Abstract

A three dimensional imaging device is presented which uses a single pulse from a pulsed light source to detect objects which are obscured by camouflage, fog or smoke but otherwise enveloped by a light-transmitting medium. The device simultaneously operates in two modes, light reflected from the nearest object is processed to form a three-dimensional image by an array of pixels. This first image is based upon the light-pulse transit time recorded in each pixel. Each pixel also contains a high-speed analog memory that sequentially stores reflected signals at a repeated time interval. The first reflection acts as a time base that controls when the analog memory begins or ends the storage sequence. The first return could be from a camouflage net and the amplitudes of the return signals, after the first return, would then be from objects behind the net. Computer processing these amplitudes reveals the three-dimensional nature of the obscured objects.The device consists of the pulsed light source, optics for collecting the reflected light, a sensor for detecting the light and converting it to electrical data, drive and output electronics for timing and signal conditioning of data generated by the sensors and a computer for processing the sensor data and converting it to a three dimensional image. The sensor collects and processes the light data in a unique manner, first converting it to electricity by a number of alternate detector technologies and then using integrated circuit chips which consist of a two dimensional array of electronic pixels also called unit cells. The two dimensional array defines two dimensions of the image. Stored within each unit cells is data associated with the third dimension, ranges of targets, and amplitudes of target reflections. This data is read out of the integrated circuit chip in the time interval between laser pulses to a processing computer. The processing computer corrects the data and, by means of computer algorithms specific to the device, converts the data to a three-dimensional image of one or more targets. This image may be viewed or processed electronically to isolate targets.