Abstract: To compensate for variations in a laser's peak power output due to changes in slope efficiency, a feedback loop is provided to monitor light output and effect compensatory changes in the drive current. In the feedback loop, the light output is detected by a photodiode. The output of the photodiode is filtered by a bandpass filter. The mean power of the filtered signal is determined and compared with a reference to control the laser drive. The reference takes account of the relationship between the filtered signal power and the peak power in the frequency spectrum of the pseudo-random input signal. The use of this reduced-bandwidth signal allows a relatively cheap, low bandwidth photodiode to be used with a long-wavelength laser.

Abstract: A laser apparatus comprises a case, a laser tube positioned within the case, and a temperature control means for controlling the temperature of the atmosphere within the case. The temperature is controlled within the range of 35.degree. to 70.degree. C. The temperature control means is an air cooling means for generating air streams flowing from an air inlet formed in one side wall of the case to air outlets formed in the opposite side wall.

Abstract: A temperature responsive, gas entrapping material contained in a chamber connected to a gas laser tube selectively entraps gas to regulate the pressure in the laser tube. A temperature regulator adjusts the temperature of the gas entrapping material and thereby controls the pressure of the gas in the laser tube. The temperature of the gas entrapping material can be adjusted by cooling or by heating. The pressure in the laser tube is monitored. The tube voltage can be used to monitor the pressure. Temperature adjustment of the gas entrapping material permits development of optimum gas pressure in the laser tube for different wave lengths. In one embodiment the laser is a krypton gas laser and the gas entrapping material is activated charcoal or alumino-silicate. The gas entrapping material may be heated, during assembly of the gas laser, to a temperature high enough to remove foreign material which might otherwise interfere with the operation of the laser tube.

Abstract: The apparatus includes a semiconductor laser diode, a mounting for the laser diode and a casing with a window through which light from the diode passes. The casing hermetically seals the diode. A magneto-optical member is provided between the end face of the laser diode and the window. The magneto-optical member has a spontaneous magnetization oriented in the direction of the light transmission and a magnetic field is applied to saturate the magneto-optical member.

Abstract: Apparatus is disclosed which stabilizes the temperature, and thereby the output wavelength, of an injection laser. Means (50 and 23) monitor the laser terminal voltage across a laser (11) and derive a voltage laser therefrom which is proportional to the junction voltage of the laser. Means (24) compares the voltage to a reference value from source (27) and a temperature controller (35) adjusts the laser temperature in response to the results of the comparison.Further embodiments of the present invention vary the output wavelength of the laser by varying the reference value from source (27) against which the laser junction voltage is compared.

Abstract: A low-divergence 1.06 micrometer wavelength beam from a total-internal-reflection, face-pumped laser (TIR-FPL) is focused onto the end of a quartz optical fiber to a spot having a size smaller than the fiber diameter and with a beam cone angle less than twice the numerical aperture of the fiber. The fiber transmits the energy to emerge at the other end where it is collimated and focused onto material to be processed. A laser average output power level greater than 400 watts can be transmitted through an optical fiber having a diameter less than 600 micrometers.

Abstract: Power supply apparatus for a gas laser discharge tube (10) having anode and cathode electrodes (11 and 12) comprises a first power supply (13) operable to satisfy the running power requirements of the discharge tube. A second power supply (16) is also provided and is operable to generate a voltage which, when connected in series with the output of the first power supply (13) causes the initiation of a discharge in the discharge tube (10). A spark gap (17) is operable to connect the outputs of the two power supplies in series with one another when the discharge is to be initiated.

Abstract: A system is provided for compensation of maladjustments caused by operational and/or environmental factors in laser resonant cavities of the folded type, which employs a support construction of a light weight construction double T-profile section. The present construction allows the construction of low cost, powerful lasers with substantially reduced mass and volume and of a sufficient temperature stability for industrial applications. A thermal carrier medium flowing through all supports and mountings for all optical components is brought from an ambient temperature to an increased temperature and serves as a control medium for the optical components.

