Abstract: Apparatus 10 (FIG.

Abstract: A device and process for adjusting, locking, and mounting a mirror. The device, in one embodiment, comprises three adjustor bolts which are threadably engaged with a mirror assembly and a support plate. Two locking bolts per adjustor bolt apply torque symmetrically to the adjustor bolt to preserve micro-radian adjustments during the locking process. The invention's design also results in extremely high structural stiffness at the adjustor-locking bolt joints.

Abstract: A microlaser is disclosed comprising: a gain medium having one face which is adapted be coupled to a source of optical pumping radiation and having an opposite face; harmonic conversion means having a close face which is located adjacent to and spaced apart from the opposite face of the gain medium and which is coated for high transmission at a fundamental and high reflectivity at a harmonic and having an opposite face which is coated for high transmission at the fundamental and some transmission at said harmonic; and polarization control means, located adjacent to and spaced apart from the opposite face of the harmonic conversion means, for controlling the polarization of the fundamental.

Abstract: The aim is to provide a new power laser configuration enabling the delivery of a beam of high spatial quality with an optimum efficiency of extraction of energy. It can be applied, more particularly, to Q-switch solid-state lasers, in doing away with recourse to specific elements for compensation of aberrations. The structure of emission of a power pulsed laser signal, of the type comprising, firstly, an oscillator stage with low-level output beam and, secondly, a power amplifier stage, is characterized in that the power amplifier stage is formed by a laser amplifier that produces a pump beam cooperating with distinct means for energy transfer without phase transfer from said pump beam towards said low-level beam coming from the oscillator.

Abstract: An optical pulse source for producing short optical pulses comprises first and second optical loops coupled together by a beam splitter so as to define a figure eight optical path in which a light beam propagating toward the beam splitter in one of the first and second loops is split by the beam splitter to form two light beams propagating in opposite directions around the other of the first and second loops. The first loop includes a direction dependent loss element for reducing the intensity of light propagating in a predetermined direction around the first loop, and the second loop includes an element having an intensity dependent nonlinear optical transmission characteristic. One of the first and second loops includes an optical gain medium. Coupling apparatus is also provided for coupling pump light into the loop including the gain medium and for coupling optical pulses out of the source.

Abstract: In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies ("colors") cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers.

Abstract: A light amplifying device comprising an optical oscillator constituted by first and second reflective mirrors and a common reflective mirror disposed in an optically opposite relation to each other, a polarized beam splitter for making a laser beam incoming from the side of the common reflective mirror incident on the first or second reflective mirror, and for making laser beams incoming from the sides of the first and second reflective mirrors incident on the common mirror, first and second amplifying media disposed in optical paths of the respective laser beams for amplifying the laser beams, and an optical element for rotating the polarizing plane of the laser beam reflected by the common reflective mirror by a predetermined angle.

Abstract: An improved optical isolator (6) for a semiconductor laser (2) for use in optical communication systems consists of a polarizer (4) and a birefringent medium (5). An electric field is applied to the birefringent medium (5) via electrodes (7) for varying the indices of refraction of the birefringent medium (5). By the variation of the indices of refraction, the optical isolator (6)can be adapted to different light wavelengths.

Abstract: A laser application system comprises an amplifier and two rotating polarization devices so that a laser beam is given with linear polarization which is converted into a circular polarization. Then the beam passing through amplifier means, is reflected into a second pass and reflected back to the amplifier. The system further includes a stimulated Brillouin scattering non-linear isolator for transmitting substantially all of the light beam when its energy is below a predetermined threshold and reflecting substantially all of the light beam without substantially reducing the quality of the beam, when its energy exceeds the threshold.

Abstract: A structure and method for operating a copper-vapor laser involves splitting and polarizing the exiting beam of radiation into two beams of different polarization orientations. One beam is completely reflected back to the laser medium within a first external cavity, and the other beam is partially reflected back to the laser medium in a second external cavity and is also partially transmitted to provide an output beam of short pulse duration that is selectively shaped in response to the interaction within the laser medium of the two segregated beams.

Abstract: A laser device includes a resonant cavity with a gain medium therein, and first and second reflectors at either end, to form a quasi-isotropic laser. A feedback section is formed between the second reflector and a third reflector. A polarizer and modifier are provided in the feedback section. The polarizer and modifier can modify a variety of parameters, for example the polarization, phase, intensity or frequency of the feedback. The light feedback into the resonant cavity has an intensity much less than that within the resonant cavity, but sufficient to overcome any residual anisotropies. Control of the modifier causes the device to be operated in one of two or more polarization modes.

