Direct optical digital detection of diaphragm deflection: maximum resolution.
The direct optical digital detection of analog mechanical motion of a diaphragm is described both experimentally and theoretically. The conversion is made by a Michelson interferometer which detects deformation of the diaphragm caused by acoustic pressure. Theoretical calculation shows that the maximum resolution is strongly dependent on the detector width, it becomes 9 bits when a single-mode optical fiber is used as the detector. An 8-bit A-D conversion is experimentally obtained using a Michelson interferometer constructed with a He-Ne laser, a 2.54-cm (1-in.) diam diaphragm, and a detector of 50-microm diam multimode optical fibers.
Mada
H
H
Tokyo University of Agriculture & Technology, Faculty of Technology, Department of Electronic Engineering, Koganei, Tokyo 184, Japan.
Muramatsu
Y
Y