690 results about "Double crystal" patented technology

The invention relates to a double-femtosecond laser frequency comb ranging system. The double-femtosecond laser frequency comb ranging system is characterized in that a first femtosecond laser frequency comb transmits light pulses to a first frequency doubling crystal, the first frequency doubling crystal performs frequency doubling and transmits the two light pulses to a first light splitter, and the light pulses reflected by the first light splitter are transmitted to a light splitter through a first corner reflector and the first light splitter; the light pulses transmitted by the first light splitter are reflected to the light splitter through a second corner reflector and the first light splitter; a second femtosecond laser frequency comb transmits light pulses to a second frequency doubling crystal, and the second frequency doubling crystal performs frequency doubling and transmits the two light pulses to the light splitter simultaneously; the light pulses transmitted by the light splitter are mixed with light pulses emitted by a Michelson interference system, fundamental frequency light pulses of the mixed light pulses are transmitted to a first photoelectric detector through a color selective mirror, frequency doubling light pulses are reflected to a second photoelectric detector, the first photoelectric detector and the second photoelectric detector are connected to a central processing unit through an analog to digital (A / D) acquisition card, and the central processing unit processes signals to obtain a distance measuring value. The double-femtosecond laser frequency comb ranging system is widely applied to laser absolute distance measurement.

A method and circuit is disclosed for a laser system wherein the power of the laser signal is kept at a constant near optimum value and a portion of an frequency doubled output signal is monitored and detected so that noise within the frequency doubled output signal can be minimized. A feedback signal is used to dither the temperature of a frequency doubled crystal so as to minimize the noise in the frequency doubled output signal.

The invention relates to the non linear optical frequency conversion. To realize output of high power THz wave which can be continuously tuned, and stable running at room temperature, the technical scheme used by the invention is that: a tunable terahertz radiation source based on difference frequency cherenkov effect is composed of a laser device, a frequency doubling crystal, a double wavelength parametric oscillator, a harmonic mirror, a polarization filter, a combined beam mirror, a column lens and a difference frequency crystal; the harmonic mirror is placed between the frequency doubling crystal and the double wavelength parametric oscillator; the double wavelength parametric oscillator is II type phase matching KTP (Potassium Titanyl Phosphate) crystal OPO (Optical Parametric Oscillator); the polarization filter, the combined beam mirror and the column lens are arranged between the parametric oscillator and the difference frequency crystal; the difference frequency crystal is amagnesium oxide doped lithium niobate crystal with molecular formula of MgO:LiNbO3 or MgO:LN, and the generated THz wave is coupled and output by an Si prism on the side surface of the difference frequency crystal. The tunable terahertz radiation source based on difference frequency cherenkov effect is mainly applied to the optical frequency conversion.

The invention provides a method for preparing a two-dimensional periodic metal particle array structure through dual-wavelength femtosecond lasers. The method and an implementation device for preparing the two-dimensional periodic particle array structure on the surface of metal by focusing two-color femtosecond laser pulses are provided. The method and the implementation device are characterized in that the metal particle structure is distributed in the two-dimensional direction in a periodic submicron dimension mode; two-color femtosecond lasers with different characteristic parameters are collinearly focused and irradiated on a sample after common channel or branch channel time delay through a nonlinear frequency doubling technology, and formed two-dimensional periodic structure patterns can be effectively adjusted and controlled by changing the azimuth angle of frequency doubling crystals and the power ratio of the two-color lasers. The method has the advantages that through the combinational design of different wavelengths and the polarization property of the femtosecond lasers, the submicron dimension two-dimensional periodic metal particle array structure can be conveniently and quickly prepared. The novel method for preparing the structure through the two-color femtosecond lasers has potential and important application value in the field of material micro-nano processing.

