Patent ID: 6501539
Filing Date: 2002-12-31
Classification: G01S

Abstract:
A laser range finder comprising:a laser driver connected to an infrared pulse laser diode for driving the infrared pulse laser diode to fire a laser pulse signal to a target; an automatic peak control loop connected to the laser driver for receiving a reflected laser pulse signal from the target and controlling the laser driver so as to decide the strength of the emitted laser pulse signal, wherein the automatic peak loop control loop comprises: an avalanche photo-detector for receiving the reflected laser pulse signal from the target and converting the reflected laser pulse signal to a current signal; a laser receiver connected to the avalanche photo-detector for receiving the current signal from the avalanche photo-detector and converting the current signal to a voltage signal; a peak holding circuit connected to the laser receiver for detecting a peak amplitude strength of the voltage signal received from the laser receiver; an integrator connected to the peak holding circuit for receiving an output voltage signal from the peak holding circuit and comparing the output voltage signal to a reference voltage to obtain a difference voltage value and integrating the difference voltage value; and a high-voltage generator connected to the integrator, the laser driver and the laser receiver for receiving the output signal from the integrator to control the strength of the emitted laser pulse signal of the laser driver and the grain of the avalanche photo-detector; a main amplifier connected to the automatic peak control loop for amplifying the reflected laser pulse signal and outputting an amplified voltage signal; a one-shot circuit connected to the main amplifier for converting the amplified voltage signal to a time pulse relating to a distance to the target; a time to amplitude converting circuit connected to the output of the one-shot circuit for receiving the time pulse from the one-shot circuit and outputting a digital signal according to the time pulse; a microprocessor connected to the time to amplitude converting circuit and laser driver for controlling the laser driver to emit laser pulses and providing the reset signal for the time to amplitude converting circuit; and a liquid crystal display device connected to the microprocessor for displaying the distance value calculated by the microprocessor.