124results about How to "Narrow pulse width" patented technology

The invention consists of pumping source, cavity, and a group of coupling device set between the pumping source and cavity, and connected with pumping source through optical fiber. The cavity consists of front cavity mirror and back cavity mirror coated with film. The double-doped crystals and active Q-switch are set between the front and back mirrors. A cooling device is set on the double-doped crystals. The invention features using active Q-switch to control the passive Q-switch for getting prelase pulse, and using saturable absorption crystals as longitudinal mode selector for making the solid single longitudinal mode laser work under higher pumping power.

The invention discloses a device and a method for improving the surface quality of a selective laser melting (SLM) forming piece through an integrated double-type laser light. The device comprises anoptical fiber laser, an optical fiber laser beam expanding collimator, a femtosecond laser, a femtosecond laser beam expanding collimator, a scanning galvanometer, a lens and the like. During an SLM layered manufacturing process, a femtosecond laser technology is used for ablating and reconditioning spheroidization, bulges, powder adhesion and other defects probably occurred in each forming layerand a profile, so that the surface quality of each SLM forming layer is improved without producing an extra heat influence, the roughness of an upper surface and side surfaces of an SLM forming pieceare improved during an accumulation process, performance indexes such as the compactness and the size precision of the parts are improved, and the rejection rate of SLM processing is reduced.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The mode-locked fiber laser further includes an all fiber based laser cavity including a dispersion management fiber segment for generating a negative (anomalous) to match a positive normal dispersion. The dispersion management fiber segment further coordinates with a polarization-controlling device for generating a polarization maintenance (PM) output laser pulse with a narrow pulse width.

An all-fiber Q-switched laser includes a gain fiber spliced between narrowband and broadband fiber gratings that define a polarization-dependent resonant cavity. The narrowband grating is, for example, formed in a PM fiber to create a polarization-dependent reflection band. A modulator applies stress to the fiber chain to induce birefringence and switch the cavity Q-factor to alternately store energy in the gain fiber and then release the energy in a laser pulse.

The invention relates to a high repetition frequency harmonic wave mode locking fiber laser based on external continuous light injection, comprising a laser pumping source, a wavelength division multiplexing device, an optical isolator, a continuous light source, an optical coupler, a saturable absorber and a gain fiber, wherein the laser pumping source is connected to the pumping input terminal of the wavelength division multiplexing device, and the wavelength division multiplexing device is in connection with the optical isolator, and is then connected to the optical coupler together with the continuous light source; the optical coupler comprises a laser signal output terminal and a signal connection output terminal, wherein the signal connection output terminal is successively in connection with the saturable absorber and the gain fiber; the gain fiber is then in connection with the wavelength division multiplexing device; glowing ions are doped in the fiber core of the gain fiber. The high repetition frequency harmonic wave mode locking fiber laser has the characteristics of simple structure and low cost; through the combination between the continuous light source and a passive mode locking fiber laser, high repetition frequency harmonic wave mode locking is realized; in addition, outputted optical pulses possess the advantages of high repetition rate and narrow pulse width.

The present invention relates to an apparatus for use in geophysical surveying. Geophysical surveying typically involves stimulating an area of interest with a seismic source (204) and detecting the response in a sensor array. The application describes a fiber optic distributed sensing apparatus having a source (112) of electromagnetic radiation for repeatedly launching interrogating electromagnetic radiation into an optic fiber (104) deployed in said of area interest, a sampling detector (116) for sampling radiation back-scattered from the fiber; and a processor (108) arranged to process the back-scattered radiation to provide, for each of a plurality of longitudinal sensing portions of optic fiber, an indication of any incident acoustic signals affecting that sensing portion. The sampling detector is arranged to acquire a plurality of diversity samples for each said longitudinal sensing portion. The processor is configured process the diversity samples in diversity channels to determine a measurement signal indicative of any acoustic disturbance; correlate the measurement signal from each channel with a signal indicative of the seismic stimulus applied; and combine the correlated measurement signals to provide an overall measurement signal for the longitudinal sensing portion. The processor may apply a quality metric to the correlated data before performing the combination based on the quality metric. By correlating the individual diversity channels with the stimulus signal prior to performing the analysis of the measurement signal for a particular longitudinal section of optic fiber, the signal to noise ratio can be improved.

The invention discloses a circuit structure of a narrow-pulse-width high-repetition-frequency pulse current source. The circuit structure is characterized by comprising an adjustable reference voltage input module (1), a current source module (2), an adjustable narrow pulse generating and shaping module (3), a high-speed selection module (4) and a current mirror module (5), wherein the adjustable reference voltage input module (1), the current source module (2) and the current mirror module (5) are electrically connected in sequence; and the adjustable pulse generating and shaping module (3), the high-speed selection module (4) and the current mirror module (5) are electrically connected in sequence. By adopting the circuit structure, the pulse width, the current magnitude and the pulse frequency can be adjusted. Moreover, the circuit structure has the advantages of narrow pulse width, high repetition frequency, high current, small overshoot and steep leading edge.

