Abstract: The present invention provides an apparatus for passively stabilizing the tuning element in tunable lasers. Lasers stabilized using the passive stabilization of the tuning element exhibit reduced mode hop and increased wavelength stability during temperature variations of the laser or surrounding environment. The stabilization makes the laser suitable for a broad range of applications including optical signal generators and optical multimeters.

Abstract: The invention relates to an external cavity, continuously tunable monomode laser source, comprising, in a resonant cavity, resonating at the emission wavelength &lgr;e, a retroreflecting wavelength dispersing device, arranged to produce a selectivity curve with a peak 80 s. According to the invention, additional fine-control means, enable, from the approximate continuous tunability position, to monitor the deviation &lgr;e-&lgr;s during the variation of the emission wavelength ke while preventing this deviation from reaching one of the limits causing mode hopping. Such a configuration enables to avoid imperfections usually associated with mechanical adjustment and to guarantee continuity of the wavelength variation and to compensate for the latter as long as its fluctuations remain smaller than approx. &Dgr;&lgr;e/2 where &Dgr;&lgr;e is the distance between two successive resonance modes of the cavity.

Abstract: An arrangement is disclosed for geometrically shaping a radiation field, in particular the radiation field of a diode laser array which propagates in the z direction and has a radiation cross section which is larger, in a direction defined as the y direction, which is perpendicular to the first, and has a lower radiation quality in said direction. X, y and z form a Cartesian coordinate system. The radiation is grouped into radiation fractions in the x direction and the radiation fractions are reoriented as regards their radiation cross sections. The arrangement has at least two reflective elements (6) and is characterized in that each reflective element has a pair of reflection surfaces (7,8) at approximately or exactly 90° to each other. This opening angle (9) is oriented against the direction of propagation. The line (10) at which the reflection surfaces intersect is oriented at approximately below 45° to the x direction.

Abstract: A failure analysis system and method for multi-layer semiconductor devices, including a molecular fluorine laser system for producing a 157 nm beam and an imaging system for imaging the beam onto the semiconductor device. The laser beam etches away one or more top (passivation) layers to expose layers disposed underneath. Circuitry formed in exposed layers can then be tested.

Abstract: A method for fabricating a Fabry-Perot laser having a cavity length and facet reflectivity product tuned to cause the laser to exhibit a relaxation oscillation frequency of at least 10 GHz, wherein the laser is capable of being modulated at 10 Gb/sec at drive currents between about 20 and 40 mA.

Abstract: A wavelength stabilized laser system includes a laser that produces a laser light having an amplitude and a wavelength that varies as a function of a temperature of the laser. A temperature control device controls the temperature of the laser. A beam splitter deflects a portion of the laser light. A first detector receives the portion of the laser light from the beam splitter and provides a first signal representing the amplitude of the laser light. A filter has a gain that is a function of the wavelength of the laser light. The filter receives the laser light and outputs a filtered light having an amplitude that varies with the wavelength of the laser light. A second detector provides a second signal representing the amplitude of the filtered light. A sealed housing contains the laser, the first and second detectors and the filter. The housing has a window.

Abstract: An optical system (in FIGS. 1A and 1B) wherein a rectilinear laser beam of homogeneous energy distribution is defined for annealing a non-single crystalline semiconductor film (a surface to-be-irradiated 1108), is constructed of reflectors (1106, 1107 etc.) easily and inexpensively without including lenses of transmission type. The rectilinear laser beam can be defined having a length of at least 600 (mm) which corresponds to the shorter latus of a large-sized substrate for mass production.

Abstract: The invention refers to a laser having first and second reflecting elements (3, 4) defining a laser cavity; a laser microchip (1) provided in the laser cavity to generate laser radiation of a fundamental wavelength; and a quasi-phase matching non-linear optical element (2) provided in the laser cavity to receive said laser radiation of the fundamental wavelength from the laser microchip (1) and to emit frequency doubled laser radiation (SH) of a wavelength half as long as the fundamental wavelength.

