Abstract: A zoom lens is provided, in which a fixed first lens group having a positive refracting power, a second lens group having a negative refracting power and which realizes a variable magnification, a fixed third lens group having a positive refracting power and a fourth lens group having a positive refracting power which compensates fluctuation of an image surface caused by the variable magnification and which focuses an image are sequentially provided from an object side. In this zoom lens, the third lens group is composed of two separate lenses of a positive lens (31) and a negative lens (32). At least one surface of the positive lens (31) is formed as an aspherical surface and a surface of the negative lens (32) opposing the image surface side is concaved to the image surface side. Thus, the zoom lens of this invention can be miniaturized and reduced in weight without deteriorating the characteristics such that a variable magnification is large and that an F number is small.

Abstract: A focus error detecting apparatus in which a light emitting and receiving element including a light emitting portion and light receiving portions all of which are formed in a common semiconductor substrate, a hologram element diffracts a light beam reflected by an object to generate plus and minus first-order diffraction light beams and to introduce an astigmatism into the plus and minus first-order diffraction light beams such that shapes of spots of the diffraction light beams formed on the light receiving portions of the light emitting and receiving element vary into substantially reverse directions to each other, and a focusing condition is detected in accordance with outputs of the light receiving portions. Therefore, in this apparatus, positioning adjustment of the light receiving portions with respect to the light emitting portion is not necessary, and thus a number of the adjusting process can be remarkably decreased and the cost for manufacturing the apparatus can be reduced.

Abstract: An infrared filter that is formed as a laminated structure including a plurality of layers having substantially uniform thicknesses. The various embodiments include first layers that are relatively thick which are interleaved with second layers that are relatively thin as compared to the first layers. The second layers are generally one quarter wavelength optical thickness at a particular tuned wavelength, whereas the first layers are generally a plurality of quarter wavelength optical thicknesses. Methods for manufacturing the filters are described, including grinding and polishing procedures for obtaining the desired uniformity of thicknesses of said layers.

Abstract: A computer hood is provided for a computer having a monitor that contains a cabinet and video display screen behind a keyboard on a desk located in a building having overhead lighting in a ceiling and/or an uncovered window in a wall. The computer hood consists of a structure for covering the front of the cabinet about the video display screen of the monitor of the computer to reduce glare on the video display screen from the overhead lighting in the ceiling and the uncovered window in the wall of the building. It will improve sharpness of display, relieve eyestrain and improve productivity of a person operating the computer.

Abstract: Disclosed is a variable lens assembly having a water chamber defined with a front lens holder between two flexible, transparent diaphragms and filled with a fluid, and a syringe connected to the front lens holder and controlled to vary the volume of the water chamber. The diaphragms are stretched to curve outwards and form into a biconvex lens as the plunger of the syringe is pushed forwards in compressing the fluid; the diaphragms are induced to curve inwards and form into a biconcave lens as the plunger of the syringe is pulled backwards in releasing the fluid.

Abstract: A volume phase type hologram has a diffraction lattice recorded in a poly(N-vinyl carbazole) polymer layer where the diffraction lattice is recorded throughout the thickness direction of the polymer layer. A method for preparing the volume phase type hologram has the steps of exposing a photosensitive polymer layer provided on a substrate to an interference pattern; subjecting the polymer layer having been exposed to a first development treatment with a first organic solvent; and peeling the polymer layer off the substrate and subjecting the polymer to a second development treatment with a second organic solvent preferentially from the face that had been in contact with the substrate.

Abstract: The invention relates to a compact, lightweight and inexpensive zoom lens system which, even when used with a small image sensor, allow the convex lenses to have a sufficient peripheral thickness and the concave lenses to have a sufficient central thickness and which comprises, in order from the object side, a first unit having a positive refracting power, a second unit having a negative and being movable during zooming, a third unit having a positive refracting power and remaining fixed in place and a fourth unit having a positive refracting power and being movable during zooming and focusing; said third unit comprising, in order from the object side, two lenses in all, one being a positive lens having a strong curvature on the object side and the other a negative lens having a strong curvature on the image side, and said third and fourth units each having at least one aspherical surface whose refracting power decreases as it is spaced away from the optical axis and conforming to the following conditions (1)

Abstract: A method and apparatus for imaging of an atomic environment are disclosed. The method includes detecting and measuring the intensity of a diffuse low energy electron diffraction pattern. The diffraction pattern may be formed by directing a beam of electrons against the surface of a sample, or by directing a beam of X-rays against the surface of a sample. The diffraction pattern may be energy-filtered to obtain a diffraction pattern corresponding to the lower energy electrons emitted by the surface. Data corresponding to reconstructed amplitudes of a waveform is generated by operating on the intensity data. The data corresponding to the reconstructed amplitude is capable of being displayed as a variety of slices or two-dimensional planes of the three-dimensional image of an atomic environment, and is capable of being displayed holographically.

Abstract: A real image type view finder comprising at least one cemented lenses. Of the lens components constituting the cemented lens, a lens component is made of resin. The lens component may be made of material of high transmittance to ultraviolet rays.

Abstract: Optical elements, and methods for fabricating them, are described wherein each element includes a free standing (self supporting) polycrystalline continuous thin film of diamond combined with a non-hydrogenated amorphous diamond like carbon (DLC) film having a high percentage of sp.sup.3 bonding. These elements may be designed to have optically smooth surfaces, have wide optical transmission ranges (for example, be transparent across the infrared portion of the spectrum), and exhibit exceptional durability characteristics. Optical instruments that include such elements are also described, along with the derivative benefits, such as improved operating performance and lower maintenance requirements, realized using the novel optical elements. In particular, a polarization Michaelson interferometer (PMI) is taught which is operative over the entire range from far infrared into the visible portion of the spectrum without requiring the exchange of beam splitters or beam polarizers.