The invention provides a WS ₂ A method for preparing a graphene heterojunction thin film, and a method for building a passively mode-locked fiber laser based on the heterojunction thin film. The method includes: First, a large area of ​​uniform WS ₂ The films were prepared by magnetron sputtering, and then the graphene was transferred to |WS ₂ thin film, forming WS ₂ / graphene heterojunction, and then etched by strong alkali solution to obtain independent WS ₂ /Graphene heterojunction thin film, which can be used as a saturable absorber to generate ultrashort pulse laser when placed in the optical fiber optical system. The present invention innovatively adopts WS ₂ / graphene heterojunction films while overcoming WS ₂ The passive mode-locked pulse width is not narrow enough and the graphene modulation depth is small, so that an ultrashort pulse fiber laser with a large modulation depth can be obtained.

The invention provides a magnetron drive circuit which drives a magnetron to produce a generally rectangular-shaped narrow transmission pulse having sharply shaped rising and falling edges. The magnetron drive circuit includes a nonlinear load circuit and an active damper circuit. The nonlinear load circuit becomes on at around 80% of a peak output voltage of a pulse transformer (at which the magnetron begins to oscillate) is connected to a secondary winding of the pulse transformer in parallel with the magnetron. The active damper circuit absorbs residual energy left in the pulse transformer without any need for an absorption resistor conventionally connected between both ends of a primary winding of the pulse transformer.

An adaptive intelligent electronic horn (100) comprises a mechanical soniferous apparatus (112), an electromagnetic coil (106), a driver circuit (104) and an oscillating circuit (102). A sensor (110) is provided between the mechanical soniferous apparatus (112) and the oscillating circuit (102). An on-off ratio adjusting circuit (108) is provided at the input end of the oscillating circuit (102). The sensor (110) measures the oscillation frequency of the mechanical soniferous apparatus (112) and feedbacks the measured oscillation frequency signal to the oscillating circuit (102). The on-off ratio adjusting circuit (108) controls a pulse width of an oscillation signal from the oscillating circuit (102) based on a voltage of power supply and/or an ambient temperature. The oscillating circuit (102) outputs corresponding oscillation signal to the driver circuit (104) based on the oscillation frequency signal received from the sensor (110) and/or the control signal from the on-off ratio adjusting circuit (108).

The invention discloses an all-solid-state femtosecond laser of passive mode locking Nd,Y:CaF2 of diode pumping. An Nd,Y:CaF2 laser crystal of the laser receives pumping laser penetrating through an optical coupling focusing system and a dichroic mirror; a first concave mirror, a second concave mirror and the dichroic mirror form a compact type confocal folded cavity; a third concave mirror focuses gain laser in a resonant cavity to a semiconductor saturable absorber mirror; the semiconductor saturable absorber mirror is used for starting and maintaining stable mode locking; a first GTI mirror and a second GTI mirror are used for compensating for positive chromatic dispersion in the resonant cavity; a coupling output mirror is used for outputting a stable passive mode locking pulse sequence. The all-solid-state femtosecond laser formed in the mode that a pumping source based on a laser diode is obtained, CaF2 with Nd3+ and Y3+ co-doped serves as a gain medium, the GTI mirrors are used for compensating for chromatic dispersion and the semiconductor saturable absorber mirror is used for starting mode locking, and the stable mode locking pulse sequence with the pulse width of 264 fs is output inside the resonant cavity. A laser diode pumping technology is adopted, so that the all-solid-state femtosecond laser has broader application prospects.

A high-repetition-frequency passive-mode-locking ultrashort-pulse all-fiber laser belongs to a laser technology and the nonlinear optics field. The laser mainly comprises: a laser pumping source, a wavelength division multiplexer, a fiber bragg grating, a doped fiber, a saturable absorber and the like. A short linear cavity is used to realize the high repetition frequency of the passive mode locking and ultrashort laser pulse output. The high-repetition-frequency ultrashort-pulse fiber laser uses a design of an all-fiber structure. Through multistage fiber power amplifiers, average output power can reach hundred watts. Therefore, by using the high-repetition-frequency ultrashort-pulse all-fiber laser, industrialization application is easy to be realized.

Provided is a circuit for controlling a data bus connecting a bitline sense amplifier to a data sense amplifier in accordance with a variation of an operating frequency of a memory device, being comprised of a pulse width adjusting circuit for varying a pulse width of an input signal in accordance with the operating frequency of the memory device after receiving the input signal, a signal transmission circuit for buffing a signal outputted from the pulse width adjusting circuit, and an output circuit for outputting a first signal to control the data bus in response to a signal outputted from the signal transmission circuit.

