Abstract: A laser oscillator control circuit controls a command voltage to control the output power of a laser. The laser oscillator control circuit has pulse generating means (8) that employs a timer for generating a pulse train in response to a signal from time setting means (5, 6) which sets an on-time and an off-time. The laser oscillator cotnrol circuit also has bias command voltage setting means (9) for setting data defining a bias command voltage at which an electric discharge can be started, and output voltage setting means (10) for setting data defining an output power voltage which is the sum of the output power and the bias command voltage. A selector (11) selects and outputs the output power voltage when the pulse train is on and selects and outputs the bias command voltage when the pulse train is off. The output from the selector is converted by a D/A converter (12) into an analog voltage to control a high-frequency power supply (21).

Abstract: A controlling apparatus for a laser diode which is used in a laser printer or the like to transmit laser beam light rays. According to the output characteristics of the laser diode, a bias is applied in the current region (from 0 to Ixm) of approximately 0 in radiation output. The control object period (from Ix to Ixm) is divided into many stages to perform the radiation output control so as to effect the high-precision output control without the provision of a more complicated circuit. The central processing unit outputs the control signal into the duty controlling means, so that the output of the laser diode may be automatically held constant in accordance with the predetermined process or the operation arranged in advance.

Abstract: A highly repetitively pulsed laser stabilizing device which comprises a laser resonator, a feedback system for optically delaying an optical pulse emitted from the laser resonator and returning it in such a manner that it is superposed on an optical pulse in the laser resonator, and a feedback system control section that monitors one of the optical pulses of the laser resonator and feedback system, and controls the optical path length of the feedback system so that the monitored optical pulse is optimum in intensity.

Abstract: A highly repetitively pulsed laser device is provided including a feedback system simple in construction which returns a light pulse emitted from a laser resonator to the laser resonator so that the light pulse is superposed on a light pulse in the laser resonator.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from an injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiment, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHz. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a difference frequency in the microwave range, say, above 5,000 MHz. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: A method of and a device for pulse-mode driving a semiconductor laser in which the semiconductor laser (60) is operated by first driving the laser into the LED region with a pedestal current pulse from a first current source (41) and by superposing thereon an information current pulse from a second current source (51) after current stabilization. Due to this two-stage drive, switching transients can be reduced so that shorter pulses are possible and unnecessary power dissipation between the information pulses is avoided, which extends to the lifetime of the semi-conductor laser.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from a injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiment, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHz. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a different frequency in the micorwave range, say, above 5,000 MHz. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: A femtosecond dye laser comprises a dye amplifier assembly (30) pumped by a mode-locked neodymium YAG laser (35) operating with frequency doubling. The main dye laser cavity as defined on one side of the amplifier assembly (30) by a linear prism structure (11 and 14) leading to an outlet mirror (15), and on the other side of the amplifier assembly by an assembly (20) constituting an anti-resonant mirror disposed about a saturable absorption device (40). An error signal is tapped by leakage from one of the mirrors (22) and is spectrally analyzed and compared with a reference wavelength (at 50) enabling a high tension amplifier (60) to be controlled to act on a piezo-electric stack (19) in order to fix the position of the outlet mirror (15) so as to adjust the optical length of the cavity as a function of the spectral characteristics of the pulses it produces.

Abstract: A system for generating a stable optical frequency from a laser signal having inherent frequency fluctuations. The signal from an injection-controlled pulsed laser is divided into two parts. One part is mixed with the signal from a stable CW laser to generate beat frequencies. These signals are amplified and recombined with the pulsed laser signal in an output modulator. In one embodiement, the difference frequency between the pulsed laser and the reference signal is less than 1000 MHZ. The beat frequencies are increased by an X-band mixer to the microwave range where they can be readily amplified in an available broad band amplifier. In another embodiment, the transmitter laser and the reference laser operate at a difference frequency in the microwave range, say, above 5,000 MHZ. The beat frequencies are obtained by a high frequency mixer such as a bulk crystal in a waveguide or cavity. In still another embodiment, two independent transmitter lasers generate pulses that occur with a significant time delay.