Abstract: A laser oscillator system which transmits laser input beam pulses through optical diode and into a plurality of time-multiplexed phase conjugate amplifier which sequentially amplify in chronological order subsequent input beam pulses. The optical diode is positioned on the oscillator laser beam pulse axis and is comprised of a polarizer, a half-wave plate which rotates the pulse polarity by 45.degree. in one direction and a Faraday rotator which rotates the pulse polarity 45.degree. in the opposite direction. A plurality of grouped Pockels cells and polarizers are positioned on the oscillator axis past the Faraday rotator. The polarizers route the input beam pulse toward a phase conjugate amplifier when a half-wave voltage is applied to the Pockels cell. Each phase conjugate amplifier has a phase conjugate mirror, at its output for retroreflecting the once amplified input laser beam pulse back therethrough for a second amplification.

Abstract: A laser adapted to operate at a constant, predetermined wavelength includes the following elements disposed in order within a laser cavity and aligned along the path of light flow therethrough: a highly reflective rear mirror, a halfwave plate, a Brewster window, an active laser medium, and an output coupler. The halfwave plate is designed to rotate incident light beams by 180.degree. at the predetermined wavelength and to rotate incident light beams by an amount other than 180.degree. at wavelengths other than the predetermined wavelength. In a preferred embodiment, the Brewster window is a thin film polarizer designed for the predetermined wavelength.

Abstract: A low coupling beam splitter with no cross-polarization error or critical alignment tolerances is formed of a quartz piece having a first planar face in the optical path in the plane of the cross-polarization and at or near Brewster's angle to the beam. A second planar face is in the interior optical path in the plane of the cross-polarization and off of Brewster's angle to the beam, so that a majority of the component having the dominant polarization is transmitted along the optical path, while a small fraction of the component having the dominant polarization and a portion of the cross-polarized component are reflected along a first interior sample path. A third planar face is in the first interior sample path in the plane of the dominant polarization and at or near Brewster's angle to the reflected beam. Thus, a portion of the component having the dominant polarization is reflected as a sample beam, and the majority of the component having the cross-polarization is transmitted away from the sample beam.

Abstract: A laser apparatus comprises an optical resonator including first and second mirrors, and lasing medium. An wavelength selection element is provided in the resonator for narrowing band-width. A polarizing conversion element for changing ratio of S to P components and polarizing beam splitter are provided for amplifying laser beam to output after wavelength selection and for reducing light load of the wavelength selection element. The polarizing conversion element is provided in the resonator light path. In another embodiment, the polarizing conversion element is provided in a branch light path formed by a second polarizing conversion element and a third mirror, where the second polarizing conversion element reflects and transmits P component at a given ratio and reflects S component. The wavelength selection element comprises a Fabry-Perot etalon, grating, or prism. The polarizing conversion element comprises a quarter-wave plate or a phase retarder mirror.

Abstract: A self-injection locking system is disclosed that internally narrows the prepulse of a laser cavity before it is replicated as the laser output using: two quarter wave plates, an air spaced etalon, and a polarizing beam splitter. The air spaced etalon will separate the off-center frequency signals from the center frequency signals of the prepulse by inducing a phase shift. Following this, the polarizing beam splitter impedes the off-center frequency signals by a power loss of about ten percent while the center frequency signals are unaffected. In operation, this can cause the off-center frequency signals to fail to reach the threshold at which stimulated emission takes place. The result is that the laser replicates only the center frequency signals as the laser output.

Abstract: A laser oscillator is provided with a folded laser resonator which includes an output coupling mirror (4), a rear mirror (10) and folding mirrors (11,12). The rear mirror (10) has a maximum reflectivity with respect to a linear polarization component of the laser beam, in which the linear polarization component has an E vector the direction of which is rotated from an incident plane of the nearest folding mirror by .pi./4. The folding mirrors (11,12) function as a whole as a phase retarder imposing a .pi./2 phase delay with respect to parallel and perpendicular polarization components of the laser beam, and accordingly, a circularly polarized laser beam is obtained from the laser oscillator.

Abstract: A method and apparatus for stabilizing the frequency at which a laser cavity oscillates comprising a passive system which provides a plurality or continuum of optical paths of differing lengths. The various paths correspond to differences in mode parameters in the cavity, and involve compensating changes in polarization, beam direction, beam divergence, and the like, in exchange for a constant optical path length in the laser cavity. The unchanging optical path length results in a stable frequency of oscillation despite physical changes in the cavity which might otherwise alter that path length.