Abstract: A method and apparatus for reducing gas pressure in a laser wherein a miniature cryogenic pump is constructed to comprise an integral part of a laser plasma tube. The pump includes a container which holds molecular sieve material, a conduit which permits communication between the container and the plasma tube, and a valve which controls the communication along the conduit. All connections between the container, conduit, valve and plasma tube are gas-tight so as to maintain the ion integrity of the plasma tube with respect to the atmosphere. In operation, a service engineer immerses the container in a refrigerant, such as liquid nitrogen, and opens the valve until the pressure in the plasma tube reaches the desired level. Thereafter the valve is closed and the container permitted to return to ambient temperature. Further in accordance with the present invention, means are provided for preventing over pressure in the container.

Abstract: In accordance with one embodiment of the present invention, a controlling laser beam at a first wavelength is introduced into an interferometer such that one half of it contains the aberrations of the laser beam to be controlled and the other half is and remains undistorted. The aforementioned two halves of the controlling laser beam are combined at the output of the interferometer and then, together with the laser beam to be controlled at a second wavelength is introduced collinearly into a gas cell or phase corrector. Upon combination or interference of the two halves of the controlling laser beam the phase-front aberrations are translated to intensity modulations across the cross section of the beam.

Abstract: Prior power supplies adapted to provide power to the lasers of multiple ring laser gyros were inefficient in that they were required to have power output capabilities far in excess of that required to sustain laser operations. Such inefficiency is greatly reduced by the present power supply comprising a DC power source (30) for producing a firing voltage at a first terminal (40) and a sustaining voltage at a second terminal (42), and interface means (50) associated with each laser (12, 13, 14) for coupling the laser to the first and second terminals. The firing voltage is capable of firing each laser, and the sustaining voltage is capable of sustaining current flow through each laser after firing. Each interface means comprises a resistor (52, 53, 54) connecting the laser to the first terminal and a diode (55, 56, 57) for connecting the laser to the second terminal such that the diode does not permit current flow between the first and second terminals.

Abstract: A predistortion circuit is disclosed for correcting distortions in an optical communication system caused by the characteristics of a light-emitting diode. The invention makes use of the existence of automatic gain control circuitry in the receiver portion of an optical communication system to assist in correction of distortions which occur at the transmitter end. In particular, the present invention provides passive pre-distortion circuitry in the transmitter which dynamically modifies the level with respect to which the video signal in the transmitter is clamped. The automatic gain control circuit in the receiver will detect the DC level of the received video. A shift in the DC reference level transmitted causes the receiver AGC to correct the receiver gain.

Abstract: A pulsed electrical discharge gas laser uses acoustic diodes to cause the gas to circulate between the active region of the laser and a gas heat exchanger. The diodes take the form of asymmetrical obstacles placed within the gas flow exhibit asymmetrical resistance to the passage of compression waves in the gas that are generated by the electrical discharge and, as a consequence, cause a net flow of gas in one direction through the obstacles, thus causing the gas to circulate from the active region of the laser through the gas heat exchanger and return. A series of columns having cup-shaped cross sections act as the acoustic diodes.

Abstract: A transistor is connected between one terminal of a semiconductor laser and a power supply, a control terminal of the transistor is connected to an output terminal of an amplifier, a voltage is applied to one input terminal of the amplifier, and a junction of the semiconductor laser and a resistor is connected to the other input terminal of the amplifier.

Abstract: The turn-on delay of a cold cathode gas tube, such as a gas laser, is significantly reduced by the inclusion of an electric field concentrator in a region of the tube between the tube anode and cathode. The concentrator can take the form of a projecting conductive member having a sharp corner, linear or curved knife edge, needle like points, or combinations of such geometries.

Abstract: Laser devices being capable of calling freely any desired mode out of a variety of irradiation modes stored beforehead and of reproducing the mode quickly. Specifically, such devices in which a variety of working condition parameters, such as laser output, irradiation time and pulse width, etc., are stored as one set beforehand in a memory within the laser device, and an operator can call a particular mode as the case demands so as to operate the device in a desired state instantly. And further, such devices in which the working condition parameters stored in the said memory can freely be eliminated and changed.