The invention relates to an object compound motion detecting device based on vortex light multiple frequency transform. The object compound motion detecting device mainly comprises parts of a laser unit, a polarizing film, a lens set, a beam splitter prism, a spatial light modulator, a plane mirror, a 4f filtering system, a frequency doubling crystal, a plano-convex lens, a photoelectric detectorand a micro oscilloscope. Firstly, a laser light source and the spatial light modulator are combined to generate superposition state vortex light, and first order diffracted light is filtrated by using the 4f filtering system; secondly, the vortex light is used for illuminating a moving object under the condition with a non-multiple frequency crystal for twice; and finally, the photoelectric detector is used for detecting intensity change of scattered beam of the surface of the object in the two times and sending signals to the oscilloscope to be analyzed. According to signal values of the twotimes of frequency displayed by the oscilloscope, the linear velocity and angular velocity of motion of the object can be calculated correspondingly. The object compound motion detecting device is simple in structure, and still can effectively work under all kinds of extreme conditions.

A system and method are disclosed for the simultaneous optical disinfection and detection of biological particles in a flowing fluid, such as air or water, medium. A light source for irradiating the flowing medium is a dual wavelength laser element simultaneously emitting a visible laser beam and an ultraviolet laser beam. In particular, a laser diode may generate a first visible laser light beam, and a second ultraviolet laser light beam may be generated by passing the first laser light beam through a frequency doubling crystal. Optical detectors measure scattering, fluorescence and / or transmission of the laser light beams from the air or water medium to determine the presence of biological particles in real-time.

The invention relates to BaMgBO3F non-linear optical crystal, a preparation method and applications thereof. The crystal has the following cell parameters: a=17.59, b=30.50, c=8.05, alpha=beta=gamma=90, and z=48. Mg2+is coordinated by four Os and two Fs. The solid-solid phase transition temperature is 900+ / -10 DEG C, the low temperature phase has frequency doubling effect, and the ultraviolet or deep-ultraviolet wave band beams are allowed to penetrate. The frequency doubling effect of the high-temperature phase is zero, the decomposing temperature is 1050 DEG C, and the crystal does not generate deliquescence in air, and is not dissolved in the water solution with the pH valve of 2-12 at normal temperature. The method has the following preparation steps of: mixing the BaMgBO3F with a fluxing agent, and heating into a melt body; forming seeds under the temperature of 0.5-5 DEG C above the temperature of the saturation point of the melt body; subsequently, decreasing the temperature to 0-1 DEG C below the temperature of the saturation point, and rotating along with decreasing temperature to grow the crystal; separating the melt body when the crystal is grown to the required size, and decreasing to the room temperature to obtain the BaMgBO3F single crystal. The crystal can be used as the frequency doubling crystal in the optical parametric oscillator or the harmonic generator.

The invention relates to an ultrasonic inspection method which refers to the specific ultrasonic inspection method for an Omega weld line beneath a driving mechanism of a reactor pressure vessel. In the method, the Omega weld lines is scanned with a ultrasonic probe, signals are collected through a digital ultrasonic device, then analyzed through a PC machine. During the inspection, four ultrasonic probes are used for scanning the weld lines and all the four probes enter with a refraction angle of transverse waves for 35-degree incidence. The focal point of the focusing probe falls on the axial lead of the Omega weld line that runs vertical to the vocal axis. In addition, a double crystal probe is used in the method to conduct a penetration scan of one deliver and one receive at the bottom and the medium parts of the Omega weld, and a eddy current probe is used for checking defects on the surface of the Omega weld line and the near surface. With the single sided array, the method can conduct overall ultrasonic inspection for the weld line beneath the driving mechanism of the pressure vessel cover for the reactor.

Relating to the technical field of hard alloy materials, the invention provides a preparation method of a hard alloy with a double crystal structure. The preparation method comprises: 1. adding coarse grains and fine grains of tungsten carbide into a mixture; 2. conducting pre-ball milling: putting cobalt powder, titanium element and fine grains of tungsten carbide into a ball mill, adding dispersants, and taking alcohol as the mixture medium; putting alloy balls used for grinding into the ball mill; adding the element of titanium in the form of a solid solution; 3. carrying out second charging ball milling; 4. subjecting the uniformly mixed mixture to drying, granulation, and compression moulding by an alloy blade; 5. sintering the compressed compact in a pressure sintering furnace, and adding pressure for sintering, thus obtaining a tissue structure with uniformly distributed tungsten carbide crystal grains. The preparation method of the invention can improve the fracture toughness of the alloy and can endow the prepared hard alloy with a service life longer than traditional materials by 0.5-1 time.

