates the pseudo monolithic optical transmitter and the at least one optical receiver;
a signal processor comprising a beam direction element and a target signal mixer, the beam direction element being operatively connected to the plurality of planar micro-mirrors and operating to register the rotation of the micro-mirrors at each instant in time for recording the specific direction of the transmitted laser beam; the target signal mixer operatively connected to the at least one optical receiver and the high frequency chirp modulator; the target signal mixer comprising an operating system for mixing the detected laser beam reflected off of the scanned object with the at least one output signal of the high frequency chirp modulator for generating an intermediate frequency that is used for determining the distance of the scanned object from the optical tracking and ranging device; and
a target location and range element operatively connected to the signal central processor for storing the target location and range information to thereby track the target;
whereby the device detects an object using a wide-angle, substantially conically shaped scanning pattern, or tracks the object in a very specific direction using a particular field of view.