Abstract: A laser oscillator/amplifier system in which thermally induced birefringence in the gain media of the oscillator is compensated by thermally induced birefringence in the gain media of the amplifier. The system produces a quality output beam efficiently and with high power density in the preferred polarization. The oscillator cavity is characterized by a high reflector at one end and an output coupler at the second end with an oscillator gain medium exhibiting thermally induced birefringence in between. An amplifier exhibiting thermally induced birefringence which matches the thermally induced birefringence in the oscillator gain medium is mounted to receive the output of the oscillator cavity. A ninety degree rotator is mounted between the oscillator gain medium and the amplifier so that compensation for thermally induced birefringence in the oscillator gain medium is compensated by the matching thermally induced birefringence in the amplifier.

Abstract: A laser beam shaper which provides polarized output with a high spatial quality, utilizing induced stress birefringence. The laser beam shaper in which light resonates along a resonant path defined by reflective surfaces includes a solid state medium, such as a Nd:YAG rod which exhibits thermally induced stress birefringence that is of known, azimuthally independent distribution in planes perpendicular to the resonant path. On either side of the medium, quarter-wave retardation plates are provided which create essentially circular polarization of the resonant light within the medium. Sandwiching the quarter-wave plates and the medium are the first and second polarizing elements, both of which are aligned along the same preferred plane. By inducing stress birefringence in the medium, an output beam is produced. A shape defined by the distribution of the birefringence is provided. With media such as YAG, the shape of the beam is round with high quality.

Abstract: A laser tube having two integrated laser mirrors and a polarization mean in the form of at least one polarizing layer arranged on a laser mirror. The layer is applied or formed at an angle of at least 80 degrees to a surface normal of the mirror. As a result, special polarization elements are eliminated, the structure is simplified, and the laser emission yield is increased.

Abstract: A laser resonator generates a polarized output beam with a laser medium exhibiting thermally induced birefringence and a Y-shaped resonant cavity. A lasing axis extends between a first side and a second side of the laser medium, Radiation transmitted out of the first side of the laser medium has its polarization rotated by 90 degrees and is guided back along the lasing axis into the laser medium for a second pass. A polarizer is mounted on the second side of the laser medium for guiding the radiation having a first polarization along a first path and radiation having a second polarization that is 90 degrees from the first polarization along a second path. Both the first path and the second path include the lasing axis of the laser medium and form a Y-shaped resonant cavity. Along the first path, a high reflecting means is provided to reflect the radiation back along the first path.

Abstract: The invention relates to means for generating a laser beam with an essentially constant angle of divergence over a wide range of operating conditions. The invention further relates to a method of generating such laser beam. The oscillator-amplifier laser system of the invention comprieses in combination an optical resonator, a first active medium and first optical means located within said resonator for generating an oscillator beam; a second active medium for amplifying said oscillator beam and a second optical means external to said resonator. Said first and second optical means have each, according to the invention, a predetermined optical power which maintains a constant divergence-angle of the output beam, even under variations in the induced optical power of the active media.

Abstract: A semiconductor laser beam splitting device comprises a beam splitting optical system which is disposed on the optical path of light generated from a semiconductor laser and splits the light in a fixed proportion irrespective of the polarized light components contained therein.

Abstract: An optical system for a semiconductor laser beam comprises a semiconductor laser which generates light comprising both stimulated emission light and spontaneous emissions in accordance with the amount of electric current applied thereto, a convergent lens disposed in the light path of the beam emitted by the semiconductor laser, and an optical element disposed in the light path of the beam from the convergent lens which cuts more spontaneous emission than stimulated emission.

Abstract: An optical component of a laser, of the type including a hot gas plasma region, a cold gas region, and producing large photon fluxes, includes an optical element and a coating means on a surface of the optical element exposed to the photon fluxes. The coating means is comprised of a material adapted to minimize photoreduction of the optical element induced by exposure to the photon fluxes. Optical elements of the present invention include windows, birefringent plates, intracavity lenses, polarizers and mirrors. The coating means includes a material selected from the group comprising Al.sub.2 O.sub.3, BeO, Y.sub.2 O.sub.3, MgO, B.sub.2 O.sub.3, Sc.sub.2 O.sub.3, LiF, NdF.sub.3, ThF.sub.4, Na.sub.3 AlF.sub.6, and mixtures thereof.

Abstract: An optical resonator for a power laser comprises between one of a pair of totally reflecting mirros flanking the end of a pumped active element such as a Nd:YAG crystal, a passive Q switch and between the passive Q switch and the active element, a polarizer which reflects the output transversely to the optical axis of the reflecting beams of the cavity. A phase shifter is provided between the polarizer and the approximal end of the active element. This system prevents the full output energy from impinging upon the passive Q switch so that the passive Q switch or other low-damage-threshold optical elements associated therewith do not have to take the full power.

