24 results about "Brewster's angle" patented technology

An aircraft radome and radar assembly includes: a radome arranged on the nose of the aircraft; a radar inside the radome, the radar operating in the millimeter domain and including a transmission antenna for emitting a TM polarized wave and a reception antenna; the radome includes an integrated window in front of the radar, the window being of a material transparent to millimeter waves; the radar being arranged so the angle between the maximum gain direction of the transmission antenna and the normal to the window is within an angular range [θB−θ1; θB+θ2], with OB being the Brewster angle for an air / window interface, θ1 and θ2 determined to obtain reflectivity at said air / window interface less than a predefined threshold; and an isolation partition between the transmission antenna and the reception antenna, the isolation partition being substantially in contact with the window and with the radar.

This application provides a green fiber laser, comprising, in sequence, a high repetition rate (PRR) polarization-maintaining fiber laser, a first Brewster window, a second half-wave plate, a first plano-convex lens, a laser crystal, a second plano-convex lens, and a first dichroic mirror. The PPR fiber laser outputs a high repetition rate polarization-maintaining fundamental frequency signal light. The first Brewster window is an optical lens placed at a Brewster angle, and the 1000-1100nm fundamental frequency signal light passing through the first Brewster window has a specific polarization state. The second half-wave plate can be rotated to adjust the polarization state rotation angle of the infrared beam after passing through the first Brewster window. By using the second half-wave plate and the first Brewster window to adjust the polarization state rotation angle to a suitable polarization state, the optical-to-optical conversion efficiency of the entire system is greatly improved, resulting in high repetition rate, high energy conversion efficiency, high power, and stable green light output.

The application discloses a Brewster window stack polarization modulation device. The device comprises a Brewster window stack assembly, a clamping assembly, and an installation base. The Brewster window stack assembly comprises a plurality of optical window pieces arranged in parallel and at intervals, and the included angle between the surface normal and the incident light is a Brewster angle. The installation base has a vertical part and a horizontal part. The clamping baffle is arranged opposite to the vertical part of the installation base at intervals. The optical window pieces and the gaskets are alternately arranged in parallel at intervals. One adjusting screw is arranged on each side of the installation base. The adjusting screw passes through the clamping baffle and each gasket in sequence, and is screwed with the vertical part of the installation base. The rotation of the adjusting screw is converted into the linear motion of the clamping baffle along the support surface, so as to change the distance between the clamping baffle and the vertical part and / or realize the clamping and fixing of the Brewster window stack assembly. The device can realize linearly polarized light output with high extinction ratio and high stability in a wide range of incident angles and spectral bands.

This invention discloses a reflective film for automotive applications and a display structure for eliminating ghosting, belonging to the field of automotive displays. It includes a first liquid crystal layer and a second liquid crystal layer. The first liquid crystal layer has a direction pointing in the same direction and a thickness of 1 / 4 waveplate. The second liquid crystal layer is a reflective layer with a spiral structure in the longitudinal direction. The first liquid crystal layer is bonded to the windshield. The reflective film reflects the light beam generated by the display device incident at Brewster's angle inside the vehicle, reducing the energy of the beam that causes ghosting and eliminating it. For natural light from outside the vehicle, it only reflects P-polarized light with a wavelength close to that of the display device, while allowing other wavelengths and polarization directions of natural light to pass through, giving the automotive reflective film both high reflectivity and high transmittance.

The invention relates to the technical field of OTDR (Optical Time Domain Reflectometer), in particular to an optical transceiving integrated device and method for inhibiting an overlarge front-end blind area, and the device comprises a laser which is used for generating test light; the polarization controller is used for adjusting the test light into linearly polarized light only containing an S component; the slide is arranged on the emergent light path of the polarization controller, and the included angle between the normal and the incidence direction of the adjusted test light is a Brewster angle; the detection end of the device is arranged in the direction of a reflection light path of the adjusted test light by the slide and is used for placing an optical fiber to be tested, so that the device emits the test light reflected by the slide to the optical fiber to be tested; enabling the device to receive backward Rayleigh scattering light returned by the optical fiber to be detected; and the avalanche photodiode is arranged on a transmission light path of the slide to the backward Rayleigh scattering light and is used for receiving the backward Rayleigh scattering light penetrating through the slide. Therefore, the advantages of preventing APD supersaturation during short-distance testing and improving the signal-to-noise ratio during long-distance testing are achieved at the same time.

