| 摘要 |
PURPOSE:To measure an angle with high accuracy by a simple mechanism, by extracting the characteristics of the interference patterns of two lights in order to arrange the equiphase surfaces of two luminous fluxes on a photodetector. CONSTITUTION:In order to measure the relative angular change between a fixed object and a moving object, a light source is mounted on one object and a receiving system is mounted on the other object. In the receiving system, the lights 6', 6' from light sources are received by condensing lens 8, 8' to set two systems of light paths and mutually overlapped on a light receiving element 12 through a reflecting mirror 10, a light synthesizer 11 and a slit 13 to be allowed to interfere with each other. Since the equiphases of the components of the lights 6', 6' do not perfectly coincide with the interference pattern on the element 12 at that time, concentric circular bright parts (or dark parts) 14', 14 and a dark part (or bright part) 15 appear. When the angle (incident angle) theta of a reference axis 5' and the axes of the lights 6', 6' changes, the brightness of the bright part 14' changes to cosphi times (phi is formula phi=2pidsintheta/lambda-2piN and N is a number of interference amplitude max. points) and the same amplitude change as that when equiphases are arranged is obtained.
|
