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 microlaser is described which is electrostatically tunable. One of the reflectors includes at least one reflecting part whose distance from the other reflector can be adjusted to change the effective optical distance between the reflectors and thus tune the optical frequency at which lasing occurs. The disclosure brings out that the inventive aspect is also applicable to other optical devices having reflectors defining a Fabry-Perot cavity. An optical interconnecting scheme for processors using the microlaser is also described.

Abstract: A laser light beam generating apparatus includes at least one light beam source, resonator and an optical system. The resonator generates a type II second harmonic laser light beam. The resonator has a first reflector, a second reflector, a laser medium provided between the first and second reflectors and irradiated a light beam emitted from the light beam source through the first reflector and a non-linear optical crystal element provided between the laser medium and the second reflector. The optical system radiates the type II second harmonic laser light beam emitted from a virtual luminance point of the resonator to a conjugate point. In this laser light beam generating apparatus, with an effective length of the resonator L, an effective distance Le from the resonator to the conjugate point is set to thatLe=(m+1/2)Lwhere m is an integer.

Abstract: Frequency modulated radar transmitters with a repetitive linear increase in frequency with time, referred to as "frequency chirps", are required for many radar applications. The present invention provides a simple way of obtaining such a chirped frequency modulation for a laser radar transmitter or the like. The principle is to translate an optical wedge in the direction of its wedge gradient at constant velocity across the optical path of a laser resonator. The resulting increase or decrease in the effective optical length of the resonator causes frequency chips. In a first embodiment of the present invention, a rotating phase plate on the face of a rotating wheel with the added phase varying linearly with angular position around the wheel is placed within a laser's resonator cavity to tune the optical pathlength of the cavity and thereby the longitudinal mode of the resonator to produce the chirp. This embodiment can be used in either a reflective or a transmissive mode.

Abstract: A solid-state laser having a laser resonator which includes an etalon to allow a single longitudinal mode of oscillation to occur in the width of the wavelength which permits the oscillation of the medium of the solid-state laser. The etalon is interposed in the resonator which is constituted of a surface of a resonant mirror and one end surface of a solid-state laser medium, and wherein the interval of the longitudinal modes of the etalon is set to be in the range from approximately one half to one width of the oscillation wavelength of the medium of a solid-state laser. At the same time, the ratio, with respect to the optical length, of the etalon to the resonator is selected to be about a half integer.

Abstract: A stripline laser includes a housing having two sides. An exit window is disposed at one of the sides for a laser beam traveling in a given direction. Two metal electrodes are mutually spaced apart defining a discharge gap therebetween. At least two mutually parallel bars having very low coefficients of temperature expansion retain two resonator mirrors at a precisely fixed mutual spacing. The electrodes are rigidly joined to the housing and to the bars in the given direction at only one location in a reference plane. The electrodes are secured at another location against motions relative to the housing running perpendicular to the discharge gap. A holder adjustably fastens an inclination of at least one of the mirrors relative to the discharge gap. The bars fix an axial position and an angular position of the at least one adjustable mirror relative to the reference plane. The reference plane is disposed at least approximately midway between the mirrors.

Abstract: A thin film coating deposited on a substrate, the substrate having a first surface and a second surface opposite the first surface. The coating comprises a first dielectric layer, on the first surface of the substrate, having an index of refraction n.sub.1 and having an optical thickness of about d; a second dielectric layer, on the first dielectric layer, having an index of refraction n.sub.2 and having an optical thickness of about d; and a third dielectric layer, on the second dielectric layer, having an index of refraction of n.sub.1 and having an optical thickness of about 2d. The coaing is substantially reflective over at least two regions of wavelengths, each region separated by a region of high transmissiveness. In one aspect, the first dielectric layer is silicon dioxide, the second dielectric layer is titanium dioxide, and the third dielectric layer is silicon dioxide.