Abstract: A scalable high power laser system includes a plurality of parallel connected modular power amplifier arms, coupled to a common master oscillator to provide a high average power laser system with a scalable output power level, particularly suitable for laser weapon systems with varying power level output applications. Adaptive optics devices are provided in order to provide pre-compensation of phase front distortions due to the modular amplifier arms as well as encode the wave front of the laser beam with a phase conjugate of atmospheric aberrations.

Abstract: A wavelength-stabilized laser system includes a laser that produces a laser light. The laser light has an amplitude and a wavelength that varies with the temperature of the laser and/or a bias signal provided to the laser. A temperature control device controls the temperature of the laser. A first detector outputs a first signal representing an amplitude of a laser light. A filter receives the laser light and outputs a filtered light having an amplitude that varies with the wavelength of the laser light. A second detector outputs a second signal representing the amplitude of the filtered light. An electromagnetic radiation source transmits electromagnetic radiation through the filter and through a diverging lens. A third detector receives the electromagnetic radiation that passes through the diverging lens. The second detector may be between the diverging lens and the third detector. The third detector outputs a third signal representing an amplitude of the electromagnetic radiation.

Abstract: A monitoring and control assembly for an optical system includes a tunable laser. The laser generates a divergent output beam along an optical axis. A first photodetector is provided. A wavelength selective filter is tilted at an angle relative to the optical axis that provides an angular dependence of a wavelength reflection of the wavelength selective filter and directs the reflected output beam towards the first photodetector.

Abstract: A lens duct is used for pump delivery and the laser beam is accessed through an additional component called the intermediate beam extractor which can be implemented as part of the gain element, part of the lens duct or a separate component entirely.

Abstract: A laser system includes a gain medium for providing and amplifying a laser beam within an optical resonator. According to the invention, the laser system actively provides a plurality of different optical modes for stabilizing the laser beam, preferably by forcing the laser beam to jump between different optical modes more frequent than environmental disturbances occur. Providing the plurality of different optical modes can be achieved e.g. by varying the phase of the laser beam and/or by varying the optical length of the optical resonator. The laser system can be employed in a gas monitoring system, e.g. for monitoring a respiration and/or anaesthetic gas, for providing a Raman spectrum of the gas to be monitored.

Abstract: A scalable high power laser system includes a plurality of parallel connected modular power amplifier arms, coupled to a common master oscillator to provide a high average power laser system with a scalable output power level, particularly suitable for laser weapon systems with varying power level output applications. Adaptive optics devices are provided in order to provide pre-compensation of phase front distortions due to the modular amplifier arms as well as encode the wave front of the laser beam with a phase conjugate of atmospheric aberrations.

Abstract: The invention relates to a wavelength-tunable laser configuration. The interspace between a laser source (200) and a control element (202), forming an external cavity, is short and has a length of preferably at most a few hundreds of wavelengths of the laser source (200). Also, the control element (202) is electrically tunable, which means that the control element (202) changes the optical properties of the external cavity with a movement of at least one tuning part (206, 402).

Abstract: A speckle reduction system divides pulses of coherent radiation into successions of temporally separated and spatially aberrated pulselets. One or more beamsplitters divide the pulses into the successions of pulselets that are circulated through delay lines. Spatial aberrators located along the delay lines modify wavefront shapes of the pulselets. Together, the temporal separation and spatial aberration of the pulselets produce a succession of different speckle patterns that can be averaged together within the integration interval of a detector to reduce speckle contrast.

Abstract: In a method and an apparatus for driving a diode-pumped solid-state laser, the light power emitted by the solid-state laser (1) is determined as a measurement signal, using a measurement apparatus. By comparison of the measurement signal with a predetermined light power target value, a control deviation is determined in a control amplifier the deviation being converted in a generator into a driver current for a laser diode used as a pump diode for the resonator of the solid-state laser. For the damping of high-frequency disturbances of the light power, in a high-bandwidth negative feedback branch the high-frequency components of the measurement signal are filtered out by means of a high-pass filter and are supplied to a fast control amplifier. In a control element connected in parallel to the laser diode, a portion of the driver current supplied to the laser diode is controlled dependent on the high-frequency components of the measurement signal.

