The sensor is particularly suitable to determine movement between a ground vehicle or aircraft over a ground surface, and a portion of the reference surface (10) is imaged on a grid plane (12, 30, 40) which, in accordance with the invention, is formed as a photo-sensitive transducer, for example a plurality of photo-sensitive diodes formed on a single chip and suitably connected in a grid or matrix pattern, made, for example, by a planar process by monolithic integration. Correlation-optical measurement of relative movement thus is simplified, and precise grid structures can be readily made, the output signals from the individual photo-sensitive junctions being summed and, if interdigited grid structures are used, the so summed signals can then be subtracted from each other to eliminate ambient light, or slowly varying low-frequency components and derive only a movement signal. By arranging two or more such grid structures at an angle with respect to each other, vectorial movement directions and, by using four interdigited grids with phase comparison, forward-reverse direction of movement can also be sensed. Summing can be effected by connection of individual photo junctions or by bundling light guide fibers arranged in a matrix of a grid pattern, and conducting the fibers to common electro-optical transducers.
A scanning unit for an optical position measuring device, the scanning unit having a structured optoelectronic photodetector that includes: a semiconductor substrate, a plurality of radiation-sensitive detector areas, which are arranged next to each other on the semiconductor substrate and a strip conductor, wherein at least a portion of the strip conductor is positioned across a surface defined by the plurality of detector areas and forms a connection with an associated detector area of the plurality of detector areas.
In order to measure the movement of a vehicle, especially an aircraft, an imaging optical system 2 which is to be positioned on the vehicle is used to detect an image of the environment 4, and an optoelectronic shift sensor 3 chip of the type comprising an inherent evaluation unit is used to measure any shift of the image from structures thereof. The shift sensor is equal or similar to the sensor used on an optical mouse. The sensor is positioned in such a way that infinite objects are focused. The measuring signal is evaluated to indicate movements and/or the position of the aircraft. The inventive system can also be used to measure distances e.g. in order to control the flight altitude. The invention further relates to methods for automatically controlling particularly a hovering flight by means of a control loop using optical flow measurement.
The present disclosure describes an optical displacement sensor having a dense multi-axis array of photosensitive elements. Generally, the sensor includes a two dimensional array of multiple photosensitive elements. In one embodiment, the array includes multiple linear arrays of photosensitive elements arranged along three or more axes in a space-filling, close-packed multi-axis array. The photosensitive elements are connected to each other in such a way that motion is determinable along each of the axes by measuring differential photocurrents between photosensitive elements along each of the axes. The inventive architecture advantageously increases signal redundancy, and reduces signal drop-out or low signals due to random fluctuations in the incident or absorbed light or in the signals from the photosensitive elements.