Abstract: A single focus backward Raman laser that is a compact, efficient apparatus for converting light at a first wavelength provided by a pump laser to light at a Raman-shifted wavelength. The laser is comprised of a gas cell, two lenses, a feedback mirror, an optical isolator, and a dichroic mirror, and the gas cell contains a Raman gas medium. The Raman gas medium may be methane, hydrogen, or deuterium, for example. The two lenses bring the pump and Raman light to a single focus in the gas cell and also recollimate the light after it exits the cell. The optical isolator is used to prevent the backward-scattered pump light from reentering the pump laser. The dichroic mirror is used to reflect out the backward-scattered Raman light, while transmitting the pump laser light. The present laser has a much improved beam divergence and is much less sensitive to optical misalignments than conventional Raman half-resonator designs.

Abstract: A multi-beam raster output scanner is disclosed which utilizes a deflection wedge for modifying the beam separation independent of the spot size to generate a desired relationship between spot separation and spot size. The beam separation can be modified by moving the deflection wedge back and forth. Depending on the distance between the deflection wedge and a spot size control aperture, the beam separation varies. In this invention, as in the prior art, the spot size can be modified by changing the size of the control aperture, but to avoid the loss of intensity, the size of the control aperture will be changed only for fine adjustments to achieve the proper spot size.

Abstract: A waveguide laser having a pair of electrodes mounted opposite one another in the gas discharge space is provided with a spacer extending between the two electrodes. The spacer prevents movement of the electrodes from a mutually parallel position which may otherwise occur due to mechanical stresses in the laser. Beam quality is thereby maintained. The spacer has only a limited extent in the direction transverse to beam travel and/or is of a material transmissive to laser light to prevent detrimental effects on the laser. The spacer is particularly useful in CO.sub.2 lasers, such as pulsed lasers.

Abstract: A method and apparatus for producing a laser diode assembly package is taught. Briefly stated, in a first embodiment, a housing having an access area at one end has a laser mounted therein. A collimator lens is placed at the other end of the housing and is movable along the optical axis of the laser output. This enables the collimator to be adjusted along the optical axis in order to produce an optimum amount of collimated light, with the housing and lens then be hermetically sealed with UV curable epoxy. In an alternate embodiment, the laser is mounted on a socket module which is then inserted into the housing.

Abstract: A wavelength division multiplex type mode-lock laser device which simultaneously generates high-speed optical pulse trains for more than one wavelength. This device simultaneously generates high-speed optical pulse trains at two or more wavelengths. A ring resonator type mode-lock laser device or a Fabry-Perot type mode-lock laser device is modified so that it has an optical path difference providing structure which provides different refractive indices for the polarization directions which are at right angles at one another. This enables configuring a resonator corresponding to the optical path lengths formed according to the refractive indices and hetero-wave length optical path equalizing means to provide different refractive indices for different wavelengths.

Abstract: A process for making a custom phase-conjugated circular mirror to be used in a laser resonator that will suit specifications of a user is provided. The mirror reverses wavefront of one particular input beam .PSI..sub.o (x) determined by the user, the input beam .PSI..sub.o (x) having a given wavelength, the laser resonator including the mirror and an output coupler cooperating with the mirror and separated therefrom by a laser gain medium, the mirror being at a distance L from the output coupler. The process comprises steps of (a) determining the input beam .PSI..sub.o (x) that will suit need of the user; (b) calculating equation of .PSI..sub.L (x) which is a value of the input beam .PSI..sub.o (x) that is propagated through said laser gain medium at distance L; (c) calculating phase .PHI..sub.o (x) of the input beam, which is a phase of the input beam .PSI..sub.o (x) at distance L, the phase .PHI..sub.

Abstract: An intensity stabilized laser including a gain cavity containing a gain medium; and an absorbing cavity containing a nonlinear absorbing medium, wherein the absorbing cavity is located with respect to the gain cavity and the characteristics of the nonlinear absorbing medium are selected so as to provide negative feedback from the absorbing cavity to the gain cavity during operation of the laser to thereby control the gain of the gain cavity.

Abstract: A frequency-doubled laser contains laser diodes as a pumped light source and a resonator (R) comprising in the stated order a first mirror (5), a laser medium (6), a Brewster plate (7) as a polarizer, a nonlinear crystal (8) for frequency doubling and a plane mirror (9) as an output mirror. The plane mirror ensures that shifts of rays taking place within the nonlinear crystal remain in the radiation area even when returning through the crystal, in contrast to the prior art which uses a concave mirror as an output mirror that causes shifted rays from the nonlinear crystal to be deflected out of the beam path. The inventive measure achieves a laser light that has high efficiency and is virtually free from intensity fluctuations.

