Abstract: An alignment cross hair apparatus for partially eclipsing a laser beam includes a laser generator that emits a laser beam. A frame includes a pair of members that cross one another at an intersection within the frame. The frame is attachable to the laser generator in such a manner that the intersection of the members is within the laser beam so that the laser beam is partially eclipsed by the pair of members.

Abstract: A cylindrically shaped gain medium for a laser resonant cavity. The gain medium has an outer cylindrical side surface and two opposing end faces. An annular groove is formed in the side surface. An energy source excites the gain medium to create a laser beam inside the cavity. The laser beam passes longitudinally through the gain medium. The annular groove defines an annular aperture inside the gain medium for the laser beam. The annular aperture has a diameter that is smaller than a diameter of the side surface and the end faces.

Abstract: A high power laser resonator with improved efficiency of the lasing mechanism, for outputting a laser beam (6) of improved geometric and quality factors characteristics, adapted to the specific needs of high-speed-high-power laser material processing. In particular, conditions for output laser beam (6) geometric dimensions Dx, Dy, and corresponding quality factors, Kx, Ky, are set, such that the laser beam could be usable directly from the output of the resonator without adding beam shaping optics, and such that a better optimization of the extraction efficiency of laser power can be achieved. These four factors are in specific relationship with the wavelength of the laser radiation and the output laser power.

Abstract: A laser system capable of providing light of high intensity is disclosed. This system includes a laser gain medium and three reflectors. A first reflector and a second reflector spaced from the first reflector define a laser cavity that contains the laser gain medium. Light reflected by the first reflector is amplified by the laser gain medium. A third reflector is spaced from the second reflector to define a resonant cavity external to the laser cavity. Light passes from the laser cavity to resonate in the external resonant cavity. Part of the light passes from the external resonant cavity to the laser cavity. A light-screening device, e.g., an aperture, is disposed between the second reflector and the gain medium to screen light reflected from the external cavity such that the light portion of constructive interference is preferentially passed over the light portion of destructive interference. This enables the gain medium to optically lock to the resonant frequency of the external cavity.

Abstract: An X-ray laser generating apparatus comprises a laser oscillator for generating a pulse laser beam, a pulse train converter for converting the pulse laser beam into a pulse train laser beam, an optical device for focusing the pulse train laser beam to a thin line, a target material placed at the laser beam focused position and generating high temperature plasma containing highly charged ions with irradiation of the linearly focused pulse train laser beam, a vacuum chamber for keeping a vicinity of the irradiated region of the target material under a decompressed state, and a pair of X-ray reflecting mirrors positioned on both sides of the target material and on the extended thin line, and at least one of the paired mirrors partially transmits X-ray.

Abstract: A diffusion-cooled laser has a lasing region shaped to provide a high power output laser beam of a high optical quality. The lasing region, which contains a lasing medium, has a narrow-aperture section and a free-space section. The narrow-aperture section is defined by resonator walls spaced apart a sufficiently small distance that enables effective excitation and cooling of the lasing medium. The free-space section is defined by resonator walls spaced apart a sufficiently larger distance that enables the laser beam to expand without restriction from the resonator walls in the free-space section. The narrow-aperture section enables the laser to generate a high power laser beam using a relatively low (40 MHz) ISM frequency. The free-space section allows the laser beam to expand sufficiently to exit the lasing region with a shape that is easily focused by inexpensive optical elements.

Abstract: Described are a method for generating a laser beam and a laser device for practising the method. In a first step gas is ionised by means of X-rays. In a second step the electron density is increased by means of a pre-discharge. In a third step the main discharge takes place. Between the second and third steps, an electron redistribution occurs. According to the invention, the electron redistribution rate and/or the time delay between the pre-discharge and the main discharge are adjustable and controllable in relation to each other, for achieving a particular desired beam profile, such as a uniform profile. Because that delay is preferably set by varying one or more process parameters, an improtant advantage is achieved in that it is possible with one and the same laser device to modify the beam profile in a simple and flexible manner even during the operation of the laser device.

