Canon Kabushiki Kaisha

Yoichi Hirabayashi

Akiyoshi Suzki

Yasushi Sato

Kazuo Minoura

Setsuo Minami

Katsumi Masaki

Kazuhiro Hirayama

Takeshi Goshima

Disclosed in this specification is a scanning device which scans an object having a flat reflection surface and an inclined reflection surface with an inclination relative to the flat reflection surface such as, for example, a mask and a wafer to be used in manufacturing IC, LSI, etc., with light beam, and detects only the reflected light from the inclined reflection surface with a light detector. In order to make it possible to detect only the reflected light from the inclined reflection surface with the light detector, a telecentric lens is used as the scanning lens in this scanning device, and the original point of deflection of the above-mentioned light beam coincides with the center of the pupil of this telecentric lens. In addition, a filter is disposed on the pupil surface to intercept light from the flat reflection surface.

Device for scanning an object with a light beam

Disclosed in this specification is a scanning device which scans an object having a flat reflection surface and an inclined reflection surface with an inclination relative to the flat reflection surface such as, for example, a mask and a wafer to be used in manufacturing IC, LSI, etc., with light beam, and detects only the reflected light from the inclined reflection surface with a light detector. In order to make it possible to detect only the reflected light from the inclined reflection surface with the light detector, a telecentric objective lens is used as the scanning lens in this scanning device, and the original point of deflection of the above-mentioned scanning light beam coincides with the center of the pupil of this telecentric objective lens. In addition, a filter is disposed on the pupil surface to intercept light from the flat reflection surface. An optical system between the scanning device and the object is of f-.theta.lens characteristics in order to compensate the non-linearity of the scanning beam caused by uniform angular velocity movement of the scanning device or the like.

A prism anamorphic optical system is disposed in the path of deflected beam from a rotatable polygonal mirror or a galvano-mirror. This prism anamorphic optical system includes at least two prisms, so that different amounts of displacement of the deflected beam at each angle of deflection and in a direction perpendicular to the direction of deflection caused by the first of the prisms are corrected by the second and subsequent prisms, as viewed from the incidence side. Thus, a straight scanning line may be obtained.

Light beam scanning device

A method of eliminating a ghost image in an image forming process wherein a recording medium is scanned with a light beam reflected by a polygonal rotary mirror, and wherein the light beam for scanning is directed toward the rotary mirror along a path so that the angle between the path and the rotary axis of the rotary mirror is not equal to 90.degree. so as to displace the ghost image formed on the recording medium to a position out of the scanning line on the recording medium.

Method and arrangement for eliminating ghost image

A catoptric projection system in which a projection lens and a spherical convex mirror are arranged with their optical axes intersecting at a point on the mirror at an angle with respect to each astigmatism so that an image is projected from the film plane with light after reflection from the mirror onto a light transmissive screen, thereby it being made possible to achieve a much-desired increase in the magnification of image projected on the screen without involving any increase in the magnification power of the projection lens or in the distance between the film plane and the screen. There is provided a cylindrical refracting surface disposed between the projection lens and the mirror to perform a refractive action in a plane containing both of their optical axes and to contribute an amount of astigmation which is balanced out by that of astigmatism introduced by the convex mirror.

Growing community of inventors

Machida, Japan

Yoichi Hirabayashi