Method and apparatus for detecting gap of liquid-crystal...

Optics: measuring and testing – By polarized light examination

Reexamination Certificate

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C356S367000, C250S208100, C359S489040

Reexamination Certificate

active

07079245

ABSTRACT:
Light from a light source10is linearly polarized by a polarizer11.Then it propagates via a half-mirror12almost parallel to the normal to a reflective liquid-crystal panel13and falls on the reflective liquid-crystal panel13.The reflected light reflected by the reflective liquid-crystal panel13is received by a detector15via the half-mirror12and an analyzer14.In this state, the reflective liquid-crystal panel13is rotated about an axis almost parallel to the normal to the reflective liquid-crystal panel13and an angle (extinction angle) at which the output signal of detector15reaches minimum is measured. Then, the gap of the reflective liquid-crystal panel13is detected based on the measured extinction angle. It is also possible to measure the output signals of detector15by arranging the analyzer14in a state in which the transmission axis thereof is almost parallel to the polarization direction of the incident light and a state in which it is almost perpendicular thereto and to detect the gap of the reflective liquid-crystal panel13based on the measured signals.

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