The utility model provides a frequency-doubled laser linewidth narrowing device. The device comprises a pumping module and a laser resonant cavity, the pumping module is used for providing linearly polarized light in a specific polarization direction to a light path; the laser resonant cavity is internally provided with a gain medium, at least one birefringence optical filter and a frequency doubling crystal which are sequentially arranged along an optical path, and the at least one birefringence optical filter is inserted into the optical path at a Brewster angle; wherein the linearly polarized light is focused in the gain medium, the central wavelength of the linearly polarized light is the same as the absorption peak wavelength of the gain medium, and the polarization direction of the linearly polarized light is the same as the maximum absorption direction of the gain medium. According to the invention, the birefringence optical filter (group) inserted into the laser resonant cavity can be specifically adjusted, so that narrow-band filtering can be conveniently and quickly realized in various intracavity frequency doubling lasers, and compared with the prior art, the introduced power loss is relatively small.

The invention provides a monitoring device and a monitoring method for monitoring the quality of a coated photoresist, the monitoring device comprises a transmitting device, a receiving device and two angle adjusting devices, the transmitting device transmits laser containing S polarized light and P polarized light to the surface of the coated photoresist; the receiving device separates S polarized light and P polarized light in the reflected light reflected by the photoresist and respectively receives the S polarized light and the P polarized light; the first angle adjusting device adjusts the angle of the emitting device so as to adjust the included angle between the incident light and the vertical direction. The second angle adjusting device adjusts the included angle between the receiving device and the vertical direction to receive the reflected light. The monitoring device is used for measuring the Brewster angle of the photoresist so as to calculate the refractive index of the photoresist, and the quality of the photoresist is judged on the basis of the mapping relation between the refractive indexes under different Q-times after the photoresist is coated and key parameters and yield of a photoetching process, so that the purpose of monitoring the quality of the coated photoresist is achieved.

The present invention relates to a preparation method for a trigonal nonlinear optical crystal frequency converter and an operating method. The frequency converter has a first group of parallel surfaces and a second group of parallel surfaces, wherein the first group of parallel surfaces is parallel to a c-axis and an a-axis of an optical crystal, an angle α is formed between a normal of the second group of parallel surfaces and the c-axis, and an included angle β is formed between the projection of the normal on an a-b plane and the a-axis; and θPM having a relation shown in Formula (1) and Formula (2) is a phase matching angle of the nonlinear optical crystal satisfying an incident fundamental frequency light and an emergent variable frequency light, where θB=arctann, which is a Brewster angle, n is the refractive index of the nonlinear optical crystal corresponding to the incident fundamental frequency light, and the second group of parallel surfaces includes a light transmission input surface and a light transmission output surface of the frequency converter. The present invention provides, on the basis of a thin sheet-like primary crystal, a preparation method for a nonlinear optical crystal frequency converter having a length in a light transmission direction as large as possible and suitable for continuous wave application and an operating method.

An object of the present invention is to provide a projection image display member capable of reducing a double image even at a projection angle other than a Brewster's angle.SOLUTION: A P-polarized light reflective layer and an absorptive light control layer, wherein an average reflectivity at a wavelength of 400 nm to 700 nm is 5% or more and 100% or less when P-polarized light is incident from the P-polarized light reflective layer side so as to form 60 ° with respect to a normal direction of a surface on the P-polarized light reflective layer side, the projection-image-displaying member satisfies (Tv + Rv) ≤ 95, where Tv (%) is an average transmissivity of wavelengths 400nm to 700nm when p-polarized light is incident perpendicularly to a front face of the projection-image-displaying member from the p-polarized light reflecting layer side, and Rv (%) is an average reflectivity of wavelengths 400nm to 700nm when p-polarized light is incident from the p-polarized light reflecting layer side so as to form an angle of 12 ° with respect to a normal to the front face.SELECTED DRAWING: Figure 4

Provided is a method for measuring the concentration of an optically active substance in aqueous humor and an apparatus for measuring the concentration of an optically active substance, which can measure the concentration of an optically active substance in aqueous humor simply and with high accuracy. The method for measuring the concentration of an optically active substance includes a first step of irradiating incident light, which is polarized light, to the aqueous humor of an eye and measuring the polarization state of reflected light obtained by reflection at the interface between the aqueous humor and the lens, wherein the first incident light is irradiated so that the angle between the normal at the point where the incident light intersects the surface of the lens and the incident light is smaller than the Brewster angle, and the polarization state of the first reflected light is measured; a second step of irradiating second incident light so that the angle of the incident light is equal to or greater than the Brewster angle, and the polarization state of the second reflected light is measured; a third step of calculating the optical rotation of the aqueous humor using the information on the polarization state of the first reflected light and the information on the polarization state of the second reflected light; and a fourth step of calculating the concentration of the optically active substance in the aqueous humor based on the optical rotation of the aqueous humor.

