Laser sound detector system with source generating light beam - has reflecting means at distance from source

摘要

The light from the light beam which is generated by a laser is reflected after being modulated by sound waves which are made to interact with it. The modulated reflected light is then fixed or demodulated. Recording means connected to the detector facilities can be used to record a quantity representing the sound, and converter equipment connected to the detector facilities can convert the sound-modulated light into an audible tone. Modulation of the light by sound can include amplitude modulation. The apparatus is also suitable for use as a penetrating alarm. The alarm can be triggered off as a result of an invisible light beam being broken.