| 摘要 |
PURPOSE:To achieve a smaller size and a lower cost without degrading the accuracy, by converting a divergent light emitted to a light waveguide direct to a convergent light for a photodetector to detect a diffraction light and a non-diffraction light when a surface elastic wave is made to cross the convergent light obliquely. CONSTITUTION:A divergent light 9 guided with a light waveguide 2 after emitted from a semiconductor laser 3 is converted to a convergent light with a diodesic lens 15 to be focused on a photoconductor 8. At this point, when a high frequency electrical signal is applied to a transducer 6, a surface elastic wave 13 is excited in the light waveguide 2 and made to cross the convergent light obliquely. A part of the convergent light is refracted to make a refraction light 12, which is focused at a point B on the photodetector 8. The non- refraction light is focused at a point A. The frequency of the high frequency electrical signal is determined from the distance between the points A and the B on the photodetector 8. This requires only one diodesic lens thereby realizing a smaller size and a lower cost of the apparatus. |