Abstract: Light generated in the optical resonator of a gas laser is polarized by disposing an array of fine, parallel, highly light reflective wires in the path of the light beam propagating in the resonator. The wires are cooled by conduction of heat to a heat sink or by causing gas to flow through the array. In one embodiment, the wire array is arranged to be rotated to enable the plane of polarization to be turned to any desired orientation. The difference in absorption by the wire array between two orthogonal components of the flux in the resonator need be only in the order of 1% to cause nearly complete linear polarization of the light emerging from the resonator. The parallel wires, preferably, are spaced so that they are situated at the peaks of the lower order modes in the resonator. In lieu of using fine wires, very fine parallel lines or grooves whose width and spacing are such as to provide a low efficiency diffraction grating may be provided in the surface of an optical element of the resonator.

Abstract: A method and apparatus for producing preferential polarization of the output light beam from a laser of the kind having a three surface retroreflector comprises mounting the three reflecting surfaces of the retroreflector so that the surfaces are orthogonal in the retroreflector. The preferential polarization is obtained by controlling the combined effects of the orientation of the retroreflector assembly, with respect to the axis of the beam, and the selection of the coatings on the three reflecting surfaces.

Abstract: A low divergence laser oscillator of the kind wherein an intra-cavity oscillator beam is propagated along a resonator axis and within a portion of the volume of the active medium and wherein a part of the intra-cavity oscillator beam intensity is coupled out of the oscillator by a first outcoupler as an extra-cavity beam. One of the oscillator beam is expanded and collimated so as to produce an expanded and collimated extra-cavity beam having a cross-sectional area substantially greater than the cross-sectional area of a portion of the active medium. Substantially the total intensity of the expanded collimated extra-cavity beam is introduced into the active medium so as to fill a volume of the active medium which is substantially greater than the volume of the above portion, thereby giving rise to amplification of the reintroduced beam. A polarizing element located within the resonator is used for the introducing.

Abstract: A comb-shaped polarizing device for use in a laser is compact, inexpensive and easily adjusted. The device includes an annular member having a number of comb-shaped teeth projecting opposite similarly shaped teeth from a rectangular aperture. The comb-shaped teeth are arranged in a plane transversing a laser beam which is under oscillation. Cooling water passages are formed in the annular member. In one embodiment the annular member is provided at its periphery with gear teeth which mate with a motor for selection of the direction of polarization of the laser beam.

Abstract: An optical component of a laser of the type including a hot gas plasma region, a cold gas region and producing large photon fluxed includes an optical element and a coating means on a surface of the optical element exposed to the photon fluxes. The coating means is comprised of a material adapted to minimize photoreduction of the optical element induced by exposure to the photon fluxes. Optical elements of the present invention include windows, birefringent plates, intra-cavity lenses, polarizers and mirrors.

Abstract: A laser apparatus is disclosed comprising a resonator for emitting a laser beam, an assembly for circularly or elliptically polarizing the laser beam emitted from the resonator, a lens assembly for focusing the laser beam from the polarizer to a workpiece with the laser beam from the polarizer to the lens having an axis, and the resonator having a folding mirror assembly for linearly polarizing the laser beam with the resonator being positioned relative to the polarizer so that the plane of reflection of the mirror assembly is approximately 45 degrees relative to the axis.

Abstract: Laser apparatus with an electro-optic Q-switch assembly comprises a lasing medium which produces an unpolarized light beam when pumped, a polarizing beam splitter dividing the unpolarized beam into two orthogonally polarized parallel sub-beams, and a totally reflecting turning element which returns each sub-beam to the beam splitter along the path of the other sub-beam. A Q-switch is located in the path of one of the sub-beams. When the Q-switch is energized, the reflected polarization-shifted sub-beams are recombined at the splitter and pass through the lasing medium and adjacent partially-reflecting element as the output. When the Q-switch is deenergized, the sub-beams are dumped at the splitter which prevents the laser from oscillating.

Abstract: The invention deals with a face pumped slab laser in which the slab is of a rectangular configuration, favoring use of an optical resonator cavity capable of producing a rectangular beam of good quality within the cavity. The novel optical resonator cavity, which produces this rectangular beam, is stable on one axis corresponding to the smaller beam dimension and unstable on an axis orthogonal to the first axis corresponding to the larger beam dimension. The result is both high efficiency, excellent power and a good quality output beam is produced.

Abstract: In a semiconductor laser device wherein the laser beam emitted from an output end face of a semiconductor laser having antireflection coating for the opposite output end faces thereof is returned back to the output end face to induce self-coupling effects of the laser beam, the polarization characteristics of the output beam from the semiconductor laser are changed by controlling the polarization characteristics of the return beam.

