Equipment and method for measuring transmittance of...

Details Equipment and method for measuring transmittance of... Equipment and method for measuring transmittance of...

2007-11-07

2009-12-08

Nguyen, Sang (Department: 2886)

Optics: measuring and testing

For light transmission or absorption

C356S237400, C219S121730, C359S305000

Reexamination Certificate

active

07630079

ABSTRACT:
Provided are equipment and a method for measuring a transmittance of a photomask. The system includes an acoustic optical deflector (AOD) substrate interposed between a light source and the photomask. The AOD is adapted to deflect a laser beam to an oblique incidence angle with respect to a surface of the photomask. A radio frequency (RF) signal source is coupled with the AOD substrate. Varying the frequency of the signal applied to the AOD substrate acts to change the refractive degree of the substrate, thereby changing an angle of deflection of the incident laser beam. A photodetector is positioned to receive the laser beam passing through the photomask and is adapted to measure an intensity of the laser beam which has penetrated the photomask. As a result, a transmittance of the photomask can be measured under off axis illumination (OAI).

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English language abstract of Korean Publication No. 2002-0025222.
English language abstract of Japanese Publication No. 2005-011461.
English language abstract of Japanese Publication No. 2005-326549.

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