3926 results about "Beam splitters" patented technology

The invention discloses a special environment laser radar system and method based on polarization modulation and laser coding. The laser radar system comprises a polarization modulation laser emitting unit, a multi-channel receiving unit and a compressed sensing reconstruction unit. The polarization modulation laser emission unit comprises a laser, a beam expanding module, a spatial light modulator, a micro galvanometer array, a spatial filter and a first focusing lens which are arranged in sequence; the multi-channel receiving unit comprises a second focusing lens, a polarization beam splitter and a single-pixel detector array which are arranged in sequence; and the compressed sensing reconstruction unit comprises a compressed sensing processing module, an image reconstruction module and a loop adaptive control module which are arranged in sequence. The anti-interference capability in a complex environment is enhanced through polarization modulation, the detection resolution and the signal-to-noise ratio are improved in combination with laser coding, the imaging quality and stability of the laser radar in a special environment are greatly improved, and the method can be widely applied to the fields of military reconnaissance, disaster rescue, unmanned driving and the like.

The invention relates to a compact polarization rotation beam splitter, which comprises an input waveguide, a mode conversion region, a mode coupling region and an output waveguide, a TM0 mode optical signal in the optical signals is converted into a TE mode high-order optical signal in the mode conversion area; the mode coupling region is used for coupling the TE mode high-order optical signal into a TE0 mode optical signal with the first adiabatic coupling waveguide; and the output waveguide is used for outputting a TE0 mode optical signal which is not subjected to mode conversion in the optical signals, and outputting a TE0 mode optical signal obtained after mode conversion of the mode conversion area and the second adiabatic coupling waveguide. According to the invention, the polarization rotation path can be shortened through high-order mode conversion in the mode conversion area, efficient beam splitting is realized by using the asymmetric adiabatic coupling waveguide in the mode coupling area, the size reduction of a redundant structure is avoided through function integration, the performance of the beam splitter is ensured, and the problems of large size and low cost of the existing polarization rotation beam splitter are solved. And the performance is not good.

The invention relates to the technical field of optics, in particular to a gas concentration regulation and control interference imaging system applied to shape righting of a nozzle handle, a shape righting tool and a nozzle are prepared, the shape righting tool is provided with a downward pressing mechanism, the downward pressing mechanism is provided with a downward pressing telescopic column for correcting the nozzle handle, and a displacement measurement interferometer system is assembled on the shape righting tool; the displacement measurement interferometer system is provided with a reflecting movable mirror and a beam splitter, and the reflecting movable mirror is mounted on the pressing telescopic column; the displacement measurement interferometer system further comprises an interference light path stroke difference fine tuning system. The interference light path stroke difference fine adjustment system comprises a glass container for containing sulfur hexafluoride, the end faces of the two ends of the glass container are flat and transparent, the glass container is arranged on a light path between the beam splitter and the reflective moving mirror, and the end faces of the two ends of the glass container are perpendicular to laser on the light path; the glass container is provided with an air supply port; the air supply port is connected to an air pump, and the air pump is connected with a sulfur hexafluoride air source. And the shape correcting position of the nozzle handle is accurately controlled.

The present disclosure relates to an active graded magnetic compensation system and method for an unshielded SERF magnetometer. The system comprises: a detection laser, a half-wave plate, a magnetic field compensation coil, a magnetic field modulation coil, a non-magnetic heating assembly, an alkali-metal atomic vapor cell, a polarizing beam splitter prism, a balanced photodetector, a graded feedback control module, a pump laser, a quarter-wave plate, a focusing lens and a photodetector. By means of the present disclosure, a graded compensation system is used to realize high-precision compensation for a magnetic field within a large dynamic range in a geomagnetic environment, thereby ensuring that an instrument carries out high-sensitivity magnetic field measurement under geomagnetic conditions.

