1707 results about "Optical pathlength" patented technology

The invention discloses a heat shrink tube detection method based on image recognition, particularly relates to the technical field of electric power material defect detection, and is used for solving the problems of defect contour distortion, positioning deviation and insufficient classification precision caused by optical ghost interference in heat shrink tube detection. A mapping relation of light refraction paths is established based on brightness gradient difference and refractive index difference, theoretical ghost interference fringes are generated by dynamically adjusting optical path difference of an interferometer, and abnormal areas deviating from theoretical distribution are screened; meanwhile, light source incident angle optimization and defect displacement calculation are combined, residual ghost interference is eliminated, finally, accurate classification and positioning of defects are achieved through multi-dimensional matching of geometric parameters and historical defect data, complex algorithm dependence is reduced while the detection precision is improved, and the real-time detection requirement of an industrial production line is met.

The invention discloses a vehicle-mounted holder laser telemetering scanning type gas leakage positioning system, and relates to the technical field of gas leakage monitoring. The vehicle-mounted pan-tilt laser telemetering scanning type gas leakage positioning system comprises a data acquisition unit for acquiring laser absorption second harmonic signal intensity of an inspection vehicle on a set route; the concentration inversion processing unit is used for inverting the gas concentration on the basis of the signal; the concentration analysis unit is used for identifying an abnormal inspection point by comparing the concentration change rate; the leakage direction analysis unit is used for predicting the leakage direction by combining wind direction concentration data; according to the invention, a signal saturation upper limit value and an optical path length value are introduced to carry out normalization processing, concentration inversion calibration is carried out in combination with a gas absorption coefficient, independent calculation is carried out at each inspection position point, and the accuracy of the inspection is greatly improved by combining remote measurement concentration distribution data, image data and a leakage position analysis unit for accurately positioning a leakage point in combination with a gas diffusion model. And continuous, dynamic and high-precision concentration distribution reconstruction in space is realized.

The invention relates to the cross technical field of atmospheric science and communication technology, in particular to an atmospheric refraction and waveguide environmental parameter detection and prediction method and device, and the method comprises the following steps: carrying out the power distribution of a light beam of a broadband light source through employing a light splitting element based on the emission of the broadband light source, and forming a detection light beam and a reference light beam, and guiding the detection light beam to pass through a preset open atmosphere optical path, and guiding the reference light beam to pass through a known refractive index stabilizing medium or a vacuum pipeline. The detection light beam and the reference light beam are formed through light splitting of the broadband light source, the detection light beam penetrates through the open atmosphere path, the reference light beam passes through the stable medium, Fourier transform is carried out on interference signals of the two light beams to extract wavelength phase difference mapping data, and tiny optical path change caused by atmospheric refractive index disturbance can be captured. Compared with the traditional single-point or single-path measurement, the sensing sensitivity and the measurement dimension of the atmospheric refractive index spatial nonuniformity are improved by using the broadband spectral information.

The invention provides a container multi-angle imaging quality detection method and system, and the method comprises the steps: carrying out the illumination and imaging of a target container from a plurality of preset visual angles through employing light sources with different wavelengths, and obtaining a refraction displacement fingerprint data set; carrying out regional division on the surface of the container according to the data set, calculating the refraction influence degree of each region under different visual angles, and generating a regional visual angle weight distribution diagram; performing optical path reverse tracking processing on the images acquired at each view angle by using the distribution map, constructing a light propagation path model, and performing position mapping and distortion compensation to obtain a corrected image; and finally, according to the corrected image and the regional view angle weight distribution diagram, defect detection is carried out by adopting a regional adaptive fusion algorithm. According to the method, through technical means such as region adaptive division, optical path reverse tracking and region adaptive fusion, multi-view images can be accurately aligned and fused, meanwhile, observation characteristics of different regions are considered, and the reliability of a defect detection result is ensured.

The invention relates to an error compensation method of a birefringence self-calibration laser level meter, in particular to the field of laser level meters, and aims to improve the precision of the laser level meter by combining a birefringence effect, physical modeling and neural network optimization. Firstly, temperature data are collected in real time, Kalman filtering is used for noise reduction, and accurate data are provided for physical modeling; then, through physical constraints such as a heat conduction equation and a Jones matrix, a coupling relation between the temperature gradient and optical parameter changes is established; then, dynamically optimizing the refractive index correction by using a physical information neural network to avoid an overfitting problem; and finally, calculating optical path difference compensation by using a hardware accelerator, correcting a system error in real time, and feeding back and adjusting a network weight. According to the method, the precision and the stability of the laser level meter in an environment with relatively large temperature change are effectively improved.

