56 results about "Double pass" patented technology

The invention provides a femtosecond laser pulse compression device, and relates to the technical field of ultrafast lasers. The polarization state management module, the compression grating group and the tail end reflecting mirror jointly form a multi-pass folding light path; the polarization state management module is configured to guide an incident light beam with an initial polarization state to enter the multi-pass folding light path and execute one-time two-way compression; in response to the light beam which is returned after completing one-time two-way compression and has changed polarization state, guiding the light beam to the inlet of the multi-pass folded light path again so as to execute next-time two-way compression; the multi-pass folded light path and polarization state management module is configured to enable the light beam to automatically circulate for at least one time in the multi-pass folded light path based on the switching of the polarization state of the light beam; the polarization state management module is further configured to respond to the light beam which returns after completing at least one cycle and has the polarization state meeting the preset output condition, guide the light beam out of the multi-pass folding light path and output the light beam as compressed pulses.

The invention discloses a waste heat recovery and heat exchange device for a waste mineral oil treatment process, and belongs to the technical field of waste mineral oil treatment device.The waste heat recovery and heat exchange device comprises a shell, the two ends of the shell are each provided with an end plate and an end socket, a shell cavity is defined by the shell and the two end plates, and the two ends of the shell cavity communicate with a shell pass inlet and a shell pass outlet correspondingly; a plurality of two-way pipes are installed between the two end plates, each two-way pipe is in a U shape, the interior of one end socket is divided into a feeding cavity and a discharging cavity in a sealed mode, and one end of each two-way pipe is communicated with the feeding cavity. Through overall cooperation of the U-shaped double-pass tube, the spiral supporting plate, the rotatable turbulent flow structure and the detection regulation and control assembly, a special structure matched with waste mineral oil waste heat recovery is formed, a tube pass heat exchange path can be prolonged through the double-pass tube, a shell pass medium is guided through the spiral supporting plate to form an ordered spiral flow field, and the waste mineral oil waste heat recovery efficiency is improved. And the heat exchange effect can be enhanced by means of a rotatable turbulent flow structure, and dirt attachment is reduced.

The invention relates to a quasi-differential wavefront segmentation double-beam interference device with a planar light path structural design, which has the structural characteristic of a non-closed optical path for transmitting a measurement light beam in a one-way manner. Space coherent light of a transverse mode vector filtering mechanism based on the Huygens principle / phased array principle instead of homologous transmission time coherent light is used as each light source, and a non-closed optical path is realized under the cooperation of a one-way transmission mode on a divided measuring light beam. The problem that the sum of the loop wavelength increment or the frequency increment of a closed path interference device is zero is solved, so that the purpose of measuring the first-level effect of anisotropic physical parameters of a measured object in a linear system is achieved, and the device is particularly suitable for immersion type online measurement. The optical elements have stable performance and sound self-adaptive mechanism and self-diagnosis capability through careful layout of the optical elements; and the method also has wide application prospects in basic physical research and novel navigation / positioning systems. The invention also provides a differential wavefront segmentation and semi-transparent and semi-reflective mirror beam combination interferometer device based on the planar light path structure design, and a wavefront segmentation interferometer device based on the planar light path structure design and provided with a pre-crossing area and a bending type one-way-two-way-common mode combination light path structure. The invention relates to a wavefront segmentation interferometer device of a one-way-two-way combined light path structure which is designed based on a planar light path structure and adopts polarization light splitting-beam combination, optical rotation processing of a reference light beam and original path returning, and a use method of an interference device.