Abstract: The light emitted by a laser diode 1 is entered into a beam splitter 5, and its reflected light is given to an optical band pass filter 8. The light passing through the optical band pass filter 8 is received by a photo diode PD1.The light once reflected by the optical band filter 8 and passing through the beam splitter 5 is received by a photo diode PD2. The reception ratio of the photo diodes PD1, PD2 is calculated in output ratio calculator 9. By controlling the emission wavelength of the laser diode 1 so that its ratio may be constant, laser light of high precision and stable wavelength is emitted.

Abstract: An apparatus for monitoring and controlling the wavelength of laser radiation includes at a least one optical filter for receiving laser radiation and for transmitting and reflecting first and second filtered beams, respectively. The beams are filtered according to respective first and second spectral filter functions that cross at least one crossing wavelength. A beam comparing element compares the intensities of the first and second filtered beams and produces an error signal responsive to the deviation of the wavelength of the laser radiation from a set point wavelength. The beam comparing element can include first and second optical detectors and an error circuit for producing the error signal by taking a ratio or the difference of the signals detected by the detectors. Varying the angle of incidence of the laser radiation upon at least one optical filter varies the spectral filter function of that for selecting or varying the operating wavelength of the laser.

Abstract: This invention discloses an optical resonator (24) including at least one spiral optical element (44) operative to change the angular phase distribution of modes in the optical resonator (24), thereby to generally eliminate undesirable modes.

Abstract: A hybrid tunable Bragg laser including a double heterostructure gain section, a Bragg reflector section optically coupled to said gain section, and an optical extension constructed to yield a plurality of longitudinal modes. Preferably, the optical section has a predetermined length and effective reflectivity adapted to yield the plurality of longitudinal modes.

Abstract: In an optical path of a laser beam, a reflection mirror (11) is located to divide the laser beam into two split laser beams. By the use of the split laser beams, workpieces (17a, 17b) are simultaneously processed.

Abstract: Laser systems, and optical elements for laser systems, are disclosed for providing a pumped laser light with improved output efficiency while having simple construction and simple alignment adjustment. A pump light flux from a diode pumping laser irradiates and thus pumps a solid-state laser crystal. The irradiation by the pump light flux is coaxial with an output laser beam produced by the laser crystal. The pump light flux is conducted by an optical element, preferably frustoconical in shape with an entrance face larger than an exit face, that functions as a light funnel. The entrance face is disposed proximal to the pumping laser 11, and the exit face is disposed proximally to the laser crystal 14. A portion of the pump light flux entering the entrance face passes through the optical element without being reflected by a side surface of the optical element. The remaining pump light flux reflects at least once by the side surface during passage through the optical element.

Abstract: A semiconductor excitation solid-state laser apparatus, in which a cross-sectional area of an optical guide plate leading an excited beam emitted from a semiconductor laser element to a solid-state laser medium is made larger in the side of the semiconductor laser element thereof, while a cross-sectional area thereof is made smaller in the side of the solid-state laser medium.

Abstract: The present invention describes the use of a pair of acoustooptic devices in a laser or other optical resonator to produce a wavelength-dependent deflection of the light without incurring a net frequency shift. This permits rapid electronic tuning of the resonator wavelength, as well as rapid electronic variation of cavity loss, out-coupling fraction, and round-trip phase shift. The dispersive quality of acoustooptic devices in transmission is utilized as a reflection grating substitute. Two mirrors, one an output coupler, a gain medium and two acoustooptic devices arranged for maximum efficiency such that the incident and diffracted beams are approximately at the Bragg angle for each acoustooptic device permit the laser wavelength to be determined by the acoustic frequency.

Abstract: A source/transmission fiber strategy results in a WDM system with negligible FWM penalty even for closely-spaced channels. The combined performance of a source which provides chirped wavelength pulses with a precise synchronism, along with a transmission fiber dispersion map avoids pulse overlap.

