Abstract: A pickup system for an optical disc reading/recording apparatus in which a micro Fresnel lens, formed with concentric circular gratings, is used in place of an optical element, such as an objective lens, for focussing and collimating light beams from a semiconductor light source. The pickup system so formed is light in weight, easily miniaturized, and inexpensive to manufacture. The micro Fresnel lens can be formed as an integral unit with the semiconductor laser by mounting the lens in a window of the case of the semiconductor laser.

Abstract: A variable transmission output coupler and deviationless tuner forms a part of a tunable laser cavity. The device uses frustrated total internal reflection to provide variable output coupling and laser tunability simultaneously. Two Pellin-Broca prisms are pressed against each other by a variable spring pressure mechanism. An adjustable screw regulates the variable force, controlling the thickness of an air film between two prism faces. The Pellin-Broca prisms enable tuning the laser without angular deviation of the output beam. All beams enter and exit at Brewster's Angle, minimizing losses. No coatings are used on the optical elements, reducing the possibility of damage at high operating power of the laser. The coupler may be used in pulsed as well as continuous wave lasers.

Abstract: Apparatus and methods for producing an intensity image from a transparent phase object. A laser beam is generated and expanded. A shutter disposed in the path of the expanded laser beam is opened, and the expanded laser beam is split into first and second beams. The first beam is directed through the transparent phase object and focused into a photorefractive hologram recording crystal for the write time of the crystal. The shutter is closed, and the position of the transparent phase object is shifted an incremental amount. The shutter is opened again so that the first beam is directed through the shifted transparent phase object and into the photorefractive hologram recording crystal such that a phase-conjugate beam is produced traveling in the opposite direction of the first beam. The phase-conjugate beam is collimated, directed through the shifted transparent phase object, and split into third and fourth beams.

Abstract: An optical system is disclosed for an endoscope having a generally tubular distal end in which an objective lens assembly and a solid-state video camera are internally housed so that an image formed by the lens assembly is focussed upon the video camera. The video camera is disposed along or in proximity to the center axis of the distal end of the endoscope. The video camera may be positioned in this way due to the provision of a reflecting surface which is angularly disposed in opposing relationship with an input surface of the video camera, and deflection means disposed in front of the lens assembly and within the objective lens assembly, or between the lens assembly and the reflecting surface, so that an image formed by the lens assembly can be focussed on the input surface of the video camera.

Abstract: A metallic pattern is applied to a dielectric substrate to form the inventive device. The pattern is a mesh or array of islands with two-fold symmetry, i.e., bisymmetrical but with unequal orthogonal dimensions. Lamination of the devices may be formed to make various types of waveplates and filters.

Abstract: An optical imager includes a sensor and a diffraction lenticular array. The sensor includes a substrate of a semiconductor material having a pair of opposed major surfaces and a plurality of photodetectors arranged in a plurality of columns along one of the major surfaces. The diffraction lenticular array includes a plurality of stripes of a material which will diffract the radiation being sensed. The stripes are arranged in a plurality of repetitive patterns with each pattern being formed of a plurality of spaced, parallel stripes extending longitudinally along a column of the detectors. The pattern of the stripes has a large spacing between the stripes at the center of the pattern and smaller spacing at the edges of the pattern. The stripes may be on a separate substrate of a material which is transparent to the radiation being detected or directly on the major surface of the semiconductor substrate.

Abstract: A holographic recording device includes an acoustical and vibration protection package having, mounted in an enclosure, at least three spaced apart supporting elements, a means for producing reference and object beams being secured to the supporting elements, while a coherent source is rigidly secured to at least two supporting elements. Supporting elements are rigidly secured to at least two rods and a screen set perpendicular to said supporting elements. A holographic recorder is positioned after the means for producing reference and object beams in the path of the source beam.

Abstract: An endoscope whose magnification may be continuously varied from zero to a microscopic magnification of 40.times. or more while providing full correction for aberrations at widely different magnifications. The objective comprises a positive lens group in a microscope objective configuration, and a front group which typically includes a negative lens generally near the focal plane of the positive lens group. To achieve high magnification, the objective is moved away from the transfer optics, and placed in contact with the object to be viewed. In such a configuration, the positive lens group functions as a microscope objective while the negative lens group's contribution to the aberrations is small. At low magnification, the negative lens group cooperates with the positive lens group to provide a wide angle lens.

Abstract: A plurality of light beams emitted by a plurality of light sources are combined together to obtain a power-multiplication effect of the beams by use of a holographic diffraction grating. The holographic diffraction grating diffracts a plurality of light beams incident thereto into such directions that the diffracted light beams advance in parallel to one another or are collimated, advance toward a point or converge, or advance as if they were emitted from a point or diverge so that the diffracted light beams can be focused to a point by use of or without a focusing optical system to multiply the power of the beams in effect. The holographic diffraction grating may be of area division type which diffracts the light beams at different portions thereof or of a multiple type which diffracts the light beams at the same portion thereof.