Abstract: An ultrashort pulse laser apparatus of the this invention includes (1) a laser medium, (2) a laser resonator which stores the laser medium and externally extracts a laser beam, and (3) an excitation source for outputting an excitation energy to the laser resonator to excite the laser medium. The laser resonator includes (i) a plurality of resonant mirrors disposed on both sides of the laser medium to form a resonant optical path, and (ii) a phase dispersion compensation unit which includes two optical members respectively arranged on two light input/output surface sides of the laser medium on the resonant optical path and compensates phase dispersion of light in the resonant optical path. That is, the laser medium is disposed in the optical path between the two optical members of the phase dispersion compensation unit.

Abstract: A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

Abstract: This invention teaches a method for fabricating a microlens within a window of a laser diode assembly, and a laser diode assembly fabricated in accordance with the method. The method includes the steps of (a) providing a laser diode assembly that includes a window that is substantially transparent at wavelengths emitted by a laser diode within the assembly, the window comprising a wavelength-selective absorber of electromagnetic radiation; and (b) irradiating a portion of a surface of the window with electromagnetic radiation having wavelengths within a range of wavelengths that are absorbed by the wavelength selective absorber such that a portion of the electromagnetic radiation is absorbed for heating and melting the material adjacent to the surface region, whereby the melted material rises up above the surface to form, when re-solidified, the microlens.

Abstract: A gas stable/unstable resonator laser having a folded internal beam path includes a front reflective surface (25) mounted substantially perpendicular to the electrodes (21(1),21(2)), and a rear reflective surface (24) mounted substantially parallel to the front reflective surface. A lower fold reflective surface (26') is mounted substantially adjacent to and at approximately a 45 degree angle with respect to the front reflective surface (25) and an upper fold reflective surface (28') is mounted at approximately a 90 degree angle with respect to the lower fold reflective surface (26'). Light energy (27) is reflected between the front reflective surface and rear reflective surface and subsequently reflects off the lower fold reflective surface (26'). Light energy is then reflected from the lower fold reflective surface (26') to the upper fold reflective surface (28'), passing the light energy substantially perpendicular to the front reflective surface and rear reflective surface.

Abstract: In a laser cavity having an optical axis, a laser medium for forming a laser beam, the laser medium having a central axis off-set from the optical axis, the laser medium exhibiting focusing characteristics that vary with changes in optical power pumped into the laser medium, at least one pair of mirrors oppositely positioned for reflecting at least a portion of the laser beam, one of the mirrors being an output coupler, the laser cavity further comprising at least one focusing element having a central axis positioned between one of the mirrors and the laser medium such that the central axis of the focusing element is displaced from the optical axis a distance that is a function of the displacement of the laser medium central axis from the optical axis and the optical axis passes through the focusing element to substantially eliminate lensing effects produced by the laser medium.

Abstract: A laser system which generates pulses with a duration in the range of about 60 to 300 ps at an energy level of up to a few milli-Joules per pulse (mJ/p) with near diffraction limited beam quality. A laser crystal is pumped (excited) by diode lasers. A resonator having at least two mirror surfaces defines a beam path passing through the laser crystal. The beam path in the resonator is periodically blocked by a first optical shutter permitting pump energy to build up in the laser crystal, except for a short period near the end of each pumping period. While the first optical shutter is open a second optical shutter blocks the light in the resonator except for periodic subnano-second intervals, the intervals being spaced such that at least one light pulse traveling at the speed of light in the resonator is able to make a plurality of transits through the resonator, increasing in intensity by extracting energy from the excited laser crystal on each transit.

Abstract: A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

Abstract: A laser apparatus includes a hollow cylindrical solid state laser medium and an optical resonator having reflective surfaces at each end of the laser medium in the axial direction of the laser medium for causing a light emitted into the laser medium to travel back and forth along the elongated axial direction of the laser medium. One of the reflective surfaces of the optical resonator is shaped to reflect the beam at an angle to the beam impinging thereagainst to thereby walk the beam tangentially around the hollow cylindrical solid state laser medium at a fixed radial distance from the elongated axis of the laser medium. An exit slot is formed in one of the reflective surfaces. A pumping means for exciting the laser medium includes at least one flashlamp positioned adjacent the laser medium along the laser medium axis through the hollow cylindrical portion of the laser.

