50 results about "Laser pulse duration" patented technology

A combination of specific laser pulse durations and repetition rates are incorporated into a semiconductor wafer laser scribing/dicing process. The disclosed combination can reduce factors that contribute to thermal effects, explosive melting and evaporation, and laser/plasma interactions, thereby reducing problems with microcracks, delamination, and particles that can affect semiconductor die yields and reliability.

A hair removal device (22) includes a cooling surface (34) which is used to contact the skin (6) prior to exposure to hair tissue-damaging laser light (74) passing from a radiation source (36) through a recessed window (46). The window is laterally offset from the cooling surface and is spaced apart from the cooling surface in a direction away from the patient's skin to create a gap between the window and the skin. The window preferably includes both an inner window (46) and an outer, user-replaceable window (48). The laser-pulse duration is preferably selected according to the general diameter of the hair.

There is described a method for producing a hole using e.g. a lasers, wherein short laser pulse durations are used. The laser pulse durations are varied, short laser pulse durations being utilized only in the area to be removed in which an influence on the penetration behavior and discharge behavior is noticeable while longer pulse durations of >0.4 ms are used. This is the case for the inner surface of a diffuser of a hole, for example, which can be produced very accurately by means of short laser pulse durations.

Holographic methods for recording fast movies whose speed is limited by the laser pulse duration if the recording material has sufficient sensitivity to reliably record a frame of the fast event with a single pulse. The method we describe uses the selectivity of multiplexed holograms to resolve frames that are recorded with adjacent pulses. Specially designed pulse generators are used to generate the signal and reference pulse trains. We experimentally demonstrate the system by making movies of laser induced shock waves with a temporal resolution of 5.9 ns, limited by the pulse width of the Q-switched Nd:YAG laser used in the experiments.

A method of making an at least one hole in an optically transparent body comprises the following steps: (i) providing an ultrashort pulse laser for producing a laser output with a wavelength λ, the laser output having a subpicosecond laser pulse duration; (ii) providing a laser output focusing lens for focusing the laser output, the focusing lens having a numerical aperture NA; (iii) providing an optically transparent body, the optically transparent body having a transparency at λ of at least 90%/cm; (iv) providing a liquid filled container situated proximate to the optically transparent body, such that the optically transparent body is in direct contact with the liquid; and (v) directing the laser output through the focusing lens to produce a focused laser output with a subpicosecond laser pulse duration proximate the optically transparent body, wherein the focused laser output traces at least one hole track pattern through the transparent glass body while the optically transparent body and said focused laser output move relative to one another in X-Y-Z directions. The at least one hole track pattern is in contact with the liquid and the focused laser output, in conjunction with the liquid, creates at least one hole in the optically transparent body.

Sample light is delivered into the anatomical structure having a target voxel, whereby a portion of the sample light passing through the target voxel is scattered by the anatomical structure as signal light, and another portion of the sample light not passing through the target voxel is scattered by the anatomical structure as background light that is combined with the signal light to create a sample light pattern. Reference light is combined with the sample light pattern to generate an interference light pattern, such that the signal light and the reference light are combined in a heterodyne manner. Ultrasound is delivered into the target voxel, such that the signal light is frequency shifted by the ultrasound. The ultrasound and the sample light are pulsed in synchrony at the target voxel, such that at least one pulse of the sample light has a combined duration less than a pulse width of the ultrasound.

Conventional methods for producing a hole in a component are time-consuming and costly as special lasers featuring short laser pulse durations are used. In the inventive method, the laser pulse durations are varied, short laser pulse durations being utilized only in the area to be removed in which an influence on the penetration behavior and discharge behavior is noticeable while longer pulse durations of >0.4ms are used. This is the case for the inner surface (12) of a diffuser (13) of a hole (7), for example, which can be produced very accurately by means of short laser pulse durations.