The invention relates to a femtosecond laser carrier envelope offset frequency lock system based on a heterodyne interferometric method. The system is characterized by comprising a femtosecond laser light source system, an acousto-optic modulator, a controllable optical path retardation device, a light splitting prism, a first photoelectric detector, a phase lock amplifier, a phase difference voltage conversion device and a PID controller. Heterodyne interferometry can be conducted on first-level phase-shift diffraction light modulated by the acousto-optic modulator and zero-level diffraction light which is not modulated, and after mixing of interference signals with different wavelengths, direct-current level lock pulse envelope alignment is achieved; optical frequency comb envelope offset frequency is locked by means of interference signal phase, the linear process does not exist, high non-linear optical fibers, frequency doubling crystals and the like are not needed, and the system is simple in structure and low in requirement for laser energy.

The invention belongs to the field of phase difference detection and provides a phase difference detection method, a phase difference detection system, a dual crystal resonator mixer circuit and a distance measurement device. The phase difference detection method comprises the following steps: generating two high frequency oscillation signals of different frequencies, and dividing each high frequency oscillation signal into two paths, wherein one path is a local reference signal used for local reference and the other path is a distance measurement signal for distance measurement; mixing the two paths of local reference signals and outputting a low frequency first difference frequency signal; mixing a return signal of light waves which are modulated according to one path of distance measurement signal and transmitted to the position of a measured target to be reflected and the other path of distance measurement signal, and outputting a second difference frequency signal; and subtracting the first difference frequency signal from the second difference frequency signal to obtain the phase difference between the second difference frequency signal and the first difference frequency signal. The phase difference detection system has the advantages of high precision, low cost, good stability, low energy consumption, and the like, and is used for high-precision phase difference detection, and can achieve millimetre-sized measurement precision.

The invention discloses an ultrasonic inspection device which uses a TR double-crystal composite probe to carry out longitudinal wave ultrasonic scanning so as to find such defects as delamination and slag inclusion and the like in a board, detects the crackles in the board by using a large angle probe and carries out back checking on the delamination and slag inclusion, and a method using the ultrasonic inspection device to carry out fault detection, also provides a reference block for sensitivity adjustment. The ultrasonic inspection device and the fault detection method thereof can effectively prevent unqualified raw materials from entering the product manufacturing process to influence the quality and final service performance of the product, simultaneously, have the characteristics of simple structure, stable process, high production efficiency and low comprehensive manufacturing cost.

The invention discloses double active ion doped bicrystal glass ceramic fluorescence temperature probe materials and a preparation method thereof. The glass ceramic comprise components as follows: 30 mol%-50 mol% of SiO2,15 mol%-30 mol% of Al2O3, 0-20 mol% of NaF, 0-20 mol% of LiF, 0-15 mol% of ZnO, 5 mol%-15 mol% of ReF3, 5 mol%-20 mol% of Ga2O3, 0.001 mol%-2 mol% of LnF3 and 0.001 mol%-2 mol% of TM compounds, wherein Ln is the rare earth ion luminescence center; TM is the transition metal ion luminescence center. The glass ceramic is prepared with a melt quenching method and through follow-up crystallization and heat treatment. The glass ceramic has strong temperature-dependent emission intensity and can be taken as a self-correcting fluorescence temperature detecting material, and the sensitivity at the highest temperature can reach 8% K<-1>.

The invention relates to a full-solid-state single longitudinal mode yellow light laser which is characterized in that pump light emitted from a pump source is collimated and focused through an optical coupling system and is emitted to a self-Raman crystal through an input mirror, and the self-Raman crystal absorbs base frequency light generated by pump light energy in a self-Raman resonant cavity; the base frequency light is spread in the self-Raman resonant cavity in a reciprocating mode, is polarized through a Brewster window to form linear polarized light, lambda / 4 wave plate combination is used for enabling light spread in the self-Raman crystal on the inner side of the lambda / 4 wave plate combination to be circular polarized light and light spread in the self-Raman crystal on the outer side of the lambda / 4 wave plate combination to be linear polarized light, and therefore multimode oscillation caused by space burning holes can be effectively eliminated, and single longitudinal mode base frequency light is output; when the light field strength of the base frequency light gradually increases to reach a Raman threshold, the single longitudinal mode base frequency light is subjected to stimulated Raman scattering of the self-Raman crystal and is converted to single longitudinal mode Stokes light, and the Stokes light passes through a frequency doubling crystal to generate single longitudinal mode yellow light which is output to the outside of the cavity through an output mirror or a beam splitter. The full-solid-state single longitudinal mode yellow light laser can be widely applied to the manufacturing process of full-solid-state single longitudinal mode yellow light lasers.

