51 results about "Laser pulse duration" 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 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.

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.

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.

The invention discloses a laser etching method of a transparent conductive thin film. The method comprises the following steps of (1) outputting pulse laser beams with an output wavelength of 1.4-3.0 mu m through a short-wave long-infrared pulse laser device at a pulse width of 0.1-800 ns, and performing collimation treatment, wherein the short-wave long-infrared pulse laser device is an optical fiber laser device and has a single-pulse laser power capacity of 1-2000 microjoules and a pulse frequency of 1 KHz-1 MHz; (2) enabling the laser beams to illuminate a film substrate on a two-dimensional moving table, controlling the relative movement of the laser beams and the two-dimensional moving table to enable the focus point of the laser beams to move on the transparent conductive thin film according to a set path to perform etching, and controlling the laser beams and the transparent conductive thin film to move relatively as a speed of 50-9000 mm / s and to have a spot overlapping degree of 10-90%. The laser etching method of the transparent conductive thin film can overcome the problems of high laser focusing precision requirements and implementing complexity in the prior art.

The invention discloses a pulse coding distribution-type fiber Raman and Brillouin scattering sensor which comprises a waveform generator, a semiconductor F-P (Fabry-Perot) cavity broadband fiber laser, a semiconductor outer cavity narrow-band pulse fiber laser, a fiber wave separator, a pulse coding photomodulator, an one-way device, an Er-doped fiber amplifier, a bidirectional coupler, a sensing fiber, an integrated wavelength division multiplexer, two photoelectric receiving and amplifying modules, a direct detection system, a narrow-band transmission fiber bragg grating, a circulator, a coherent detection system and an industrial personal computer. The sensor adopts tow laser sources, wherein the semiconductor F-P cavity broadband fiber laser measures temperature by use of a spontaneous fiber Raman scattering intensity ratio; and the other one semiconductor outer cavity narrow-band pulse fiber laser measures strain of frequency shift by use of the spontaneous fiber Brillouin scattering ray. A time sequence codes laser pulse, the spatial resolution is improved by lowering laser pulse width while the transmission photon number is improved, the signal to noise ratio of the systemis improved, and the measurement precision is measured and improved while on-line temperature and strain are realized in space.

A laser with a wide continuous wavelength tuning range is desirable for optimized selective photothermolysis (SP) laser surgeries that treat light-absorptive lesions and unwanted pigments in human tissue with minimal collateral damages. However, current SP laser surgical systems are limited to a few lasing lines including 1024 nm by Nd:YAG, 755 nm by Alexandrite, 694 nm by Ruby, and 532 nm by second harmonic generation of 1064 nm. This invention discloses techniques to implement a high power, tunable optical parametric oscillator (OPO) system for demanding SP applications such as laser tattoo removal. In addition to wavelength tuning, the OPO laser system's output pulse energy, pulse duration, and pulse-train duration are also adjustable by tuning the pump laser pulse energy, pump laser pulse duration, and pump laser pulse-train duration for optimizing SP laser surgical outcomes.

Laser pulses from pulsed fiber lasers are directed to an amorphous silicon layer to produce a polysilicon layer comprising a disordered arrangement of crystalline regions by repeated melting and recrystallization. Laser pulse durations of about 0.5 to 5 ns at wavelength range between about 500 nm and 1000 nm, at repetition rates of 10 kHz to 10 MHz can be used. Line beam intensity uniformity can be improved by spectrally broadening the laser pulses by Raman scattering in a multimode fiber or by applying varying phase delays to different portions of a beam formed with the laser pulses to reduce beam coherence.

The present invention is related to a method for forming a metal silicide layer on a textured silicon substrate surface. The method includes providing a metal layer on a textured silicon substrate and performing a pulsed laser annealing step providing at least one UV laser pulse with a laser fluence in the range between 0.1 J / cm2 and 1.5 J / cm2 and with a laser pulse duration in the range between 1 ns and 10 ms. Then, the method includes converting at least part of the metal layer into a metal silicide layer. In addition, the present invention is related to the use of such a method in a process for fabricating a photovoltaic cell, wherein the dielectric layer is a surface passivation layer, or wherein the dielectric layer is an antireflection coating.

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.

The invention discloses a pulse coding fiber Brillouin optical time domain analyzer which comprises a pulse coding waveform generator, a narrow-band single-frequency fiber laser, a fiber shunt, an optical pulse coding modulator, two fiber circulators, an heterodyne receiver, a digital signal processor, a fiber bragg grating filter, a sensing fiber, a fiber Raman pump sensor and an industrial personal computer. The sensor adopts a time sequence to code laser pulse to improve the spatial resolution by reducing laser width while the transmission photon number is improved; a continuously operated fiber Raman pump laser serves as a pump light source to overcome the difficulty that the Brillouin optical time domain analyzer needs to strictly lock the frequency of a detection laser and a pump laser; and strong laser generated by the continuously operated fiber Raman pump laser is amplified by stimulated Raman scattering light in a sensing fiber instead of being amplified by the narrow-band Brillouin, the gain of the back coherent amplification stimulated Brillouin scattering can be increased, the signal to noise ratio is improved, the measurement precision is improved, and the measurement length is increased.

The invention discloses a method for cleaning a cadmium coating on the surface of a workpiece through laser and a laser cleaning device. The cadmium coating on the surface of the workpiece is cleaned through the laser with the laser output power smaller than or equal to 100 W, the laser output repetition frequency ranging from 100 kHz to 1000 kHz, the laser pulse width ranging from 12 ns to 500 ns, the laser spot overlap rate smaller than or equal to 50% and the laser single pulse energy smaller than or equal to 0.5 mJ, and the number of laser cleaning times is larger than or equal to 8. The method can be used for fully cleaning the cadmium coating on the surface layer of the workpiece without causing an overburning phenomenon on the workpiece.

The invention discloses a pulse thulium-doped fiber laser device, which is characterized in that a thulium-doped active optical fiber is arranged in a resonant cavity of a 1.5 [mu]m band erbium-doped (Er<3+>) optical fiber laser device, the 1.5 [mu]m band erbium-doped (Er<3+>) fiber laser device can operate in a passive Q-switched pulse mode due to the fact that the thulium-doped active optical fiber has a saturable absorption effect on 1.5 [mu]m band laser emitted by the erbium-doped optical fiber, and the process that the thulium-doped optical fiber absorbs laser in the 1.5 [mu]m wave band so as to make the erbium-doped optical fiber laser device operate in a pulse mode is the process that the thulium-doped optical fiber absorbs pump light to generate 1.7-2 [mu]m laser gain based on transition from 3F4 to 3H6; and the 1.5 [mu]m wave band laser runs in a passive Q-switched nanosecond (ns) pulse form, so that the thulium-doped fiber laser device works in a gain switch mode, and 1.7-2 [mu]m wave band pulse laser output which is narrower than the 1.5 [mu]m laser pulse width and higher in peak power can be generated.