Design and implementation of Infrared Laser Object Vibration Sensor circuit

Abstract

In this work, an electronic device which is able to receive a vibration modulated laser signals had been designed, and these vibrations will be converted through the device to hearable sound with high quality. The transmitter represented by infrared laser diode of 808 nm and the receiver is a complicated detector which consists of phototransistor to detect the reflected laser beam from the window, an integrated circuit of LM358 to pre-amplify the electronic signal. First order filter is to eliminate noises and unwanted signals, TDA2002 integrated circuit is to amplify signal to nearly ten times from the incident signal to the TDA2002, speaker to hear the voice. The vibrations are made by the source –which can be living or non-living source- will causing a resonant frequency with the window. So, the incident lR laser beam will have this frequency and through reflection from the window the reflected laser beam will have vibrations, these vibrations will be incident on the photo-transistor and the receiver will work to output the sound. Experimental results proved that this device is able to function properly through 20 meter with good sound quality, this was because of the use of (1 W) laser diode of 808nm.