Abstract: A rotatable, bakeable vacuum sealed mount for an optical element, suitable for use on an endbell assembly for a gas discharge tube or as an integral part of a gas discharge tube for an ion laser comprises an elongated support member, having an axis and a passage along the axis of the support member. A first end of the support member is connected by a vacuum tight seal to the vacuum sealed chamber of the gas discharge tube, so that the passage has an opening toward the vacuum sealed chamber. A second end of the support member is connectable by vacuum tight seal to the optic, so that the second end of the passage has an opening toward the optic. A portion of the support member has a yield strength allowing adjustment by twisting of the support member about the axis for establishing a rotational alignment of the optic without breaking the vacuum of the vacuum sealed chamber.

Abstract: A buried heterostructure type distributed feedback semiconductor laser comprises a semiconductor substrate transparent to an oscillation light beam, a laser stripe including a diffraction grating, an active layer, and a guiding layer formed on the semiconductor substrate, and semiconductor peripheral region formed so as to cover the laser stripe on the semiconductor substrate. The semiconductor peripheral region is transparent to an oscillation light beam. Rectangular grooves are formed near both sides of emission facet of the laser stripe more deeply than the laser stripe. Since a radiation mode from the laser stripe is reflected and scattered by the grooves, it cannot hardly reach the emission facet. Therefore, the radiation mode does not interfere with an output beam from the laser.

Abstract: Apparatus for transforming a conventional beam of coherent light, having a Gaussian energy distribution and relatively high divergence, into a beam in which the energy distribution approximates a single, non-zero-order Bessel function and which therefore has much lower divergence. The apparatus comprises a zone plate having transmitting and reflecting zones defined by the pattern of light interference produced by the combination of a beam of coherent light with a Gaussian energy distribution and one having such a Bessel distribution. The interference pattern between the two beams is a concentric array of multiple annuli, and is preferably recorded as a hologram. The hologram is then used to form the transmitting and reflecting zones by photo-etching portions of a reflecting layer deposited on a plate made of a transmitting material. A Bessel beam, containing approximately 50% of the energy of the incident beam, is produced by passing a Gaussian beam through such a Bessel zone plate.

Abstract: According to the present invention there are provided a solid-state laser device using a laser rod not smaller than 180 mm in length as a laser medium, thereby capable of providing a high output power, facilitating maintenance and inspection, and permitting the reduction of size and simplification in comparison with a conventional laser device using plural laser rods, as well as a machining apparatus using the said laser device as a machining energy source, and a solid-state laser device wherein a laser medium is held in a free state within a resonator so that a longitudinal direction of the laser medium is coincident with an optical axis direction of laser beam and so that the laser medium is capable of expansion or contraction in the said optical axis direction, thereby preventing the breakage of the laser medium and the deviation of the optical axis of laser beam.

Abstract: A solid state lasing medium is pumped to produce a high repetition rate laser beam. The laser medium is pumped to cause maximum population inversion. The laser medium is greater in diameter than the aperture that defines the allowable beam path. In the preferred embodiment the off-axis laser beam that is produced is steered to become an on-axis laser beam using a novel SBSA (spinning beam steering assembly). The output of the laser is increased because as the SBSA spins, the area of the lasing medium that is not lasing is being charged or pumped. The laser medium can also be hollow to allow for pumping from either outside or inside the hollow bore or both. Similarly, this hollow bore in the laser medium could also allow cooling fluids to be circulated therethrough. Different embodiments of the SBSA are disclosed, including a variety of methods to pump the laser medium. Also, disclosed is a novel field removable or replaceable laser medium housing assembly.

Abstract: For small line width tuning of a laser, especially a pulsed dye laser, a reference beam is uncoupled from the laser resonator (10,18) and directed to a beam position photosensor such as an adjacent pair of photo diodes. A control signal for synchronizing the movements of a grating (10) and an etalon (18) of the laser resonator is derived from a local change of the reference beam in order that synchronism may be achieved in the movement of both the etalon and the grating.