Abstract: Circuitry and apparatus for stabilizing the output of a laser diode when modulated with a wideband analog signal. The circuitry provides for continuous operation of the laser diode with a pin diode positioned for receiving a portion of the output from the laser diode via optics positioned between the laser diode and the pin diode. The optics includes a collimator, a linear polarizer and a polarization beam splitter. The circuitry includes a high gain amplifier which receives the analog signal with a compensating network connected between the amplifier output and the laser diode. The circuitry also has a feedback circuit portion including the pin diode connected to one input of the amplifier.

Abstract: An improved method and apparatus for producing high power, high efficiency pulsed TEA laser energy at N.sub.2 O wavelengths by suppressing discharge arc formation with H.sub.2 or CO that is added to the N.sub.2 O lasing medium. Energy loading levels up to in the range of 266 J/L atm are achieved with gas mixtures of N.sub.2 lasing mediums and H.sub.2 or CO additives comprising N.sub.2 O:He:N.sub.2 :H.sub.2 ::0.03:0.69:0.27:0.01 and N.sub.2 O:He:N.sub.2 :CO::0.03:0.66:0.26:0.05 mole fraction.

Abstract: In a pulsed gas laser having a flexible exit gas line, such as polymer tubing, a device is disposed just upstream of the flexible tubing to attenuate certain characteristics of the exit gas before it reaches the flexible line. The device comprises a walled chamber having an inlet and an outlet and constructed and arranged to attenuate the peak pressure waves at the pulse frequency. The device also provides attenuation of temperature and for this purpose is made of a good thermal conductor such as copper. The invention enhances the effectiveness of the flexible polymer tubing exit gas lines and permits a laser to be pulsed at higher pulse frequencies than are conventionally done.

Abstract: A transmitter employing a light-emitting diode as an output element, this element being included in series with a resistor in the output circuit of a difference amplifier the inverting input of which is coupled to the junction point of the diode and resistor, includes a network for compensating for the non-linear output power versus energizing current characteristic of the diode. This network comprises a field effect transistor (fet) biased to operate in the pre-pinch-off region and having its source-drain path connected to the diode. The source-drain path of the FET may shunt the diode and a further resistor in series therewith, or alternatively may be included in a feedback path to the inverting input of the amplifier.

Abstract: Methods and apparatuses for operating a gas laser which utilize the electrical discharge between the electrodes to increase gas circulation. In a first embodiment, electrical discharges cause a control current (pulse) which activates an electromechanical device disposed within a closed gas flow loop. The electromechanical device acts as a pump and effects gas exchange and heat dissipation with a minimum of elements. In other embodiments, electrical discharges cause pressure fluctuations which increase gas circulation without the use of mechanically moved parts. To this end, connecting lines that determine the direction of the flow are placed between the chambers in order to facilitate equalization of gas pressure. A flow circulation loop is thereby created in a quasi-passive manner when suitably constructed.

Abstract: A gas laser having a metal inlet gas feed line assembly shaped as a coil, to function as an electrical inductance and therefore high impedance to pulses of electric current applied to electrodes at opposite ends of a discharge tube of a laser, for example. This eliminates a discharge path for the laser through the inlet gas feed line. A ferrite core extends through the coil to increase the inductance of the coil and provide better electric isolation. By elimination of any discharge breakdown through the gas supply, efficiency is increased and a significantly longer operating lifetime of the laser is provided.

Abstract: A silent discharge type pulse laser device having a pair of opposing electrodes, at least one of which is an electrode covered by a dielectric, which is mounted opposite to a metallic electrode with a silent discharge space in between, a laser resonator consisting of a total reflection mirror and a partial reflection mirror mounted opposite to each other with the silent discharge section in between, a source of high frequency voltage for supplying to the pair of electrodes a high frequency voltage having a predetermined period for silent discharge, and a controller for controlling the high frequency voltage from the source with respect to a first interval and a second interval that form a period longer than the period for silent discharge.

Abstract: A push-pull pulsed gas laser which utilizes piston action to displace a laser gas from the laser cavity to a heat exchanger and return of the gas to the laser cavity between laser pulses to significantly reduce the volume of gas required for repetatively pulsed gas lasers and to reduce the average power required to recondition the laser gas.

