Laser-acoustic testing method for production lines

The optical microphone does not have an oscillator. In its purely optical process, the sound changes the wavelength of a laser beam, which is reflected back and forth between two small mirrors.

This also changes the brightness of the decoupled light, which is measured without the detour via a mechanical vibration. In this way, the optical microphone achieves a detectable frequency interval that is at least twenty times larger than that of a conventional ultrasonic sensor. In addition, contact with the examinee can be dispensed with.