The utility model belongs to the technical field of heat supply equipment, and discloses a double-channel slurry preheating system which comprises slurry storage equipment, a spray drying tower and air draft equipment, and a suction port of the air draft equipment extends into the spray drying tower. The slurry storage equipment comprises a body, a containing cavity formed in the body and used for containing slurry, a discharging port formed in the body and communicated with the containing cavity and a first heat exchange pipeline arranged in the containing cavity, the input end of the first heat exchange pipeline is connected with an air outlet of the air draft equipment, and the discharging port is connected with a spray gun of the spray drying tower. The first heat exchange pipeline and the second heat exchange pipeline are used for heating slurry at the same time, the slurry can be rapidly and effectively preheated, the temperature of the slurry can reach 85 DEG C + / -5 DEG C, hot air in the spray drying tower can rapidly dry the slurry, and the drying efficiency of the spray drying tower is greatly improved; and meanwhile, the water content of the powder can meet the required requirement.

The invention discloses a two-way shape memory alloy driving tubular paper folding driver, and relates to the technical field of underwater robots, the two-way shape memory alloy driving tubular paper folding driver comprises a thin-walled tubular paper folding mechanism, a plurality of first shape memory alloy wires are uniformly distributed on the tube wall of the thin-walled tubular paper folding mechanism in the circumferential direction, and one end of the thin-walled tubular paper folding mechanism is connected with a control part in a closed manner; and the control part is electrically connected with the plurality of first shape memory alloy wires. The driver is ingenious in conception and reasonable in layout, the size of the thin-wall tubular paper folding mechanism is driven to periodically change through self deformation of the shape memory alloy wires, then underwater driving force is obtained, and compared with motor driving, the driver is better in mute performance and higher in concealment performance.

The utility model discloses a two-way invisible buckle, which comprises a two-way buckle and a pull-explosion buckle which are matched with each other for use, the two ends of the two-way buckle are symmetrically provided with mutually communicated sliding chutes, the pull-explosion buckle comprises a pull-explosion opposite buckle and a pull rod arranged in the pull-explosion opposite buckle, and the pull-explosion opposite buckle can be pulled by a conical table of the pull rod to explode and expand outwards. The pull rod can be installed in the two-way buckle through the sliding groove in any end of the two-way buckle and enables the two-way buckle to expand towards the two sides. Hidden connection between the plates is achieved, two-side bidirectional random assembly and disassembly are achieved, and installation and design are more flexible and convenient and are not limited by the space direction; meanwhile, a pull rod type adjusting space and a fixed space are cooperatively adjusted by applying the mechanical principle, the elastic reset function can be activated in the transportation and application process, external vibration assistance can pull a pull rod based on the mechanical principle, a conical table is triggered to expand a pull explosion buckle, and when unloading force is released, space extrusion can trigger the pull rod conical table to rebound and retract inwards; and the gap between the pulling buckle and the two-way buckle can be automatically adjusted.

The utility model belongs to the technical field of tee joint manufacturing, and particularly relates to a metal tee joint pipe cutting and welding machine for an air conditioner, which comprises a welding positioning groove and a cutting positioning groove, a one-way joint and a two-way joint are placed in the welding positioning groove and the cutting positioning groove, and two ends of the cutting positioning groove are respectively provided with a baffle plate I; the one-way joint and the two-way joint are placed in the cutting positioning groove and are perforated through a perforating drill, the welding positioning groove comprises a bottom plate, and a lifting ring for placing the two-way joint is fixedly mounted on the upper surface of the bottom plate; according to the metal three-way pipe cutting and welding machine for the air conditioner, a single-way pipe and a double-way pipe are connected with lining wood in a sleeved mode to be placed in a cutting positioning groove and fixed through a pressing ring, a hole is formed through a hole forming drill, the hole forming drill is divided into a friction section, the bottom end of the friction section is fixedly connected with a positioning section, and the friction section is divided into a cylindrical part at the top end and a boss part connected with the cylindrical part. Through the arrangement, the hole cannot be separated from the circle center in the hole opening process, meanwhile, the machining precision of removing materials through friction is high, and the materials are not prone to deformation.

