Abstract: Projection-optical systems are disclosed for projecting an image of a first object M onto a second object P. Each such projection-optical system comprises, in order from the first-object side: a positive first lens group; a negative second lens group comprising a pair of negative lens elements forming a pair of concave surfaces facing each other; a positive third lens group comprising a lens element, positioned nearest the second object within the third lens group, having a concave surface facing the second object; an aperture stop; a positive fourth lens group comprising a lens element, positioned nearest the first object within the fourth lens group, having a concave surface facing the first object; a negative fifth lens group comprising a pair of negative lens elements that form a pair of concave surfaces facing each other; and a positive sixth lens group. The projection-optical systems satisfy any of several quantitative conditions.

Abstract: A polarization converter for unpolarized light. The polarization converter comprises a prism, a wedge, a set of lens arrays, a first reflecting plane, and a second reflecting plane. The wedge comprises a tilt plane. The tilt plane is coated with multi-layer polarization dichronic thin film. The set of lens arrays comprises a light distributor and a light integrator. The tilt plane of the wedge is glued on the first reflecting plane. A second reflecting plane is the unglued plane of the wedge. When a light beam is incident towards the incident plane, the first reflecting plane splits and polarizes the light beam into a first type polarized and a second type polarized lights. Through the multi-layer polarization dichronic thin film, about 99% of the first type polarized light is reflected, and about 99% of the second type polarized light is transmitted and incident on the second reflecting plane.

Abstract: A structure for holding a decentered lens inside a lens barrel, as well as an axisymmetrical lens. The structure includes: a lens barrel with a lens receiving part projecting inwardly and radially from an inner surface thereof; a decentered lens, with a first lens surface as a reference surface a centering axis of which is made to coincide with an axis of the lens barrel, and a second lens surface, which includes an annular flat surface around the second lens surface, in which the annular flat surface forms a recessed surface relative to the second lens surface, in which the annular flat surface is perpendicular to the axis of the lens barrel, and in which the annular flat surface contacts the lens receiving part of the lens barrel; and a washer, installed on the inner surface of the lens barrel, to fixedly hold the decentered lens, relative to the lens barrel, by pinching the decentered lens between the washer and the lens receiving part of the lens barrel.

Abstract: The instant invention relates to a method and a device for optical phase modulation by means of semiconductor amplifiers. In this case an optical semiconductor amplifier comprises optical waveguides 10, which rise over its length and change in its lateral extension, so that light supplied at the optical inlet 11 undergoes an amplification on its way to the optical outlet 12.

Abstract: An electro-optical element such as a light deflection element which allows high speed random accessing and can provide a large deflection angle and wherein a plurality of of functions can be integrated stably with a high degree of accuracy in a single element. The electro-optical element includes a ferroelectric substrate, electrodes provided on principal faces of the ferroelectric substrate, and function sections each having a polarization reversal domain formed in a predetermined shape in the ferroelectric substrate such that a light beam passes through the domain. The function sections may have a function of for converging at least part of the light beam, another function for diverging at least part of the light beam, a further function for deflecting a propagation direction of at least part of the light beam or/and a still further function for switching a propagation direction of at least part of the light beam, in response to a voltage applied to the electrodes.

Abstract: A switchable optical birefringent filter for polarized light incident thereon includes first and second retarder networks in optical series and a switch associated with at least one of the first and second retarder networks for selectively altering one of the polarization state and the angular orientation of the polarization state relative to the angular orientation of the second network, of light as it is received by the second network. In one operating mode, the filter produces a spectral filtration of light passing through the filter and in another mode transmits all light within a specified range of wavelengths without significant alteration.

Abstract: A lens barrel having a cam cylinder formed with a cam groove having two side surfaces and a lens holding frame provided with a cam follower inserted into the cam groove and guided in contact with one of the two side surfaces. The cam follower includes an elastic member in elastic contact with the other side surface of the cam groove to absorb a play between the cam groove and the cam follower. A distance between the two side surfaces of the cam groove becomes smaller in a direction of depth of the cam groove; and there is a clearance between the cam follower and the other side surface.