Abstract: There is disclosed a bi-level focusing plate of phase grating type in which micro unit patterns, each of which is comprised of one or more projections and one or more recessions, are arranged regularly and repeatedly at a pitch of 10 to 30 .mu.m. The phase difference between each of projections and each of recessions is set at .pi. radian against a light having a wavelength of 400 to 700 nm and the ratio in area of total area of projections or recessions in one unit pattern to the area of said one unit pattern is set so as to fall into a range of 0.3 to 0.5. The focusing plate is characterized in that the boundaries in each unit pattern each defined between the projection and the recession adjacent to each other therein are comprised of straight-lined portions and curved portions.

Abstract: An imaging device is disclosed which comprises a noble metal photosensitive glass having formed on the surfaces a plurality of raised spherical surfaces which form an array of thick lenses. The array can be positioned between an object and image plane to project images from the object plane onto the image plane. Lens spherical aberrations are reduced and lens array imaging performance is optimized by an optimum lens aperture radius or an optimum lens numerical aperture.

Abstract: Responsive to a plurality of parallel light beams and electric signals corresponding to the parallel light beams, an acoustic modulation element produces output light beams modulated by acoustic waves resulting from the electric signals. The element comprises a single acoustooptic medium block receiving the parallel beams on a first surface thereof and emitting the output light beams from a second surface opposite to the first surface. A plurality of transducer units are laid in parallel on a third surface of the block between the first and the second surfaces along the respective parallel beams so as to propagate the acoustic waves into the block when activated by the electric signals. The block may have a fourth surface opposite to the third surface and arcuately or triangularly recessed towards the third surface.

Abstract: The invention relates to a compound blazed optical phase grating. The grating comprises at least two grating sections which are disposed opposite each other in parallel planes. The gratings have grooves which extend parallel to each other. The grating sections have equal grating periods and are movable relative to each other within their planes and perpendicular to the grooves. Over one grating period, the optical path length varies at least substantially parabolically and symmetrically relative to the grating period. The path length varies in such a manner that when both grating sections are symmetrically arranged relative to a common line perpendicular to the grating planes, the optical path length through the compound grating is uniform across the grating. Various optical switches and switching matrixes can be formed by using such compound phase gratings.

Abstract: This invention relates to an image forming optical apparatus in which a number of micro-lenses are arranged, and images formed by said lenses are superposed to obtain a synthesized image. In the optical apparatus of this kind, individual images have their respective irradiance distribution, and therefore, unevenness in the irradiance distribution of the synthesized image has to be minimized. Where this optical system is used for a copier or the like, exposure is carried out through a slit. The width and position of the slit greatly influence the irradiance for exposure and on unevenness in irradiance. According to the invention, optimum width and position of the slit can be selected to minimize the unevenness in irradiance and provide sufficient exposure.

Abstract: A photo scanner device including a rotary disk having a plurality of holograms thereon and arranged in at least two concentric circles with respect to the axis of rotation of the disk, and a light source which generates a beam of light which is incident on the disk at a selected radial distance which may be varied so as to illuminate the holograms arranged on a selected concentric circle. The holograms on the same concentric circle each subtend the same angle from the axis, and the holograms on different concentric circles subtend different angles from the axis, thereby permitting the angle of scan to be switched by selection of the radial distance at which the beam of light is incident.

Abstract: In accordance with one embodiment of the present invention, a controlling laser beam at a first wavelength is introduced into an interferometer such that one half of it contains the aberrations of the laser beam to be controlled and the other half is and remains undistorted. The aforementioned two halves of the controlling laser beam are combined at the output of the interferometer and then, together with the laser beam to be controlled at a second wavelength is introduced collinearly into a gas cell or phase corrector. Upon combination or interference of the two halves of the controlling laser beam the phase-front aberrations are translated to intensity modulations across the cross section of the beam.

Abstract: Lack of versatility and efficiency in optical multiplexing/demultiplexing is countered by progressing incident light along a wavelength selective holographic reflection filter which reflects different wavelengths at different positions along the filter. Light from a fibre optic input cable is directed by mirrors to make successive passes at the filter at respective different positions therealong and detectors receive the respectively reflected wavelengths. The filter preferably varies the reflected wavelength continuously and progressively as the incident light progresses along the filter.

Abstract: A well defined passband for an optical reflection filter is achieved by causing light to be reflected at least twice from a holographic wavelength selective reflector. Preferably the wavelength/reflectivity characteristics differ at the two reflections to give relatively shifted, but overlapping, spectral passbands. The apparatus may comprise a fibre optic input cable which directs light at the holographic reflector and a corner cube reflector which returns the reflected light for a second reflection prior to receipt by a detector.

Abstract: The device consists of a transparent container, partly filled with a ferromagnetic fluid surrounding a bubble of a transparent liquid. By an external magnetic field the ferromagnetic fluid is displaced within the container and moves the bubble making it pass between a light source and a light sensitive element.

Abstract: A security element for authenticating bank notes, credit cards, security passes and the like is disclosed. The security element incorporates a reflective-type diffraction grating, which grating comprises a continuous layer of reflecting material on which is deposited a layer of dielectric material. Non-continuous reflecting layer portions are embedded in the dielectric material. It is practically impossible to lay bare the diffraction grating without destroying it.