Novel Distance Sensor Principle based on Objective Laser Speckles

This work describes a new sensor principle for non-contacting optical distance measurement based on objective laser speckles. In contrast to existing optical distance sensors, the proposed approach uses neither optical imaging systems nor laser sources of high coherency. In the sensor setup a laser beam is split into two beams directed onto the technical surface at unknown distance from the sensor. Laser light scattered from the surface leads to the formation of a modulated objective speckle pattern, bearing information about the distance between the imaging sensor and the surface. Distance estimation is accomplished by FFT-based signal processing of the electronically acquired intensity pattern. The described sensor principle can be used for low cost non-contacting distance sensing with measurement ranges from centimeters up to several decimeters.