98 results about "Thermal lensing" patented technology

A method for operating an extracavity frequency-converted solid-state laser for performing a laser processing operation is disclosed. The laser has a laser-resonator including an optically-pumped gain-medium. The resonator is configured to compensate for a predetermined range of thermal lensing in the gain-medium. An optically-nonlinear crystal located outside the resonator converts fundamental laser radiation delivered by the resonator into frequency converted radiation. The laser processing operation is performed by a train of pulses of the frequency-converted radiation having sufficient power to perform the processing operation. The power of frequency-converted radiation is dependent on delivery parameters of the laser radiation from the laser-resonator. The laser is operated in a manner which provides that the resonator delivers effectively the same average power of fundamental laser radiation before and during the laser processing operation. This provides that thermal-lensing in the gain-medium is within the predetermined range before and during a laser processing operation. Delivery parameters of the laser radiation before and during the processing operation are varied such that power of frequency-converted radiation generated before the processing operating is insufficient to perform a laser processing operation.

An optical signal optical path switching method comprising steps of using a thermal lens based on a distribution of refractive index produced reversibly caused by temperature increase generated in an area of the light-absorbing layer film of thermal lens forming devices 1, 2 and 3, that has absorbed control light beams 121, 122 and 123, and in the periphery thereof, causing the converged signal light beam to exit from the thermal lens forming device with an ordinary divergence angle when the control light beams 121, 122 and 123 have not been irradiated and no thermal lens has been formed, and causing the converged signal light beam to exit from the thermal lens forming device with a divergence angle larger than the ordinary divergence angle when the control light beams have been irradiated and a thermal lens has been formed, and causing the signal light beam to travel straight through holes 61, 62 and 63 of mirrors provided with the holes for the signal light beam to pass through when the control light beams have not been irradiated and no thermal lens has been formed, and changing the optical path by reflecting the signal light beam using the hole-provided mirror when the control light beams have been irradiated and a thermal lens has been formed.

A method of operating a continuously pumped, Q-switched laser to provide trains of pulses for laser operations is disclosed. The laser includes a solid-state gain-medium that exhibits a thermal-lensing effect on being optically pumped. Pulse delivery is controlled by a Q-switch that is in a normally-open state when the laser is not delivering pulses. This allows the laser to deliver CW laser radiation when pulses are not being delivered. A train of pulses is delivered by repeatedly interrupting the CW operation by closing then reopening the Q-switch. When the Q-switch reopens after the interruption, the laser delivers a pulse of laser radiation, then resumes delivery of CW operation until the next interruption. The interruption periods may be varied to provide pulses of different peak power in a pulse train.

The disclosed thermal-lensing compensation method for laser rod comprises: setting the holophote with a step-motor driving movable mechanism in optical resonator of laser as raised convex mirror toward the laser rod; controlling the step motor by a computer to make the distance from mirror to rod as a = f - R/2 - d/2n. Wherein, R for curvature radius of the mirror, d for rod length, n for refractive index of rod, and f for lens focus. This invention simplifies system structure, affects no energy conversion efficiency, and applies computer to control laser frequency N and pumping energy density Ep for complete automatic compensation.

A method of altering a refractive property of a crosslinked acrylic polymer material by irradiating the material with a high energy pulsed laser beam to change its refractive index. The method is used to alter the refractive property, and hence the optical power, of an implantable intraocular lens after implantation in the patient's eye. In some examples, the wavelength of the laser beam is in the far red and near IR range and the light is absorbed by the crosslinked acrylic polymer via two-photon absorption at high laser pulse energy. The method also includes designing laser beam scan patterns that compensate for effects of multiphone absorption such as a shift in the depth of the laser pulse absorption location, and compensate for effects caused by high laser pulse energy such as thermal lensing. The method can be used to form a Fresnel lens in the optical zone.

A method for measuring focal distance of a thermal lens located in an analyte, the method including: providing an exciting optical beam passing through the analyte and creating the thermal lens therein; emitting a coherent probe optical beam passing through the analyte and being propagated substantially perpendicular to the exciting optical beam; intercepting the probe optical beam by a detector after passing through the analyte; focusing the probe optical beam upstream or downstream of the thermal lens such that only a fraction of the probe optical beam passes through the thermal lens; acquiring an interference image by the detector; and processing the interference image to calculate the focal distance of the thermal lens. Such a method may find application in physico-chemical analysis of the analyte.

