An EDFA may include an input photodiode configured to generate a control signal based on an input signal. The EDFA may include a blind stage configured to generate an amplified signal based on the control signal and the input signal. The EDFA may include a non-blind stage configured to generate an output signal based on the amplified signal within the blind stage, the control signal, and a feedback signal. The EDFA may include a filter configured to generate a filtered signal based on the output signal. The EDFA may include an output photodiode configured to generate the feedback signal based on the filtered signal. The EDFA may include an alarm device. A signal within the non-blind stage may be generated based on the feedback signal and the control signal. The alarm device may be configured to generate an alarm signal when the signal exceeds a threshold value.

A solid-state laser system according to an aspect of the present disclosure includes a first non-linear crystal that generates first wavelength-converted light based on a first laser beam, a first adjustment unit configured to perform phase matching of the first wavelength-converted light in the first non-linear crystal, a second non-linear crystal that generates second wavelength-converted light based on a second laser beam and the first wavelength-converted light, a second adjustment unit configured to perform phase matching of the second wavelength-converted light in the second non-linear crystal, a light detection unit configured to detect light having a selected wavelength, and a processor configured to control the first adjustment unit based on intensity of at least one of the first wavelength-converted light and the first laser beam and to control the second adjustment unit based on intensity of at least one of the second wavelength-converted light and the first wavelength-converted light.

An electrodeless laser-driven light source includes a laser that generates a CW sustaining light. A pump laser generates pump light. A Q-switched laser crystal receives the pump light generated by the pump laser and generates pulsed laser light at an output in response to the generated pump light. A first optical element projects the pulsed laser light along a first axis to a breakdown region in a gas-filled bulb comprising an ionizing gas. A second optical element projects the CW sustaining light along a second axis to a CW plasma region in the gas-filled bulb comprising the ionizing gas. A detector detects plasma light generated by a CW plasma and generates a detection signal at an output. A controller generates control signals that control the pump light to the Q-switched laser crystal so as to extinguish the pulsed laser light within a time delay after the detection signal exceeds a threshold level.

A discharge excitation gas laser device may include a laser chamber in which a laser gas containing a halogen gas is encapsulated, a pair of discharge electrodes disposed to face each other inside the laser chamber, a fan disposed inside the laser chamber to make the laser gas flow between the pair of discharge electrodes, a motor for rotating the fan, a motor power supply for supplying power to the motor, a magnetic bearing configured to levitate the rotary shaft of the fan magnetically, a displacement sensor for detecting the position of the rotary shaft through a can, and a controller configured to measure the rotational speed of the fan on the basis of a detection signal from the displacement sensor and control the motor power supply in such a manner that the measured rotational speed becomes a target rotational speed.

An optic-microwave frequency discriminator includes: a fiber coupler receives and combines a first laser and a second laser, than the fiber coupler respectively generates and outputs a first light signal and a second light signal; a photodiode module respectively receives the first light signal and the second light signal, and converts the first light signal into a first microwave signal and converts the second light signal into a second microwave signal; a microwave phase shifter generates a shifted microwave signal by introducing a phase shift to the second microwave signal; a 90° microwave bridge combines the first microwave signal and the shifted microwave signal for generating a first bridge signal and a second bridge signal; a normalized balanced detection module generates an error signal; and a control module generates a controlling voltage signal according to the error signal for tuning a frequency of the second laser.

There is provided a photoacoustic measurement apparatus including a laser light source unit that has a flash lamp for emitting excitation light and a laser rod for emitting laser light in response to incidence of the excitation light, an excitation light source power supply unit that has a capacitor bank for supplying a voltage to the flash lamp, an IGBT for controlling an output of the voltage charged in the capacitor bank to the flash lamp, a discharge control circuit for generating a driving pulse for driving the IGBT, and a pulse width limiting circuit for limiting a pulse width of the driving pulse output from the discharge control circuit, the pulse width limiting circuit being formed of a passive element, and a photoacoustic wave detection unit that detects photoacoustic waves generated inside a subject by emission of light emitted from the laser light source unit to the subject.

A laser apparatus including an optical element made of a CaF.sub.2 crystal and configured to transmit an ultraviolet laser beam obliquely incident on one surface of the optical element, the electric field axis of the P-polarized component of the laser beam propagating through the optical element coinciding with one axis contained in <111> of the CaF.sub.2 crystal, with the P-polarized component defined with respect to the one surface. A method for manufacturing an optical element, the method including causing a seed CaF.sub.2 crystal to undergo crystal growth along one axis contained in <111> to form an ingot, setting a cutting axis to be an axis inclining by an angle within 14.18±5° with respect to the crystal growth direction toward the direction of another axis contained in <111>, which differs from the crystal growth direction, and cutting the ingot along a plane perpendicular to the cutting axis.

A coherently beam combining (CBC) fiber laser amplifier system including beam shaper array assembly and a beam source that provides a plurality of beams having a low fill factor profile. The assembly includes an input beam shaper array having a plurality of input cells positioned adjacent to each other that are shaped to cause the beam to expand as it propagates away from the input array to be converted from the low fill factor profile to a high fill factor profile and cause the profile to taper to a lower value at a perimeter of each input array cell. The assembly further includes an output beam shaper array having a plurality of output cells positioned adjacent to each other that are shaped to cause the beam to stop expanding so that the output array provides a plurality of adjacent beams with minimal overlap and a minimal gap between the beams.

Generator for wholly optical tunable broadband linearly chirped signal comprising a mode-locked laser, a first optical coupler, a first optical filter, a first dispersion module, a second optical filter, a second dispersion module, a tunable time delay module, a second optical coupler, an optical amplifier, and a photodetector. The generator of the present invention employs just one mode-locked laser as a light source, thus preventing instability of the generated signal resulting from independent unrelated lasers. By making use of the principle of wavelength-time mapping and by means of adjusting the center wavelength and the filter bandwidth of the first optical filter and the second optical filter, easy and flexible tuning of the center frequency and sweep bandwidth of the generated linearly chirped signal is realized. The present invention possesses a big advantage on the aspect of generating a broadband linearly chirped signal over other solutions.

Disclosed is a method of performing a measurement in an inspection apparatus, and an associated inspection apparatus and HHG source. The method comprises configuring one or more controllable characteristics of at least one driving laser pulse of a high harmonic generation radiation source to control the output emission spectrum of illumination radiation provided by the high harmonic generation radiation source; and illuminating a target structure with said illuminating radiation. The method may comprise configuring the driving laser pulse so that the output emission spectrum comprises a plurality of discrete harmonic peaks. Alternatively the method may comprise using a plurality of driving laser pulses of different wavelengths such that the output emission spectrum is substantially monochromatic.