DEVICE FOR OBTAINING PARALLEL SCANNING LUMINOUS FLUX FROM INCIDENT LUMINOUS FLUX

摘要

PURPOSE:To obtain parallel scanning luminous flux by deflecting the 1st and the 2nd reflecting mirrors in mutually opposite-phase relation, and coupling both reflecting mirrors optically through a fixed reflecting mirror. CONSTITUTION:The 1st and the 2nd movable reflecting mirrors 11 and 12 are provided to oscillation terminals of a U-shaped tuning fork 10 and laser light P is reflected in the order of the 1st movable reflecting mirror 11, fixed reflecting mirror 13, and the 2nd movable reflecting mirror 12. When an alternating electric current is flowed through a coil 14 to apply electromagnetic force to the tuning fork 10, the tuning fork 10 enters natural oscillation and the reflecting surfaces of the movable reflecting mirrors 11 and 12 vary. The incident luminous flux is changed in progression path by the 1st and the 2nd movable reflecting mirrors 11 and 12, but projected as parallel luminous flux eventually. Then, a stable oscillation mode is obtained by controlling the amplitude of the alternating electric current flowed through the coil 14 for oscillation so that the voltage developed across a coil 15 for oscillation detection is constant. In this case, the 1st and the 2nd rotary polygon mirrors 21 and 22 which are coupled through a gear may be used.