The invention discloses an optical time stretching sweep frequency interference measurement Doppler effect compensation method and device, and relates to the technical field of non-cooperative target absolute distance measurement. In order to solve the defect that the absolute distance measurement precision is reduced due to the fact that the Doppler effect cannot be efficiently suppressed in a complex environment in the prior art, the technical scheme provided by the invention comprises the following steps: generating a sweep frequency laser signal and splitting the sweep frequency laser signal to form measurement light, reference light and resampling light; performing time stretching processing on the reference light to obtain a chirp signal; performing interference on measurement light and the chirp signal to obtain a measurement interference signal; performing interference on the reference light and the resampling light to obtain a reference interference signal; performing cross-correlation processing on the measurement interference signal and the reference interference signal, and extracting an optical path difference; and carrying out distance calculation by combining the resampling data, and outputting a target distance after the Doppler effect is compensated. The method is suitable for optical measurement work for performing high-precision absolute distance measurement on a non-cooperative target in a tiny vibration or disturbance environment.

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 relates to the technical field of length measurement, and particularly discloses a length measurement device based on laser interference, which comprises a laser measurement module, an air curtain channel module, an air curtain construction module and a channel adjustment module, the laser measuring module is used for transmitting and receiving laser, the optical path difference change is measured according to the interference principle, and the micro length change of the workpiece can be continuously and accurately measured in real time while the machining module carries out machining operation on the workpiece; a linear channel is formed between the laser head and the measuring reflector through the air curtain channel module, inert gas is continuously introduced into the channel through the air curtain construction module, and an air curtain atmosphere with stable laminar flow is formed, so that pollutants and interference factors such as oil mist, dust, cutting fluid splashing and hot air turbulence generated in a machining area are effectively blocked, and the machining precision is improved. Therefore, the measurement light beam is prevented from being interfered by environmental factors in the propagation process.

The invention discloses a high-precision spectral interference signal demodulation method for micro distance measurement. The method comprises the steps of S1, interference spectrum shaping; measuring an interference spectrum and a reference spectrum; selecting a six-item combined cosine window as a primary function of an interference signal to obtain a shaped interference spectrum; s2, performing non-uniform Fourier transform to obtain a frequency spectrum of the target signal; s3, on the basis of a multi-spectral-line interpolation algorithm, interpolation is carried out on the window function to solve a fitting function, and a center frequency k is obtained; and S4, outputting a result. And solving and outputting an optical path difference d. According to the method, a six-item cosine combination window is selected as a primary function of an interference signal, and the problem that the accuracy of signal extraction is influenced by mutual superposition of side lobes and even main lobes of a direct current item and a solved frequency item is solved; an interference spectrum is processed by using a fast non-uniform Fourier transform algorithm, accuracy can still be kept under the conditions that the distance to be measured is increased and sampling is gradually sparse, and the problem of resampling deviation caused by a traditional interpolation method can be solved.

The invention discloses a method and a device for correcting laser focusing aberration in a transparent material, and belongs to the technical field of laser processing. The method comprises the steps that a machining light path containing an object plane, an aspheric reflector and a 4F device is built in Zemax, the surface type of the aspheric reflector is optimized with the minimum focus aberration as the target, and a rise table is derived; an optical path difference and a laser phase are calculated through Matlab, and a phase diagram is generated; and an actual machining light path is built, and a phase diagram is loaded to achieve low-aberration machining. Simulation optimization and phase modulation are combined, aberration caused by refractive index difference is effectively counteracted, wavefront errors are reduced by 58%, the thickness of a machining damage layer is reduced by 70%, the method is suitable for various transparent materials, the machining precision and the material utilization rate are improved, and the method is suitable for high-precision laser machining scenes.

The invention relates to the technical field of real-time rendering, in particular to a real-time light and shadow tracking and rendering system for a virtual reality environment, and the system comprises a light source reachability pre-calculation module which projects a connecting line to a light source to each unit in a three-dimensional grid covering a volume medium based on the scene geometry of the virtual reality environment and the position of the light source. According to the method, the connection line shielding proportion judgment is executed based on the scene geometry and the light source position, the optical path density field data reflecting shielding space distribution is established, and the density representation of illumination reachability is constructed on the voxel level, so that the subsequent light path propulsion has the density sensing capability, and the recognition precision of the complex shielding structure is enhanced. And extracting a normal gradient in the G-Buffer and a brightness variance of a previous frame, fusing an inter-frame geometric boundary change and a brightness fluctuation behavior, constructing a pixel-level feature intensity value set, and writing the pixel-level feature intensity value set into a two-dimensional map for guiding subsequent sampling density regulation and control and realizing local response of cross-frame dynamic information.