Abstract: A waveguide laser (10) incorporates a guide (12) and two concave resonator mirrors (14, 16). The guide (12) is of square section with side (2a), and of length L equal to 4a.sup.2 /.lambda., where .lambda. is a laser operating wavelength. The mirrors (14, 16) are phase matched to respective Gaussian intensity profile radiation beams with beam waists at respective waveguide end apertures (20, 22). Each beam waist has a radius w.sub.0 in the range 0.1a to 0.65a to avoid waveguide edge effects and excitation of unwanted high order waveguide modes. The laser (10) has good transverse spatial mode characteristics.

Abstract: A semiconductor light emitting device includes a semiconductor light amplifier, a mirror which reflects light emanating from the rear end face of the semiconductor light amplifier to return the light to the rear end face of the semiconductor light amplifier, and a band pass filter which is inserted into the optical path of the light emanating from the rear end face of the semiconductor light amplifier and has a narrow transmission wavelength band.

Abstract: The apparatus of the present invention significantly improves the optical intensity induced damage limit of optical quality crystals, and in particular crystals used in the conversion of laser radiation at a specific wavelength to another wavelength or other wavelengths through non-linear interaction of the input laser radiation with the optical crystal medium. In accordance with the present invention, passive optical elements are positioned at the laser beam exiting and entrance surfaces of the active optical element. The surfaces of the passive optical elements are placed up against respective exiting and entrance surfaces of the active optical element. Since the optically transparent passive optical elements have higher mass than optical coatings, they provide vastly superior cooling, and therefore, considerably higher laser damage threshold for the surfaces.

Abstract: A semiconductor laser device that is modular can readily be changed to produce laser configurations for a broad spectrum of applications, using a minimum of components. A set of semiconductor modules covering wavelengths and polarizations of interest in specific technologies can be coupled to one of two beam shaping modules and projected through a selected objective optics module to provide large and small circular beams as well as broad and narrow line segments. Resolution enhancing and diffraction limiting filters may be included in the objective optics.

Abstract: A laser diode package couples laser diode outputs into a plurality of fibers, and these are bundled and brought to an output face that produces a divergent composite beam from the fiber ends. The beam end pumps a solid-state laser across a gap, and the divergence allows a wide tolerance in alignment of the pump and crystal. Preferably, one cavity mirror is a focusing mirror that reconcentrates residual pump light in the desired mode. In a preferred embodiment, the output face of the package is at a short stub or ferrule that provides a simple and effective pump beam centering alignment. The solid-state laser may be a rod or crystal and is preferably sufficiently short, in relation to pump beam diameter and divergence in the rod, that the pump beam within the rod lies in the TEM.sub.OO mode volume of the laser cavity. A concave mirror then refocuses residual pump light back into that mode. The rod preferably has a high index at the pump wavelength, but need not have high absorption.

Abstract: There is provided a scanning laser beam delivery system for use in pulsed laser deposition of a target evaporant (40) onto a substrate (50). The system includes a laser beam source (10) for generating a pulsed laser beam, a beam transfer assembly (20) optically coupled to laser beam source (10) for directing the generated pulse laser beam along an optical path (15) having a terminal segment (15') which impinges upon target evaporant (40); and, a control mechanism (30) coupled to beam transfer assembly (20). Beam transfer assembly (20) includes a scanning mechanism (22) for reversibly translating terminal segment (15') of optical path (15) along a scan direction substantially normal to the direction along which terminal segment (15') has a directional component. Actuation of scanning mechanism (22) is automatically controlled by control mechanism (30).

