| 摘要 |
PURPOSE:To reduce the titled device in size and weight by detecting interference light (f1-f2) by a reference light detecting optical system, detecting interference light (f1-f2+ or -DELTAf) and calculating the + or -DELTAf corresponding to the variable quantity of a movable reflecting plate from the phase difference between detecting frequency values of both the systems. CONSTITUTION:An optical beam having frequency f0 and obtained from a linearly polarized laser generator 1 is separated into P and S waves by a polarized beam splitter 2 and light (f0+f1)(P) and (f0+f2)(S) are obtained by a acoustic optical modulators 3, 4. Both the light rays are interfered each other by a polarizing plate 13 through a nonpolarized beam splitter 7 and a reference signal having frequency (f1-f2) is obtained by an optical detector 14. The light advanced up to a polarized beam splitter 8 is divided into P and S waves, the S wave is turned to a P wave through a lambda/4 plate 9 and a reflecting plate 10 and advanced in the left direction and the P wave becomes (f0+f1)(S) + or - DELTAf through the movable reflecting plate 12. Then, (f1-f2+ or -DELTAf) is obtained by a polarizing plate 15 and compared with a reference signal by a counter 17 to find out the + or -DELTAf. |