The invention provides a rapid evaluation method and system for the soil fertility level, and relates to the technical field of soil fertility detection.The rapid evaluation method comprises the steps that an original absorbance spectral data curve is obtained by scanning a soil sample, the moisture peak absorbance, the actual peak position wavelength and the moisture synthetic frequency characteristic peak width are extracted, and a spectral data basis is provided; a water-salt optical path coupling factor is calculated, water-salt correction operation is carried out in combination with a volume correction coefficient, a virtual dry soil spectrum data curve is obtained, interference of salt on a water optical path is quantified, and a water background and salt masking are eliminated; constructing a characteristic virtual baseline of the organic matter and the total nitrogen, calculating an integral area to obtain characteristic intensity of the organic matter and the total nitrogen, and providing a physical input variable for quantitative inversion; introducing a water-salt optical path coupling factor to invert the organic matter content and the total nitrogen content, and correcting signal depression caused by salt stress; the effective fertility index is calculated and graded by combining the organic matter content and the total nitrogen content of the soil, and the actual fertilizer supply capacity of the soil is comprehensively evaluated.

The invention relates to the technical field of image processing, in particular to an optical thin film quality detection method based on image processing, which comprises the following steps: S101, acquiring a transient light field image sequence of an optical thin film in a dynamic stress field; s102, performing spectral analysis on the brightness time sequence of each pixel point, extracting a dominant frequency component as a brightness oscillation period, processing time domain fluctuation data by adopting a Fourier transform algorithm, and calculating a local optical path difference variation based on the brightness oscillation period of each pixel point in the image sequence; and S103, projecting the phase distortion field to a preset film elastic modulus distribution model, establishing a phase distortion-stress distribution-defect mapping relation, and identifying a modulus mutation region. A dynamic stress field is generated through the synergistic effect of mechanical vibration and thermal radiation, remarkable stress concentration can be generated at the micro-defect position, the deformation difference of the micro-defect is amplified, and therefore the sensitivity of defect detection is improved.

The invention discloses a phytoplankton primary productivity in-situ fluorescence detection device and method, and belongs to the technical field of aquatic ecology monitoring. The device adopts a modular integrated design and comprises a multi-band LED excitation light source, a laser induction module, a photomultiplier receiving system and an anti-vibration circuit structure, and synchronous detection of chlorophyll concentration and photosynthetic activity is realized through a short-optical-path optical design. The method is based on spectrum inversion and fluorescence kinetic analysis, a standard spectrum library is constructed, chlorophyll concentration distribution and photosynthetic parameters are calculated through least square fitting, and primary productivity data are output in combination with a photoresponse model. The device has the diameter of 67 mm, supports deployment of Argo and other mobile platforms, solves the problems that a traditional method is poor in timeliness and equipment is discrete, and has the advantages of being high in detection efficiency, high in anti-interference performance and wide in applicable water depth range.

The invention is suitable for the technical field of optical measurement, and provides a back drill stub length detection method, a signal processing assembly and a system. The method for detecting the length of the back drill stump comprises the steps that the optical path difference between first reflected light and second reflected light is obtained, the first reflected light is reflected light generated by reflecting an incident light beam of a back drill hole to be detected on the surface of a dielectric layer of the back drill hole to be detected, and the second reflected light is reflected light generated by reflecting the incident light beam of the back drill hole to be detected; the second reflected light is reflected light obtained by reflecting a light beam, passing through the dielectric layer, of the incident light beam by the signal layer of the back drilling hole to be detected; and according to the optical path difference and the refractive index of the dielectric layer, determining the stub length of the back drilling hole to be measured. According to the embodiment of the invention, the same incident light beam can be reflected by different layers of the back drilling hole to be detected, the stub length is determined based on the optical path difference between the two reflected light beams, and the detection efficiency is improved.

A laser processing apparatus includes a laser oscillator that oscillates processing laser light to be incident on a processing point on a processing surface of a workpiece, a coupling mirror that deflects or transmits the processing laser light and measurement light to be incident on the processing point toward the processing point, a measurement light deflection unit that changes an incident angle of the measurement light on the coupling mirror, a lens that concentrates the processing laser light and the measurement light on the processing point, a controller that controls the laser oscillator and the measurement light deflection unit, a measurement processor that measures a depth of a keyhole generated at the processing point by the processing laser light by using an optical interference signal based on an interference generated by an optical path difference between the measurement light reflected at the processing point and reference light, and a beam position measurement unit that measures positions of the processing laser light and the measurement light.