The utility model relates to a device for monitoring the output power of a linear polarization laser in real time, which comprises a carrier, a purification assembly and a power sampling assembly are sequentially arranged on the carrier at intervals along the transmission direction of incident laser, the purification assembly comprises an optical adjusting frame A, and a Brewster polaroid pile is arranged on the optical adjusting frame A; a residual light collector is arranged in a direction in which incident laser is reflected by the Brewster polaroid stack; the power sampling assembly comprises an optical adjusting frame B, a Brewster window sheet is arranged on the optical adjusting frame B, and a power detector is arranged in the direction in which the incident laser is reflected by the Brewster window sheet; the included angle between the mirror surface of the Brewster polarizer stack and the transmission direction of the incident laser is a Brewster angle, and the included angle between the mirror surface of the Brewster window sheet and the transmission direction of the incident laser deviates from the Brewster angle. The device has the advantages of being reasonable in structural design, capable of achieving high-precision and low-interference real-time monitoring of the output power of the linear polarization laser, easy to assemble and debug and the like.

The application discloses a water surface three-dimensional reconstruction method based on oblique view geometric constraint and attitude blind correction, and belongs to the technical field of precision engineering measurement, computer vision and physical oceanography, and comprises the following steps: acquiring point clouds by oblique scanning of a 905nm laser radar near Brewster angle, removing noises through straight-through filtering and statistical outlier removal, realizing IMU-free attitude leveling based on SVD and Rodrigues formula, taking a preset low quantile of a Z axis as a dynamic reference to perform height normalization, and finally generating a continuous three-dimensional wave surface model through two-dimensional gridding, morphological closing operation and Gaussian smoothing. By using the above method, the low-cost near-infrared laser radar can be used to realize high-precision three-dimensional reconstruction of micro-scale waves without external inertial measurement hardware and physical targets, so that the hardware cost is greatly reduced, and the convenience and precision of non-contact measurement are improved.

The invention discloses a passive Q-switched pulse laser and a pulse generation method thereof. The laser comprises an optical pumping device, a laser gain medium and a laser resonant cavity. The laser is characterized in that a saturated absorber crystal with an uncoated light passing surface is arranged in the resonant cavity, and the crystal is arranged in a laser light path in the resonant cavity at a Brewster angle. Through the configuration, the saturable absorber crystal serves as an intra-cavity polarization selection element while realizing a passive Q-switching function, so that the structure is simplified, and linear polarization output is realized.

The invention discloses a maneuvering method and device for avoiding lightweight calculation based on flare interference, and belongs to the field of load maneuvering planning. The method comprises the following steps: establishing a first spherical triangle taking a satellite centroid as a sphere center under a satellite body coordinate system based on a sun vector, an observation direction of a satellite and a vector of a target point pointing to the earth surface by the earth center; in a plane formed by the sun vector and the earth core pointing earth surface target point vector, by taking the earth core pointing earth surface target point vector as a bisector, constructing a light reflection vector symmetrical to the sun vector so as to establish a second spherical triangle under the satellite body coordinate system; based on the first spherical triangle, the second spherical triangle and the Brewster angle of water, judging whether the satellite photographing is in a flare interference area or not; and based on the judgment result, calculating a yaw offset angle which is superposed to the original yaw angle so as to avoid flare interference. According to the scheme, the calculation process can be greatly simplified, and the calculation amount and memory occupation are less than 1 / 10 of those of an original method.

The application discloses a head-up display reflection film manufacturing method, and belongs to the field of vehicle display. The head-up display reflection film is manufactured through the steps of preparing a reflection layer, calculating compensation layer parameters, preparing a compensation layer, and forming a head-up display reflection film, etc. The head-up display reflection film reflects the light beam generated by the display device which is incident at Brewster's angle in the vehicle, so that the light beam energy forming ghost image is small, and the ghost image is eliminated. The head-up display reflection film only reflects right-handed circularly polarized light with a wavelength close to the working wavelength of the display device for the outside natural light, and transmits the natural light with other wavelengths and polarization directions, so that the head-up display reflection film has high reflectivity and high transmittance.

