| 摘要 |
PURPOSE:To correct automatically an illuminance distribution by installing plural pieces of photoelectric detectors on a photomask or reticule, detecting simultaneously the intensity of illumina at each point, determining the difference between the outputs of the detectors, and driving the motor in the position X-Y-Z direction of the light source so as to minimize the difference thereof. CONSTITUTION:A light source 2 is held by a support base 1 which is made slightly movable by means of a driving motor 10 in an X or Y direction. The light from the light source 2 is condensed by an ellipsoidal mirror 3 and is converted by a condenser lens 4. The converted luminous flux illuminates a photoelectric detector 5 constituted of plural sensors and at the same time the intensity of illumination at each point is detected. The intensity of illumination signal detected photoelectrically is amplified by preamplifier circuits 6 and 7, and is inputted to a differential amplifier 8, the differential output signal wherefrom is made into a motor driving voltage by a motor driving circuit 9 to drive the motor 10 in the X or Y direction. The motor is stopped when the differential output between the sensors attains the voltage within a certain specified voltage. The uneven intensity of illumination is thus automatically corrected within the certain specified value. |