The invention provides a pulse infrared differential absorption laser radar system for detecting a carbon dioxide concentration profile, which comprises a laser emitting subsystem, an optical receiving subsystem and a data acquisition processing subsystem, wherein the laser emitting system comprises a seed laser, an Nd: YAG laser, a dye laser, a first reflecting mirror, a first half-reflecting half lens, a second half-reflecting half lens, a frequency doubling crystal, a difference frequency crystal, a first spectroscope and a wavelength control unit. The system can not only detect column concentration of atmospheric CO2, but also can obtain CO2 concentration profile distribution on a vertical path, particularly atmospheric CO2 concentration information near a boundary layer, and has important significance for carbon cycle research. The system has the advantages of low technical requirements, high stability, high detection precision and easy popularization, and is an important means for achieving atmospheric CO2 concentration profile measurement.

The invention relates to BaMgBO3F non-linear optical crystal, a preparation method and applications thereof. The crystal belongs to a hexagonal system and a P-6 space group, and has the following cell parameters: a=5.06, c=4.28 and z=1. Zn2+ in the crystal is coordinated by three Os and two Fs. The frequency doubling effect is equivalent to LBO. The decomposing temperature is 860+ / -10 DEG C, and the crystal does not generate deliquescence in air, and is not dissolved in the water solution with the pH valve of 2-12 at normal temperature. The method has the following preparation steps of: mixing the BaMgBO3F with a fluxing agent, and heating into a melt body; forming seeds under the temperature of 0.5-5 DEG C above the temperature of the saturation point of the melt body; subsequently, decreasing the temperature to 0-1 DEG C below the temperature of the saturation point, and rotating along with decreasing temperature to grow the crystal; separating the melt body when the crystal is grown to the required size, and decreasing to the room temperature to obtain the BaMgBO3F single crystal. The crystal has the equivalent frequency doubling effect with LiB3O5 (short for LBO), and can be used as the frequency doubling crystal in the optical parametric oscillator or the harmonic generator.

The invention belongs to the technical field of laser and relates to a laser device, in particular to a laser device capable of freely switching laser between 1064nm wavelength and 355nm wavelength. The laser device comprises a pumping source (1), an energy transfer fiber (2), a coupling system (3), a laser gain dielectric crystal (5), a Q switch (6), an activizer (7), a polarizing spectroscope (8), a frequency doubling crystal (11) and a sum frequency crystal (12). The activizer (7) is used for controlling rotation of a laser polarization plane, so that the laser penetrates through the polarizing spectroscope (8) or are reflected to select different channels of laser oscillation, thus realizing different wavelength output; and under the control of the activizer (7), the laser can be freely switched in the different output wavelengths.

The invention relates to a self-frequency-doubling all-solid-state yellow-light laser. The laser comprises an excitation source, a focusing system, a self-frequency-doubling crystal and a laser resonator, wherein the self-frequency-doubling crystal is a ytterbium-ions-doped rare-earth calcium oxoborate crystal and is cut along the maximum direction of the effective nonlinear coefficient of a non main plane of the crystal; the excitation source is a 900-980nm light source; and the laser resonator is composed of an input cavity mirror and an output cavity mirror, the input cavity mirror and the output cavity mirror are each provided with a medium membrane for inhibiting vibration of a 1020-1080nm wave band, excitation light is subjected to collimating focusing and is injected into the self-frequency-doubling crystal through the input cavity mirror, the self-frequency-doubling crystal absorbs energy of the excitation light to generate fundamental frequency light in the laser resonator, and the fundamental frequency light carries out selection wavelength frequency multiplication through the self-frequency-doubling crystal so that 570-590nm yellow-light laser is output. The laser provided by the invention has the advantages of high output power, simple and compact structure, low cost, high temperature adaptability and the like.

