Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2004-08-05
2008-12-30
Epps, Georgia Y (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S231140, C250S231150, C356S616000
Reexamination Certificate
active
07470892
ABSTRACT:
An optical encoder includes an incoherent light source; a first grating, which is an amplitude grating having a first grating period, for spatial amplitude modulation of the incoherent light from the light source; a second grating, which is a phase grating having a second grating period, for spatial phase modulation of light from the first grating; a third grating, which is an amplitude grating having a third grating period, for spatial amplitude modulation of light from the second grating; and a light detecting element for detecting light from the third grating. The encoder detects relative displacement between the respective gratings. The optical transfer function from the light source to the light detecting element is enhanced, and the efficiency in utilizing light is improved.
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Nakajima Hajime
Ohmura Yoichi
Oka Toru
Epps Georgia Y
Ko Tony
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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