Abstract: A compact, hand-held, rechargeable, tunable, self-contained laser instrument is presented for use in dentistry, oral surgery, orthopedic surgery, and other medical procedures such as sterilization and curing of photo-polymerizable materials. The inventive instrument includes microchip lasers that consume at most 10 Watts and generate a peak output laser beam power of at least 20 mWatts that is adjustable to the light absorbing characteristics of the target material. Laser microchips, pumping laser, thermo-electric heat exchanger, rechargeable batteries, and laser optics are all contained within the same housing which is cordless, lightweight, and inexpensive to manufacture.

Abstract: The present invention relates to a rotating laser beam irradiating apparatus, and more particularly to a rotating laser beam irradiating apparatus which, by synchronizing an emission timing of a pulse laser with a rotation of an irradiating means, makes it possible to describe intermittent dot-shaped marks, to tremendously increase a visual recognition distance, and to enlarge a work area; wherein a pulse driving means drives a pulse laser light source, and an irradiating means irradiates an irradiated object with a pulse laser light beam from the pulse laser light source, and a rotation driving means rotates the irradiating means, and a rotation detecting means detects the rotation of the irradiating means, and an arithmetic processing means, in accordance with a driving timing from the pulse driving means and a detection signal from the rotation detecting means, controls the rotation driving means to synchronize an emission timing of the pulse laser with the rotation of the irradiating means.

Abstract: A Q-switch laser apparatus includes a laser cavity formed with a pair of reflective surfaces having a laser medium mounted therebetween and a power supply operatively connected to the laser cavity to pump the laser medium. An electro-optic Q-switch is mounted in the laser cavity in a saturable absorber of less than 100% saturable transmittance is located in the laser cavity between the laser medium and the electro-optic Q-switch for suppressing prelasing in the laser. The saturable absorber may be a Cr4+:YAG used with an electro-optic Q-switch of LiNbO.sub.3. The method includes selecting the laser apparatus and selecting a saturable absorber of less than 100% saturable transmittance and attaching the selected saturable absorber in the laser cavity between the laser medium and the electro-optic Q-switch for suppressing prelasing therein.

Abstract: A resonator (1) for electromagnetic waves with a stabilizer can, for example, be part of a mode-coupled fiber laser. The stabilizer (2) is provided to stabilize the effective length of the resonator (1). Stabilization is accomplished in a first embodiment via two temperature controllers (3, 4) controlling the temperature of a first portion (L1) and the temperature of a second portion (L2) of the resonator (1). The temperature of the second portion (L2) is controlled as a function of an error signal generated by deviations of the resonator (1) from a nominal length. The second portion (L2) is significantly shorter than the first portion (L1).

Abstract: An optical communication device is provided. One or more pairs of matched diode lasers are located at first and second stations and are connected by a fiberoptic cable. A bit stream is applied to the output beam of the laser or lasers at the first station. The output beam carrying the bit stream passes through the fiberoptic cable to the matched laser or lasers at the second station and combine with the output beam of the receiving laser cavity at the second station to form a combined output beam. The power of the combined output beam is measured and time-dependent changes in the measured output power of the combined output beam is used to read the bit stream. Multiple pairs of matched lasers using different wavelengths may be positioned at the first and second stations. In yet another form of the invention, a frequency injection technique is utilized to modulate the output beam and a deconvolution system is provided to read the bit stream or streams.

Abstract: A method is provided for directly determining the length of sub-picosecond electron bunches. A metallic grating is formed with a groove spacing greater than a length expected for the electron bunches. The electron bunches are passed over the metallic grating to generate coherent and incoherent Smith-Purcell radiation. The angular distribution of the coherent Smith-Purcell radiation is then mapped to directly deduce the length of the electron bunches.

Abstract: An optical sensing apparatus is provided for sensing changes of index of refraction and sensing changes of length of a fiberoptic cable, for example. A transmitting laser cavity produces a stable-resonator output beam which is modulated with a compound beam pattern including a first wave of frequency f.sub.1 and a second wave of frequency f.sub.2. The reflected compound modulated beam enters a receiving laser cavity and fundamental and harmonic waves f.sub.1 and f.sub.2 are generated in the receiving laser cavity. The power of the compound modulated output beam of the receiving laser cavity is measured by a photodiode and a deconvolution system is connected to the photodiode for filtering the fundamental frequency of f.sub.1 and the second harmonic of wave f.sub.2. Time-dependent changes in the measured power of the modulated compound output beam are used to derive changes of index of refraction or changes in length.