The invention discloses a constant temperature control device of frequency doubling crystals of a solid laser, comprising a temperature control unit, wherein the temperature control unit is connected with the input end of a power drive circuit via refrigeration control signals and heating control signals, and the output end of the power drive circuit is connected with a semiconductor refrigeration film in a gripper via a drive current line. A light inlet window is used for accommodating the frequency doubling crystals and the gripper is internally provided with a cooling water tunnel. The invention can realize accurate and stable temperature control with the temperature difference range of + / -0.1 DEG C, and has the characteristics of easy implementation and operation. Under the condition of high precision and high stability temperature control, frequency doubling crystals can achieve optimum frequency doubling conversion frequency by matching temperature with phase. The temperature control unit also can be interconnected with a computer via an RS485 interface, thus realizing remote control and parameter management on the temperature of the frequency doubling crystals of the solid laser by a computer.

The invention relates to a manufacturing method of an underglaze white double crystal fancy glaze. The method comprises the steps of preparing materials according to a formula, manufacturing a frit, sieving by using a ball mill and modulating, wherein the frit is made from borax, potash feldspar and quartz; a ground glaze is made from potash feldspar, zinc oxide, calcite, quartz and frit; and an overglaze is made from frit, barium carbonate, iron red, potash feldspar, titanium oxide, zinc oxide, bentonite, quartz, iron oxide red and zirconium silicate; dry grinding frit materials, burning the frit materials at 1250 DEG C, and cooling fast to obtain the frit; sieving ground glaze and overglaze materials by using the ball mill; wet ball milling, and sieving by using a 250 mesh sieve; modulating the ground glaze and the overglaze: mixing the crushed frit respectively with the ground glaze and overglaze materials which are sieved and wet ball milling mixtures so as to modulate the mixtures into slurries at 45-50 baume degree; burning: spraying glaze on a green body, wherein the thickness of the ground glaze is 0.4-0.7mm, the thickness of the overglaze is 0.3 mm, and feeding the green body into a roller way to be burnt into the underglaze white double crystal fancy glaze in an oxidizing atmosphere; after burning, natural, smooth and crystal clear decorative patterns can be generated.

A diode pumped, multi axial mode, intracavity doubled, intracavity tripled laser, includes at least two resonator mirrors defining a resonator cavity. A laser crystal and a doubling crystal are positioned in the resonator cavity. A tripling crystal is also positioned in the resonator cavity. A diode pump source supplies a pump beam to the laser crystal and produces a laser crystal beam with a plurality of axial modes that are incident on the doubling crystal. This produces a frequency doubled output beam. Further, a diode pumped, multi axial mode, intracavity nonlinearly-converted laser is provided and includes at least two resonator mirrors defining a resonator cavity, a laser crystal and a nonlinear conversion apparatus positioned in the resonator cavity. A nonlinear conversion apparatus is also positioned in the resonator cavity. A diode pump source supplying a pump beam to the laser crystal and produces a laser crystal beam with a plurality of axial modes that are incident on the nonlinear conversion apparatus. The result is a nonlinearly converted output beam that has a % RMS noise of less than 3%.

The invention discloses an ultrashort laser pulse shape measurement device. In the device, a detected vertically-polarized parallel laser beam passes through a light splitter and is divided into transmitted light and reflected light, reflected fundamental frequency light is subjected to beam expanding and then is divided by a biprism into upper fundamental frequency light and lower fundamental frequency light which are parallel to each other and which enter a frequency doubling crystal at symmetric angles, then horizontally-polarized frequency-doubled light is generated, time intensity information is converted into intensity autocorrelation one-dimensional space information, the frequency-doubled light and the transmitted light after the light splitter achieve frequency conversion on a frequency conversion crystal, then third-order correlation signal light is generated, the time intensity information is converted into intensity third-order correlation two-dimensional space information, and finally, pulse shape information is obtained though the simple reconstruction technology. The ultrashort laser pulse shape measurement device is low in cost, compact and simple in structure and convenient to adjust, and can measure picosecond and femtosecond pulse shapes.

