The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 29, 1991
Filed:
Dec. 20, 1989
Kazuhiko Fujita, Nagoya, JP;
Yoshinori Bessho, Mie, JP;
Brother Kogyo Kabushiki Kaisha, Aichi, JP;
Abstract
Method and apparatus for detecting the roughness or undulation of a subject surface, by using a light beam which is converged on the subject surface by an object lens and which is reflected by the subject surface. A relative position between the object lens and the subject surface in the direction parallel to the optical axis of the lens is controlled so that the measuring light reflected by the subject surface has a plane wave. On the other hand, an amount of relative displacement between the object lens and the subject surface is detected, based on a heterodyne interference between a light beam reflected by a stationary mirror and a light beam reflected by a movable mirror which is moved as the relative position is changed. The surface condition is detected based on the amount of relative displacement between the object lens and the subject surface which is detected when said plane wave of said measuring light beam is obtained.