A thermo-electric cooling (TEC) system is presented for cooling of a device, such a laser for example. The TECT system comprises first and second heat pumping assemblies, and a control unit associated at least with said second heat pumping assembly. Each heat pumping assembly has a heat source from which heat is pumped and a heat drain through which pumped heat is dissipated. The at least first and second heat pumping assemblies are arranged in a cascade relationship having at least one thermal interface between the heat source of the second heat pumping assembly and the heat drain of the first heat pumping assembly, the heat source of the first heat pumping assembly being thermally coupled to the electronic device which is to be cooled by evacuating heat therefrom. The control unit is configured and operable to carry out at least one of the following: (i) operating said second heat pumping assembly to provide a desired temperature condition such that temperature of the heat drain of said first heat pumping assembly is either desirably low or by a certain value lower than temperature of the heat source of said first heat pumping assembly; and (ii) operating said second heat pumping assembly to maintain predetermined temperature of said thermal interface.

The present invention has as its object to provide a laser welded joint excellent in joint strength preventing a bead from cracking and comprised of exactly the number of weld beads required for joint strength and a laser welding method for the same in overlay laser welding of steel sheets forming multiple ring-shaped weld beads. The present invention is a laser welded joint excellent in joint strength preventing a bead from cracking and comprised of exactly the number of weld beads required for joint strength in overlay laser welding of steel sheets forming multiple ring-shaped weld beads, produced by a step of overlaying a plurality of metal sheets and forming a first weld bead and a step of firing a laser beam to successively form a further two or more weld beads at the outside of the first weld bead by laser irradiation, the surface hardness of the weld bead increasing from the inside bead to the outside bead.

The present invention has as its object to provide a laser welded joint excellent in joint strength preventing a bead from cracking and comprised of exactly the number of weld beads required for joint strength and a laser welding method for the same in overlay laser welding of steel sheets forming multiple ring-shaped weld beads. The present invention is a laser welded joint excellent in joint strength preventing a bead from cracking and comprised of exactly the number of weld beads required for joint strength in overlay laser welding of steel sheets forming multiple ring-shaped weld beads, produced by a step of overlaying a plurality of metal sheets and forming a first weld bead and a step of firing a laser beam to successively form a further two or more weld beads at the outside of the first weld bead by laser irradiation, the surface hardness of the weld bead increasing from the inside bead to the outside bead.

A power control method for a laser system comprising laser diodes arranged in diode banks is provided. Each diode bank comprises at least one of the laser diodes and has a maximum power. The method comprises operating a first diode bank of the diode banks to output a first power; and concurrently operating other of the diode banks to output other powers, at least one of the other powers being different than the first power.

A MOPA laser system that includes a seed laser configured to output pulsed laser light, an amplifier configured to receive and amplify the pulsed laser light emitted by the seed laser; and a pump laser configured to deliver a pump laser beam to both the seed laser and the amplifier.

An object information acquiring apparatus is used which includes a laser medium that oscillates laser light, an excitation source that excites the laser medium, a voltage accumulator that applies a voltage to the excitation source, a voltage supplier that supplies a voltage to the voltage accumulator, a voltage controller that limits a maximum supplied voltage from the voltage supplier, a receiver that receives a photoacoustic wave generated by an object irradiated with the laser light, and a constructor that acquires characteristic information relating to the object in use of the photoacoustic wave, wherein the voltage controller compares a measured voltage value obtained by implementing division of a supplied voltage from the voltage supplier with a reference voltage value defining the maximum supplied voltage.

The embodiments of the present invention disclose a method and an apparatus for determining a gain of a Raman optical amplifier and a Raman optical amplifier. The method includes: acquiring present gain parameter information of a Raman optical amplifier; and determining a present gain of a monitoring channel of the Raman optical amplifier according to the present gain parameter information and a correspondence between a gain of the monitoring channel of the Raman optical amplifier and gain parameter information. According to the method and apparatus for determining a gain of a Raman optical amplifier and the Raman optical amplifier that are in embodiments of the present invention, a present gain of a monitoring channel can be accurately determined; therefore, a gain spectrum of the Raman optical amplifier can be accurately monitored, and the gain of the Raman optical amplifier can be accurately adjusted to a target gain.

A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.

A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.

A system includes a master oscillator configured to generate a first optical beam and a beam controller configured to modify the first optical beam. The system also includes a PWG amplifier configured to receive the modified first optical beam and generate a second optical beam having a higher power than the first optical beam. The second optical beam has a power of at least about ten kilowatts. The PWG amplifier includes a single laser gain medium configured to generate the second optical beam. The system further includes a feedback loop configured to control the master oscillator, PWG amplifier, and beam controller. The feedback loop includes a laser controller. The laser controller may be configured to process wavefront information or power in bucket information associated with the second optical beam to control an adaptive optic or perform a back-propagation algorithm to provide wavefront correction at an output of the PWG amplifier.