| 摘要 |
PURPOSE:To prevent a decrease in diffraction efficiency providing supporting devices for the 1st and the 2nd acoustooptic a deflectors in the same case, and setting the rotation center axis of the 1st supporting device perpendicular to an optical axis of incidence while slanting the rotation center axis of the 2nd supporting device. CONSTITUTION:The acoustooptic deflectors 10 and 11 are provided in the case 24 while supported on mounts 12 and 13 rotatably and independently. The center axis of the horizontal optical deflector 11 slants to the plane formed of the rotation center axis of the vertical optical deflector 10 and the axis of incidence at an angle theta expressed by fc/v from the perpendicular axis. In this case, lambda is the wavelength of an incident beam, (v) is the acoustic velocity of an acoustooptic medium, and fc is the center frequency of the optical deflection band of the vertical deflector 10. Consequently, light diffracted by the vertical deflector 10 strikes the horizontal deflector 11 without decreasing in opening area substantially, preventing a decrease in diffraction efficiency. |