In one aspect the invention provides a method for laser induced breakdown of a material with a pulsed laser beam where the material is characterized by a relationship of fluence breakdown threshold (Fth) versus laser beam pulse width (T) that exhibits an abrupt, rapid, and distinct change or at least a clearly detectable and distinct change in slope at a predetermined laser pulse width value. The method comprises generating a beam of laser pulses in which each pulse has a pulse width equal to or less than the predetermined laser pulse width value. The beam is focused above the surface of a material where laser induced breakdown is desired. The region of least confusion (minimum beam waist or average spot size) is above the surface of the material in which laser induced breakdown is desired since the intensity of the beam falls off in the forward direction, preferably the region of the beam at or within the surface is between the region of least confusion and sufficient to remove material and the minimum intensity necessary for laser induced breakdown of the material to be removed, most preferably the region of minimum intensity is disposed at the surface of the material to be removed. The beam may be used in combination with a mask in the beam path. The beam or mask may be moved in the x, y, and Z directions to produce desired features. The technique can produce features smaller than the spot size and Rayleigh range due to enhanced damage threshold accuracy in the short pulse regime.

The invention discloses a range gating super-resolution three-dimensional imaging method based on spatial differencing shaping. The method comprises the following steps: acquiring a first slice image used for three-dimensional reconstruction; building a first space energy envelope shaper in space overlapping with the first slice image; adopting the first space energy envelope shaper to carry out space difference shaping treatment to the first slice image, so as to obtain a first new slice image; obtaining two new slice images with overlapped spaces by adopting gating delayed stepping treatment according to the former step, and carrying out range gating super-resolution three-dimensional reconstruction on the basis of the new slice images. The equivalent narrowing laser pulse durations of the new slice images are half of that of the original laser pulse duration, so that the purposes of narrowing laser pulse duration and improving range resolution are achieved. According to the method provided by the invention, the limitation of the minimal pulse duration of an impulse laser is broken, three-dimensional imaging in higher range resolution is achieved, and the application of range gating super-resolution three-dimensional imaging is developed.

A method and a system for laser pulse wavefront correction and focusing optimization for laser Wakefield interaction to accelerate electrons to high energy, and more generally for laser matter interaction where both far field and intermediate field optimization are important, allowing a robust wavefront correction and focusing optimization with a high-power laser system at its nominal laser pulse energy and laser pulse duration. The method comprises, after laser beam focusing by focusing optics, coupling an imaging unit to a wavefront sensor, thereby measuring the laser beam wavefront, and adjusting the measured laser beam wavefront to converge to a reference wavefront of the imaging unit using a spatial phase-modifying device.

The invention discloses an ultrafast laser cutting method and device for a transparent material. Pulse string seed lasers are provided through semiconductor laser modulation, third harmonic generationis carried out after the lasers are amplified through an optical fiber amplifier, and laser pulse strings are focused on a to-be-processed position of the transparent material through a Bethel cutting head. Three or more focusing points are formed in the processed material, and the transparent material is cut by moving the focusing positions. Each laser pulse string comprises at least four laserpulses, the pulse width is smaller than 60 ps, the peak power is larger than 1 MW, and the time between the adjacent laser pulses is shorter than 30 ns; the interval time between the adjacent pulse strings is longer than 100 ns; and the widening amount and compression amount of the laser pulse width both do not exceed 40% of the laser pulse width. According to the ultrafast laser cutting method and device, the reliability of light beam cutting is guaranteed, the waste heat of the former pulse is effectively utilized, the quality of cutting machining is guaranteed, and the linear and various special-shaped appearances of the material are cut.

The invention discloses an ultrafast laser cutting method and device for transparent materials. Pulse train seed laser is provided by semiconductor laser modulation, after being amplified by an optical fiber amplifier, a laser pulse train is focused to the to-be-processed position of the transparent materials through a Bezier cutting head, three or more focus points are formed in the processed materials, and cutting of the transparent materials is realized by moving the focusing position; At least four laser pulses are included in each laser pulse train, the pulse width is less than 60 ps, thepeak power is greater than 1 mW, and the time between adjacent laser pulses is less than 30 ns; the interval time between adjacent pulse trains is greater than 100 ns; and the laser pulse width broadening amount and the compression amount do not exceed 20% of the seed laser pulse width. The reliability of a cutting light beam is ensured, the waste heat of previous pulse is effectively utilized, the cutting machining quality is ensured, and outline cutting in a straight line shape and various special shapes of the materials is realized.