The embodiment of the invention provides an eyepiece system and optical equipment. The eyepiece system comprises a first element group and a second element group; the first element group is arranged close to the human eye side and comprises a first lens, the first lens is provided with a first surface close to the display side and a second surface close to the human eye side, the first surface is provided with a light splitting element and a circularly polarized light generation assembly, and the circularly polarized light generation assembly is located on the side, away from the first lens, of the light splitting element; a first phase retarder and a polarization reflection element are sequentially arranged on the second surface; the second element group is arranged close to the display side and comprises at least two lenses, and the Abbe number of at least one lens is less than or equal to 40; the eyepiece system satisfies the following conditions: 0.01 < = (D1max * phi1) / (D2max * phi2) < = 0.3; wherein phi 1 is the focal power of the first element group, phi 2 is the focal power of the second element group, D1 is the maximum effective optical aperture of the first element group, and D2 is the maximum effective optical aperture of the second element group.

The invention provides an optical measurement method and device, and belongs to the technical field of optical measurement, and the method comprises the steps: starting a light source with the wavelength changing dynamically to generate a sweep frequency optical signal; dividing the light into a measuring beam and a reference beam by using a light splitting component, guiding the measuring beam to irradiate a target to be measured and then return along the same path, and guiding the reference beam to enter an optical component of which the optical path changes along with the wavelength and then return; based on the low-coherence characteristic of the light source, when the optical paths of the two light beams meet the interference condition, detecting an interference signal by using a sensing component; the optical path difference is determined according to time information in the interference signal, and the thickness of each reflection interface is calculated by combining refractive index data of a target to be measured. Different from the traditional low-coherence interference measurement which depends on a motor and the like to control the movement of a reflector, the method avoids the limitation of mechanical driving on the measurement frequency, and achieves the high-speed optical thickness measurement.

The invention discloses a double-comb non-cooperative target ranging system based on single photon detection, which is characterized in that an optical pulse output by a first optical frequency comb is divided into two paths of light through a first beam splitter, the first path of light is combined with one of two paths of light divided by a second optical frequency comb through a second beam splitter, and the combined light is transmitted to a first nonlinear frequency up-conversion module; a sum frequency light pulse in the wave band of 780 nm is generated and detected by a base avalanche diode photoelectric detector, and then a time-dependent single photon counter is triggered to start counting; the second path of light is output to a beam expanding collimator through the circulator and irradiates a target to be measured through spatial propagation, the beam expanding collimator collects diffuse reflection light and returns the diffuse reflection light to a third port of the circulator along the original path, and the diffuse reflection light and the other path of light split by the second optical frequency comb through the second beam splitter are combined and transmitted to a second nonlinear frequency up-conversion module; the up-conversion light after sum frequency conversion passes through the optical filter group and then is recorded by a stop end of the single photon counting module, multi-cycle accumulative statistics is carried out by the time correlation single photon counter, and finally a photon counting waveform is reconstructed and the flight time difference of the to-be-measured target is calculated by the computer.

The invention discloses a polarization-state-based optical fiber vibration sensing system and application, and relates to the technical field of optical fiber sensing, and the polarization-state-based optical fiber vibration sensing system mainly comprises a transmitting end and a receiving end. The transmitting end comprises a laser diode, a first erbium-doped optical fiber amplifier, a first circulator, a polarization scrambler, a single-mode optical fiber link, a second circulator and a second erbium-doped optical fiber amplifier which are connected in sequence; and the receiving end comprises a polarization beam splitter, a first shunt module, a second shunt module, an optical mixer, a first balanced photoelectric detector, a second balanced photoelectric detector, a third balanced photoelectric detector and a polarization analysis module. According to the optical fiber vibration sensing system based on the polarization state and the application, the vibration monitoring performance and reliability in a long-distance and high-noise environment can be improved.