Abstract: A device is disclosed for delivering laser radiation to a target. The device includes an elongated, hollow, tubular member having an input end and a delivery end. A window is mounted near the delivery end of the device. The window provides a seal preventing smoke and debris from contaminating the interior of the device. In the preferred embodiment, the window is formed from a crystalline material, such as diamond, which has low absorption level for laser light and excellent thermal characteristics. In addition, the thickness of the window is selected to reduce reflection losses and increase the transmission level through the window without the need for fragile antireflection coatings.

Abstract: An optical head apparatus for recording and reproducing data to and from optical disks, the apparatus boosting recording density by use of an objective lens with a higher numerical aperture (NA) than ever. A phase plate is added to the pupil position of the objective lens or to a position close thereto. The phase plate arrangement provides a deeper focal length, reduces the adverse effects of aberration and eliminates the need for a tilt servo mechanism despite the use of the objective lens having a greater numerical aperture than before.

Abstract: A narrow-band excimer laser employing a diffraction grating as a wavelength selective element, which is particularly suited for a light source of a reduction projection aligner. The grating used in the narrow-band excimer laser of the invention is so disposed that the ruling direction of the grating is nearly perpendicular to the direction of laser discharge. When a beam expander is used to expand laser beam falling on the beam expander is so disposed that the direction of beam expansion is nearly perpendicular to that of discharge of the laser. Further, when an aperture is to be used in the laser cavity, the aperture is placed so that the longitudinal direction may be parallel to the direction of laser discharge. Moreover, the front mirror of the laser cavity is a cylindrical one, whose mechanical axis is in parallel with the direction of laser discharge. This makes it possible to provide a narrow-band excimer laser having very high efficiency and excellent durability.

Abstract: A laser apparatus including a laser crystal composed of a fluoride which contains chromium (Cr), a resonator which includes the laser crystal, a means for exciting the laser crystal, a first laser beam produced from light which is emitted from the laser crystal and oscillated in the laser resonator, and at least one optical component which is inserted in said resonator; wherein an aperture in the resonator is substantially five or more times the diameter of the first laser beam. A small, low-power SHG laser light source is achieved.

Abstract: A composite, glass or crystalline laser rod having a doped, light-absorbing core portion surrounded by a transparent cladding portion that is either undoped or doped with a nonabsorbing material is side-pumped with a plurality of laser diodes dispersed angularly around the laser rod. A reflective coating or sleeve substantially surrounds the laser rod, except for entrance slits for the pump light, to confine unabsorbed pump light in the crystalline laser rod by reflecting and re-reflecting the pump light in the rod to increase the likelihood of absorption by the core portion. The reflective coating is substantially reflective of all the pump light, but it can be transparent to laser radiation emission by the rod. An absorptive coating that absorbs radiation of the wavelength of the laser radiation emission of the rod can be positioned around the outside of the reflective coating to absorb lateral laser emission of the rod.

Abstract: A method of producing collimated x-radiation by suitably subjecting metallic ions in the presence of lower Z ions to a pulse of laser energy from a conventional laser. An improvement on said conventional laser in order to increase the reliability of production of said collimated x-radiation. An alternative improvement on said conventional laser for similar improvement of said collimated x-radiation. An example of the application of the use of said collimated x-radiation to the art of producing micro-circuitry.

Abstract: A laser is end pumped by laser diodes and is repetitively Q-switched using an intracavity variable speed moving aperture. The aperture apparatus includes a precision motor which drives a pair of matched aperture blades and produces efficient Q-switched operation over a wide range of output powers and repetition rates. Each aperture blade may contain an identical number of transmissive and opaque regions, and two aperture blades may be mounted onto the motor in a manner that allows continuous adjustment of the aperture width. In a preferred embodiment the aperture blades are shaped as circular discs. The laser resonator mode is nearly hemispherical, and the aperture blade is located at or near the laser resonator mode waist. When pumped with the optimum pump flux, efficient repetitively Q-switched operation is obtained as long as the Q-switch opening time is shorter than the pulse build-up time.

