Patent ID: 7154113
Filing Date: 2006-12-26
Classification: G03F,H01L

Abstract:
1. A prealignment sensor comprising: a frame fixed to a base and having a U-shape when viewed from its side; a light source attached to a lower part of the frame; a convex lens attached to a lower part of an inside of the frame by which diffused light of the light source is transformed into parallel light; a lens holder for fixing the convex lens to the frame; an optical receiver attached to an upper part of an inside of the frame by which the parallel light is received and is transformed into an electrical signal; and a signal processing circuit attached to the frame by which the electric signal is transformed into a desired displacement magnitude; wherein the frame is formed of aluminum subjected to sulfuric-acid hard alumite treatment and then to steam sealing, wherein the convex lens is disposed such that a center position thereof is slightly offset from a center of an optical axis connecting a center of the light source and a center of the optical receiver in a horizontal direction perpendicular to a sensed direction.