Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1993-10-21
1995-11-07
Turner, Samuel A.
Optics: measuring and testing
By particle light scattering
With photocell detection
356356, 356363, G01B 902
Patent
active
054651484
ABSTRACT:
A first Savart plate and an object to be measured are arranged on the light path of a Zeeman light source. The object to be measured is constructed of a diffraction grating on a mask and a diffraction grating on a wafer. A second Savart plate, a deflection plate and a photoelectric detector are sequentially arranged in the light path for the diffracted beams from the measured object. The output of the photoelectric detector is connected to a phase-difference unit to detect the phase difference between two beat signals. Herein, the light is split into two beams by the Savart plate. After a diffraction is caused by the diffraction gratings, thereafter, the beams are re-synthesized by the Savart plates. The two beams travel on the same light path, thereby improving a measurement accuracy.
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Matsumoto Takahiro
Nose Noriyuki
Saito Kenji
Sentoku Koichi
Canon Kabushiki Kaisha
Turner Samuel A.
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