241 results about "Laser pulse width" patented technology

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 to a point at or beneath the surface of a material where laser induced breakdown is desired.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.

Systems and methods are provided for scribing wafers with short laser pulses so as to reduce the ablation threshold of target material. In a stack of material layers, a minimum laser ablation threshold based on laser pulse width is determined for each of the layers. The highest of the minimum laser ablation thresholds is selected and a beam of one or more laser pulses is generated having a fluence in a range between the selected laser ablation threshold and approximately ten times the selected laser ablation threshold. In one embodiment, a laser pulse width in a range of approximately 0.1 picosecond to approximately 1000 picoseconds is used. In addition, or in other embodiments, a high pulse repetition frequency is selected to increase the scribing speed. In one embodiment, the pulse repetition frequency is in a range between approximately 100 kHz and approximately 100 MHz.

Patterns with feature sizes of less than 50 microns are rapidly formed directly in semiconductors, particularly silicon, GaAs, indium phosphide, or single crystalline sapphire, using ultraviolet laser ablation. These patterns include very high aspect ratio cylindrical through-hole openings for integrated circuit connections; singulation of processed die contained on semiconductor wafers; and microtab cutting to separate microcircuit workpieces from a parent semiconductor wafer. Laser output pulses (32) from a diode-pumped, Q-switched frequency-tripled Nd:YAG, Nd:YVO₄, or Nd:YLF is directed to the workpiece (12) with high speed precision using a compound beam positioner. The optical system produces a Gaussian spot size, or top hat beam profile, of about 10 microns. The pulse energy used for high-speed ablative processing of semiconductors using this focused spot size is greater than 200 μJ per pulse at pulse repetition frequencies greater than 5 kHz and preferably above 15 kHz. The laser pulsewidth measured at the full width half-maximum points is preferably less than 80 ns.

An improved electrical pulse generator incorporating MOSFET components, a programmable high voltage power supply, and a shaping network for generating short duration signals having narrow pulse widths and short rise times.

The laser beam produced by titanium jewel femto second laser is split into two beams and the two laser beams are focused by lenses to realize temporal and spatial coherent superposing before acting on metal film on quartz, common glass or silicon substrate. The laser pulse width, pulse frequency and single pulse energy are so controlled that the laser beam can burn out metal film and produce no damage of the substrate. The coherent laser beam is fixed and the sample on 3D platform is computer-controlled to move to prepare periodical microstructure of metal film.

A device and method for LADAR ranging using relatively long laser pulse widths and slower system clock speeds is provided. The center points of the sent and received laser signal such as Gaussian laser pulses are identified by time sampling the sent and received laser signal waveforms at predetermined time positions.

The signal energy within each time sample of the respective sent and received laser signals defines a clock “bin”. The received laser signal generates an output from a photodetector cell on a focal plane array that is converted into voltage. The signal energy is integrated using a capacitor array for each of the clock bins and is representative of the signal energy in each time sample.

The output of the capacitor array is collected in buffer and digitized. Signal processing means extracts the center of the transmitted and received pulses and the time-of-flight calculated as the time between the transmitted and returned centers of the laser signal pulses.

The invention discloses a distributed optical fiber Raman temperature sensor coding and decoding by adopting sequential pulses, which is a distributed optical fiber temperature measuring system coding and decoding a signal on the basis of S-matrix transformation and carrying out optical fiber on-line positioning temperature measurement by utilizing the effect of optical fiber Raman light intensity modulated by temperature and an optical time domain reflection principle. The distributed optical fiber Raman temperature sensor can obtain better signal-to-noise radio under the condition of spending same measuring time by using a sequential multidigit laser pulse coding and decoding technology, increase the number of emitted photons, enhance the space resolution by narrowing the thicknesses of laser pulses and also effectively prevent the nonlinear effect of optical fibers by lowering the requirements on the peak value power of a single laser pulse; and in addition, the invention effectively solves the contradiction of space resolution enhancement-signal-to-noise radio reduction and signal-to-noise radio enhancement-space resolution reduction or measuring time increase of the traditional optical fiber distribution temperature sensor, enhances the temperature measuring precision, can be used for a distributed optical fiber temperature sensor which has ultra long range and high space resolution.