Abstract: A pulse laser has a laser resonator, a laser medium in the laser resonator, and a deflecting device. The laser medium emits an emission light. The deflecting device switches an optical path of the emission light to output the emission light as a laser pulse. The deflecting device includes a deflecting member and a pumping device. The deflecting member is arranged in the optical path of the emission light. The deflection member has a refractive index which changes based on a pumping light incident thereon. The pumping device radiates the pumping light on a predetermined region of the deflection member and varies the refractive index of the predetermined region to switch the optical path of the emission light.

Abstract: Angles of inclination of the two wavelength selection elements arranged on an optical path of a laser beam source are varied to make a laser output variable. Light transmitting ranges of the two wavelength selection elements are coincided with each other so as to adjust the light wavelength bands, thereby the laser beam is narrowed without increasing its fineness.

Abstract: In a photon storage ring for storing SR light to generate the same through an outlet port, a reflection mirror is disposed to surround a circular orbit along which bundles of charged particles revolve at a speed close to the velocity of light, generating SR light at a direction tangential to the circular orbit. The reflection mirror has curvature such that the SR light generated in the tangential direction is reflected on the reflection mirror and sent as reflection SR light which is tangential to the orbit. The SR light and the reflection SR light interfere with each other and are guided towards the outlet port.

Abstract: An optical parametric oscillator/laser system includes an optical pump source for generating pump radiation and an embedded dual optical resonator containing an optical parametric oscillator/laser crystal. The embedded dual optical resonator includes a laser resonator and an optical parametric oscillator resonator. The OPOL crystal is an optical parametric oscillator material doped with ions that exhibit lasing transitions. The pump radiation stimulates generation of laser radiation. When the laser radiation reaches the parametric threshold, optical parametric radiation is generated. In one embodiment, the laser resonator and the OPOL resonator are each defined by spaced-apart mirrors. In another embodiment, the OPOL system includes an OPOL rod having end caps at each end. Each end cap includes surfaces for internally reflecting the laser radiation and the parametric optical radiation in a closed loop path so that the OPOL rod and the end caps define an optical resonator.

Abstract: A linear cavity laser system having a yttrium-aluminum-garnet laser rod for producing a fundamental wavelength of radiation having a front face and a longitudinal axis, a first mirror reflective of the fundamental wavelength but transmissive of a desired harmonic wavelength located in front of the laser rod along the longitudinal axis, a second mirror reflective of both the fundamental wavelength and the desired harmonic wavelength located to a rear of the lasing rod along the longitudinal axis, a phase matched crystal harmonic wavelength generator responsive to the fundamental wavelength for generating the desired harmonic wavelength of radiation arranged between the front mirror and the lasing rod along the longitudinal axis and a dichroic member transmissive of the fundamental wavelength but reflective of the harmonic wavelength arranged between the laser rod and the harmonic wavelength generator along the longitudinal axis.

Abstract: A mode locked pulsed laser incorporates an intracavity element to compensate for the dispersion caused by other intracavity elements. This element reduces the tendency of the pulse to broaden in the cavity due to group velocity dispersion and results in very short pulses. In the laser of the present invention, mode locking is initiated by detecting the beat frequency between adjacent longitudinal modes using a high speed photodiode. This signal is amplified and then the frequency is divided by two. The signal is passed through an electronically adjustable phase shifter and then to a power amplifier. This signal is applied to the acousto-optic modelocker. If the cavity length drifts the beat frequency between the longitudinal modes changes. The rf signal applied to the modulator changes in exactly the right manner to track the drift in cavity length. Thus the modelocker is automatically synched to the round trip of the laser cavity.

Abstract: A method and apparatus for automatically maintaining the length of a laser cavity in a laser system in an optimum single length mode regardless of changes of frequency in the dispersive optics feedback, by sensing a group of pointing directions of a laser beam over a determined range of operating conditions, determining the average pointing position of the laser system for the group of sensed pointing directions and adjusting the length of the laser cavity to conform the pointing direction of the laser system to the average pointing direction.