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: An autofocusing system for a laser transmitter is provided. A laser beam is swept across a target having a plurality of sections. The target includes a first reflective section and a second reflective section with a non-reflective section positioned therebetween. A photodetector detects a signal representative of the laser beam reflected from the target. The laser beam is focused by adjusting the focusing lens until a ratio of the duration of the non-reflective portion of the signal to the sum of the durations of the reflective portions of the signal is maximized.

Abstract: A method and apparatus maps a Gaussian beam into a beam with a uniform irradiance profile by exploiting the Fourier transform properties of lenses. A phase element imparts a design phase onto an input beam and the output optical field from a lens is then the Fourier transform of the input beam and the phase function from the phase element. The phase element is selected in accordance with a dimensionless parameter which is dependent upon the radius of the incoming beam, the desired spot shape, the focal length of the lens and the wavelength of the input beam. This dimensionless parameter can also be used to evaluate the quality of a system. In order to control the radius of the incoming beam, optics such as a telescope can be employed. The size of the target spot and the focal length can be altered by exchanging the transform lens, but the dimensionless parameter will remain the same. The quality of the system, and hence the value of the dimensionless parameter, can be altered by exchanging the phase element.

Abstract: A laser has an optical laser cavity one end of which is constituted by a partial reflector formed in optical waveguide by an unbalanced Michelson interferometer comprising an optical waveguide splitter/combiner (23; 33) and two optical waveguide Bragg grating reflectors (24a, 24b; 34a, 34b; 44a, 44b).

Abstract: A Q-switched solid-state laser has a narrow-band laser diode (18) whose narrow-band output radiation serves as seed radiation for exciting a solid (14), with the result that only a single wavelength-stable longitudinal mode oscillates in the resonator (10, 12) of the solid-state laser and corresponding radiation (16) is emitted.

Abstract: A phased array Raman laser amplifier includes a beam generator for generating a fundamental laser beam and a Raman seed frequency laser beam, and a fiber optic laser amplifier array for forming a diffraction limited output laser beam at the Raman seed frequency by amplifying the fundamental laser beam to a power level corresponding to the Stimulated Raman Scattering (SRS) threshold to thereby pump the SRS process and provide Raman gain to the Raman seed frequency laser beam.

Abstract: The laser apparatus according to the present invention comprises an output mirror for reflecting a portion of a laser beam and transmitting therethrough a remaining thereof; a full reflection mirror located at a position opposite to this output mirror for completely reflecting a laser beam and changing the curvature; a laser medium provided between the output mirror and the full reflection mirror for causing induced emission; an aperture means for deciding a beam mode of a laser beam generated between the output mirror and the full reflection mirror and changing the aperture diameter; and a converging means for converging an outgoing laser beam from the output mirror and changing a distance from the output mirror according to a machining path; and the laser apparatus changes a curvature of the full reflection mirror and also changes a diameter of the aperture means.

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: Disclosed is an apparatus for generating laser pulses, which has a Q-switched solid state laser and at least one nonlinear crystal, and the application of this apparatus for removing material in the biomedical field. The present invention is distinguished by the nonlinear crystal being disposed inside the resonator of the solid state laser and by a pulse prolongation unit determining the pulse form and duration of the light pulse developing in the resonator.

Abstract: A narrow band excimer laser capable of easily adjusting the rotation of the laser beam by an image rotator provided between a laser chamber and a grating and on the laser beam optical axis. The image rotator is supported with freedom of rotation on the laser beam optical axis and rotates the laser beam about the optical axis so that the plane containing the direction in which the width of the laser beam incident upon the beam expander is narrower is parallel with the plane containing the beam-expansion direction of the beam expander, and the beam expansion direction of the laser beam incident upon the grating is perpendicular to the direction of the grooves of the grating. With this arrangement, a laser beam of narrowed bandwidth can be obtained with high efficiency.

