US 5,633,721 AGranted

Surface position detection apparatus

AssigneeNikon Corporation

InventorHideo Mizutani

Life of this patent

Estimating the term…

Loading patent…

Abstract

A surface position detection apparatus for detecting a surface position on a surface to be detected, comprises a projection pattern formed on a first surface, a projection optical system for projecting the pattern from an oblique direction onto the surface to be detected, a condensing optical system for condensing a light beam reflected by the surface to be detected, and forming an image of the pattern on a second surface, and a detector for photoelectrically detecting the image of the pattern. The first surface and the surface to be detected are arranged to satisfy a Scheimpflug condition in association with a principal plane of the projection optical system. The surface to be detected and the second surface are arranged to satisfy a Scheimpflug condition in association with a principal plane of the condensing optical system.

Claims26

Dependent claims

A surface position detection apparatus for detecting a surface position of a surface to be detected and for improving the accuracy of position detection in a direction perpendicular to the surface, comprising:

a projection pattern formed on a first surface;
a projection optical system which projects a light beam from said first surface in an oblique direction onto said surface to be detected and forms an image of the pattern thereon;
a condensing optical system which condenses a light beam reflected by said surface to be detected, and forms an image of the pattern on a second surface;
and
a detector system which receives a light beam emerging from said second surface and which photoelectrically detects the image of the pattern thereon,
wherein said first surface and said surface to be detected are arranged to satisfy a Scheimpflug condition in association with a principal plane of said projection optical system, and
said surface to be detected and said second surface are arranged to satisfy a Scheimpflug condition in association with a principal plane of said condensing optical system;
wherein said apparatus includes a deviation device, arranged on said second surface, which deviates the light beam emerging from said condensing optical system in a direction that reduces the angle of incidence of the emerging light beam on a light-receiving surface of the detector system, said deviation device including a wedge-shaped prism, said wedge-shaped prism being arranged so that an incident surface of said wedge-shaped prism is located on said second surface, and a relay optical system arranged between said second surface and said light-receiving surface of said detector system, which sets a conjugate relationship between said second surface and said light-receiving surface.

5 more elements

A surface position detection apparatus for detecting a surface position of a surface to be detected, comprising the following parts arranged along an optical path in the order recited:

a projection pattern;
a projection optical system;
a condensing optical system;
a wedge-shaped prism;
a relay optical system;
and
a detector system;
wherein said projection optical system has a first optical axis extending to said surface to be detected in an oblique direction with respect to said surface to be detected;
said condensing optical system has a second optical axis extending from said surface to be detected in an oblique direction with respect to said surface to be detected;
said projection pattern and said surface to be detected satisfy a Scheimpflug condition in association with a principle plane of said projection optical system;
said surface to be detected and an incident surface of said wedge-shaped prism satisfy a Scheimpflug condition in association with a principal plane of said condensing optical system;
the incident surface of said wedge-shaped prism and a light-receiving surface of said detector system are conjugate with respect to said relay optical system;
and
light from said projection pattern reaches said light-receiving surface of said detector system via said projection optical system, said surface to be detected, said condensing optical system, said wedge-shaped prism and said relay optical system.

11 more elements

Dependencies are inferred from the claim text.