The present application belongs to the technical field of oil and gas seismic exploration, and particularly relates to a pre-stack depth migration imaging method based on generalized diffraction stacking. The present application uses one-way wave equation to calculate the Green's function required for imaging, thereby avoiding the defects of two-way wave equation, making the imaging result not containing the wave field component useless for imaging, ensuring good imaging effect, and reducing the calculation amount, accelerating the operation speed, and improving the imaging efficiency. Moreover, the Green's function is solved in the frequency domain, and there is no sampling rate dispersion problem in the time domain, so that the calculation mode of one-way wave equation can adapt to larger spatial grid interval. Moreover, the relative positions of the imaging point, the source point and the receiver point are judged through angle calculation, so as to perform regional decomposition on the velocity model, and only the necessary region needs to be recursively calculated when solving the Green's function, without recursively calculating in the whole velocity model space. On the basis of ensuring the recursive effect, the useless calculation region is removed, and the imaging efficiency is further improved.

The present application relates to the technical field of optical sensing, and particularly relates to a temperature monitoring chip of a reflective asymmetric interference structure, which comprises an input waveguide, a Y-branch beam splitter, an asymmetric interference arm, a Y-branch combiner, an output waveguide and a total reflection structure; the asymmetric interference arm comprises an asymmetric sensing arm waveguide and a reference arm waveguide; the end of the input waveguide is connected to the head of the Y-branch beam splitter, the first end and the second end of the Y-branch beam splitter are respectively connected to the head of the sensing arm waveguide and the reference arm waveguide; the end of the sensing arm waveguide and the end of the reference arm waveguide are respectively connected to the first head and the second head of the Y-branch combiner; the total reflection structure is arranged at the end of the Y-branch combiner; the total reflection structure is used for reflecting the light wave output by the output waveguide, so that the light sensing arm waveguide and the reference arm waveguide propagate back and forth twice, thereby forming a double-path interference path and generating a fourth-order interference output. The present application effectively improves the temperature detection precision.

The utility model belongs to the technical field of reamers, particularly relates to a double-inner-cooling-hole hard alloy reamer used for cutting, and aims to solve the problems that an existing single-inner-cooling-hole reamer is limited in cooling effect and difficult to meet some high-precision and high-efficiency machining, the following scheme is provided: the double-inner-cooling-hole hard alloy reamer comprises a reamer body, a reamer holder and a mounting head, the double-channel structure is adopted, the flow of a cooling medium is greatly increased, the heat dissipation area is greatly increased, heat in the cutter body can be taken away more quickly, the cooling effect is more remarkable than that of a single channel, the first inner cooling branch channel, the inner cooling branch pipe and the second inner cooling branch channel extend to the outer side of the cutter body, and the cooling effect is better. The cooling medium can be directly guided to cutting areas such as the cutting edges, especially near the first cutting edge and the second cutting edge, the parts generate most heat in the cutting process, targeted efficient cooling can be achieved, tool abrasion can be reduced, the service life of the cutting edges can be prolonged, the cutting performance of the cutting edges can be improved, and the requirements for high-precision and high-efficiency machining are met.

The invention discloses a satellite-borne large-energy single-frequency laser which comprises an oscillation stage, a pre-amplification stage and a main amplification stage which are sequentially connected through a light path. The oscillation stage adopts a resonant cavity formed by a first reflection element, a second reflection element and an oscillation stage polarization beam splitting element, the two reflection elements are orthogonally arranged and work based on the cross-polarization standing wave elimination principle, the space hole burning effect is effectively restrained, and stable single-frequency pulse laser seeds are generated. The pre-amplification stage may include a two-pass amplification structure to improve amplification efficiency. And the main amplification stage is used for finally amplifying the laser and outputting hundred millijoule magnitude pulse laser, and closed-loop stable control of output energy is realized through an energy monitoring device. The device combines a high-stability single-frequency seed source, a high-efficiency amplification technology and an energy stability control technology, has the advantages of being compact in structure, high in anti-interference capability, high and stable in output energy, good in light beam quality and the like, and is particularly suitable for spaceborne and other severe environments.

