Abstract: An illumination optical system for illuminating an object surface using light from a light source, the illumination optical system includes, a first optical system that includes a movable unit that is movable along an optical axis, said first optical system guiding the light to the object surface and varying an irradiation area on a certain plane, and a second optical system that can be located on and removed from an optical path of said first optical system, the second optical system varies, when located on the optical path of said first optical system, the irradiation area on the certain plane in cooperation with said first optical system, while maintaining a shape of a light intensity distribution on the certain plane, relative to the irradiation area irradiated only by said first optical system.

Abstract: An illumination optical system for illuminating an object surface using light from a light source, the illumination optical system includes, a first optical system that includes a movable unit that is movable along an optical axis, said first optical system guiding the light to the object surface and varying an irradiation area on a certain plane, and a second optical system that can be located on and removed from an optical path of said first optical system, the second optical system varies, when located on the optical path of said first optical system, the irradiation area on the certain plane in cooperation with said first optical system, while maintaining a shape of a light intensity distribution on the certain plane, relative to the irradiation area irradiated only by said first optical system.

Abstract: An illumination optical system for illuminating an object surface using light from a light source, the illumination optical system includes, a first optical system that includes a movable unit that is movable along an optical axis, said first optical system guiding the light to the object surface and varying an irradiation area on a certain plane, and a second optical system that can be located on and removed from an optical path of said first optical system, the second optical system varies, when located on the optical path of said first optical system, the irradiation area on the certain plane in cooperation with said first optical system, while maintaining a shape of a light intensity distribution on the certain plane, relative to the irradiation area irradiated only by said first optical system.

Abstract: Disclosed is an illumination optical system having an imaging optical system for imaging a predetermined object plane upon an image plane, by use of light supplied from an integrator that functions to produce a plurality of light sources using light from a light source. In one preferred form of the invention, the imaging optical system includes, in an order from a light incidence side thereof, a first lens group having a positive power, a second lens group having a negative power, and a third lens group having a positive power, wherein the second lens group includes a concave lens at a light exit side thereof and wherein the third lens group includes a convex lens at a light entrance side thereof. The position of intersection between an optical axis of the imaging optical system and a principal ray of abaxial light is defined between the second lens group and the third lens group.

Abstract: Disclosed is an illumination optical system having an imaging optical system for imaging a predetermined object plane upon an image plane, by use of light supplied from an integrator that functions to produce a plurality of light sources using light from a light source. In one preferred form of the invention, the imaging optical system includes, in an order from a light incidence side thereof, a first lens group having a positive power, a second lens group having a negative power, and a third lens group having a positive power, wherein the second lens group includes a concave lens at a light exit side thereof and wherein the third lens group includes a convex lens at a light entrance side thereof. The position of intersection between an optical axis of the imaging optical system and a principal ray of abaxial light is defined between the second lens group and the third lens group.

Abstract: An illumination optical system for illuminating an object surface using light from a light source, the illumination optical system includes, a first optical system that includes a movable unit that is movable along an optical axis, said first optical system guiding the light to the object surface and varying an irradiation area on a certain plane, and a second optical system that can be located on and removed from an optical path of said first optical system, the second optical system varies, when located on the optical path of said first optical system, the irradiation area on the certain plane in cooperation with said first optical system, while maintaining a shape of a light intensity distribution on the certain plane, relative to the irradiation area irradiated only by said first optical system.

Abstract: An illumination optical system for illuminating an object surface using light from a light source includes a condenser optical system for directing the light from the light source to the object surface, wherein the condenser optical system includes first and second optical systems, one of which forms a beam expander optical system for varying a diameter of incident light, the beam expander being adapted to be movable as one element along an optical axis.

Abstract: An exposure apparatus includes a condensing optical system for condensing light from a light source to a specified plane, an imaging optical system for imaging the light in the specified plane onto a reticle or a mask or near the reticle or mask, a projection optical system for projecting a pattern on the reticle or the mask onto an object to be exposed; and a beam splitting member that is provided between the condensing optical system and the specified plane, and generates a split beam, wherein 18.3°≦&thgr;≦36.4°, 1.0≦|B|≦2.5 and 0.16≦NA2≦0.23 are met where &thgr; is an angle formed between a splitting plane in the beam splitting member and a plane perpendicular to an optical axis, B is the magnification of the imaging optical system, and NA2 is a maximum numerical aperture on a light exit side of the imaging optical system.

