Jacobson, Price, Holman & Stern PLLC
Position measuring apparatus
 A position measuring apparatus includes a light source 1, an illumination optical system 100, a light-reception optical system 400 and a light-receiving unit 500. Illuminating beam emitted from the light source 1 is diffracted by a two-dimensional pattern on an object 10, and then enters the light-reception optical system 400. The light-receiving unit 500 receives diffracted lights consisting of a combination of a higher-order diffracted light appearing on the object side for the zero-order diffracted light in the receive diffracted lights with a zero-order diffracted light different in frequency from the higher-order diffracted light and another combination of higher-order diffracted lights different in frequency from one another and appearing on the object side for the zero-order diffracted light, thereby forming a position measuring interference measurement signal within the plane including the object. A signal processing unit is adapted to measure the position of the object 10 based on the phase of the position measuring interference measurement signal. 
Kabushiki Kaisha Topcon Kabushiki Kaisha Toshiba
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inventional inventional inventional inventional
Toru Kazuo Susumu Hitoshi Ryoichi Shinya
Tojo Abe Saito Suzuki Hirano Watanabe