The invention discloses a ghosting-free waveguide type head-up display system and a ghosting-free imaging method, and belongs to the technical field of vehicle-mounted display. The system comprises an image generation module, a collimation optical system, a waveguide assembly and a vehicle windshield. The HUD light emitted by the waveguide assembly only contains the P polarization component and is emitted to the glass surface at the incidence angle close to the Brewster angle of the windshield, and the characteristic that the reflectivity of the first surface approaches zero when the P polarization light is emitted at the Brewster angle is utilized, so that an HUD image is only reflected by the second surface to form a single virtual image; therefore, the ghosting problem caused by double reflection of the front surface and the rear surface in the traditional HUD is thoroughly eliminated. According to the system, a wedge-shaped windshield is not needed, the manufacturing complexity and cost are reduced, meanwhile, the waveguide technology is combined to achieve compact structure and large-view-field display, and the imaging definition and the driving safety are remarkably improved.

Proposed concepts thus aim to provide schemes, solutions, concepts, designs, methods and systems pertaining to detecting the presence of a mirror. In particular, embodiments aim to provide a system for detecting the presence of a mirror by analysing measured polarised light. This is because shiny surfaces, e.g., mirrors, will polarise unpolarised light if they hit the mirror at or close to Brewster's angle. The presence of polarised light can thus be used to infer the presence of a mirror. In other words, it is proposed that by measuring incoming light of at least one polarity (i.e., at least light polarised in a certain direction), the presence of a mirror can be detected. This is because mirrors are capable of polarising unpolarised light from natural light or room lights, and thus the presence of polarised light can be used to detect the presence of a mirror.

The present invention relates to a preparation method and an operating method of a trigonal nonlinear optical crystal frequency conversion device. The frequency conversion device has a first group of parallel surfaces and a second group of parallel surfaces. The first group of parallel surfaces is parallel to the c-axis and the a-axis of the optical crystal. The normal of the second group of parallel surfaces forms an angle α with the c-axis, and the projection of the normal on the a-b surface and the a-axis forms an angle β. The relationship θ is shown in Formula 1 and Formula 2. PM The nonlinear optical crystal satisfies the phase matching angle between the incident fundamental frequency light and the outgoing frequency-converted light, θ B =arctann, where n is the Brewster angle, and n is the refractive index of the nonlinear optical crystal corresponding to the incident fundamental frequency light. The second set of parallel surfaces constitute the light-transmitting input and output surfaces of the frequency converter. The present invention provides a method for preparing and operating a nonlinear optical crystal frequency converter device based on a thin sheet-like primary crystal, having a maximum possible light-transmitting length and suitable for continuous-wave applications.

The invention relates to a wide-spectrum mid-infrared polarization separation device and a preparation method and application thereof.The wide-spectrum mid-infrared polarization separation device comprises a first reflector and at least two second reflectors based on silicon carbide crystals, and the reflecting face of the first reflector is arranged relative to an incident beam and the reflecting face of at least one second reflector; the incident angle of the first reflector relative to the second reflectors is adjustable, the two adjacent second reflectors are arranged at intervals according to a preset Brewster angle, and the incident beam is separated into TE polarized light and TM polarized light. The polarization separation device has the advantages of being simple in structure, convenient to install and capable of achieving efficient and low-loss polarization separation in a wide-spectrum middle-infrared band, and the preparation method has the advantages of being low in production cost, high in yield and suitable for mass production. The polarization separation device overcomes the problems of narrow working bandwidth, lower damage threshold, higher cost and the like of the traditional polarization element, and can be widely applied to the fields of thermal imaging, molecular spectrum, free space communication and the like.

The application relates to the technical field of tube cover closure detection, and discloses a visual recognition-based ultrafiltration centrifuge tube cover closure integrity detection method, which comprises the following steps: collecting basic polarization data, performing polarization heterogeneity preliminary screening, collecting geometric and full Stokes data, performing curved surface geometric artifact correction, collecting topography and multi-scale texture data, performing elastic deformation compensation, and performing multi-scale texture arbitration. The visual recognition-based ultrafiltration centrifuge tube cover closure integrity detection method realizes rapid non-contact detection and efficient preliminary screening of the tube cover closure state, eliminates the interference of Brewster angle artifacts caused by complex curved surfaces, significantly reduces the geometric misjudgment rate, compensates for the micro-deformation interference caused by clamping and temperature, enhances the adaptability of the system to changes in the production line working conditions, accurately identifies the mold parting line and the real closed gap, fundamentally solves the problems of overkill and missed detection, and comprehensively improves the reliability and accuracy of the ultrafiltration centrifuge tube cover closure integrity detection.

