Abstract: A new type of optical element for diverging a laser beam in several directions, for example to produce a relatively uniform cross, has a number of cylindrical segments. Each segment has at least two surfaces, a primary and a secondary surface. The primary surface has a relatively sharp apex and is shaped to conform to a curve defined in a (x,y,z) cartesian coordinate system by the equation ##EQU1## where z and y are independent of x, c is the curvature at the apex and Q is the conic constant which is less than -1.The element is useful e.g. for precision alignment.

Abstract: A photon-counting spatial light modulator that has an avalanche photodiode structure and is designed to operate in Geiger mode is sensitive to a single photon of light. An avalanche photodiode having an applied electric field is excited by an optical wave comprising one or more photons whose energies exceed the band-gap energy of the photodiode material. This localized electrical excitation alters the refractive index of the material through various effects, most notably the transient thermo-optic effect and the photorefractive effect. A second optical wave is incident during or shortly after the electrical excitation, and comprises photons whose energy is less than or nearly equal to the band-gap energy. This second optical wave is then used to read out the avalanche-induced variation in refractive index.

Abstract: A semiconductor optical modulator includes a light absorbing layer having a multi-quantum well structure including two quantum wells including quantum well layers bounded and separated by barrier layers, the quantum wells having respective, different .DELTA.Ev/.DELTA.Ec ratios where .DELTA.Ec is the discontinuity between the barrier layer and a quantum well layer in the conduction band edge and .DELTA.Ev is the discontinuity between the barrier layer and a quantum well layer in the valence band edge. By this construction, the absorption peak when no electric field is applied significantly shifts toward the longer wavelength side, resulting in a large difference between the absorption peak wavelength when no electric field is applied and the absorption peak wavelength when an electric field is applied, whereby the absorption loss of a semiconductor optical modulator when no electric field is applied is reduced.

Abstract: A device for converting a mid-wave infrared or long-wave infrared thermal image into a coherent near-infrared image includes a two-dimensional array of quantum-well-based optical modulators and infrared photodetectors. Each modulator is integrated or hybridized with a respective photodetector, and the combination is connected to an electronic circuit. Variations in mid-IR or long-IR light intensity are converted by each photodetector into variations in a bias applied to its respective modulator. The bias variations modulate the intensity and/or phase of near-IR light illuminating the modulators.

Abstract: An apparatus for coupling a broad emitting area laser diode made of multiple emitters operating in parallel to a linear light valve. The apparatus images each one of the emitters onto the linear light valve, superimposing them in order to increase the immunity to defects occuring in any individual emitter.

Abstract: A lens system includes a master lens system and a conversion lens system. The master lens system has a first lens, a second lens, a third lens, and a fourth lens, which are sequentially arranged from an object side of the lens system to an image side thereof, and has a first diaphragm which is arranged between the third lens and the fourth lens. The first lens is a positive meniscus lens having a convex surface toward the object side. The second lens is a negative lens. The third lens is a positive lens. The fourth lens is a negative meniscus lens having a concave surface toward the object side. The conversion lens system is arranged in such a manner that the conversion lens system can be freely inserted and removed between the third lens and the fourth lens of the master lens system.

Abstract: A large aperture retrofocus lens system is composed of first to sixth lenses arranged in this order from the object side. The first lens has a positive refracting power, the second lens has a negative refracting power, the third lens which is a meniscus lens concave toward the object side, the fourth lens has a negative refracting power, the fifth lens has a positive refracting power and the sixth lens has a positive refracting power.

Abstract: A fast aspherical lens system is provided which includes a front lens group having a negative power, a diaphragm, and a rear lens group having a positive power, arranged in this order from the side of an object to be photographed. The rear lens group is provided with at least one lens having a diverging aspherical surface and satisfies the following conditions:-0.6<f/f.sub.F,<-0.2;tm (1)3.0<.SIGMA.d.sub.F+S /f<8.0; (2)3.0<.SIGMA.d.sub.R /f<6.0; (3)-0.9<.DELTA.I.sub.ASP <-0.1; (4)where f represents a focal length of the entire lens system, f.sub.F represents a focal length of the front lens group, .SIGMA.d.sub.F+S represents a sum of the thickness of the front lens group and a distance between the front lens group and the rear lens group, and .SIGMA.d.sub.r represents a thickness of the rear lens group, and .DELTA.I.sub.ASP represents an aberration factor of the aspherical surface term of the third-order spherical aberration factor of the aspherical lens.