The invention discloses a method for subjecting overwelding holes of profile steel to ultrasonic testing. The method comprises the following steps: (1) welding with a backing plate, that is, marking the position in which H-steel needs to be arranged on a deck, and carrying out the backing plate welding; (2) cleaning and polishing a test surface; (3) polishing inside welds in the overwelding holes; (4) carrying out single crystal inspection, that is, inspecting butt welds of a flange plate with a transverse wave single crystal angle probe; (5) carrying out flaw detection with a double-crystal probe, that is, inspecting welds in the overwelding holes with a longitudinal wave double-crystal angle probe; and (6) carrying out the follow-up step, that is, ending the operation if no quality problem emerges, and repairing and rewelding in case of the presence of quality problems. The invention skips procedures such as skylight construction, overturning and back chipping. In addition, the double-crystal probe can scan within a larger range by moving within a small range. The flaw detection in the overwelding holes has no bad influences on the surfaces of welds.

The invention provides a design method of a semiconductor diode double-end-pumped high-power UV laser, which comprises following steps: constituting a double-end-pumped laser crystal by using two semiconductor diodes; outputting a pumped beam with 808 nm; coupling the pumped beam by an aspherical optical coupling system and a lens to a laser crystal to generate a laser beam with 1064 nm; oscillating the laser beam in a resonant cavity consisting of five planar mirrors; modulating with Q switch; converting the modulated fundamental frequency light with 1,064 nm into a frequency-doubled light with 532 nm by a frequency-doubling crystal; mixing the unconverted fundament frequency light with 1,064 nm with the frequency-doubled light with 532 nm by a frequency-tripling crystal to obtain a UV laser with 355 nm; and outputting the UV laser from a surface of the frequency-tripling crystal cut by Brewster angle. According to the scheme, the laser cavity has the advantages of large mode volume, smaller laser spot at the frequency-doubling crystal, greatly reducing intracavity loss by cutting the frequency-tripling crystal with Brewster angle and high power laser output.

The present invention relates to a high-contrast pulse measurement method and device. The method is characterized in that a beam splitting device divides a to-be-measured pulse into two same pulses, one pulse is modulated and outputted by a modulator, and a time delay device carries out the time delay on the other pulse; finally, the two pulses are combined by a beam combination device and then are connected with a spectrum analyzer; modulation signals from high to low or from low to high changing along with the time delay length are obtained on the spectrum analyzer and are the pulse autocorrelation signals represented in a logarithm format, and by the computer analysis and processing, the width and the contrast of the to-be-measured pulse are finally obtained. According to the present invention, a conventional method of utilizing the non-linear effect of a frequency doubling crystal to measure the autocorrelation signals is avoided, the interference of the noise signals introduced by the non-linear effect is reduced, and not only the width of the pulse can be measured, but also the contrast of the pulse can be distinguished directly, so that the measurement is more accurate, and the error amount is smaller.

The invention belongs to the technical field of new energy, and relates to a rotary piezoelectric power generation charger driven by wind force. The rotary piezoelectric power generation charger is used for collecting wind energy in environments and converting the wind energy into electric energy. The rotary piezoelectric power generation charger comprises a rotary piezoelectric power generation assembly, an interface processing circuit and a rechargeable battery. Piezoelectric crystal layers and metal neutral layers of the rotary piezoelectric power generation assembly form piezoelectric double-crystal beams, and the piezoelectric double-crystal beams are distributed around a spindle to form a circumferential array and are fixed onto a body of a motor by the aid of fixtures. The interface processing circuit comprises a rectifier circuit, a voltage regulating circuit and a battery charging circuit. The rotary piezoelectric power generation charger has the advantages that the piezoelectric power generation charger is simple in structure and low in manufacturing cost, and is clean and pollution-free; the quantity of peripheral electronic components required by the interface processing circuit is low, a design principle of low power consumption is met, and the interface processing circuit can be integrated easily, has an over-charge and over-discharge protection function and is high in stability; the piezoelectric power generation charger is applicable to low-speed wind energy and can be used with sensor nodes.