A half-wave plate and a focusing lens are sequentially arranged on an output light path of an infrared laser with adjustable pulse width, the focusing lens is connected with a frequency doubling crystal, the frequency doubling crystal is connected with a frequency tripling crystal, an output end face of the frequency tripling crystal is cut into a Brewster angle, and the output end face of the frequency tripling crystal is connected with an infrared laser. The output infrared laser is shielded by the infrared light blocking block after being transmitted in the space, the output green laser is shielded by the green light blocking block after being transmitted in the space, the frequency tripling crystal is connected with the imaging lens, the imaging lens is connected with the input surface of the wedge-shaped lens, and the input surface of the wedge-shaped lens is cut into a Brewster angle. Through fine adjustment of the distance between the imaging lens and the frequency tripling crystal and the distance between the wedge-shaped lens and the imaging lens, the ultraviolet laser output by the wedge-shaped lens becomes circular and is output. The Brewster angle output surface of the frequency tripling crystal reduces the ultraviolet damage probability and separates infrared light, green light and ultraviolet light. The position of the imaging lens is finely adjusted to compensate a light spot ellipse caused by a walk-off effect during frequency doubling.

The present application relates to the technical field of tidal creek geomorphology monitoring, and particularly relates to a tidal creek geomorphology monitoring method based on airborne adaptive polarization hyperspectrum, which comprises the following steps: obtaining initial hyperspectrum data flow and establishing a water body index matrix; monitoring the spatial difference gradient of the matrix, and calibrating the detection field of view to enter the shallow water and wet silt mixed zone when detecting that the adjacent pixels produce numerical jump; calculating two limit phase points constituted by the pure water surface and the pure wet silt theoretical extinction angle according to the calculated double Brewster angle difference, driving the polaroid to complete micro-step reciprocating switching within the single imaging integration time; guiding the incident light beam to alternately strip the contained water surface and silt surface glare through the switching action, and generating photoelectric signals by using high and low gain double channels; and using adaptive threshold to carry out pixel-level reconstruction, and outputting a wide dynamic hyperspectrum data cube which eliminates data saturation and shows the spectral characteristics of the water body bottom sediments and microalgae.

The invention discloses a mid-infrared ultrafast laser for additive manufacturing, which is characterized in that a pumping source unit adopts a dual-wavelength semiconductor laser array and is connected to a gain medium unit through an optical fiber coupler, the gain medium unit adopts disordered crystals regulated and controlled by local coordination, rare earth ions are doped to destroy lattice symmetry and broaden an emission spectrum, and the gain medium unit is connected to a laser source unit through an optical fiber coupler. And meanwhile, 45-degree Brewster angle cutting and a water-cooled holder are adopted, so that the thermal lens effect is reduced. And the nonlinear broadening unit comprises a distributed Kerr medium group and a non-collinear light path layout, so that the problem of insufficient self-phase modulation efficiency of the mid-infrared crystal is solved, and effective spectrum broadening is realized. The pulse compression unit is composed of a chirp mirror pair and a fused quartz prism pair, and compresses the broadened spectrum to ultra-short pulses of 50-100 fs. The industrial adaptation unit integrates an acousto-optic deflector and an F-theta lens, closed-loop control is achieved through an EtherCAT industrial bus, and it is ensured that laser accurately acts on an additive manufacturing workpiece.

The present invention relates to a trigonal nonlinear optical crystal frequency conversion device, wherein the frequency conversion device comprises a first group of parallel surfaces and a second group of parallel surfaces, wherein the first group of parallel surfaces is parallel to the c-axis of the optical crystal and forms a first angle β with the a-axis, and the second group of parallel surfaces is perpendicular to the first group of parallel surfaces and the normal of the second group of parallel surfaces forms a second angle α with the c-axis of the optical crystal, and the second angle α and the first angle β have a relationship θ shown in equations 1 and 2. PM The nonlinear optical crystal satisfies the phase matching angle between the incident fundamental frequency light and the outgoing frequency-converted light, θ B =arctann, where n is the Brewster angle, and n is the refractive index of the nonlinear optical crystal corresponding to the incident fundamental frequency light. The second set of parallel surfaces constitute the light-transmitting input and output surfaces of the frequency converter. The present invention provides a method for fabricating a nonlinear optical crystal frequency converter device suitable for continuous-wave applications, having a maximum possible light-transmitting length, based on a thin sheet-like primary crystal.