Abstract: An objective lens assembly provides up to 60 degrees field of view for the NVIS image intensifier goggle. A first lens subassembly positioned on the focal axis faces a external view and substantially corrects pupil aberrations in an aperture stop located after the first subassembly. A second lens subassembly is then located after the aperature stop on the focal axis. Color and field aberration corrections is provided while maintaining substantially high quality focus by a third lens subassembly. A lens element after the third lens subassembly on the focal axis flattens the image plane over the intensifier image format such that there results a format of up to 25 mm with a photocathode resolution for up to a 60 degree field of view.

Abstract: In an external modulator for optical communication, a piezoelectric element section is formed by laminating a lower electrode, a piezoelectric thin film and an upper electrode in this order on one surface of a substantially flat substrate which has substantially the same acoustic impedance as the clad layer of a single mode optical fiber to be disposed on the substrate. At least one single mode optical fiber is disposed on the other surface of the substrate on the upper electrode, and the single mode optical fiber is at least partly coated with a material having an acoustic impedance substantially equal to that of the clad layer in a place in which the single mode optical fiber is disposed.

Abstract: A method and apparatus for modulating an optical signal using a micromechanical modulator are disclosed. The modulator comprises a membrane, which consists of at least one layer, and a substrate, spaced to form an air gap. The layers of the membrane are characterized in that there is a relationship between the refractive indices of the layers and the refractive index of the substrate. The membrane is suspended in a first position over the substrate by a flexible support arrangement. Bias is applied to the membrane and the substrate to create an electrostatic force to move the membrane towards the substrate to a second position. The reflectivity of the device to an optical signal changes as the membrane moves from the first position to the second position, thereby modulating the signal.

Abstract: The zoom lens of the present invention comprises, in the order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, in which, at a refractive power varying operation from the wide angle end to the telescopic end, at least the first and fifth lens groups move toward the object side, while the air gaps between the first and second lens groups and between the second and third lens groups increase and the air gap between the fourth and fifth lens groups decreases, and there is satisfied a condition:0.4<.DELTA.Bf/(ft-fw)<0.8wherein .DELTA.

Abstract: An amplitude optical modulator which utilizes a two-electrode DFB laser structure. The amplitude optical modulator includes a current generator which can modulate at least one of two currents injected into the DFB laser structure. This modulation displaces a spontaneous emission peak of the DFB laser structure, which leads to an amplitude modulation of the injected optical beam. Such an amplitude optical modulator may find particular application in an optical telecommunications system.

Abstract: An electro-optic imager, used for exposing photosensitive media, wherein a modulator, e.g. an array of PLZT light valves, is used to modulate one or more light beams. Temperature control is applied to the modulator to reduce or eliminate variations in response characteristics which would otherwise change the color balance of the final print from the desired color balance.

Abstract: A fast ultra-wide angle lens system is provided which includes a front lens group having a negative power, a diaphragm, and a rear lens group having a positive power, arranged in this order from a side of an object to be photographed. The lens system satisfies the following conditions:-0.5<f/f.sub.F <-0.2; (1)7.0<.SIGMA.d.sub.F+S /f<12.0; and (2)5.0<.SIGMA.d.sub.R /f<10.0, (3)wherein f represents a focal length of the entire lens system, f.sub.F represents a focal length of the front lens group, .SIGMA.d.sub.F+S represents a sum of the length of the front lens group and a distance between the front lens group and the rear lens group, and .SIGMA.d.sub.R represents a length of the rear lens group.

Abstract: A projection lens system includes a cathode ray tube which projects the image to be projected on the screen through a set of six projection lens, which include non-spherical surfaces. The projection lens system is obliquely positioned in order to incline the optical axis of the projection lens at a predetermined angle with regard to the optical axis which exits from the projection lens and reaches the screen.

Abstract: A small-sized diaphragm device for an image pickup lens system having an electrochromic element the light transmitting properties of which are changed on application of an electrical voltage. The diaphragm device also includes a first set of plural concentrically arranged transparent electrodes, a second set of plural concentrically arranged transparent electrodes and third electrodes formed on the outermost peripheries of these sets of transparent electrodes for acting as counter-electrodes for the transparent electrodes. The diaphragm device has a sufficient light transmittance when in the transparent state, while having high light interrupting properties when in the light interrupting state.

Abstract: An optical modulator device comprised of a semiconductor laser acoustically coupled to a thin film resonator is disclosed herein. The thin film resonator includes a piezoelectric crystal layer having first and second opposing surfaces, with the first opposing surface being in contact with a metallic electrode. The semiconductor laser is interposed between an acoustically reflective surface and the second surface of the thin film resonator. In a preferred implementation the acoustically reflective surface is defined by a submount underlying a substrate upon which is mounted the semiconductor laser.A frequency modulator exhibiting an improved modulation index may be achieved by integrating a superlattice structure within the active region of the semiconductor laser.