The invention relates to the technical field of laser ranging, in particular to a double-optical-comb hybrid ranging device which comprises a signal detection optical path system and a signal demodulation optical path system. Wherein the signal detection optical path system comprises a first optical frequency comb, a first optical isolator, a first optical collimator, a first beam splitter prism, a reference mirror, a Faraday rotator, a convergence mirror and a target reflector; the signal demodulation optical path system comprises a second optical frequency comb, a second optical isolator, a second optical collimator, a half-wave plate, a second beam splitter prism, a third beam splitter prism, a first polarization controller, a first photoelectric detector, a reflector, a polarization beam splitter prism, a second polarization controller and a second photoelectric detector. A third polarization controller; and a third photoelectric detector. According to the invention, three ranging technologies of asynchronous optical sampling ranging, multi-heterodyne interference ranging and synthetic wavelength ranging are fused, and the problem that a large ranging range and high ranging precision cannot be simultaneously considered in the ranging process is solved.

The invention discloses a transparent part defect detection method and system based on dual-optical-path phase deflection, and belongs to the technical field of optical detection. The system comprises a camera, a reflection light source, a spectroscope, a backlight light source and a processing unit. The detection method comprises the steps of primary measurement, product overturning, secondary measurement and defect comprehensive analysis and classification. A depth map and a modulation degree map of the surface of a product are obtained through reflective measurement, a phase difference map and a backlight modulation degree map are obtained through transmission-type zero reference surface differential measurement, multi-dimensional data are fused, and accurate detection and classification of concave and convex points, foreign matter, scratches and other defects are achieved according to preset logic. The method can effectively eliminate inherent errors of the system, realizes double-sided full detection without omission, is high in detection precision and accurate in defect classification, and is suitable for defect detection of transparent parts such as multilayer transparent glass.

The invention provides a detection system of a micro optical fiber coupler based on a bidirectional optical frequency comb vernier effect, which can be applied to the technical field of photoelectric detection. The system comprises: an optical frequency comb light source configured to emit detection light; the beam splitter is arranged to split the detection light into first sub-detection light and second sub-detection light; the reference sensing unit is arranged to guide the first sub detection light to interact with a reference solution through an evanescent field of the first micro optical fiber coupler so as to output first transmission light; the detection sensing unit is arranged to guide the second sub detection light to interact with the solution to be detected through an evanescent field of the second micro optical fiber coupler so as to output second transmission light; the beam combiner is set to combine the first transmission light and the second transmission light to obtain a combined light spectrum; the spectrum analyzer is set to collect the combined light and generate a vernier spectrum; and the processor is set to determine the concentration of the liquid to be detected according to the vernier spectrum.

The invention provides a photon parallel matrix convolution operation chip which can be applied to the technical field of integrated photonics and optical calculation. The chip is integrated by a 1 * N array waveguide grating, a 1 * 2 beam splitter array, an input matrix modulator array, two N * 1 array waveguide gratings, two 1 * N beam splitters, a weight matrix modulator array, an M * M array waveguide grating detector array and a detector array. Main functional devices are integrated in a monolithic mode, the system is compact, the complexity and power consumption of the system can be effectively reduced, and the calculation efficiency is improved.

The invention discloses an external cavity tunable laser linewidth compression system for realizing wavelength phase locking based on mutual injection of gain chips. The external cavity tunable laser linewidth compression system comprises a red light semiconductor laser main gain chip, a first collimation optical system, a blazed grating, a tuning rotating mirror, a reflector, a power supply driving system and a double-path feedback amplification system, the double-path feedback amplification system comprises a first secondary gain chip, a second secondary gain chip, a second collimation optical system, a third collimation optical system and a polarization-free beam splitter prism; and the red light semiconductor laser main gain chip, the first secondary gain chip and the second secondary gain chip are all connected with the power supply driving system. Therefore, the technical problems of low output infrared light power, poor stability and narrow mode-hopping-free tuning range in the prior art are solved, and high-power, narrow-linewidth, high-stability and large-range mode-hopping-free continuous tuning red light output can be realized.

