| 摘要 |
PURPOSE: To obtain a simple economic tunable filter which can be tuned quickly to a wavelength over a wide range by providing a plurality of resonant cavities and simultaneously moving one reflecting surface of each cavity in response to a single control signal. CONSTITUTION: A rigid spacer 3 is in contact with the end section of a sleeve 1 made of a piezoelectric material and, at the same time, with one sides of mirrors 8 and 11. The reflecting surfaces 4 and 5 of mirrors 8 and 9 are faced to the internal surface of a resonant cavity 18 and the reflecting surfaces 6 and 7 of mirrors 10 and 11 are faced to the internal surface of another resonant cavity 19. With this constitution, collimated light is made incident from the left side and emitted from the right side after passing through the cavities 18 and 19. When the light is tuned to a prescribed wavelength the light is resonated to a selected wavelength by adjusting the length ratio between the cavities 18 and 19 to a prescribed integer multiple by adjusting the reflecting surfaces 4 and 5 or 6 and 7 by applying a prescribed voltage across the sleeve 1. |