The utility model discloses a double-channel large-scale sorting vibrating screen, relates to the technical field of sorting vibrating screen equipment, and aims to solve the problems that the efficiency is not high due to the fact that an existing large-scale vibrating screen is difficult to realize automatic balanced distribution of multi-channel materials, and the separation is not thorough due to the fact that part of fine particles are easy to adhere to larger particles after screening. Two groups of screens are arranged in the screen box to divide the screen box into an upper-layer channel, a lower-layer channel and a finished product channel; an automatic material distributing assembly composed of a material distributing plate, a balancing weight, a torsion spring and the like is arranged at the feeding end and used for automatically adjusting materials to enter the upper layer channel and the lower layer channel according to the feeding condition. A first filtering hole and a second filtering hole which are the same as the screen in aperture are formed in the upper-layer discharging channel and the lower-layer discharging channel of the discharging end, balanced distribution of materials is achieved through the automatic material distributing assembly, and the screening efficiency and the equipment processing capacity are improved; and the oversize materials are secondarily filtered through the filtering holes in the discharging channel, so that the purity of the finally sorted materials is improved, and more thorough separation is realized.

The invention discloses a continuous training device for a two-way memory alloy wire. The continuous training device comprises a pay-off wheel, a stretching wheel and a plurality of heating and cooling assemblies which are sequentially arranged in the advancing direction of the wire. The pay-off wheel is connected with a first motor, the stretching wheel is connected with a second motor, and the advancing speed of a wire on the stretching wheel is larger than that of the wire on the pay-off wheel; the heating and cooling assembly comprises a hollow roller and a constant tension wheel which are arranged in the wire advancing direction. Wherein a resistance wire is arranged in the hollow roller, and the constant tension wheel is arranged in the cooling box; according to the invention, the hollow roller and the constant tension wheel form the heating and cooling assembly, so that the wire can continuously advance between the two parts, and meanwhile, the wire is subjected to cold and hot variable temperature circulation, so that the cold and hot circulation training of the wire is realized, and the training efficiency is improved.

The utility model relates to the technical field of bar hot-conveying and direct-rolling, and discloses double-channel cold-control bar hot-conveying and direct-rolling equipment which comprises a water storage tank, a water suction pump is fixedly installed on one side of the water storage tank, a water conveying block is fixedly installed on one side of the water suction pump, a water outlet plate is fixedly installed on one side of the water conveying block, and a water outlet pipe is fixedly installed on the other side of the water outlet plate. A water outlet rod is fixedly installed on one side of the water outlet plate, and a water outlet block is fixedly installed on one side of the water outlet rod. Water in a water storage tank can be pumped out through operation of a water pump and then fed into a water outlet plate through a water feeding block, the water is fed into a high-pressure spray head from the water outlet block through a water outlet rod on one side of the water outlet plate to be sprayed out, and the water can be fed into a water conveying plate through a water conveying block through operation of a liquid pump; water is fed into the high-pressure nozzle to be sprayed out through a connecting pipe at the bottom of the water outlet column, and the liquid pump or the water pump can be closed to adjust the number of nozzles and the water spraying amount.

1. Name of this design product: Double-through concealed buckle. 2. Purpose of this product design: This product is used as an invisible fastener for fixing between panels. 3. The key design feature of this product is its shape. 4. Images or photos that best illustrate the design points: Refer to Figure 1 for the combined state.

The present application relates to a kind of Gaussian mirror unstable cavity optical parametric oscillator double-pass pumping structure and its building method, including the OPO input mirror, nonlinear crystal, OPO output coupling mirror, 45 degree beam splitter, concave lens, 0 degree high reflectivity lens placed in order along the light path in sequence;OPO input mirror and OPO output coupling mirror are curved mirror, the curvature of OPO input mirror is R1, the curvature of OPO output coupling mirror is R2, R1 is positive, R2 is negative.The present application is based on the defect of existing unstable cavity Gaussian output mirror coating technology to realize double-pass pumping structure, innovatively proposes cavity mirror combination idea, uses 45 degree beam splitter and 0 degree high reflectivity lens combination, realizes pump light double-pass pumping, innovatively adds concave lens in pump light return light path to compensate the focusing effect caused by unstable cavity lens, improves the output energy of signal light and idler light, expands the application scenario of Gaussian mirror unstable cavity optical parametric oscillator.

