Patent ID: 7157695
Filing Date: 2007-01-02
Classification: G01J,G02B

Abstract:
1. An optical deflection device comprising: an optical deflector including an optical deflection surface, whose attitude is controllable, to deflect a light beam; a driver, which drives the optical deflector; control means for generating a control signal to control the driver; a light intensity detector, which outputs a light intensity signal corresponding to light intensity of the light beam deflected by the optical deflector; light intensity monitoring means for monitoring a change with time of the light intensity signal output from the light intensity detector to output information on the change as a light intensity monitor signal; and control signal monitoring means for monitoring a change with time of the control signal output from the control means to output information on the change as a control signal monitor signal, the control means generating the control signal to increase the output signal from the light intensity detector based on the light intensity monitor signal and control signal monitor signal; wherein the control signal monitoring means comprises: two control signal holding sections, which hold the control signals at two different times; and a control signal comparison section, which compares the two control signals held by the control signal holding section to output the information concerning increases/decreases of the control signals as the control signal monitor signal, and the light intensity monitoring means comprises: two light intensity signal holding sections, which hold two light intensity signals at two different times; and a light intensity signal comparison section, which compares the two light intensity signals held by the light intensity signal holding section to output the information concerning increases/decreases of the light intensity signal as the light intensity monitor signal.