ROTARY POLYGON MIRROR FITTING DEVICE

摘要

PURPOSE:To provide a light deflector which eliminates the deterioration of the characteristic of a rotary polygon mirror caused by the change of temperature and whose rotational balance is excellent. CONSTITUTION:The rotary polygon mirror 4 provided with plural reflecting mirror surfaces 4-1 is fixed to a mirror supporting member 3 obtained by forming a mirror supporting pedestal 3-1 by a cap flange 6 and a screw 5 which have the same material or the same coefficient of thermal expansion as that of the mirror 4. Besides, plural balance adjusting projections 6-1 for adjusting the rotational balance at a rotating part including the mirror 4 by being made to project in parallel with a rotary shaft 2 and bent in a direction crossing the shaft 2 are provided on the circumferential edge of the flange 6. Therefore, the reflecting angle of a laser beam on the relecting mirror surfaces of the mirror 4 can be accurately maintained with respect to the change of the temperature of the light deflector and the optical characteristic of the light deflector can be accurately maintained.