The invention discloses a high-energy 1.0[mu]m laser amplification system with 100ns pulse width. The system employs a 1.0[mu]m DFB semiconductor laser as a seed source so as to obtain high-stabilitysingle-frequency laser output. The system utilizes an optical fiber amplification module for chopping, the continuous seed source is chopped into pulse laser with a Lorentz waveform rising edge through an acoustic optical modulator, and finally the width of laser pulse is continuously widened through the amplification effect of a rear-stage solid amplification module, so that 1.0[mu]m pulse laserwith the pulse width greater than 100ns is obtained. According to the invention, the single frequency and stability of 1.0[mu]m laser are ensured, and a new technical route is provided for coherent detection radar to adopt a 1.0[mu]m laser light source through the characteristic that the laser pulse width is gradually broadened through the laser amplification effect.

The invention discloses an ultrafast laser cutting method and device for a transparent material. Pulse string seed lasers are provided through semiconductor laser modulation and are converted into green light through a frequency doubling crystal after being amplified by an optical fiber amplifier, and laser pulse strings are focused on a to-be-processed position of the transparent material througha Bethel cutting head. Three or more focusing points are formed in the processed material, and the transparent material is cut by moving the focusing positions. Each laser pulse string comprises at least four laser pulses, the pulse width ranges from 50 ps to 60 ps, the peak power is larger than 1 MW, and the time between the adjacent laser pulses ranges from 10 ns to 20 ns; the interval time between the adjacent pulse strings is longer than 100 ns; and the widening amount and compression amount of the laser pulse width both do not exceed 20% of the laser pulse width. According to the ultrafast laser cutting method and device, the reliability of light beam cutting is guaranteed, the waste heat of the former pulse is effectively utilized, the quality of cutting machining is guaranteed, andthe linear and various special-shaped appearances of the material are cut.

The present invention relates to the technical field of material surface peening, and more particularly to an energy compensated equipower density oblique laser shock method. The method includes: acquiring a radius of curvature of a peening region of a part to be processed, and judging a range of a laser incident angle; determining laser parameters, such as laser pulse width, a spot diameter, and required laser energy under a vertical incidence condition; calculating the required laser energy at the minimum incident angle, and judging whether the energy falls within the technical indexes of a laser; and performing laser shock peening on the part by pulse laser beams with different energies. According to the present invention, the laser power or energy is compensated according to changes in the incident angle and the radius of curvature of the part to be processed.

The invention discloses an ultrafast laser pulse width measuring device and a control method thereof. The device comprises a beam splitting part, a first adjustable part, a rotating part and a secondadjustable part, the first adjustable part comprises a time delay assembly and an adjuster, the time delay assembly is connected with the adjuster, the second adjustable part comprises a measuring assembly and a controller, and the measuring assembly is connected with the controller; a to-be-measured light beam is divided into a first light beam and a second light beam by a beam splitting part; the reliability of pulse width measurement is ensured; based on the first adjustable part, the accurate adjustment of the optical path of the first light beam can be quickly realized. Based on the rotating part and the second adjustable part, beam pulse detection of any angle polarization state and measurement of autocorrelation signals of the beam pulse detection are achieved, so that the pulse width of a to-be-detected beam is output accurately with high precision, the device is low in structure cost and easy and convenient to operate, operation of professionals is not needed, and the detectable work efficiency is improved.

The invention discloses a thin-wall metal mechanical property changing method which comprises the following steps: step 1, fitting and assembling a workpiece and a workpiece substrate, and fixing the workpiece and the workpiece substrate on a precise moving table; 2, planning a light spot path according to the surface appearance of the workpiece; and thirdly, the power density of laser is GW/cm < 2 > magnitude, the spot diameter of the laser is micron magnitude, the pulse width of the laser is femtosecond magnitude, the surface of the workpiece is impacted by the laser, the interior of the workpiece is modified through explosive shock waves, the spot is controlled to move along the spot path, and the spot coverage rate of the surface of the workpiece is made to be 300% or above. Femtosecond laser is adopted to modify thin-wall metal, the total amount of generated plasmas is smaller, the peak pressure of shock waves is higher, acting force time is shorter, and generated impact force, namely impact momentum is smaller, so that the thin-wall metal material generates dynamic yield response to generate microstructure change and a pre-stress field, but bending deformation is not prone to occurring; the purpose of changing the mechanical property of the thin-wall metal part is achieved.