Laser pulse energy adjustments are motivated by an understanding of the effect of laser pulse width variations among different lasers on satisfying a quality metric associated with a laser-processed target. In a preferred embodiment, the adjustments normalize this effect among different lasers drilling vias in a target specimen. The number of pulses delivered to the target specimen to form each via can be modified, based on the pulse energy applied to the via location, to control different via quality metrics.

A single-mode and all-fiber coherent Doppler wind speed measurement laser radar emission source is characterized by being formed by sequentially connecting an all-fiber seed source, a seed isolator, a seed beam splitter, an acousto-optic modulation device, a pre-amplifier stage, a chopper and a main amplifier stage in a cascading mode. The single-mode and all-fiber coherent Doppler wind speed measurement laser radar emission source has the advantages that the all-fiber property is achieved, the human eyes are protected, the line width reaches megahertz, linear polarization is achieved, the pulse contrast is high, and single-mode polarization-maintaining lasers are output; repeated frequency, laser pulse width and laser waveform can be adjusted within the wide range, and the laser radar wind speed measurement requirements for different detection distances, different distance resolution ratios and different wind speed update rates from laser radars can be met.

The invention relates to a method for continuously regulating central frequency and spectrum width of THz (terahertz) wave. A bundle of ultrafast laser pulse passes through a movable birefringence crystal oblique split pair and a zero-order quarter wave plate to generate a novel specially-polarized light field by a polarizing gate method. The novel light field passes through a polarizer to obtain laser pulse with width of narrow pulse with linear polarization. Laser pulses different in width are obtained by controlling inserting quantity of the birefringence crystal oblique split pair, and accordingly the function of regulating central frequency and spectrum width of the THz wave is achieved. A device is simple and easy to operate, the width of the novel laser pulse can be changed only two crystals of the birefringence crystal oblique split pair simultaneously move oppositely at equal distance, and accordingly the central frequency and the spectrum width are adjusted. The method is suitable for light sources of various pulse widths and wavelengths.

The invention relates to the field of femtosecond laser ranging, in particular to a femtosecond laser ranging device and a femtosecond laser ranging method for active dispersion compensation. The device comprises a femtosecond laser frequency comb (FLFC), a laser isolation part ISO, a femtosecond laser beam-expanding collimation part, a Michelson ranging device part, a femtosecond laser pulse width and phase measurement part (FROG) and a data acquiring and processing part. The device is small in size and flexible to operate and has wide engineering application prospects.

The present invention is method of forming colored stereo pattern inside color-less transparent glass. Laser beam with femtosecond to nanosecond pulse width and focal spot powder density greater than1 MW/sq cm is focused into Ag, Au and Cu ion doped glass with polished surface. The glass after being laser irradiated is heat treated, so that nanometer metal grains are separated from the laser irradiation area and different colors may be produced. When irradiated with ultraviolet light, the glass may glow with various color lights depending on the previous laser irradiation and heat treatment,Capable of forming colored stereo pattern, the present invention may be used in ultrahigh density 3D light memory and 3D photon crystal.

The invention relates to a laser-impact strengthening treatment method for a steel welded joint of an X70 pipeline, wherein an energy absorption layer and a restraint layer are arranged on the surface of the steel welded joint of the X70 pipeline in sequence. The laser-impact strengthening treatment method is characterized in that during laser-impact strengthening treatment, the laser pulse width is 22ns-23ns, the wavelength is 1.054mu m, the amplification spontaneous radiation pulse width is 1mu s, a focusing system with the focal length of 2m for outputting laser is used for focusing, the focusing spot diameter is 5mm-8mm, the laser pulse power is about 2.0*109W, and the spot overlapping area on the surface of the welded joint is greater than 60%. After laser-impact strengthening, the surface of the steel joint of the pipeline generates plastic deformation, grain refinement and residual compressive stress, thus effectively improving the H2S stress corrosion resistance and hydrogen induced cracking resistance of the steel welded joint of the pipeline.

