FILTERING DEVICE USING LIQUID CRYSTAL SPATIAL OPTICAL MODULATOR OF OPTICAL ADDRESS TYPE

摘要

PURPOSE: To execute defect inspection of a photomask, etc., at a high speed by providing a filtering device with a liquid crystal spatial optical modulator of optical address type consisting of a photoconductor layer and ferroelectric liquid crystal layer which receive the light transmitted through a polarizing plate and are arranged so as to reflect this light toward this polarizing plate. ;CONSTITUTION: This filtering device is arranged with a collimating lens 3 and a convex lens 4 so as to face a laser 1. The device is arranged with the polarizing plate 5 and the liquid crystal spatial optical modulator (SLM) 6 of the optical address type so as to face the lens 4. A ferroelectric liquid crystal 29 is encapsulated between a pair of oriented films 26 and 28 of this SLM 6. The liquid crystal molecules of the liquid crystal 29 are usually arranged in the same direction as the polarization direction of the polarizing plate 5. The multilayered dielectric half mirror 30 is disposed between the oriented film 28 and an amorphous silicon layer 25. In such a case, the incident light 7 on the liquid crystal layer 29 rotates its polarization direction 90° while moving in the liquid crystal 29 back and forth and the light reflected by the SLM 6 is shut off by the polarizing plate 5. The reflected light transmitted through the polarizing plate 5 is subjected to reverse Fourier transform by the lens 4 and is taken out onto a screen 12.;COPYRIGHT: (C)1995,JPO