The invention relates to a packaging structure and packaging method for an optical module and an optical chip, and the packaging structure comprises a receiving end assembly, a stepped metal heat sink, and a silicon-based optical interconnection assembly which is pasted on the stepped metal heat sink. The silicon-based optical interconnection assembly comprises a laser, a silicon light beam splitter, a lens group, a light transmission compensation gasket, a silicon light modulator and an optical fiber array; coplanar coupling is formed between the laser and the silicon light beam splitter. The silicon light beam splitter and at least part of the collimating lens in the lens group are fixed on the light transmission compensation gasket; the optical fiber array and the silicon light modulator realize waveguide matching in an active coupling mode; the silicon light modulator and the receiving end assembly are separately arranged at least at a preset interval, and the optical fiber array and / or the receiving end assembly are / is covered with a metal isolation cover. According to the invention, the problems of high cost of multiple light sources, easy pollution of an open light path and yield bottleneck caused by low-reliability glue in the prior art are solved, and finally, a packaging scheme which is compact in structure, stable in process and high in mass production is formed.

The present invention discloses a position error calibration device and a calibration method for an industrial robot. The position error calibration device in the present invention includes a laser ranging component for measuring the three-dimensional coordinates of the target ball at the end of the robot. The laser ranging component includes a laser interferometer, a beam splitter, a two-dimensional position sensitive detector, and a housing; a two-dimensional moving platform for moving the laser ranging component in the X-axis and Y-axis directions. The two-dimensional moving platform includes a lead screw slider module and a grating scale in the X-axis and Y-axis directions; a supporting device for fixing and supporting the two-dimensional moving platform so that it can work stably in three-dimensional space. Compared with a laser tracker, the present invention does not require transformation between a spherical coordinate system and a rectangular coordinate system, thereby avoiding the amplification effect of the angle error of the inner circle grating in the laser tracker. The present invention can directly measure the three-dimensional coordinate values of the reflecting target ball in the measurement coordinate system, has a good calibration effect, and can meet the calibration requirements of industrial robots.

The invention discloses a parallel imaging OCT (Optical Coherence Tomography) system based on a metasurface area array, which relates to the technical field of medical instruments, is small in size and can realize intraocular single-shot area array imaging and a three-dimensional position depth perception function by using metasurface and optical coherence tomography imaging information in a sample tissue with a limited size. According to the technical scheme, a light beam emitted by a laser is divided into two paths through a beam splitter, and the two paths enter a sample arm module and a reference arm module respectively; the sample arm module is a probe and comprises a multi-core optical fiber and a first metasurface; the reference arm module comprises a collimator, a motor and a right-angle reflector; the probe enters a sample tissue, a light beam is focused on the sample tissue and then is backscattered, the backscattered light beam reversely passes through the first metasurface, the multi-core optical fiber, the beam splitter, the second metasurface, the third lens, the grating and the focusing lens and then forms a spectral line beam on the CCD sensor, and the computer reads a signal from the CCD sensor and performs three-dimensional reconstruction imaging on the sample tissue.

The invention relates to an electro-optical modulator, a preparation method thereof and an electro-optical chip. The electro-optical modulator comprises a substrate, an optical beam splitter, a first optical waveguide, a second optical waveguide, traveling wave electrodes and an electro-optical film, the traveling wave electrodes comprise a first signal electrode and a second signal electrode, the first signal electrode and the second signal electrode are sequentially arranged in the second direction, the first signal electrode and the second signal electrode form a differential electrode, and the first signal electrode and the second signal electrode are sequentially arranged in the second direction. The first signal electrode generates a first electric field when transmitting a first electric signal, the second signal electrode generates a second electric field when transmitting a second electric signal, the directions of the first electric field and the second electric field are opposite, and the refractive index of the electro-optical film is changed under the action of the electric fields to realize electro-optical modulation; part of the electro-optical film, the first optical waveguide overlaps with the first electric field, and the other part of the electro-optical film overlaps with the second electric field. According to the invention, the differential driving of the electro-optical modulator is realized based on the electro-optical film, and the anti-interference capability and the transmission distance of the electro-optical modulator are effectively improved.