Abstract: Apparatus and method for storing holographic synthesized information for reflection integral Bragg holograms, free of the limitations of dispersing elements (such as unilateral diffusing screens, conventional lenticular screens and Fresnel lenses), multiple reference beams, mirrorized indexing or other similar materials or techniques. These holograms accurately satisfy Bragg's condition, provide an expanded (and essentially normal) vertical viewing range and can be displayed both flat (in which case the image is behind the film plane) or concave towards the viewer (in which case the image is in front of the film plane). Flat and curved holograms can be combined together. The final holographic images are produced directly from motion picture film, without intermediate transfer prints as required by the prior art. All are front illuminated. By curving the developed hologram for viewing a high definition projection image is obtained.

Abstract: A hybrid lens for collimating, with low optical aberrations, an asymmetrically diverging input wavefront. The hybrid lens has a front surface which serves to diffract the input wavefront and a back surface which serves to refract the wavefront. Embodiments are described comprised of either a single plano-convex optical lens or a pair of lenses, one of which is a plano lens and the other or which is plano-convex. In either alternative, the convex surface is spherical. The planar surface of the single plano-convex lens or the back lens surface of the plano lens is optimized such that each ray of light from a diverging input light source will travel the same optical path length in reaching a predetermined collimation plane. This optimization is done by means of binary optic technology which uses a reactive-ion etch to form the requisite eight-level binary optic diffraction pattern.

Abstract: A method for assessing and correcting via feedback, the optical quality of an imaging device. The method has an advantage of expanding the applicability of a classical optical transfer function, heretofore a measure only of global imaging device performance, so that it can provide feedback information for correcting an imaging device defect in terms of local area modifications.

Abstract: A leak-corrected linearly variable filter comprises optical filter coatings formed on an assembly of one or more optically transmissive substrates. Leaks due to the longitudinal precession of incident light within the substrates are suppressed by forming the filter such that no two surfaces which are reflected at the same wavelength within the range of interest are parallel. Typically, the constituent substrates of the filter are oriented at a slight angle relative to one another and filter coatings having overlapping reflective wavelengths are deposited on different substrates rather than on the two parallel sides of the same substrate. Alternatively, venetian shade structures can be incorporated within the substrates to block longitudinal precession of light.

Abstract: An optical associative identifier is disclosed which is used to determine the closest match between an image to be identified and a plurality of reference images. The identifier includes a display area for displaying the various images, the display area additionally functioning as a spatial light modulator. First and second optical Fourier transform devices are included which are used to compare the reference images to the image to be identified. The output light intensity of each of the reference images is modulated in accordance with a two-dimensional intensity distribution corresponding to the correlation between the image to be identified in each of the reference images. Based upon a comparison of these output light intensities, a match between the image to be identified and one of the reference images can be made.

Abstract: A method of performing image correlation in a Fourier transform correlator utilizes phase-encoding of the input image as a phase object with a normalized amplitude component. Phase-only reference image filters are used in conjunction with the phase-encoded input objects to improve the signal to clutter ratio. This technique can employ optical or digital implementation.

Abstract: A lens system having discrete variations of focal length at discrete distances of radius outward from the optic axis for focussing light of plural wavelengths. The lens system which directs a laser beam onto a target for ablation or exposure applications includes one set of lens elements to handle short wavelength light used for ablation or exposure applications, and another set of lens elements to handle long wavelength light used for alignment applications. The lens system which provides for the ablation or exposure functions at short wavelength and for through-the-lens alignment at a longer wavelength and higher numerical aperture consists of three elements. Two outer lens elements are made entirely of fused quartz. An inner element disposed between the two outer lens is composed of any material such as optical glass. The inner lens element has a hole ground through its center.

Abstract: A head-up display device comprises an image generator, a beam combiner having a light receiving plane tilted laterally for receiving a light from the image generator and diffracting the light, and a compensator arranged between the image generator and the beam combiner for receiving the light from the image generator by a light receiving plane thereof and directing the light to the beam combiner to correct an aberration created by the beam combiner. The compensator is arranged such that a normal line extending through a center of the light receiving plane thereof and a normal line extending through a center of the light receiving plane of the beam combiner are in a common plane.

Abstract: An image processing apparatus having a third-order nonlinear stimulated photon echo medium (1). The photon echo medium (1) can store large numbers of images in the form of a Fourier transformed pattern by spectral modulation. The spectral modulation is carried out by sending optical pulses in an optical pulse train having (or not having) image information to the medium (1) so that the population in the ground and excited states are modulated after the passage of the pulse trains and pulses. The Fourier transformed pattern is converted back to temporal modulation, consisting of a sequence of echo pulses that reproduce the original data pulse train. By using the apparatus, ultrafast operation such as convolution and correlation between a number of reference images and a test image can be achieved.

Abstract: A method and apparatus for three dimensional imaging of the atomic environment of disordered adsorbate atoms are disclosed. The method includes detecting and measuring the intensity of a diffuse low energy electron diffraction pattern formed by directing a beam of low energy electrons against the surface of a crystal. Data corresponding to reconstructed amplitudes of a wave form is generated by operating on the intensity data. The data corresponding to the reconstructed amplitudes is capable of being displayed as a three dimensional image of an adsorbate atom. The apparatus includes a source of a beam of low energy electrons and a detector for detecting the intensity distribution of a DLEED pattern formed at the detector when the beam of low energy electrons is directed onto the surface of a crystal.