Enhanced applications of speaker-modulated helium-neon laser beam

Wide range of applications using He-Ne laser were carried out employing speaker for vibration modulation. The very simple method was achieved by gluing a mirror to the diaphragm of an ordinary miniature speaker. The technique allows many of the applications that depend on laser absorption coincidences to be performed by a He-Ne laser enhancing by the range of applications in which it can be used and avoiding the complications and expenses needed for sophisticated equipment. Speaker modulation was found efficient and comparable to mechanical chopper modulation. The method is sensitive enough to determine minute changes in index of refraction or transparent material thickness change and suitable for odor emission monitor.