| 摘要 |
PURPOSE:To make constant the illuminance of an illuminating light by a method wherein such a second object as a wafer is placed at a prescribed position to be lighted by an illumination optical system and the image is light-received by a detector to obtain a signal, the signal is compared with a reference value being stored in advance and the amount of light of the illuminating light is corrected. CONSTITUTION:The correction of the amount of a laser beam is performed by a method wherein an LED is lighted by an arithmetic system ARM and light is detected by a detector D. The output of the detector D is compared with the value of a reference output being stored in a memory MEM 1 by the system ARM. A wafer WF is installed at a prescribed position, a shutter being arranged in the interior of an illuminating system, which reaches to a lens EL from a light source LP2 through a fiber SF and so on, is opened and an illuminating light is lighted on the wafer WF. The reflected light reflected from the wafer surface or diffracted light is detected by the detector D through a projection lens PO and data are sent to the system ARM. The system ARM compares the measured data with a reference being stored in a memory MEM2, computes the correction amount of the illuminance on the side of the light source and commands to a driving unit KTU for correcting and controlling the amount of light. An element for adjusting the amount of light is rotated on the basis of the command to perform the correction. |
