Abstract: An interferometer utilizing interference whose object is the measurement of the configuration of a test surface with high precision by allowing accurate positioning to a predetermined measuring position for the measurement of the configuration of the test surface.The interferometer is equipped with an alignment pattern (4A) which generates a wave front that converges at the predetermined measuring position, as well as a wave front for measuring the configuration corresponding to the design configuration of the test surface (9), and by using a test surface-reflected beam of the wave front generated by the alignment pattern, an alignment observation optical system (8) measures the displacement of the test surface from the predetermined measuring position.

Abstract: In a reduction-type projection exposure apparatus provided by the present invention, a spatial filter having a predetermined complex amplitude-transmission distribution is fixed approximately at the pupil position of a projection lens thereof or at such a position that the spatial filter conjugates with the pupil. The complex amplitude transmittance of the spatial filter is controlled by a multiple-interference effect of the multi-layer coating forming the spatial filter or by the surface reflection occurring on the surface of the film which constitutes the spatial filter and has an index of refraction different from the air. The filter can thus be prevented from absorbing light, incurring neither thermal damage nor damage due to dissipated heat. As a result, the reduction-type projection exposure apparatus offers excellent resolution and an outstanding depth of focus.

Abstract: Disclosed is a projection device for projecting an image of an original on an object plane to an image plane for use in copying machines, facsimiles, image readers and the like. The projection device comprises a roof mirror and an optical member including a plurality of lens elements linearly aligned in the longitudinal direction of the slit. Each of the lens elements has a refractive surface and a reflective surface in facing relation with each other. At least one of said surfaces is toric in order to form an erecting real image in the longitudinal direction of the slit and an inverted real image in the lateral direction thereof.

Abstract: Disclosed is a lens system for projecting onto a screen a video image formed on a face plate of a cathode ray tube and including, a first positive lens unit, a second positive lens unit defined between a pair of convex surfaces and a third negative lens unit having a screen side concave surface. The lens system includes at least one aspheric surface and fulfills the following condition: 1.5f<fl<2.0f, wherein f represents the focal length of the whole lens system and fl represents the focal length of the first positive lens unit.

Abstract: A method of producing a composite optical element such as lenses and optical filters is provided. The resulting product has a high quality precision surface with a relatively low production cost. A glass substrate is treated with a silanating agent to activate its surface. An organic polymer material can then be applied to the activated surface with a mold platen forming a desired exterior configuration. The organic polymer is then polymerized to form a relatively thin layer of cured organic material having the exterior desired surface configuration of the glass substrate. The composite optical product is then released from the mold in its final configuration in a relatively short time period.