64 results about "Long pulsed laser" patented technology

The invention provides an all-optical wavelength converter based on a photonic crystal optical fiber four-wave frequency mixing effect. The all-optical wavelength converter comprises a laser, an optical crystal optical fiber and an optical filter, wherein the laser is a long pulse laser or a continuous laser with a pulse width more than tens of picoseconds, and the laser is used for outputting a pump light and providing a converting wavelength; the photonic crystal optical fiber is used for receiving and transmitting an output light of the laser; a laser beam can generate a degenerated four-wave frequency mixing effect during being transmitted in the photonic crystal optical fiber; and the laser beam output from the photonic crystal optical fiber passes through a narrow-band optical filter with a central wavelength of lambda and a proper bandwidth, thus, the laser beam with the wavelength of lambda can be obtained. According to the all-optical wavelength converter, one laser is adopted to synchronously provide the pump source and the converting wavelength, so that the all-optical wavelength converter has the advantages of simple structure, low cost and the like; and moreover, structural parameters of the photonic crystal optical fiber are designed, so that wavelength converting within a larger range can be achieved.

In a method for ultrasonic testing of objects, ultrasound is generated inside or at the surface of the object. The surface of the object is illuminated with a beam from a long-pulse laser oscillator, typically in the range 1 mus to a few 100 mus, that is substantially free of intensity fluctuations. The light from the incident beam that is scattered or reflected by the surface of the object is collected and demodulated to obtain a signal representative of the ultrasonic motion. The method allows for the use of a compact and efficient arrangement.

A method for welding transparent material includes: selecting two types of laser capable of transmitting the transparent material to be welded, one being ultrashort pulse laser and the other being long pulse laser, and synchronizing the two laser beams and combining the beams; stacking two blocks of transparent material to be welded; allowing the laser beams to focus on an interface of the two blocks of transparent material to be welded through an objective lens; when the energy (or power) of the ultrashort pulse laser is larger than or equal to multiphoton absorption threshold intensity, allowing occurrence of multiphoton absorption (ionization) near the focus center (of the two pulse laser beams) to generate free electrons which are seed electrons capable of absorbing the long pulse laser; and when the energy of the long pulse laser (absorbed by the seed electrons) reaches a melting threshold of the material to be welded, and allowing the material near the focus center to melt and fuse and connect together so as to achieve connecting or welding. Compared with the welding method using the ultrashort pulse laser only, the method has lowered cost and improved welding efficiency. Welding of the transparent material is achieved.

A method for changing an amorphous silicon film to a poly-crystalline silicon film includes the steps of irradiating an elongate pulse laser beam onto the silicon film while scanning in the direction normal to the major axis of the elongate pulse laser beam, to form a plurality of irradiated areas, irradiating flat-surface light onto the irradiated areas in the direction parallel to the major axis, and analyzing distribution of the reflected light from the irradiated areas to determine the threshold value of micro-crystallization. The threshold value is used to further determine an energy density of the elongate pulse laser beam for the phase change process.

The invention discloses a high-energy long pulse laser obtaining device, method and application. The high-energy long pulse laser obtaining device sequentially comprises a continuous laser source, an isolator, an electro-optic modulator, a polarizing plate and a laser amplifier in a laser transmission direction. According to the high-energy long pulse laser obtaining device, a continuous narrow-linewidth tunable single-frequency laser device is adopted as a seed source; the amplified laser is still tunable single-frequency narrow-linewidth laser when having relatively high energy; the center wavelength is the same as that of the seed source; the pulse width is determined by the pulse width of a modulation signal; and an output pulse waveform is determined by a modulation signal waveform, a modulation laser pulse and a time sequence of an amplifier-stage pump pulse, and is a smooth waveform.

The invention discloses an aero-engine film hole laser high-efficiency combined machining method. A long-pulse laser and ultrafast laser combined hole forming method is adopted. According to the method, firstly, a preformed hole is formed through nanosecond laser; secondly, the preformed hole is processed into the hole meeting the requirement through the ultrafast laser; the machining efficiency and machining quality are both considered, and the film hole machining efficiency is improved. As the preformed hole of a film hole is machined through long-pulse laser (rough machining), the next stepof the machining amount of ultrafast laser (finish machining) is greatly reduced. The machining efficiency is improved. The requirements for the machining efficiency during engineering machining aremet. Through the combined hole forming method, the film hole can be free of a remelting layer, burrs and splashes, and high-quality and high-efficiency machining of a low-heat influence area can be achieved.

The invention discloses a preparation method of a metal surface microstructure with abrasion resistance and hydrophobicity. The method comprises the steps that 1, stainless steel to be treated is subjected to ultrasonic cleaning, surface pollutants are removed, drying is carried out, and the clean stainless steel surface is obtained; 2, mapping software is used for doing microstructure two-dimension design drawing, and a graphic file is guided into picosecond laser machining system galvanometer control software; and 3, a picosecond laser machining system is adopted for carrying out laser scanning machining treatment on the stainless steel surface obtained in the step 1 according to the machining graph guided in the step 2, and the stainless steel surface with the specific form microstructure is prepared. Picosecond pulse laser adopted in the method has typical ultra-short pulse width and ultra-high peak power characteristic, the defects of heat effects and the like caused easily by long pulse laser machining can be avoided, compared with femtosecond laser, the machining cost is low, the machining efficiency is high, the surface friction coefficient of the prepared stainless steel microstructure is reduced remarkably, the abrasion resistance is improved, the contact angle to water is increased remarkably, and hydrophobicity is improved.