Abstract: A resilient serpentine shaped tungsten wire is formed to match a short wire section to hold a ring laser gyroscope getter. The getter-holder assembly is positioned within a stepped oblong bore so that the getter is in firm contact with the bore surface at two points. This prevents resonances of the getter or holder that might otherwise destroy the getter while subjected to vibrations.

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: Current regulator circuits using electrical feedback to stabilize the bias currents of semiconductor laser diodes are disclosed. In these electrical feedback circuits laser diode current is sensed with negative-temperature-coefficient resistance to develop voltages which are compared to zero-temperature-coefficient voltages for generating error signals, and these error signals regulate the emission from the laser diode against changes with temperature.

Abstract: Start up apparatus for starting the laser beams in a laser angular rate sensor with improved reliability and in a reduced amount of time.

Abstract: A laser utilizing mercury halides as the lasing medium is disclosed. Electrodes selectively coated with a mercury gettering material are utilized to establish a glow discharge in the lasing medium. Proper ratio of mercury to bromine is maintained in the lasing medium to ensure long life operation.

Abstract: A laser cooling system has a coolant formulated to act as a heat exchanger and a transparent optical medium of matching refractive index between the flashlamp, silver reflectors and laser rod. The coolant has one or more fluorescent dyes and an inorganic pH buffering additive therein and the lamp is in a cerium doped envelope. A method is provided for measuring the operation time of a laser having a cooling system and a coolant having fluorescent dyes therein and actuating a solenoid valve after a predetermined operational life of the laser to release a dye additive into the coolant to maintain the efficiency of the laser.

Abstract: An arrangement for the current limitation during the current supply of electrically excited gas lasers includes a rotary current transformer, self-inductances provided in front of a rotary current bridge rectifier, and a capacitor, if desired. In each phase conductor an inductance is provided between the secondary side of the rotary current transformer preferably working at power frequency and the rotary current bridge rectifier.

Abstract: Signals for controlling the discharge current and laser gas pressure are provided in predetermined combination in accordance with a selected laser output level.

Abstract: In a gas laser in which a mixture of gases is excited under the influence of an electric field, a first constituent gas of the mixture is introduced into a laser tube to allow a discharge to occur in the introduced gas at predetermined partial pressure. A second constituent gas of the mixture is then introduced into the laser tube until the combined gases reach the normally operating pressure of the mixture to allow a discharge to occur in the later introduced gas.

Abstract: A flowing gas laser utilizes a multilayer gas flow technique wherein laser gas is caused to flow in three distinct layers: an anode gas flow layer flowing adjacent the anode electrode of the laser; a cathode gas flow layer flowing adjacent the cathode electrode of the laser; and a lasing gas flow layer flowing between the anode and cathode layers and through the lasing region of the laser. A higher electron density is produced in the anode and cathode layers than in the middle lasing layer for fostering a higher electric field in the lasing layer and increased electrical efficiency of the laser. The multilayer gas flow technique is also useful in chemical processing devices for generating ozone or the like.

Abstract: Thermally induced stress birefringence in laser resonators is eliminated by inserting a waveplate in the resonating cavity. The waveplate is chosen by matching its polarization transmission matrix to the polarization transmission matrices of the laser rod and a Porro prism used as an end reflector in the resonating cavity. This produces a total polarization transmission matrix in the resonating cavity which is independent of ray coordinates. Additional control of the polarization transmission matrix is provided using a Porro prism as a cavity reflector that has an antireflection coating on its roof to change the required phase advance angle of the waveplate.

Abstract: A single frequency stabilized laser which is useful in long base line interferometers, optical inspection devices and other applications requiring a single-frequency laser source is provided having a cold-cathode and a hard-sill glass laser tube. A resistance coating, for example, Aquadag, covers the exterior surface of a laser tube which is mounted on a metallic base member. A small power supply which energizes the resistance coating for serving as a heater is coupled to this coating by fine wires, embedded in silver epoxy, for heating the glass laser tube to stabilize the frequency of the tube and eliminate mode changes in the operation thereof. A temperature sensor is provided for monitoring the temperature of the tube and is coupled to a temperature controller which controls the power supply for controlling the current applied to the resistance coating on the tube via the fine wires.