Abstract: An eye-safe laser operating at high efficiency, pulse repetition rate and power output is described. The laser comprises a diode-array pumped laser having a pumping wavelength range which produces a polarized output beam. The output beam passes through a nonlinear tunable parametric converter crystal having X, Y, and Z principal axes. Noncritical phase matching is produced in said laser by phase matching for a beam propagation parallel to a principal axis which results in a high efficiency of laser operation. The nonlinear tunable parametric converter crystal converts the wavelength of an otherwise unsafe laser beam output to one that is harmlessly absorbed by the human eye.

Abstract: A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.

Abstract: A system is described for automatically maintaining the group velocity dispersion (GVD) of a Gires-Tournois interferometer (GTI) as the wavelength of incident light is varied. In the system, the transmission through the GTI is monitored by a photodiode as the wavelength is varied. The transmission through the GTI provides a measure of its GVD. Thus, the output of the photodiode can be used as a control signal for adjusting the GTI in a manner to maintain its GVD at the desired level. The subject system is illustrated in conjunction with a pulsed, tunable, Ti:sapphire laser which is passively mode locked with the optical Kerr effect. The system allows the wavelength of the laser to be tuned over the bandwidth of the gain medium while maintaining a selected level of GVD from the GTI which in turn maintains the desired duration of the pulses. In addition, the GTI is used to compensate for the dispersion effects created by broad band optics in the resonator.

Abstract: A chromium doped solid-state high peak-power laser transmitter emits at a 4861.342 or 4340.50 Angstrom Fraunhofer line, lines of peak blue-seawater transmission and minimum solar radiation. A pink ruby gain medium doped with approximately 0.05% chromium ion is temperature tuned to an R2 line at 6924.51 Angstrom wavelength and an R1 line is dispersively suppressed in a laser oscillator cavity also tuned to 6924.51 Angstrom. The oscillator is Q-switched and the amplified high peak-power 6924.51 Angstrom R2 line output is frequency doubled to 3462.26 Angstrom and hydrogen Raman down-shifted 8310 cm.sup.-1 to the second-Stokes at 4861.342 Angstrom to produce said high peak-power output centered on the 4861.342 Angstrom hydrogen-beta Fraunhofer line. Optionally, a temperture tuned 6927.00 Angstrom R2 line laser oscillator wavelength from the pink ruby gain medium doped with approximately 0.05% chromium ion relies on frequency doubling the R2 line at 6927.00 Angstrom to 3462.

Abstract: A passively mode-locked laser (110) is disclosed that includes a resonant cavity (112, 114) having a gain medium (116) therein. A transmissive element (116), which may be the gain medium, is also located in the cavity and is formed from a material which varies the two-dimensional, lateral spatial profile of the beam with respect to intensity due to the Kerr effect. The resonator is arranged such that the round trip gain of the system increases with respect to the intensity of the beam so that mode-locking operation can be achieved. In one approach, the variation in the spatial profile is used to increase the extraction of energy from the gain medium. In another approach, the variation in spatial profile which occurs with an increase in intensity is used to decrease the loss in the system so that pulse operation is favored.

Abstract: A chromium doped solid-state high peak-power laser transmitter emits at a 4861.342 or 4340.5 Angstrom Fraunhofer line, lines of peak blue-seawater transmission and minimum solar radiation. A pink ruby gain medium doped with approximately 0.05% chromium ion is temperature tuned to an R2 line at 6924.51 Angstrom wavelength and an R1 line is dispersively suppressed in a laser oscillator cavity also tuned to 6924.51 Angstrom. The oscillator is Q-switched and the amplified high peaked-power 6924.51 Angstrom output is hydrogen Raman shifted to the first-Stokes at 9722.684 Angstrom which is frequency doubled to produce a high peak-power output at 4861.342 Angstrom hydrogen-beta Fraunhofer line. Optionally, a temperature tuned R2 line at 6927.00 Angstrom wavelength from the pink ruby gain medium doped with approximately 0.05% chromium ion is Raman shifted 2916 cm.sup.-1 in methane to the first-Stokes at 8681.0 Angstrom. Next, the first-Stokes at 8681.0 Angstrom is frequency doubled to the 4340.