The invention discloses a dynamic leaching-spectrophotometric detection method for the release rate of nutrients in a slow-release fertilizer, and relates to the field of agrochemical analys.The detection method comprises the following steps that S1, a slow-release fertilizer sample is placed in a leaching column to be leached, and leachate is collected; s2, sequentially adding a masking agent solution and a chromogenic reagent into the leachate, and carrying out chromogenic reaction; s3, pumping the solution into a double-optical-path flow cell, and measuring absorbance values under a target nutrient characteristic absorption wavelength and a background interference characteristic wavelength; s4, calculating the corrected net absorbance; and S5, calculating the nutrient concentration, and drawing a nutrient release kinetic curve. By adopting a dual-wavelength synchronous detection and real-time dynamic subtraction correction algorithm, the method can eliminate system errors of time-varying background chromaticity, so that accurate and reliable absorbance readings can be obtained at the initial stage of nutrient release even if the nutrient concentration in the leachate is very low, thereby ensuring the authenticity of the initial stage of a release curve and improving the accuracy of nutrient release. And initial release kinetic parameters are accurately captured.

A self-calibrating hybrid spectrophotometer comprises a receptacle for receiving the cuvette, first and second optodes that are configured to permit light to enter the cuvette, third and fourth optodes that are configured to permit light to leave the cuvette, and a controller that is configured to control delivery of light to one of the first and second optodes. Light entering one of the first and second optodes is received at the third and fourth optodes after having interacted with the turbid sample along different paths having different lengths. Measurements made at the third and fourth optodes in response to having illuminated both the first and second source optodes provide two slopes of optical transmittance as a function of path length. The spectrophotometer uses these slopes to identify a slope that is indicative of the absorption coefficient and the reduced scattering coefficient of the sample.

The invention relates to the technical field of medical image information processing, discloses an ICG fluorescence image and MRCP three-dimensional model registration fusion display method and system, effectively solves the problems of deep biliary tract structure blurring and form distortion caused by liver tissue scattering effect in intraoperative fluorescence imaging, uses a preoperative model as anatomical prior, and improves the accuracy of the intraoperative fluorescence imaging. A viewpoint correlation optical path depth field is constructed through reverse ray tracing, a spatial variation point spread function is generated accordingly, physical reverse recovery of scattering halo in a fluorescence image is achieved, non-specific background noise such as vascular leakage is effectively inhibited in combination with topological gravitational constraint of a central skeleton, and the detection accuracy is improved. The real pipe diameter and the center line position of the deep bile duct are accurately recovered, non-rigid registration correction is performed on the three-dimensional model based on the recovered high-fidelity image, and projection errors caused by respiratory movement and soft tissue deformation are eliminated.

The invention relates to a self-coherence optical fiber interference device and method for simultaneously measuring morphology and thickness. The device comprises a light source module (1), a measurement light path (2), a compensation light path (3), a spectrograph (4), a mechanical motion module (6) and a data processing module (5), the measuring light path (2) comprises an optical fiber circulator (21), an optical fiber retroreflector (22) and an optical probe (23) and is used for realizing focusing measurement and enabling reflected light of the end face of the optical fiber retroreflector (22) and reflected light of a transparent object to be measured to return; reflected light of the end face of the optical fiber retroreflector (2) and reflected light of the transparent object to be measured form a measuring light beam, and the measuring light beam enters the compensation light path (3); the compensation light path (3) comprises an optical fiber splitter (31), an optical fiber delay line (32) and an optical fiber coupler (33), the measuring light beam is subjected to optical path compensation to generate a compensation light beam, and the compensation light beam and the measuring light beam are combined and input into the spectrograph (4) together.

The invention relates to the technical field of water environment remote sensing monitoring, solves the technical problem of systematic overestimation or underestimation under the condition of algae bloom outbreak or strong stratification due to the fact that a water body is regarded as an optical uniform monolayer parameter in a traditional method, and particularly relates to a stratified light field correction chlorophyll-a remote sensing inversion method and system for an eutrophic lake. Performing vertical type identification and three-layer layering by using multispectral / hyperspectral remote sensing reflectivity, a synchronous chlorophyll-a vertical profile and a diffusion attenuation coefficient, calculating light field weight and light path weighted concentration of each layer, constructing a layered light field correction coefficient, performing layered light field correction on the remote sensing reflectivity, and establishing an empirical chlorophyll-a inversion relationship; and generating a chlorophyll-a spatial distribution map and an algae bloom risk map. According to the method, the layered light field correction coefficient with clear physical significance is constructed to correct the water surface remote sensing reflectivity, so that the inversion precision and robustness under strong layering and complex optical conditions are improved.