This 2μm single-frequency pulsed laser, based on synchronous modulation and solid-state graded-doping, comprises a fiber-optic synchronous modulation cascaded amplifier and a solid-state non-uniformly graded-doped two-way amplifier. Synchronous modulation in the fiber section suppresses noise, improving the signal-to-noise ratio and solid-state amplification efficiency. The non-uniformly graded-doped gain crystal group in the solid-state section enables small-signal amplification, high-energy extraction, and high amplification efficiency. This allows for high-efficiency, high-repetition-rate, high-energy, narrow-linewidth pulsed laser output in the tens to hundreds of millijoules range, significantly improving the detection accuracy and capability of radar systems.

The application discloses a double-pass vacuum pressing process for mixed substrate multilayer copper-embedded PCB and relates to the technical field of printed circuit process technology. A positioning interface is formed around the copper-embedded groove, guide channels are arranged on the groove wall and groove bottom, a circumferential groove is processed on the outer periphery of the copper-embedded part, a detachable holding layer is used for light holding, initial positioning information of the copper-embedded part and the communication state of the guide channels are collected. The pre-permeated resin fills along the guide channels and is discharged under reduced pressure, the holding position of the copper-embedded part and the gas stagnation identification mark are confirmed according to the gas outlet state of the guide channels and the interface wetting state. The second pass pressing is implemented by combining soft pressing surfaces, the pressing force is transmitted to the positioning interface, the resin is discharged along the guide channels, and the interface shaping result and the interlayer bonding state are output. The detachable holding layer is removed and is stably and non-destructively confirmed, the position of the copper-embedded part is compared with the interface shaping result, and the interlayer bonding state is uniformly written into a pressing parameter card for subsequent reuse and release.

The invention discloses a diffraction grating sheet detection method and system in semiconductor laser processing, and relates to the technical field of grating sheet detection. The method comprises the following steps: deploying a grating detection module in a semiconductor processing production line, carrying out two-way detection and association on a target grating sheet, and generating an acousto-optic association fingerprint; according to a grating piece quality inspection device deployed at a production line quality inspection end, executing grating parameter-based decoupling distribution on the acousto-optic associated fingerprints, performing distribution entropy analysis and empowerment comprehensive calculation on grating parameters one by one, and determining a grating piece quality coefficient; performing quality judgment and production line shunting management on the target grating sheet according to the grating sheet quality coefficient; if the product is judged to be a good product, but the comprehensive entropy difference does not meet the preset relaxation degree, defect positioning and production line backflow rework management are executed. The technical problems of single diffraction grating piece quality detection dimension, incomplete detection result and insufficient accuracy in the prior art are solved, and the technical effect of improving the accuracy and comprehensiveness of the diffraction grating piece detection result is achieved.

The invention relates to the technical field of ball valves, and discloses a double-flow-channel control ball valve which comprises a valve body and a valve element structure, the valve element structure comprises a spherical valve element, a ball sleeve structure is arranged outside the valve element structure and comprises a spherical valve sleeve, and the spherical valve sleeve is arranged on the outer side of the spherical valve element in a matched and sleeved mode. A plurality of water outlets of different structures are formed in the surface of the spherical valve sleeve, the structure that the spherical valve sleeve is matched with the strip-shaped water outlets extending in the circumferential direction is innovatively adopted, the strip-shaped water outlets are evenly distributed along the spherical surface radian of the spherical valve sleeve, the hole channel width of the strip-shaped water outlets is consistent, and the strip-shaped water outlets are completely attached to the outer surface of the spherical valve element. The communicating area of the strip-shaped water outlet and the flow channel of the spherical valve element is linearly and gradually changed along with the rotation angle, the flow area variation corresponding to each rotation of 1 degree is kept uniform and consistent, through flow of cold and hot water can be accurately increased or decreased along with operation due to the design, and stable transition of the water temperature can be achieved even through millimeter-level fine angle adjustment is achieved.

