| 摘要 |
<p>An optical microphone is described that is composed of the body of the microphone proper, of a proof laser (7), of a thin film (1), and of a detector (11) sensitive to position. The pressure waves due for instance to the absorption by a sample of the electromagnetic radiation modulated periodically, modulate the movement of a thin reflective film (1) in the shape of an extended drop. This film has its wider extremity fixed to the body of the photoacoustic camera (10), either resonant or non-resonant, with the other end, unattached, at an approximate distance of 0.1 mm from a duct which is extended to the length of the photoacoustic camera sample (10). The periodic movement of the reflective film (1) deflects periodically a laser beam which, after being reflected in the film (1), falls upon a detector (11) sensitive to position composed of two silicon photodiodes. The electric signal issued by the detector sensitive to position is then processed, for instance, by a lock-in amplifier (14).</p> |
