Patent Number: 7,084,982

Title: Optical apparatus, measurement method, and semiconductor device manufacturing method

Abstract: An optical apparatus includes an optical device arranged on an optical path extending from a light source to a predetermined position, an optical sensor, and a measuring device which measures an optical characteristic or a change in an optical characteristic of the optical device on the basis of an output from the optical sensor. The optical sensor is arranged outside the optical path and senses light which is emitted from a second light source arranged outside the optical path and is reflected by the optical device.

Inventors: Yamamoto; Takeshi (Tochigi, JP), Miyake; Akira (Tochigi, JP)

Assignee: Canon Kabushiki Kaisha

International Classification: G01N 21/47 (20060101)

Expiration Date: 8/01/02018