Endovascular devices with enhanced single-beam cut patterns are disclosed. An elongated member includes a plurality of fenestrations defining a plurality of axially extending beams interspersed between a plurality of circumferentially extending rings. The beams are formed using a double pass cutting method in which a blade makes two rotationally offset passes of a cut at a given longitudinal location of the elongated member. The resulting beams have an enhanced structure that avoids overly sharp edges and minimizes structural weaknesses.

The present application relates to the technical field of optical communications, and is used for ameliorating the problem of costs of optical amplifier systems being relatively high. Provided are an optical amplifier system and an optical communication system. The optical amplifier system comprises multiple stages of optical amplifiers, which are connected in sequence, wherein at least one stage of optical amplifier is a double-pass optical amplifier, and a pump bidirectional bypass is provided between a first optical amplifier and a second optical amplifier from among the multiple stages of optical amplifiers; and the pump bidirectional bypass, which is used for directing residual pump light in the first optical amplifier into the second optical amplifier or directing residual pump light in the second optical amplifier into the first optical amplifier. At least one stage of double-pass optical amplifier is used in the optical amplifier system provided in the embodiments of the present application, such that the pump conversion efficiency can be improved and the residual pump can be reduced; and by means of providing a pump bidirectional bypass between different stages of optical amplifiers, and sharing residual pump light between two stages of optical amplifiers, the pump conversion efficiency can be improved, and the costs of the optical amplifier system can then be reduced by means of reducing the pump power or reducing the pump consumption.

The invention discloses a high-stability and high-energy lath green laser system with a multi-point light beam regulation and control function, and relates to the technical field of high-energy green laser systems. Acousto-optic Q-switched double-end-face pumping Nd: YAG crystals are adopted, 1064nm fundamental frequency light is output, the average power is larger than 50W, and the degree of polarization is larger than 98%. Trapezoidal Nd: YAG is used as a gain medium, multi-pass bi-pass Innoslab amplification is carried out, and fundamental frequency light with the average power larger than 500 W is output through normal-temperature water cooling; the Nd: YAG batten realizes two-way amplification and outputs fundamental frequency light with the average power greater than 1200W; the LBO crystal is in non-critical phase matching and is matched with temperature control and light beam regulation and control, and the average power of output green light is greater than 600W; the system further comprises a pumping and homogenizing module, a water cooling / conduction cooling module, a high-stability temperature control module, a multi-point light beam regulation and control module and a system control module, and centralized control and stable operation are achieved. The composite MOPA technology is adopted to reduce the heat effect, high-stability temperature control guarantees the frequency doubling efficiency, multi-point light beam regulation and control prevents film surface damage, the laser power, the light beam quality and the operation stability are improved, and the requirement of industrial processing for high-energy green laser is met.

The utility model relates to the technical field of wall surface polishing, in particular to a switching device for switching single-channel and double-channel dust collection of a polishing machine, which comprises a shell, a main pipeline and two branch pipelines which are communicated with each other are formed on the shell, a mounting position is formed at the intersection of the main pipeline and the two branch pipelines, and a cylindrical mounting sleeve is arranged in the center of the mounting position. A switching assembly is rotatably mounted in the mounting sleeve, the switching assembly comprises a rotating shaft inserted into the mounting sleeve and a wind shield arranged on the outer wall of the rotating shaft, the wind shield is matched with a baffle assembly arranged at an inlet of the branch pipeline so as to isolate the main pipeline from one branch pipeline, and a placement vacancy capable of placing the wind shield is formed between the two branch pipelines. The two branch pipelines, the baffle assembly and the switching assembly are arranged, the baffle can be controlled by rotating the switching assembly to rotate between the branch pipelines and the placement vacancies, and therefore switching of the circulation states of the branch pipelines is achieved, and switching operation is simple and convenient.