The invention discloses an LD pumped co-gain double-cavity very large frequency difference double-frequency Nd:YAG laser, comprising: LD, LD controller, LD tail fiber, collecting optical system and laser resonance cavities, where the left end face of the Nd:YAG crystal and a first output coupling mirror compose a straight line cavity, KTP frequency doubling crystal and polarizing light splitting prism are arranged in order behind the Nd:YAG crystal in the straight line, a second output coupling mirror is arranged in the direction vertical to the axis of the straight line cavity and in the position corresponding to the polarizing light splitting prism, the left end surface of the Nd:YAG crystal and the second output coupling mirror compose a right angle cavity, the two resonance cavities contain the same Nd:YAG crystal and birefracting filter plate composed of polarizing light splitting prism and KTP frequency doubling crystal, making them both operate in single longitudinal mode; the straight line cavity and the right angle cavity can contain two KTP frequency doubling crystals which compose two birefracting filter plates with the polarizing light splitting prism, thus making the two resonance cavities both operate in single longitudinal mode. And two single-frequency green lights outputted by the straight line cavity and the right angle cavity are merged into orthotropic linear polarizing double frequency 532 green light whose maximum frequency difference can reach 360GHz.

The invention relates to a two-tone femtosecond laser collinear pumping detecting thermal reflection system which comprises a polarization output pulse laser, a wave plate, a beam splitting element, a reflecting mirror, an electro-optical modulator, a frequency doubling crystal, an optical filter, a beam expander, an electronic control displacing platform, a cold-light mirror, a fixing adjusting frame, a focusing lens, a photoelectric detector and a filter amplifier, wherein the polarization output pulse laser is used for outputting a pulse laser; the wave plate is used for causing the laser to rotate along a polarization direction; the laser beam is divided into two mutually vertical beams along the polarization direction by the beam splitting element; the laser beam is received and reflected by the reflecting mirror; the laser beam is modulated by the electro-optical modulator; the frequency doubling crystal is used for causing the laser to generate second harmonics; the laser within an appointed wavelength interval is filtered by the optical filter; the diameter of the laser beam is expanded by the beam expander; the electronic control displacing platform can move back and forth; the laser beams with different wavelengths are combined by the cold-light mirror; a sample is fixed by the fixing adjusting frame; the laser is irradiated on the surface of the sample by the focusing lens; the photoelectric detector is used for receiving the laser passing through the optical filter and generating an electric signal; and the signal of the photoelectric detector is amplified by the filter amplifier. According to the two-tone femtosecond laser collinear pumping detecting thermal reflection system, femtosecond pulse lasers with different wavelengths are applied to pumping light and detecting light; the pumping light after being subjected to frequency doubling is filtered by the optical filter with high selective permeability; the interference of the pumping light to a detecting signal is avoided; and the accurate high-efficient measurement is realized.

A doubled, external cavity laser comprises an external cavity pump laser section and an extra-cavity frequency doubling section. The pump laser section comprises an edge-emitting, semiconductor chip having: i) an anti-reflection coating on the chip facet facing the cavity ii) a low reflectivity coating on the output facet of the cavity, iii) a wavelength selective element on the anti-reflection side of the chip for producing a single-mode output beam, iv) at least one lens on the output side of the chip which operates to collimate the chip output beam and direct it to the frequency doubling section. The doubling section comprises: i) a second harmonic generating crystal consisting of gray track resistant PPKTP, stoichiometric PPLT, MgO doped stoichiometric PPLN, or MgO doped congruent PPLN, ii) doubling optics configured such that the chip output beam makes from one up to four collinear passes through the doubling crystal, and the second harmonic generation achieved through multiple passes is constructive, iii) beam shaping optics to create a collimated, frequency doubled output beam.

The invention discloses a novel acoustic logging instrument with a sonic system array structure, which comprises a pedestal. The pedestal comprises a receiving zone and a transmitting zone, wherein the receiving zone is provided with five receiving transducers at equal intervals in turn; and the transmitting zone is provided with a transmitting transducer and a high-voltage pulse excitation part which drives the transmitting transducer. The novel acoustic logging instrument adopts the structure of one transmitting transducer and five receiving transducers, greatly simplifies the structure of the instrument and reduces the manufacture cost; moreover, the transmitting transducer adopts a double-crystal parallel mechanism to improve the sound source incentive efficiency and signal receiving sensibility, and has higher measuring accuracy in slow formation. When the instrument is used to measure cementing quality, the receiving transducer closest to the transmitting transducer can complete CBL amplitude logging, and the receiving transducer farthest from the transmitting transducer can complete VDL full wave logging.