The invention discloses a grating displacement encoder grating spacing error in-situ detection and self-compensation method, and belongs to the technical field of optical measurement, and the method comprises the steps: generating elliptically polarized light, modulating the elliptically polarized light into S polarized light, reflecting the S polarized light through a polarization beam splitter, converting the S polarized light into circularly polarized light through a quarter-wave plate, and enabling the circularly polarized light to enter a diffraction grating ruler; the diffraction grating ruler diffracts incident light to form first-order diffraction light and second-order diffraction light; processing and interference detection are carried out on the first-order diffraction light, and precise displacement conversion is carried out in combination with the Doppler effect of grating displacement; constructing an auto-collimation angle detection sensing module by using second-order diffraction light, and converting the distance manufacturing deviation of diffraction gratings by detecting the tiny change of a diffraction angle; and compensating the displacement measurement error of the grating encoder in real time according to the real-time detection result of the grating spacing manufacturing deviation. According to the invention, the off-line detection time and cost of the grating are greatly saved.

The invention provides a laser radar ranging method based on parallel detection, which relates to the technical field of laser radar ranging, and comprises the following steps: generating N lasers with different wavelengths, splitting beams by a beam splitter, separating optical channels with N independent wavelengths by a demultiplexer, performing frequency shift processing, combining N paths of optical signals after frequency shift through a beam combiner, and combining the N paths of optical signals after frequency shift through a beam splitter; generating a beam of composite reference light containing N wavelengths, wherein each wavelength has a specific frequency shift; signal light returned from a target and the composite reference light are jointly input into a coupler for frequency mixing so as to generate an optical beat frequency signal, and operation processing is performed to calculate the target distance and the target radial speed corresponding to each wavelength. According to the laser radar ranging method provided by the invention, parallel detection of the laser radar can be realized, beat frequency signals corresponding to a plurality of different wavelengths can be distinguished only by integrating a group of detectors, a cross-group amplifier and an analog-to-digital converter, the cost is greatly reduced, and the complexity of the system is reduced.

The invention provides a compact hyperspectral imager optical system and an imaging method thereof, which are used for solving the technical problems that the overall size of a front telescopic assembly in a traditional hyperspectral imager optical system is difficult to compress, the installation and adjustment difficulty is relatively large, or the incident energy is lost and the space coverage capability is insufficient. And the technical problems of low energy utilization rate and difficulty in improving the sensitivity and the signal-to-noise ratio of the hyperspectral imager of the traditional Dyson type dispersion light splitting assembly are solved. The invention provides a compact hyperspectral imager optical system, which comprises an off-axis two-image-reflection telecentric optical path system based on a free-form surface and a Dyson light splitting system based on a curved surface prism, and realizes high regulation and control capability on light through multiple degrees of freedom of a curved surface shape. Compared with the prior art, the high-spectral imaging device has the advantages that the high-spectral imaging device is simple in structure, high image quality, small distortion and good telecentricity are achieved, meanwhile, the curved prism serves as a dispersion light splitting element, the whole spectrum has high light splitting efficiency, and the signal-to-noise ratio and sensitivity of the high-spectral imaging device can be improved.

An optical detection device, comprising an objective lens, a bright field illumination unit and a dark field illumination unit. The objective lens is provided with a bright field light channel and a dark field light channel. The bright field illumination unit comprises a bright field beam splitting unit and a bright field light source for providing a bright field incident light beam, wherein the bright field incident light beam is reflected by the bright field beam splitting unit and then enters the bright field light channel. The dark field illumination unit comprises a dark field light source for emitting a dark field incident light beam, a prism module and a dark field beam splitting unit; the prism module and the dark field beam splitting unit are sequentially arranged in the transmission direction of the dark field incident light beam; the prism module is used for converting the dark field incident light beam into a circular light beam, wherein the circular light beam is reflected by the dark field beam splitting unit and then enters the dark field light channel; and the dark field beam splitting unit comprises a circular beam splitter and an aperture formed at the center of the circular beam splitter, wherein the aperture is located on the transmission path of the bright field incident light beam. The present invention more conveniently realizes switching between bright field detection and dark field detection, thereby improving the detection efficiency.