The invention discloses a method for rapid imaging of absorption defect distribution on the surface of a large-diameter optical element. The method comprises the following steps: carrying out collimation and beam expanding of high-energy pulse laser to form a large-size excitation light spot for radiation heating on an optical element, enabling absorption defects on the surface and the subsurfaceof the optical element to be at transient temperature distribution and refractive index distribution; after certain time delay, carrying out collimation and beam expanding of another beam of high-energy pulse laser to form a large-size detection light spot which penetrates through an identical area radiated by the optical element, and recording diffraction light field distribution of the light spot by using a CCD; controlling time delay between excitation and detection laser pulses and analyzing characteristics of diffraction light field images recorded by using the CCD, thereby confirming whether the radiated area of the optical element has absorption defects or not and corresponding characteristics. By adopting the method, advantages that a conventional optical-thermal lens technique ishigh in detection sensitivity, high in resolution ratio, and the like are retained, a single-time detection area can be greatly increased, and rapid detection on absorption defect distribution of large-diameter optical elements is achieved.

The invention relates to a method of distribution of absorption of laser crystal radial-direction non-uniform doping control pump light. The method is characterized in that after the pump light output by an optical fiber coupling laser diode optical fiber output end is gathered by a coupling system, the light field of the pump light is distributed in a Gaussian mode or flat Gaussian mode; a pump light anti-reflection film and an oscillating high-reflection film are plated on the pump end face of a radial-direction non-uniform doping crystal, an output mirror is a plane mirror, and the output mirror and the oscillating light high-reflection film on the pump end face of the crystal form a flat resonant cavity; in the working process, a thermal lens formed in the crystal can be simply equivalent to a thin lens on the pump end face of the radial-direction non-uniform doping crystal, and the resonant cavity becomes a stable cavity through the gather effect of the thermal lens; under the condition that a pump light distribution area and an oscillating light distribution area are determined, the spatial overlapping of the pump light distribution area and the oscillating light distribution area are achieved through the radial-direction non-uniform doping optimization design of the laser crystal. According to the method, ideal space coupling efficiency and ideal beam quality can be achieved.

The invention discloses a novel Raman cell capable of reducing the thermal lens effect of high repetition frequency pump light during a gaseous medium propagation process. In the design, the outermostRaman cell wall is made of stainless steel, and a three-dimensional filler is disposed in the Raman cell. Gaps between the outer wall of the Raman cell and the built-in filler can be filled with a high-pressure gas, and have inconsistent widths. A fan unit is placed in one of narrow gaps. One of the remaining narrow gaps is selected as a light passage of the pump light. When high repetition frequency pump light is configured to pump a gaseous medium, the heat in the vicinity of the pump light gradually accumulates and generates a thermal lens effect to affect the beam quality of the output light. After an electric fan operates, the high-pressure gaseous medium in the gaps flows in a fixed direction, takes away the heat in the vicinity of the pump light, reduces the thermal lens effect inthe Raman cell so as to improve the conversion efficiency of Raman light. The novel Raman cell improves the Raman light conversion efficiency and beam quality by reducing the thermal effect, and has bright application prospects.

CdSiP₂ crystals with sizes and optical quality suitable for use as nonlinear optical devices are disclosed, as well as NLO devices based thereupon. A method of growing the crystals by directional solidification from a stoichiometric melt is also disclosed. The disclosed NLO crystals have a higher nonlinear coefficient than prior art crystals that can be pumped by solid state lasers, and are particularly useful for frequency shifting 1.06 μm, 1.55 μm, and 2 μm lasers to wavelengths between 2 μm and 10 μm. Due to the high thermal conductivity and low losses of the claimed CdSiP₂ crystals, average output power can exceed 10 W without severe thermal lensing. A 6.45 μm laser source for use as a medical laser scalpel is also disclosed, in which a CdSiP₂ crystal is configured for non-critical phase matching, pumped by a 1064 nm Nd:YAG laser, and temperature-tuned to produce output at 6.45 μm.