Abstract: An unstable resonator, dc excited, is pulsed using an adjoint coupled beam of low power as the pulsing element. The resonator feedback consists of the self-feedback and the adjoint beam feedback. The self-feedback can be sufficient for self-oscillation and pulsed operation can be achieved by controlling the repetition rate and the magnitude of the adjoint beam power. Complete control and shut-off between pulses with complete freedom of repetition rate is achieved if the self-feedback is insufficient for laser oscillation. The invention was demonstrated on a 10 kilowatt average power CO.sub.2 laser with pulse control provided by with a 100 watt adjoint feedback beam.

Abstract: A substance vaporizing apparatus which uses a vapor of a substance generated by heating the substance in a gas-filled tube as an exciting medium or an ionizing medium. The apparatus employs an improved container for containing the substance within the gas-filled tube. The improved container suppresses the rate of emission of the vapor of the substance into a discharge space defined by the gas-filled tube to hold the vapor density of the substance at an optimum low value for laser oscillation relative to the buffer gas density in the discharge space. Thus, the mean free path of the atoms of the substance, namely the average distance traveled by the atoms between elastic collisions with the electrons, ions and neutral atoms of the buffer gas, is increased to increase the number of atoms of the subtance excited to a higher energy level, which, consequently, increases laser power and enhances laser beam or ion beam accelerating energy.

Abstract: A method of controlling the total energy amount of a plurality of laser pulses in which the accumulation of the energy amounts of the individual pulses is measured with an energy measuring device and the laser pulses are interrupted when a dose desired value of the accumulated energy amounts is reached, provides that for increasing the accuracy of the energy dose achieved several laser pulses before reaching the dose desired value the energy amount of the individual laser pulses is reduced.

Abstract: A sensor is disclosed for detecting a physical magnitude, comprising a mechanical resonator, adapted to be subjected to a mechanical stress representative of the magnitude to be measured, and means for causing the resonator to oscillate and maintaining its oscillations at a resonance frequency representative of the magnitude to be measured, wherein the resonator is made from a solid laser material and said oscillation means comprise means for feeding the laser resonator with a continuous pumping light beam.

Abstract: In a semiconductor laser module with a built-in optical isolator which isolator consists of a polarizer, a Faraday rotator and an analyzer, an optical refraction sheet having a wedge-shaped section is disposed on the beam incidence side of the polarizer. Accordingly, even when the mechanical center axis of the optical isolator is placed to be in parallel with the optical axis of the semiconductor laser or in other words, even when the beam incidence-outgoing surfaces of the polarizer, Faraday rotator and analyzer are placed to be vertical to the incident parallel beams, the parallel beams incident into the optical isolator are refracted by the optical refraction sheet having the wedge-shaped section, so that the parallel beams passing through the beam incidience-outgoing surfaces of the polarizer, Faraday rotator and analyzer do not pass vertically and the return of reflected beams to the semiconductor laser can be thus reduced.

Abstract: A sealed laser plasma tube for use in a gas laser system. A Brewster window seals one end of the tube (the cathode end, in a preferred embodiment), and an end mirror which seals the opposite tube end (the anode end, in a preferred embodiment). In a laser system embodying the invention, a second end mirror is positioned adjacent to, but spaced from, the Brewster window. Intra-cavity elements may conveniently be inserted and replaced in the region between the sealed Brewster window and the second end mirror. The sealed mirror which seals the tube end opposite the window is preferably coated with at least an outermost layer of Hafnium oxide, to protect it from hard UV radiation originating within the plasma tube. The inventors have recognized that the problem of sealed window degradation is substantially less severe at the cathode end of an ion laser plasma tube, and that the sealed window should be attached at the tube end at which the window degradation problem is less severe.

Abstract: Control systems for stabilizing the position of a beam from a laser are disclosed. In one aspect, lateral alignment deviations created by varying thermal effects in a solid state gain medium are compensated. A system is also disclosed which can isolate and the correct both lateral and angular alignment errors.

