| 摘要 |
PURPOSE:To improve picture quality of monitor television through optimization of amount of light for observation even when reflectivity of wafer changes largely by adjusting amount of light beam for irradiation according to wafer data input. CONSTITUTION:An output signal S5 of a video amplifier 23 is output to an analog multiplier 32 and a signal level detection circuit 24. A selector 30 selectively outputs, as an output signal S2, any of the reference voltages V1, V2, V3 in accordance with selection for positions H, M, L of the gain select switch 31 which inputs after information. The signal S2 becomes the one input of the analog multiplier 32. The analog multiplier 32 multiplies the signal S2 and an output S5 of the video amplifier 23. With a result of such multiplication, the radiation beam amount adjusting circuit 33 controls a lamp power supply 21 with the output signal S3 and thereby radiation beam amount of light source 7 can also be controlled. |