Abstract: A light source unit of the present invention is provided with a plurality of semiconductor lasers each emitting one laser beam, a bar body to which the semiconductor lasers are attached so that p-n junctions planes of respective semiconductor lasers are arranged in the same direction, and a beam restricting plate where holes for passing a part of the beam from the semiconductor laser are formed so as to correspond to the semiconductor lasers. With this feature, a plurality of laser beams of uniform optical power can be emitted at predetermined spaces.

Abstract: A laser module includes a hollow, cylindrical casing having a tapered laser beam emitting hole at one end and a lens holder coupling portion at an opposite end, a lens holder having one end fitted into the lens holder coupling portion and an opposite end made with an inner thread, a lens mounted inside the casing and retained between a cushion ring and the lens holder; a focus adjustment socket having one end made with an outer thread threaded into the inner thread of the lens holder and an opposite end sealed with a locating cap; a control circuit board fastened to the locating cap and disposed inside the focus adjustment cap to carry a laser diode chip and a photo detector and controlled to drive the laser diode chip to emit a constant laser beam out of the casing through the lens.

Abstract: A modular slab assembly for a face-pumped laser includes a slab module having top and bottom reflector segments, with first and second inner end caps joined thereto. A plurality of alignment keys are disposed between the inner end caps and the reflector segments for maintaining alignment therebetween, with the inner end caps being removably fastened to the reflector segments. The inner end caps have central apertures for supporting a slab tube, with a laser slab being disposed through the tube and supported at its ends by outer end caps removably fixedly joined to respective ones of the inner end caps. A pair of removable lamp modules are disposed on opposite sides of the slab module and contain lamps for exciting the laser slab.

Abstract: A laser oscillator that has a resonator cavity defined by oppositely disposed discharge electrodes as well as a plurality of total reflecting mirrors and a partial reflecting mirror, the resonator cavity volume containing the path of a laser beam generated by the oscillator. A laser gas medium is used to control the temperature of the oscillator and is directed in a main flow generally transverse to the path of the laser. A side flow is taken from the main flow and is directed by a duct to a position in the vicinity of the partial reflecting mirror. In order to avoid excess heating of the gas medium in the vicinity of the partial reflecting mirror and to avoid directly impacting the mirror with the gas medium, a U-shaped structure is disposed at the exit of the side flow duct, proximate to the mirror, for directing the side flow in the vicinity of but away from the mirror.

Abstract: A laser module includes a hollow, cylindrical casing having a tapered laser beam emitting hole at one end and an inner thread at an opposite end; a lens mounted inside the casing and retained between a cushion ring and a locating ring; a base having an outer thread threaded into the inner thread on the casing; a laser diode chip and a photo detector mounted on the base and connected to contact pins of the base; a control circuit board fitted into the rear open end of the casing to block the base on the inside and electrically connected to the contact pins on the base for controlling the laser diode chip to emit a constant laser beam out of the tapered laser beam emitting hole via the lens.

Abstract: Optical guiding of intense laser pulses over a distance of more than one Rayleigh length in a plasma is discussed herein using a multi-pulse technique. The first pulse or pulse sequence prepares a shock-driven, axially-extended radial electron density profile which guides a second pulse or sequence of pulses. The profile is also capable of guiding x-rays. The channel will support mode structure exactly analogous to that of an optical fiber waveguide. The method provides a means for guiding of a high intensity optical laser pulse or x-rays over distances well in excess of a Rayleigh length. The distances over which guiding occurs is limited only by the length of the preformed plasma and absorption and possible backscattering of the guided EM radiation. Applications of the method allow for compact x-ray laser devices and electron particle accelerators.

Abstract: A laser apparatus includes an unstable resonator having a total reflection mirror and a take-out mirror, and further includes shading means for shading a disturbed phase portion of a laser beam so as to derive exclusively a light having a uniform phase by shading the disturbed phase portion of the beam emitted from the resonator or the beam in the resonator.