Abstract: The present invention relates to a highly repetitive laser employing a rotating wedge, and more specifically, a laser employing a rotating wedge which can provide a laser beam having a uniform spatial intensity profile with a high repetition rate. The highly repetitive laser of the invention is characterized by positioning a rotating wedge between a main resonator and a focusing lens to change the point in which a laser beam emitted from the main resonator is focused, in a laser which comprises a main resonator consisting of a laser medium, a passive Q-switching material and partially reflective mirrors and an auxiliary resonator consisting of a focusing lens and a cell.

Abstract: The present invention relates to laser leveling device suitable for construction. The present invention uses a standard low cost laser diode module as the laser source and optical system. A novel method is provided to align the non-collimated beam emitted from the standard low cost laser diode module so that it is perpendicular to the rotational axis of the laser level. The present invention describes a laser level which can be operated in four different modes: dot mode, line mode, oscillation mode and plane mode. Dot mode provides two level laser dots. Line mode provides a short bright level line. Oscillation mode provides a long bright reference line. Plane mode provides a level 360 degree reference plane. The invention also provides a structure which allows two vertical reference planes which are perpendicular to each other and perpendicular to the horizontal reference plane to be generated.

Abstract: The invention relates to a microlaser cavity, with active Q switching, characterized in that it comprises:an active laser medium (20), an input mirror (22) and an output mirror (24, 87) defining the cavity,a micromodulator with frustrated total internal reflection, comprising two microprisms (32, 34) made of a certain material of index n.sub.1 each having at least one planar face (36, 38), the two planar faces being approximately parallel to each other and inclined on the microlaser cavity axis, thereby defining a plate (30) of a certain material of index n.sub.2 less than n.sub.1.means (44, 46, 48, 50, 52, 54) for varying the thickness of the plate.

Abstract: A laser system is described in which two laser elements are configured as an oscillator and an amplifier in a common optical pumping section. Oscillator element is in a resonator and a divergent oscillator output beam is steered by a steering arrangement back to the amplifier element. The divergence of the beam from the resonator is adjusted, by moving output coupler element or selecting particular curvatures of resonator mirrors for example, to match the thermal lensing power of the amplifier element so that a substantially collimated output beam is produced.

Abstract: A rod lens or a cylindrical lens is disposed in front of a semiconductor laser to increase a divergence angle of a laser beam emitted from the semiconductor laser so as to form a substantially circular far field pattern. In another constitution, there is disposed in front of a semiconductor laser a composite lens having two cylindrical surfaces whose cylindrical axes are perpendicular to each other. The cylindrical surface on the side of the semiconductor laser is a convex surface and the other cylindrical surface is a convex or concave surface. In still another constitution, two semiconductor lasers emitting the same optical signal are arranged adjacent each other so that respective light emitting portions of two pn junction planes are located in the same plane and perpendicular to each other, and that laser beams form orthogonal spots at a single predetermined position.

Abstract: A frequency converting laser device is disclosed which includes a laser diode adapted to produced an output laser beam and an optical fiber coupled to the output of the laser diode and including a built-in grating in the optical fiber arranged so as to provide a beam having a specific wavelength and to reflect a small portion of such beam back into the laser diode while transmitting the beam so that the laser diode will produce a beam of that wavelength. The device further includes a frequency converting structure adapted to receive the transmitted beam of light and to change the frequency of the input beam to produce the output beam at the specific frequency.

Abstract: An in-line, spectrally-selective fiber Fabry-Perot transmission filter includes an optical fiber piece having a broad-band mirror and a narrow-band Bragg grating element formed therein, the mirror and the grating forming a Fabry-Perot resonant cavity therebetween. The filter may be used to form part of a fiber ring laser configuration. The combination of the broad-band mirror and the narrow-band Bragg grating element in an optical fiber piece can also be formed into a spectrally-selective fiber Michelson filter.