Abstract: An improved bypass inhibitor attached to but not constituting part of the laser bore assembly of a ceramic gas laser tube having main and gas bypass bores comprises a ceramic disc, one side of which is both metal bonded to the tube and formed with metal surface channels to reduce bypass gas ignition without significantly inhibiting bypass gas passage therethrough.

Abstract: A circuit arrangement for controlling a multi-beam acousto-optical cell in which Bragg diffraction is used for the generation of a plurality of outgoing laser beams, in which the acousto-optical cell has at least one ultrasonic transducer from which the outgoing laser beams are coming out in a common plane, the circuit arrangement comprises VHF or UHF oscillators coupled through respective control stages to the ultrasonic transducers. The frequency of each oscillator defines the diffraction angle of an associated outgoing laser beam the intensity of which is dependent from the amplitude of the oscillator. The passage of the oscillator outputs towards the respective ultrasonic transducers is controlled by the control stages according to predetermined operational requirements.

Abstract: A transient suppression circuit is provided for starting up or turning off a light emitting diode, such as a diode laser. The circuit minimizes the possibility of turn-on or turn-off transients or overshoot, employing a time delayed voltage. A diode circuit is used which generates an output voltage equal to the higher of two voltages at its two inputs, one input being the time delayed voltage and the second being derived from photodetector which detects electromagnetic radiation emitted by the light emitting diode. The circuit also utilizes a three terminal voltage regulator which maintains a constant voltage between its sense terminal (output from the diode circuit) and its output terminal.

Abstract: Apparatus is provided which includes a laser oscillator for providing light along a first optical path, and a laser amplifier for amplifying light along a second optical path. Means for coupling light between the first and second optical paths is disposed at one end of the laser amplifier, and a nonlinear medium disposed at the other end thereof for intercepting light provided along the first and second optical paths. The laser oscillator provides a single-mode laser beam along the first optical path which is made incident upon the nonlinear medium from substantially opposite directions. A portion of the beam from the laser oscillator is coupled through the laser amplifier, which forms a probe beam that samples the laser amplifier system. This beam further impinges upon the nonlinear medium and interacts with the counter-propagating laser beams therein.

Abstract: In a high power laser the optical resonator elements, such as reflectors for the optical resonator and optical pump are supported in optical alignment from a structural beam of generally L-shaped cross section and made of high thermal conductivity material such as copper or aluminum via the intermediary of a plurality of longitudinally directed rods made of a low thermal expansion material such as quartz or Invar. The rods are supported at one end from the L-shaped beam via leaf springs and they are rigidly coupled to the L-shaped beam at their other ends. The remaining elements such as the optical pump, Q switch and polarizers are supported directly from the L-shaped structural beam.

Abstract: Iron is close to a major surface layer of a yttrium aluminate laser rod so that the layer portion may have a filtering effect. The absorption factor for the short wavelength light of this layer portion depends upon the concentration c (weight percent) of the contained iron and the thickness t (.mu.m) of the iron-containing layer. Consequently, the effect of the iron in the laser rod can be evaluated as a function of the product c.times.t (wt%..mu.m) of the concentration c and the thickness t. In the range of the product c.times.t of 1<c.t<2.times.10.sup.2, a laser output could be obtained which is higher than that of the conventional laser rod not containing iron jointly with a short wavelength light filter. The thickness of the iron-containing layer is 1/4 or less of the radius of the laser rod.

Abstract: A dithered ring laser gyro in which the effects of mode locking, or frequency locking, at low rotation rates are reduced by producing an oscillatory flow of the ionized gas in the gain section of the laser. The envelope in which the laser is sealed includes a pair of closed-end bellows. The bellows are extended and retracted in push-pull to pump the gas. There is thus created a dynamically varying pressure differential and oscillatory gas flow along the bore of the gain section of the laser which induces a corresponding oscillatory bias in the gyro output.

Abstract: This invention relates to a laser gyro coupling system which utilizes a pair of resilient rings located between a plate attached to the laser dither suspension mechanism and the lower surface of a ring laser to form a reservoir for a viscous fluid. The coupling system permits the dither suspension mechanism to drive the ring laser at its dither frequency without transmitting stresses to the ring laser due to thermal expansion.