Abstract: A laser apparatus with a laser oscillator and a subsequently connected la intensifier which has an inlet region for the laser beam to be intensified coming from the laser oscillator and an outlet for the intensified laser beam and which is provided with a folding mirror that lies opposite to the inlet region for the laser beam to be intensified. The inlet region for the laser beam to be intensified is an opening in a further folding mirror which is located opposite to the other folding mirror. The outlet for the intensified laser beam likewise is an opening in one of the two folding mirrors. The opening width of the inlet opening and the outlet opening in relation to the mirror surface of the particular folding mirror is small. The cross section of the laser beam inside the laser intensifier is at least partially greater by a multiple than in the region of the inlet opening and outlet opening.

Abstract: A sum frequency conversion efficiency can be improved and operation can be stabilized. A laser generating apparatus comprises a nonlinear optical element (3) for generating a sum frequency light having wavelengths of first and second fundamental wave laser lights having first and second wavelengths (.lambda.1) and (.lambda.2) by introducing the above first and second fundamental wave laser lights thereto, and a resonator (7) having a first fundamental wave light source (1) and the nonlinear optical element (3) incorporated therein. The resonator (7) includes at least first and second reflection mirrors (M1) and (M2) disposed on opposing entrance and exit end faces of the nonlinear optical element (3) in an opposing relation. These first and second reflection mirrors (M1) and (M2) having transmissivities as high as possible relative to the second fundamental wave laser light and a sum frequency light.

Abstract: An internal mirror argon ion gas tube is described having protective sleeve barriers at opposite ends to prevent any particulate matter which might emanate from a weakened section of the mirror holder at the corresponding end from reaching the interior face of the mirror.

Abstract: An excimer laser apparatus is provided with a compact high efficiency dust particle removal means which is capable of maintaining the windows clean with only a small volume of purging gas, and which prevents deterioration of aperture masks without having to increase the cavity length or risking the possibility of leakage from piping connections. The excimer laser apparatus uses, as dust particle removal means, filters (13a and 13b) made of metal or ceramic which is non-reactive with fluorine. A ground potential dust collector can be provided at a downstream side of a static dust particle remover, having an anode and a cathode, for collecting any dust particles which have passed through the static dust particle remover.

Abstract: A laser oscillator comprising a laser resonator having a plurality of mirrors for directing the laser energy from source to exit apertures, the mirrors being constructed and mounted adjustably for reducing parasitic oscillations. The mirrors are mounted in adjusting members that have channels therein for coolant and are provided with heat insulating members that minimize heat gradients and unwanted heat transfers that may result in the distortion of the reflecting surfaces. In addition, the mirrors are angled so that light paths are defined that present a Z-shaped turning pattern. Apertures proximate to the mirrors through which the light beams are directed are offset from a common plane so that a reflective surface is not within the aperture of the opposing reflective surface. One or more of the apertures can be so offset to reduce the possibility of parasitic oscillations. Further, the reflectors can be angled and the apertures sized so as to eliminate parasitic oscillations.

Abstract: An electrically excited gas laser includes coaxial hollow-cylindrical electrodes defining a discharge space between the electrodes. A resonator mirror is disposed at each respective end of the discharge space. At least one of the resonator mirrors forms an intersection line with a cylindrical surface being coaxial with the electrodes and the intersection line extends obliquely relative to the circumferential direction. The resonator mirrors form intersection lines with an axial plane of the electrodes and the intersection lines extend substantially at right angles to the axis. At least one of the resonator mirrors extends over only a portion of the circumference of the discharge space.

Abstract: A laser diode and a lens are fixed onto a laser fixing member. A laser beam emitted from the laser diode passes through the lens, and a part of the laser beam passes through a pinhole provided to a beam restricting plate. The pinhole is formed so that its diameter is smaller than the laser beam diameter at the beam restricting plate. The laser beam is transmitted therethrough while being diffracted.

Abstract: An apodizer according to the present invention subjects a light beam to wavefront splitting, to thereby split it into a plurality of beam components such that each adjacent pair of them have phases differing from each other. The light beam components through the apodizer have phases inverted to one another, and are converged in a desired position of an image-forming surface. The beam spot of the converged light beam is smaller than a size limited by the refractive index of an objective lens. The intensities of sidelobes occurring around the beam spot are sufficiently reduced. When the apodizer is incorporated in an optical head device, the intensity of the center beam spot of a reflected laser beam is emphasized, which enables data reading from a disk medium of a high recording density.