A double pass-around lifting device with a rotary locking mechanism, comprising an upper pass-around block (4) and a lower pass-around block (3) fixed to a lifting hook, wherein the two pass-around blocks comprise reversible connection means adapted to be reversibly configured between a connection configuration and a disconnection configuration, comprising a locking mechanism (5) and a complementary locking structure (6), comprising at least one impact hole (65) and a bolt (52) respectively, which is slidably mobile and supports a locking finger (55) adapted to be rotatably engaged with the impact hole, and a respective guide element engaged together, so as to convert the relative approach and relative distancing between the two pass-around blocks into a concomitant sliding and rotation of the bolt.

The application aims to provide a laser wind measurement radar system and method based on double-clad cascaded double-pass amplification. The system comprises a seed source, a cascaded double-pass pre-amplifier, a main amplifier, a telescope and a pump source. The cascaded double-pass pre-amplifier comprises a first double-pass amplification unit and a second double-pass amplification unit connected in sequence. An optical signal passes through the first double-pass amplification unit and the second double-pass amplification unit in sequence, and is used for two-stage double-pass amplification of an optical signal output by the seed source. The method comprises the following steps: S1, continuous light generation and beam splitting; S2, cascaded double-pass amplification; S3, pulse modulation; S4, main power amplification; S5, emission and reception; and S6, coherent detection. The application is applied to the technical field of laser radar.

The invention discloses a traveling wave amplification device and method based on thermal lens imaging, and the device comprises a laser seed source which is used for outputting seed laser with initial power and frequency; the traveling wave amplification systems are connected in series on an output light path of the seed laser in a multi-stage manner, each stage of traveling wave amplification system comprises a laser isolation module, a plano-convex lens, a laser crystal, a plano-concave dichroic mirror and a pumping source module, the laser crystal forms an equivalent thermal lens under the action of pumping light of the pumping source module, and in each stage of traveling wave amplification system, the plano-concave dichroic mirror forms an equivalent thermal lens; based on light path reflection of the plano-concave dichroic mirror, the seed laser realizes two-way amplification in the laser crystal, and the radiuses of laser modes passing through the laser crystal back and forth tend to be consistent based on thermal lens imaging; the dual-pass single-grating compression system is used for pulse time domain compression, and the thermal lens imaging principle is introduced, so that the problems of beam distortion and stability degradation in the traveling wave amplification process can be effectively inhibited while high-efficiency laser amplification is met.

An optical system includes a reflective polarizer (20), and a display (10), first mirror (30a), and second mirror (30b) disposed on a same side of the reflective polarizer (20). The reflective polarizer (20) transmits an image emitted by the display (10) after the image is reflected by the first and second mirrors (30a, 30b). A mid-plane defined by intersection points between an optical axis of the system and the display (10), reflective polarizer (20), and second mirror (30b) has one-pass through four-pass regions having respective areas, A1 through A4. The one-pass region includes portions of the emitted image rays (15) that pass at least one time across the one-pass region, the two-pass region includes portions of the image rays (15) that pass at least two times across the two-pass region, the three-pass region includes portions of the image rays (15) that pass at least three times across the three-pass region, and the four-pass region includes portions of the image rays (15) that pass four times across the four-pass region, such that the ratio A4 / A3 is between approximately 0.15 and approximately 0.40.

A spectrometer includes an entrance aperture, a lens system that receives and collimates light, a flat reflective diffraction grating that diffracts and reflects the light back through the lens system, and a sensor that detects the returned light. The lens system collimates the light during a first pass and focuses it onto the sensor during a second pass. Various embodiments include selectable entrance apertures, imaging optics, different grating geometries and groove densities, and configurations supporting telecentric performance or multi-channel spectral acquisition.