Systems and methods are provided for achieving high power and high intensity laser amplification. In a four-pass optical amplifying system, a linear polarized optical beam is directed by various optical elements four times through an optical amplifier. The optical amplifier is transversely pumped by a pumping energy source that includes laser diode arrays. The pumping module and the other optical components are provided to counteract thermal lensing effects, induced thermal birefringence effects and to achieve enhanced amplification and efficiencies.

High-power, diode-pumped solid state (DPSS) pulsed lasers are preferred for applications such as micromachining, via drilling of integrated circuits, and ultraviolet (UV) conversion. Nd:YVO₄ (vanadate) lasers are good candidates for high power applications because they feature a high energy absorption coefficient over a wide bandwidth of pumping wavelengths. However, vanadate has poor thermo-mechanical properties, in that the material is stiff and fractures easily when thermally stressed. By optimizing laser parameters and selecting pumping wavelengths and doping a concentration of the gain medium to control the absorption coefficient less than 2 cm⁻¹ such as the pumping wavelength between about 910 nm and about 920 nm, a doped vanadate laser may be enhanced to produce as much as 100 W of output power without fracturing the crystal material, while delivering a 40% reduction in thermal lensing.

The invention discloses a plasma suppression method for high-power laser welding. In existing laser welding, a high-temperature plasma cluster reversely jetted from the welding position of a plate exists in the light path transmission direction, the cluster can cause a thermal lens effect to affect the focusing position of a laser beam and the energy density of the laser beam, a laser protection lens is stained, and the welding quality and the service life are affected. The component of the laser welding plasma suppression method comprises a controller (4), the upper end of the controller is connected with a laser generator (5), an air injection device A (1), an air injection device B (2) and an air suction device (3), the air injection device A injects air in the laser beam conduction direction and is coaxial or paraxial with the laser beam, protective gas is continuously provided in the welding process, the air injection device B is arranged in the lateral direction of the plasma cluster, gas is injected in the lateral direction, and the air suction device is distributed on the opposite side of the air injection device B and is mainly used for absorbing the plasma cluster. The method is used for the plasma suppression method for high-power laser welding.

The invention discloses a laser amplifier. The laser amplifier comprises a pump light path and a laser amplification light path; and the pump light path and the laser amplification light path also comprise a laser gain medium together. A folding light path in the laser amplifier enables the overall structural size of the amplifier to be reduced, and installation and use are convenient. The pump light passes through the laser gain medium twice, so that the utilization rate of the pump light is improved. In addition, a thermal lens imaging system is introduced into the laser amplifier, so that the wavefront distortion influence introduced by the device is reduced, and the beam quality of output laser is improved.

The invention discloses a laser crystal thermal lens focal length online real-time measurement device and method for an LD end-pumped solid laser. The device comprises a He-Ne laser (1), a 5-10-time first beam expanding system (2), a variable aperture diaphragm (3), a 45-degree 632.8 nm high-reflectivity mirror (4), a beam splitting cube (5), a 45-degree dichroic mirror (6), an attenuation slice group (7), a 2-5-time second beam expanding system (8), a camera (9) and a guide rail (10). The He-Ne light and the laser pump light are adjusted to be strictly transmitted on the same optical axis byutilizing the high-reflectivity mirror (4) and the beam splitting cube (5); and the He-Ne imaging light spot on the camera (9) is as large as possible through the second beam expanding system (8), butcannot exceed the imaging surface element of the camera (9). The device is accurate in measurement result and can quickly achieve the measurement of the thermal focal length of the laser crystal under different pumping powers and provides a powerful guarantee for the compensation design of the laser.

The invention discloses a method for reducing the thermal lens effect of a laser crystal, and the method is characterized in that the method comprises the following steps: carrying out the pumping ofthe laser crystal; when the number of the pump light source is one, setting one surface of the laser crystal as a concave curved surface; when the number of the pump light sources is two, setting thetwo surfaces of the laser crystal to be concave curved surfaces. The method can counteract the thermal lens effect by changing the structural shape of the laser crystal.