Abstract: A power laser has a cavity (2) delimited at its opposite ends by a first partially transmitting window (3) and a second reflecting window ( 4). The first window (3) is constituted by at least one diamond wafer (5) with uncoated flat parallel surfaces, having a controlled thickness whose variations do not exceed 0.2 micron. The diamond wafer (5; 6) is mounted in an annular support (9; 10) of material which is a good heat conductor and is provided with a cooler (11; 12). The window (3) can comprise two parallel wafers (5.sub.A, 5.sub.B) of diamond separated by a calibrated distance (14) which is an uneven multiple of .lambda./4n, .lambda. being the laser wavelength and n the index of refraction of the medium between the wafers. Or the second window (4) can also be constituted by a diamond wafer (6) with a reflective metallic coating (60). A sweeping gas can be blown over the internal surface of at least one of the windows.

Abstract: A raman cell oscillator/amplifier arrangement comprising a cell containing a raman high pressure gas or liquid medium with an axicon being located at each end of the cell, one axicon having an input window for a laser pump beam and the axicon at the cell's other end having an output coupler for the raman process converted beam. The axicons directs the laser pump beam towards an extended line focus along the axis of the cell at a shallow angle, the extended line focus for each axicon being collinear with each other to produce an extended raman gain region. By suitable design, it can be ensured that the pump beam energy density at focus is lower than either an optical breakdown or Brillouin backscatter threshold. This provides a means of efficiently producing a raman laser or amplifier having an extended raman gain region without developing problems of optical breakdown, Brillouin backscattering or self-focusing in the case of a liquid raman media.

Abstract: A spectral line selector for a laser comprises a diffraction grating that images a waveguide exit plane back into the waveguide with an essentially exact reproduction of the waveguide output intensity and phase distribution and with a predetermined wavelength. The selector also comprises lenses disposed between the waveguide exit at a point between the exit opening and the grating, the lenses providing a magnification and a phase compensation to the beam passing therethrough such that the phase of the beam returned to the waveguide matches that of the exiting beam. Thus, coupling losses due to clipping of the returned beam at the entrance to the waveguide bore and coupling losses due to a mismatch of the returning field phase to that of the waveguide mode are made essentially zero.

Abstract: A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion.

Abstract: In accordance with the present invention, an optical sensing device and method are provided for processing with extremely low energy requirements. Spontaneous emissions from an excited optical gain medium generate a propagating waveform. Either a spatial modulator or the pattern under investigation modulates the optical wavefront generated by the fluorescing gain medium to impose a first spatial pattern thereon. When the first spatial pattern imposed on the wavefront has duality with another spatial pattern imposed by the other of the pattern under investigation or the SLM, light is directed back along pathways through a cavity defined by the gain medium, a reflector, the SLM, and the object under investigation to induce stimulated emission and eventually resonance in the cavity.

Abstract: In accordance with the present invention, an optical processing device and method are provided for processing with extremely low energy requirements. Spontaneous emissions from an excited optical gain medium generate a waveform that propagates within a cavity defined by the gain medium and a reflective device. A first spatial modulating element is disposed in the cavity in the path of the generated wavefront to impose a first spatial pattern thereon. A second spatial modulating element also is disposed in the cavity and imposes a second spatial pattern on the perturbed wavefront carrying the first pattern. When the first and second imposed spatial patterns have dual spatial pattterns, light is directed back along pathways through the cavity to induce stimulated emission and eventually resonance in the cavity.

Abstract: A window for transmitting radiation of 20 microns or longer comprises a layer supported around its periphery by a frame. The layer comprises a first major surface on one side capable of receiving the radiation and a second major surface on the opposite side to the first major surface. The layer comprises a plurality of diamonds and a bonding polymeric resin capable of transmitting the radiation. The diamonds can, in one embodiment, be diamond plates located edge-on relative to neighbouring diamond plates.