Abstract: A light transmitting and receiving device including a light projecting unit having an optical axis of projection, a light receiving unit having an optical axis of reception, and an optical member, disposed where the optical axis of projection intersects the optical axis of reception, including therewithin a light beam splitter which reflects one of the light beam of the light projecting unit and the light beam of the light receiving unit while transmitting therethrough the other of the light beam of the light projecting unit and the light beam of the light receiving unit, and having a transmission surface from which the light beam of the light projecting unit is transmitted and a surface opposing the transmission surface, wherein the transmission surface and the opposing surface are mutually in parallel and are inclined to the principal ray of the transmitted light beam from the transmission surface.

Abstract: An exposure apparatus includes a condensing optical system for condensing light from a light source to a specified plane, an imaging optical system for imaging the light in the specified plane onto a reticle or a mask or near the reticle or mask, a projection optical system for projecting a pattern on the reticle or the mask onto an object to be exposed; and

Abstract: An optical space communication apparatus includes a light-emitting device for emitting an elliptic light beam, and a light-projecting optical system for converting the elliptic light beam into a transmission light beam. The light-projecting optical system shapes a cross section of the transmission light beam into an elliptic shape immediately after having left the light-projecting optical system and also shapes the cross section of the transmission light beam into a nearly circular shape at a receiving point being located at the farthest distance in a transmissible distance range.

Abstract: An optical space communication method is for communication with a laser as a radiative source and with a light signal therefrom propagating in the atmosphere. In the method, the communication is performed under the following conditions. In case a transmission distance of optical space communication is between 100 m inclusive and 200 m, the laser is a laser with an oscillation wavelength L (nm) in a wavelength range of between 967 run inclusive and 1110 nm or in a wavelength range of between 1165 nm inclusive and 1315 nm, whereas in case the transmission distance is not less than 200 m, the laser is a laser with an oscillation wavelength L (run) in a wavelength range of between 986 nm inclusive and 1090 nm or in a wavelength range of between 1225 nm inclusive and 1295 nm. At any position in a transmission path between a transmitter exit and a receiver entrance, an irradiance is set to at most 6.47.multidot.10.sup.(L-700)/500 (W/m.sup.

Abstract: This specification discloses a communication apparatus provided with light emitting means for generating transmission light modulated by an information signal, light receiving means for receiving modulated reception light, an optical member for reflecting one of the transmission light and the reception light and transmitting the other therethrough, a reflecting member for reflecting the transmission light emerging from the optical member to the transmission side and reflecting the reception light to the optical member, light splitting means for splitting part of the reception light obtained through the optical member, detecting means for detecting the positional state of the light obtained from the light splitting means, and driving means for rotatively driving the reflecting member about two axes in accordance with the positional state of the light detected by the detecting means.

Abstract: An optical communication apparatus that includes a polarization beam splitter which synthesizes an optical axis of a light emitting optical system having a light emission element for emitting a linearly polarized light and an optical axis of a light receiving optical axis to make the optical axis for reception coincide with the optical axis for transmission. A phase plate is provided in such a manner as to be rotatable by a predetermined angle about the common axis. An optical axis of the phase plate of each of the associated communication apparatuses is set at an adequate angle before installation thereof.

Abstract: A two-way optical transmitter in which optical transmitters each having light projecting means and light receiving means on an optical axis intersecting the optical axis of the light projecting means are disposed in opposed relationship with each other with a predetermined distance interposed therebetween and which effects two-way optical transmission, wherein a polarizing beam splitter, having a cemented surface forming a certain angle with respect to the optical axes of the light projecting means and the light receiving means is installed near the point of intersection between the two optical axes, linearly polarized light from the light projecting means is reflected by the cemented surface of the polarizing beam splitter to thereby provide transmission light, and an optical axis leading from the polarizing beam splitter to the light projecting means or an optical axis leading from the polarizing beam splitter to the light receiving means is set at an angle of approximately 45.degree.

Abstract: This is to disclose an optical apparatus, comprising a plurality of optical lenses; and a plurality of light blocking plates or blocking member arranged in the direction of the optical axis for blocking harmful sagittal peripheral rays, the light blocking plates being installed in a ring shape at the pupil position of the optical lenses and being inclined, by an angle .alpha. respectively, to a plurality of imaginary planes including the optical axis.