Abstract: A laser machining apparatus includes an optical resonator for generating a laser beam and two polarizers disposed in the form of a V within the optical resonator to linearly polarize the laser beam. The linearly polarized laser beam is focussed on a workpiece for cutting purposes while the workpiece is moved in two orthogonal directions. The polarizers are rotated about the optical axis of the laser beam in correspondence with the two dimensional movement of the workpiece to rotate a plane of polarization of the beam to coincide with a cutting direction of the beam. Alternatively, a linearly polarized laser beam from a laser oscillator is circularly polarized with a quarter wave plate and then linearly polarized by a rotatable quarter wave plate to form a cutting beam. The rotatable quarter wave plate is rotated in the same manner as the polarizers to rotate a plane of polarization of the cutting beam.

Abstract: A two-mirror system for transforming an azimuthally or linearly polarized laser beam into a beam having a number of sections, the average phase and polarization of each section being substantially similar. Both mirrors are segmented into eight pie-shaped sections, each of which contains a coating that gives a .+-.90.degree. phase shift or the appropriate uniform optical path difference.

Abstract: The intracavity modulated laser includes a main cavity and an adjacent coed cavity with a gain cell in the main cavity and an electro-optic modulator in the coupled cavity, the cavities being coupled in such a way that the energy level in the coupled cavity during laser operation is much lower than that in the main cavity, and whereby the modulator can selectively affect the polarization of energy in accordance with a voltage applied thereto to selectively couple energy out of both cavities in a desired manner.

Abstract: A generator of a TE.sub.O mode wave beam, particularly adapted for confining plasmas, comprises a laser device for generating an electromagnetic wave having at least a TM.sub.O mode component. The TM.sub.O mode component is filtered by parallel sided plates or refractive surfaces disposed at the Brewster angle for the TM.sub.O component to derive an intermediate wave beam. A TM.sub.O -TE.sub.O mode converter shifts the TM.sub.O mode intermediate wave polarization vector by an angle of .pi./2 radians.

Abstract: A laser system for providing a rapidly steerable laser output beam. The laser system includes a phase conjugate reflector, laser gain medium and its associated pump source, an output coupling device, and an optical element which selectably controls the transverse lasing mode of the laser system. The components are arranged to form a laser oscillator between the phase conjugate reflector and the optical device, and is operated in such a manner that each selected transverse mode of laser operation generates an output beam from the system which has a different wavefront tilt. Accordingly, the output beam is steerable and is dependent upon the selected transverse mode which is currently lasing in the oscillator.

Abstract: A laser output coupler utilizes a birefrigent lens which has one side thereof curved so as to present a non-uniform polarization distribution across the face of the lens. A polarized beam splitter is employed to separate the output beam from the feedback beam; the feedback beam having a non uniform distribution across the laser aperture enhances mode discrimination of a pulsed resonator.

Abstract: A rapidly tunable laser system which is operative to tune the laser beam emission to a predetermined wavelength in accordance with the polarization state thereof is disclosed. The laser beam emission may be tuned between predetermined wavelengths as rapidly as it can be altered between polarization states. More specifically, the laser system includes a polarization modulator for modulating the radiation beam emitted from a laser cell between at least two polarization states, and at least two diffraction gratings which are uniquely and fixedly aligned to specularly reflect and retroreflect radiation incident thereupon. The retroreflected radiation is of a wavelength uniquely identified with the angle of incidence of the corresponding diffraction grating.

Abstract: Laser apparatus operable in the range 8 to 50 microns, has an optical cavity defined by two mirrors M1 and M2, one of which is partially transmitting. The cavity contains a laser active medium AM and a reflecting polarizer RP. The reflecting polarizer comprises a substrate carrying a metallic reflecting coating covered by a dielectric layer of alumina, silicon dioxide or magnesium oxide. The wavelength of operation determines the dielectric material to be used, and the thickness of the layer determines the absorption loss introduced into one of two perpendicular planes of polarization.

Abstract: A laser system for generating two closely spaced in time laser pulses where each pulse is a different color comprises a first and second optical cavity with a common optical leg containing a laser rod capable of emitting light of two polarities along an axis and a polarizing beam-splitter positioned at the common junction of the two cavities for splitting the radiation impinging thereon according to polarity and propagating it into the noncommon sections of the first and second optical cavities each of which contains a Q-switch. The output from the cavities is taken at the polarizing beam-splitter and comprises two closely spaced in time pulses of different polarity. The two pulses are applied to a doubler crystal such that pulses of one polarity are doubled while pulses of the other polarity are unchanged.