The invention provides an optical element laser thermal effect and light beam quality integrated measurement device and method, and the device combines key assemblies, such as a pump laser, a real-time power monitoring module, an energy transmission optical fiber, a multi-surface reflector, a beam splitter, a monochromatic optical filter, a CCD camera, an infrared thermal imager, a blackbody radiation calibration module, a Fizeau interferometer and the like. And the thermal effect of the transflective element can be measured at a specific angle. The device combines pump light and test light into one beam through the beam combiner and irradiates the surface of a sample at the same time, after transmission, the beam splitter divides the laser into two paths, one path is used for collecting far-field light spots to calculate the quality of the light beams, the other path forms an interference image to calculate thermal distortion, and meanwhile, the thermal infrared imager monitors the temperature of the sample. According to the invention, non-contact lossless integrated synchronous measurement is realized with high integration level and high flexibility, the device is suitable for temperature, thermal distortion and light beam quality measurement of an optical element under continuous or pulse laser, and thermal response characteristics of a sample are comprehensively and accurately evaluated.

A semiconductor measurement device may include an illumination apparatus having a polarizer on a propagation path of light output from a light source; an optical assembly including an objective lens configured to allow light passing through the polarizer to be incident on a sample and a beam splitter configured to transmit light reflected from the sample to first and second sensors; and a controller. The controller may be configured to determine an alignment state of patterns in a first region of the sample using a first original image output by the first sensor and an alignment state of patterns in a second region of the sample using a second original image output by the second sensor. The first sensor includes a first image sensor and a self-interference generator in a path along which light is incident on the first image sensor. The second sensor includes a second image sensor.

The invention relates to the technical field of laser radars, in particular to a laser radar near-field saturation suppression method and device based on signal splicing. The method comprises the following steps: transmitting a pulse laser beam and receiving a scattering echo signal, dividing the echo signal into a transmission light signal and a reflection light signal through an intensity beam splitter prism, and respectively obtaining a far-field channel photon profile and a near-field channel photon profile through the transmission light signal and the reflection light signal; fusing and splicing the far-field channel photon profile and the near-field channel photon profile to obtain a corrected distance square signal profile; and performing atmospheric detection by using a laser radar system, and inverting atmospheric parameters by correcting a distance square signal profile. Meanwhile, the invention discloses a device for executing the method, by adopting the laser radar near-field saturation suppression method and device based on signal splicing, the problem of near-field signal saturation of a high-power laser radar can be effectively solved, and the overall performance index of the laser radar is greatly improved while the detection precision is guaranteed.

The invention discloses a three-magnification double-telecentric light path object detection system and method. A detection part is arranged between a light source module and an object space telecentric light path module; the light source module comprises a white light annular LED array light source set and an adjustable grating arranged on one side, and a light uniformizing piece is arranged in the white light annular LED array light source set. Light emitted by the array light source group is homogenized by the built-in light homogenizing sheet and then forms uniform light beams through the adjustable diaphragm, and the uniform light beams are projected to the surface of a detection part; a light path switching mechanism is arranged on one side of the object space telecentric light path module, and the object space telecentric light path module comprises a low-magnification object space light path, a medium-magnification object space light path and a high-magnification object space light path; the light path switching mechanism is used for switching any one of a low-magnification object space light path, a medium-magnification object space light path and a high-magnification object space light path to enable light rays to be projected to the beam splitter prism, ambient light is removed through the beam splitter prism, and the transmitted light rays are transmitted towards an image space telecentric light path to enable the light rays to be projected to the industrial camera for imaging.

The invention relates to the field of wafer defect detection, in particular to a rapid zooming wafer detection microscope based on MEMS and a detection method. The microscope comprises an illumination part, a sample stage, a spectroscope, a microscope objective, an MEMS micromirror array zoom module, a CMOS image sensor, a laser interference distance measuring sensor and a synchronous control and processing module based on an FPGA. The MEMS micro-mirror array zoom module composed of a plurality of micro-mirror units is introduced into a light path, the deflection state of each micro-mirror unit is adjusted, a dynamic reflecting surface with a controllable equivalent curvature is formed, focusing regulation and control of imaging light beams are achieved, electronic focusing without mechanical movement is completed, the response speed is superior to that of traditional mechanical adjustment, and the imaging quality is improved. And the method is suitable for high-speed online detection.