Abstract: Solid state and dye lasers are described which are tunable over a wide spectral region, are operable at high repetition rate, are uniformly narrow in spectral width over the tuning range, and produce a spatially uniform, single longitudinal mode beam. In one embodiment having a simple grazing-incidence cavity, the laser comprises: (a) a longitudinal pump beam with a KiloHertz (KHz) repetition rate; (b) a resonating cavity comprising a first fixed mirror, a diffraction grating, and a second rotatable mirror; and (c) an active solid state or dye medium within the cavity. In this embodiment, (i) the pump beam is passed through the fixed mirror and directed at the active medium; (ii) the emission from the active medium strikes the grating near a grazing angle; (iii) the rotatable mirror is placed at a first order diffraction position from the grating and reflects the desired wavelength radiation back into the cavity; and (iv) the output is derived from the grating at the zeroeth diffraction order.

Abstract: A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.

Abstract: A switchable multichannel external cavity injection laser incorporates a diffraction grating between a linear array of n reflectors and a common reflector to define a set of n optical cavities having different frequency bands. Each of the (n+1) reflectors is provided by the optically distal end of an associated semiconductor laser amplifier whose optically proximal end is arranged to be substantially non-reflective.

Abstract: Part of a laser beam, which is generated by a laser tube and reflected by a reflection surface of a high-reflectance mirror to travel while diverging at the predetermined angle, is divided by a dividing mirror. The spectral band width of the divided laser beam is narrowed by an etalon and a diffraction grating. The laser beam with the narrowed spectral band width is reflected by a high-reflectance return mirror, returned to the laser tube, and amplified in the laser tube. The laser beam with the narrowed spectral band width is amplified in substantially the same space within the laser tube where the laser beam was generated.

Abstract: A semiconductor laser which includes a controllable beam splitter has three segments including laser-active zones and a monitor diode forming a cross-shaped laser connected with one another by way of the beam splitter. The beam splitter is equipped with electrodes for controlling optical coupling between the segments.

Abstract: A scatter shield attenuates off-axis illumination emanating from a light beam projector. The scatter shield comprises an elongate housing, usually cylindrical, having at least two baffles therein. The dimensions of the scatter shield are selected to assure that off-axis illumination exceeding a preselected angle of divergence is internally reflected within the shield at least three times. Such multiple reflections provide for highly efficient attenuation.

Abstract: According to the invention, a probe laser beam having a wavelength which is different from that of the laser beam emitted from a laser apparatus is introduced into the apparatus to adjust the optical device so that any fluctuations in the probe laser beam passing through or reflected from the optical device may be eliminated. Therefore, any fluctuations in output power and/or the oscillation wavelength of the narrowed bandwidth laser beam emitted from the apparatus can be directly detected and the laser apparatus can be so controlled as to ensure a stabilized operation under an optimum condition.

Abstract: An apparatus for controlling an output from an excimer laser device wherein at least two etalons each having a large diameter are arranged between a rear mirror and a laser chamber for the excimer laser device is disclosed. With the apparatus, the operative range of laser light outputted from the excimer laser device can be narrowed by executing superposition control for a wavelength of laser light which transmits through each etalon, while maintaining the number of spatial lateral modes. The apparatus is preferably employable as a light source particularly for a unit for projecting and exposing figures in a reduced size. Superposition control with the use of a superposition control unit, excitation intensity control for laser gas with the use of an excitation intensity control unit and partial gas replacement control for laser gas with the use of a gas control unit are executed in a predetermined timing relationship, respectively.

Abstract: An apparatus for applying a load to an etalon so as to enable the accurate tuning of desired frequencies or ranges of frequencies. The invention includes first and second optical surfaces separated and disposed highly parallel with respect to each other by an electric longitudinal spacer member. A biasing means applies a longitudinal load to the elastic longitudinal spacer member. The applied load is uniformly distributed throughout the spacer member by a longitudinal load distribution means, which is disposed between said biasing means and at least one of said optical surfaces. The distance, d, between the first and second optical surface is directly proportional to the load applied by the biasing means. The load may be varied, in one embodiment of the invention, using a bias adjustment means acting in mechanical cooperation with the biasing means.