The invention discloses an autocorrelator for measuring the width of ultra-short laser pulses. The autocorrelator comprises an incidence reference hole, a wedge-shaped spectroscope, a first right-angle reflector, a second right-angle reflector, a scanning device platform, a paraboloidal mirror, a detector and a control device, wherein the incidence reference hole is used for passing to-be-detected lasers which enter horizontally and straightly at equal heights to form an incidence light path; and the wedge-shaped spectroscope is positioned on the incidence light path, and the included angle of the wedge-shaped spectroscope and the incidence light path is 45 degrees. According to the autocorrelator, the wedge-shaped spectroscope is adopted to replace two beam splitting slices in the prior art, and the two sides of each beam slitting slice are parallel to each other, so that a light path structure of the autocorrelator is simple, and interference field signals formed by multiple reflections of two surfaces of the wedge-shaped spectroscope cannot coincide with an emergent light path any more, so that the detector can detect neat autocorrelation signals.

The invention discloses a compact ultra short pulse laser remote ranging system and a ranging method thereof. The system comprises a laser source, a first beam expanding module, a second beam expanding module, a beam splitter, a transmitting and receiving module, a reflector, a filter module, a focusing lens, and a photodetector, wherein the laser source is an ultra short pulse laser transmitting laser beams, and the width of the outputted laser pulse is picosecond to subpicosecond. The system whose transmitting light path and receiving light path are coaxial is adopted, one reflector is adopted to complete sampling of main wave pulse signals; through changing coating reflectivity of the reflector, the size of an incident main wave signal is adjusted, and over strong main wave pulse signals can be prevented from damaging the photodetector; and the laser ranging system is long in ranging, high in ranging precision, simple and compact in structure, and low in cost.

The invention discloses a method and a device for measuring a laser pulse width and a relative phase by a simultaneous phase-shifting interferometry, which can measure a femtosecond pulse and an attosecond pulse of which the pulse width is very narrow. In the technology, a component prism is used for splitting light beams, and simultaneously, a plurality of simultaneous phase-shifting interference fringe patterns are obtained once in a spatial domain through a polarization interference method. By computational analysis on interference fields of a plurality of paths, the pulse width and the phase of an ultra-short pulse can be directly measured. The method provided by the invention is simple, clear in principles and excellent in shock resistance of the measuring result, and can implement on-site dynamic measurement and monitoring on the pulse width and the relative phase of the ultra-short pulse in an ultra-fast process. The measuring process is simple and convenient.

The invention discloses a laser 3D printing method with a shape correction function. The method comprises the following steps that (1), projection characteristics of all points in scanning breadth are measured, and the focusing light spot deformation amount of all the points in the scanning breadth before shape correction is obtained; (2), the compensation dosage of a light spot shape correction device to all the points is set according to the measurement result in the first step, and the sizes of focusing light spots at all the points in the scanning breadth can have consistency; (3), a laser is stated, and the laser is dynamically matched with the shape correction device and a scanning device for laser 3D printing. According to the laser 3D printing method and system with the shape correction function, the laser sintering degree is controlled by changing the laser pulse width in the 3D printing process, the situation that holes, superburning and nodulizing are generated in the printing process is improved, and density is improved; and besides, the shape correction device is added, it can be guaranteed that the sizes of the focusing light spots in the scanning breadth have consistency by precisely controlling the compensation amount of the light spot shape correction device, and thus 3D printing quality is guaranteed.

The invention relates to a material dynamic tensile mechanical property test and belongs to the technical field of a material dynamic tensile mechanical property test. By using an intense laser pulse-induced impact wave as a loading condition, the material achieves a high strain rate; and different strain rates can be loaded by changing the laser pulse width and laser energy. A device comprises ahigh-power pulse laser (13), a laser head A (1), a laser head B (01), a restraining layer A (3), a restraining layer B (31), an absorbing layer A (4), an absorbing layer B (41), a loading rod A (6), a loading rod B (9), a cylindrical driving ring (8), a laser interferometer (10), a trigger A (11), a trigger B (110) and a computer (12). The device provided by the invention can be used for researching the dynamic tensile property of the material under the condition of different strain rates. The loading process is simple, the influencing factors are few, the calculation process is simple and the test cost is low.