Time domain imager

Abstract

The distance and external contour of objects are imaged using time domain measurement. An array of pixel cells receives a time-varying waveform (e.g., a ramp voltage) time synchronized to a transmitted light pulse. Each pixel cell senses light from the pulse that is reflected from objects in the field of view of the apparatus, and stores the value of the ramp voltage at the time the reflected light pulse is detected at that pixel cell. The ramp voltage at any time is known and therefore serves as a measure of the combined transmission and reflection times of the light pulse for each pixel cell. The speed of light is also known, therefore the stored voltage level at each pixel cell represents the distance between the apparatus of a portion of the object from which the light pulse is reflected. The stored pixel cell voltages can be delivered sequentially to a monochrome video monitor pursuant per any suitable video standard. The imaging technique of the present invention does not record or display the intensity of the reflected and received light; instead, the invention provides an output signal that is an x-y representation of the distance of the distance of viewed objects from the sensor pixel cells. The resulting scene on the display represents distances and external shapes of viewed objects, not patterns, shadings or textures.