Abstract: A semiconductor laser driving device using FET's as a positive element in a bias current supply circuit and a pulse current supply circuit, and having compensating circuits for compensating differences in the characteristics of the FET's and a laser diode used in the driving device. Also a pulse amplifier suitable for use as the pulse current supply circuit in the semiconductor driving device, which circuit cuts off a pulse top side portion and a pulse base side portion of an input pulse with respect to a mesial point of the input pulse to obtain an output pulse having a desired pulse amplitude in response to a control signal, without varying a pulse width.

Abstract: A bistable laser for realizing a waveshaping function, having a drive current which during normalcy biases the bistable laser to the middle point of the hysteresis region thereof. When input light exceeds a threshold level, the bistable laser is switched into the lasing state, and even when the input light thereafter disappears, the laser emits light of fixed intensity. A detector having detected this lasing state decreases the drive current temporarily after a predetermined period of time, to switch the bistable laser into the non-lasing state, whereby not only the amplification but also the shaping of an optical pulse signal is achieved.

Abstract: A drive and control circuit for laser diodes includes: a first switching element connected in series to a laser diode connected to a constant-current source for actuating the laser diode when a binary drive signal is at one level thereof; an impedance element connected in parallel to the series circuit of the laser diode and the first switching element, the impedance element being connected to receive the constant-current source together with the laser diode and having impedance characteristics substantially equal to those of the laser diode and the constant-current source; an integrator circuit for integrating the data at the one level; an impedance control circuit for variably controlling the impedance of the impedance element in response to the integrator circuit; and a second switching element connected in series to the impedance element for actuating the impedance element when the drive signal is at the other level.

Abstract: The present invention is for a pulsed laser system in which the total irradiation energy of the laser is controlled by the number of the laser pulses. The invention includes a device for controlling the output of the laser so that the laser oscillation is stopped when the sum of the laser outputs, in response to each pulses, has reached a predetermined level. This device comprises a laser oscillator for outputting a laser beam in response to a repetitive pulse discharge, a photoelectric conversion element, a sample hold circuit and an integrator for sampling and integrating the outputs from the photoelectric conversion elements, and a comparator for comparing the output of the integrator and the output from a reference voltage generator.

Abstract: A CPM pulse laser device is provided which has a means for emitting pulses in two separate directions. A return system is provided for returning one of the pulses to the laser resonator in such a manner that the returned pulse is superposed on the other pulse which was propagated in the other direction. The return system preferably includes a total reflecting mirror or a nonlinear crystal. The position of the total reflecting mirror or nonlinear crystal is precisely adjusted to create the superposition.

Abstract: A short pulse laser is described which has saturable absorption, saturable gain, group velocity dispersion, and self phase modulation means within a single optical cavity.

Abstract: A current supply is disclosed for frequency-proportional optical sensors, preferably fiber-optical sensors, having a constant amplitude modulated over time. The delay time of the modulation is kept constant as well in the current supply in order to increase the accuracy of measurement. A variable resistor that is connected in series with the LED or the semiconductor laser is used for this purpose. This resistor may for example be a photoresistor illuminated by a light source and the resistance value of this resistor is varied by an open-loop or closed-loop control circuit. The variable resistor may also be a resistor that is heated by its own current.

Abstract: A laser treatment apparatus for determining that the output power of a treatment laser beam is proper in accordance with the selected output power. The treatment apparatus comprises a laser source for generating a treatment laser pulse beam, a laser optical path for guiding the treatment laser pulse beam toward an object to be treated, a power setting means for controlling the laser source to set the power output of the treatment laser pulse beam, and a radiation switch for selectively switching the laser source on and off. A safety device is provided to cause the laser source to output a checking laser pulse beam prior to actual transmission of the treatment laser pulse beam and at a time after the activation of the radiation switch. The checking laser pulse beam has a power corresponding to the actual power of the treatment laser pulse beam to be outputted by the laser source.

Abstract: In a pulsed laser which is periodically energized so that it emits a pulse of radiation following each periodic energization, a feedback loop control system is provided for controlling energization of the laser so that the laser output radiation pulses are substantially constant over a relatively long period of operation, the feedback loop including a detector for detecting the laser pulses and producing an electrical signal representative of each pulse and a comparing circuit responsive to those electrical signals and a reference signal that represents the constant laser output level desired, for comparing the electric signals and the reference signals producing a control signal for controlling the energy of the periodic energization.