The invention provides a 2-micron high-order Poincare sphere vector vortex ultrafast laser polarization detection method, which comprises the following steps of: performing out-cavity and out-cavity beam splitting on 2-micron high-order Poincare sphere vector vortex ultrafast laser through a beam splitting module, directly detecting light intensity spatial distribution by one beam, and dynamically regulating and controlling the out-cavity of a polarization state by the other beam after the other beam enters a polarization regulation and control module; the computer communicates with the ESP32 development board to control the hollow rotary displacement table to change the forward included angle between the fast axis and the x axis of the vortex quarter-wave plate so as to change the polarization state of incident light; through the ultrafast laser polarization beam splitter, the polarization state of passing light is limited, and horizontal line polarized light perpendicular to a beam splitting surface passes through the ultrafast laser polarization beam splitter; dynamically detecting real-time data of light intensity which is dynamically adjusted outside the cavity through the polarization regulation and control module each time through a light intensity detection module; and the polarization analysis module receives regulation and control parameters of the polarization regulation and control module and light intensity parameters of the power detection module, analyzes the polarization state of a light beam input into the system, and completes 2-micron high-order Poincare sphere vector vortex ultrafast laser polarization detection.

The invention discloses a green laser and a laser welding machine. The green laser comprises a pumping source, a first reflector, a laser crystal, a polarization beam splitter, a second reflector, a frequency doubling crystal, a telescope lens group and a spectroscope; the pumping source provides pulse pumping light; the laser crystal absorbs the pulse pump light to generate fundamental frequency laser in an infrared band, the fundamental frequency laser enters the polarization beam splitter and is split into P polarized light and S polarized light, the P polarized light is transmitted out of the resonant cavity, and the S polarized light is transmitted in the resonant cavity; and the telescope lens group converges the fundamental frequency laser to the frequency doubling crystal to generate frequency doubling laser of a green light wave band, and the frequency doubling laser is transmitted by the spectroscope and then is output. The green laser is used for spot welding of high-reflection materials such as copper and aluminum, the maximum single pulse energy can reach 5 J, the maximum peak power is 2 kW, the pulse width ranges from 0.05 ms to 5 ms, the problem of low absorption of the high-reflection materials to laser in the 1-micron wave band is solved, and the green laser is an edge tool for precise spot welding of the high-reflection materials.

The present application discloses an optical module and a head-mounted display device; wherein the optical module includes a curved screen, at least one lens, a beam splitter, a phase retarder and a polarized reflective element; the curved screen is used to emit light, and the curvature direction of the curved screen is toward the propagation direction of the light; the at least one lens is located in the light emitting direction of the curved screen; the phase retarder is located between the beam splitter and the polarized reflective element, and the at least one lens is located between the beam splitter and the polarized reflective element; the curvature radius of the curved screen is R, the luminous radius of the curved screen is I, and the field curvature correction value of the optical module is V, then R, I, and V satisfy the following conditions: 0 <R‑(R 2 ‑I 2 ) 0.5

There is presented an apparatus for generating a quantum cryptographic key by outputting an EM pulse / a set of EM pulses to a further apparatus. One or more electromagnetic pulse sources are for outputting at least a first set of one or more EM pulses and a second set of one or more EM pulses. A random phase relationship exists between a first EM pulse and a second EM pulse. An optical element (BS3) receives the first EM pulse and the second EM pulse and is configured to interfere the first EM pulse with the second EM pulse and output an interfered EM pulse along an output path. Further optical elements BS4 and BS5 are used to split off a portion of the output pulses for measuring the properties of the interfered EM pulses. In one example, at least one EM attenuator is configured to attenuate the said received EM pulse such that the attenuated EM pulse comprises an average of up to one photon. The attenuated pulse is output towards a further apparatus, for generating the quantum cryptographic key.