The invention discloses a 2.79 mu m Q-switched erbium laser dental instrument. The 2.79 mu m Q-switched erbium laser dental instrument comprises a laser power supply, a laser component, a laser water cooling system, a light guide output system, a gas and water spraying system and a central control system; the laser power supply is used for providing energy to the laser component; the laser component consists of a total-reflection chamber piece, a polarizer, a Q-switched crystal, a xenon lamp, a laser rod, a light condensing chamber, a wave plate and an output chamber piece; the laser water cooling system is used for cooling the laser rod and the xenon lamp in the laser component; the light guide output system is used for conducting laser, and is convenient to operate and use; the gas and water spraying system is used for spraying a mixture of gas and water to a laser acted tooth tissue, and has the effects of reducing the temperature of the tissue and participating laser treatment; the central control system is used for controlling the parameters of the laser power supply, the laser water cooling system and the gas and water spraying system to ensure the coordination work among the subsystems. The 2.79 mu m Q-switched erbium laser dental instrument has pulse Q-switched laser which has short pulse width and high peak power and acts the tooth tissue to improve ablation precision; meanwhile, the thermal damage to peripheral tissues also can be effectively reduced; the pain of a patient can be reduced effectively.

The invention discloses a medical 2.79-micrometer electro-optical Q-switched Cr, Er: YSGG (Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet) laser device which comprises a total reflection cavity sheet, a Q-switched crystal, a polarizer, a xenon lamp, a laser rod, a condensation cavity, a wave sheet, an output cavity sheet, a laser power supply and a laser water cooling system, wherein the laser rod and the xenon lamp are mounted in parallel in the condensation cavity, and connected with the water cooling system; the water cooling system cools the condensation cavity, and the laser rod and the xenon lamp in the condensation cavity; the laser power supply provides electric energy for the xenon lamp, and has a function of coordination, such as controlling the xenon lamp, an electro-optical Q switch, and the water cooling system; a Q-switched power supply in the power supply controls the opening time of the electro-optical Q switch, provides Q-switched high voltage, and is connected with two electrodes of the Q-switched crystal; the two electrodes are positioned on the two sides of the Q-switched crystal, and clung to the surface of a Y-Z plane of the Q-switched crystal, and are parallel to a laser oscillation path; the electro-optical Q switch consists of the polarizer and the electro-optical Q-switched crystal; the Q-switched crystal is a lanthanum gallium silicate (LGS) crystal; the laser rod is a Cr, Er: YSGG laser crystal; and the wave sheet is a 1/4 wave sheet. The laser device has the characteristics of stable output power, and uniform light spot intensity distribution.

A method is presented for calibrating a time-of-flight system having a time-of-flight sensor located behind a cover plate. The method involves emitting a plurality of sending pulses of light in response to respective trigger pulses of a control signal and detecting received pulses of light. Respective difference values are determined which are representative of a time period between one of the sending pulses and one of the received pulses. The difference values are accumulated into a number of bins of at least one histogram. The method further involves recording at least one crosstalk response in the histogram within a predetermined range of bins, and calibrating the histogram using the recorded crosstalk response. Finally, an output signal is generated which is indicative of a time-of-flight based on an evaluation of the calibrated histogram.

Currently, the shield-to-shield separation of a spin valve head cannot be below about 800 Å, mainly due to sensor-to-lead shorting problems. This problem has now been overcome by inserting a high permeability, high resistivity, thin film shield on the top or bottom (or both) sides of the spin valve sensor. A permeability greater than about 500 is required together with a resistivity about 5 times greater than that of the free layer and an M_rT value for the thin film shield that is 4 times greater than that of the free layer. Five embodiments of the invention are described.

The invention discloses an ultra-wide band imaging method and device with enhanced focusing. A controller FPGA (filed programmable gate array) 1 controls a time domain transmitter to transmits a narrow pulse signal with nanosecond width and high band-width frequency spectrum. The narrow pulse signal is radiated by a transmitting antenna array 12 to probe a target. A receiving antenna array transmits a received weak reflection signal to a noise amplifier 11, the amplified signal enters a receiver 7, the receiver 7 analyzes the received high-speed weak signal into a digital signal, and the digital signal is transmitted to a signal processing and imaging module 4 through a multi-channel data acquisition unit 10. In the mean time, the controller FPGA 1 controls an inertial positioning sensor 2 to measure acceleration of equipment in real time, a data acquisition unit 3 transmits the measuring result to the signal processing and imaging module 4, and the position of the target is analyzed through an imaging algorithm program.