Patent ID: 6463393
Filing Date: 2002-10-08
Classification: G01S

Abstract:
A device for calibrating distance-measuring apparatuses, having a transmitter which emits a high-frequency modulated optical beam and illuminates an object to be measured, a measuring receiver which detects a beam reflected by the object to be measured, and a reference receiver, distance measurement taking place according to a phase measurement principle, whereina) an internal reference distance serves as a calibration distance, over which a part of the beam emitted by the transmitter is guided to the reference receiver so that beams detected in the reference receiver and in the measuring receiver can be evaluated simultaneously, and b) an electrical connecting line is provided between a frequency mixer receiving electrical signals of the reference receiver and an avalanche photodiode serving as the measuring receiver, a high mixer frequency being fed into the electrical connecting line so that the high mixer frequency is superposed on a bias voltage of the avalanche photodiode and at the same time is fed to the frequency mixer, with the result that a low-frequency calibration signal is generated in the frequency mixer and a low-frequency measuring signal in the avalanche photodiode, whose mutual phase position is determined for a distance determination.