Abstract: A pulsed laser system capable of operating in a plurality of modes for delivering a burst of laser pulses to a target wherein the pulse width of the laser pulses are automatically controlled in response to the mode selected. A special calibration procedure allows the system to determine the pulse width and pulse repetition rate when the laser is producing a predetermined power output level as measured by a power meter at the target site. Using calibrated pulse width and pulse repetition rate, the pulse width and pulse repetition rate of the laser pulses to be delivered to the target for any particular treatment burst can be determined. Means are provided for determining the energy delivered to the target for any particular treatment burst. A potentiometer coupled to a laser spot size control lense assembly provides a signal proportional to the spot size. From this signal and the energy delivered, the energy density can be calculated.

Abstract: A pulsed laser system capable of operating in a plurality of modes for delivering a burst of laser pulses to a target wherein the pulse width of the laser pulses are automatically controlled in response to the mode selected. A special calibration procedure allows the system to determine the pulse width and pulse repetition rate when the laser is producing a predetermined power output level as measured by a power meter at the target site. Using calibrated pulse width and pulse repetition rate, the pulse width and pulse repetition rate of the laser pulses to be delivered to the target for any particular treatment burst can be determined. Means are provided for determining the energy delivered to the target for any particular treatment burst. A potentiometer coupled to a laser spot size control lens assembly provides a signal proportional to the spot size. From this signal and the energy delivered, the energy density can be calculated.

Abstract: A laser apparatus using a DC-DC converter type pulse power source generates a pulse laser output of a high peak value by utilizing the negative resistance characteristic of a laser discharge tube. The peak value, pulse width, period of the pulse output are adjustable. The apparatus is capable of producing a continuously oscillating laser light; capable of operating always with approximately maximum efficiency for any value of the laser output. The power source device for the laser apparatus permits adjustment of the pulse width and period of the pulse laser output without any adverse effect on the efficiency of the laser apparatus.

Abstract: Reducing the widths of pulses in a beam from a laser by passing the beam through means to rotate the plane of polarization of the beam when a voltage is applied and reflecting the beam back through the means to rotate to a polarizer, the voltage being applied for a length of time equal to the desired pulse width, the portions of the pulses that have passed through the means to rotate when the voltage was applied being deflected by the polarizer into an output beam, the portions of the pulses that have passed through the means to rotate when the voltage was not applied being passed directly through the polarizer without being deflected into the output beam.

Abstract: The width of the output pulse of a Q-switched cavity dump laser is substantially reduced by rapidly discharging a high voltage across the cavity dump crystal with an electro-optical switch which is closed by regenerative feedback from the optical output of the laser. The switch comprises a semiconductor body in intimate contact with the cavity dump crystal and has electrodes spaced by a small gap which control discharge of the high voltage across the crystal. A small fraction of the laser output is fed back to the switch and regeneratively creates a d-c current in the semiconductor body across the gap to accelerate closure of the switch and discharge of the voltage across the crystal to produce an extremely narrow output pulse.

Abstract: A digital signal having three logic levels is repeatedly applied to opposite facing electrodes of a waveguide type gas laser apparatus in order to excite laser gas positioned between said electrodes. The three logic level pulse form includes pulses having alternate positive, zero, negative, and zero voltage levels in order to permit D class amplification.

Abstract: A laser apparatus employing a solid state lasing element pumped by a controlled pump providing pump power of adjustable amplitude, constant over the controllable duration of pumping. The laser apparatus thus embodied providing the means for producing and amplifying laser pulses of coherent radiation having generally rectangular pulse shape.

Abstract: An electro-optically Q-switched cavity-dumped laser is improved by the addition of an injection control laser, so that time jitter is reduced, frequency stability is improved, higher peak circulating power in the Q-switch pulse is achieved, an intracavity grating is no longer required.

Abstract: An emitter of unbalanced pulse-modulated energy, specifically a laser, has a feedback circuit including a first branch detecting the mean amplitude of the emitted energy and a second branch detecting the peak amplitude of its pulses. The second branch includes a band-pass filter, centered on the pulse cadence, followed by a peak detector which may comprise a coherent demodulator driven by a square wave whose frequency corresponds to that cadence. The peak detector generates a control signal for a pulse former whose output signals are superimposed upon a biasing signal from the first branch before being fed to the modulating input of the energy emitter.