The invention discloses a nano-pillar array NaKSb photoelectric cathode for enhancing light absorption, which is characterized in that through the design of a double-layer TiOtwo-dimensional nano grating and a nano-pillar array structured NaKSb photoelectric cathode layer, the optical path of light with the wave band of 450-900 nm in the photoelectric cathode is increased under the condition that the thickness of the NaKSb photoelectric cathode is not increased, the reflectivity of the wave band of 400-600 nm is reduced, and the light absorption of the NaKSb photoelectric cathode is enhanced. The absorption rate at 400-1000 nm is improved by 32.28% compared with that of a traditional planar film type photoelectric cathode, the absorption rate at 800-1000 nm near-infrared band is improved by 40.27% compared with that of the traditional planar film type photoelectric cathode, the problem that the absorption of the traditional planar film type photoelectric cathode near-infrared band is insufficient is solved, and the photoelectric cathode is suitable for high-performance low-light night vision imaging devices.

The invention discloses an automobile part location degree measuring method and device, a product and a storage medium, and relates to the field of electrical digital data processing.The method comprises the steps that three-dimensional contour coordinates of a plastic surface layer are determined based on surface reflected light intensity data, and the optical path difference of laser from the plastic surface to a metal insert is calculated according to internal refracted light intensity data; calculating the depth position of the metal insert according to the optical path difference and the refractive index of the plastic material; determining the spatial position relation of the metal insert structure relative to the plastic surface layer by combining the three-dimensional contour coordinate and the depth position; calculating an actual assembly deviation value between the spatial position relation and the standard assembly position; when the actual assembly deviation value is greater than a preset first threshold value, selecting a preset laser wavelength combination according to the actual assembly deviation value; and scanning the automobile part according to the preset laser wavelength combination to obtain a location degree measurement result. By implementing the method, the measurement precision of the metal insert in the automobile part can be improved.

The invention relates to the technical field of optical precision measurement, in particular to an ultra-high time resolution camera time characteristic detection device and method, and the device comprises a laser source which is used for generating pulse laser; the polarization modulation element is arranged on an emergent light path of the laser source and is used for modulating the pulse laser into circularly polarized light; the spectroscope is arranged on an emergent light path of the polarization modulation element and is used for decomposing the circularly polarized light into a first linearly polarized light beam and a second linearly polarized light beam; the first optical path unit is used for guiding the first linearly polarized light beam to the cylindrical optical element along a fixed optical path; the second optical path unit is used for adjusting the optical path of the second linearly polarized light beam and guiding the second linearly polarized light beam to the cylindrical optical element; and the cylindrical optical element is used for receiving the first linearly polarized light beam and the second linearly polarized light beam and respectively projecting the first linearly polarized light beam and the second linearly polarized light beam to an imaging surface of a camera to be detected to form two spatially separated light spots. The objective of the invention is to improve camera time characteristic calibration precision and efficiency.

The invention discloses a wide-spectrum interference weak signal enhancement method for high aspect ratio micro-nano structure measurement, and relates to the technical field of semiconductor measurement. The method comprises the following steps: acquiring a wide-spectrum interferogram, and performing two-layer two-dimensional discrete wavelet transform to obtain a first-stage wavelet coefficient group; performing nonlinear enhancement on the wavelet coefficient, and outputting a nonlinear enhanced wide-spectrum interferogram; performing three-layer two-dimensional discrete wavelet transform on the wide-spectrum interferogram after nonlinear enhancement to obtain a second-stage wavelet coefficient group, and calculating a Bayesian threshold value; a neighborhood sliding window function is set, and a Bayesian threshold is combined to carry out local denoising enhancement on the second-stage wavelet coefficient; reconstructing the second-stage wavelet coefficient after local de-noising enhancement to obtain a wide-spectrum interference pattern after local de-noising enhancement; and determining an optical path position by adopting an improved gravity center method according to the wide-spectrum interferogram after local denoising enhancement, and calculating a depth value of the to-be-measured sample. According to the method, the stripe contrast is enhanced, the noise is suppressed, and the depth measurement capability is improved at the same time.

The invention relates to the technical field of laser precision machining, and discloses a laser precision machining device and method for dynamically adjusting beam shaping based on light field imaging, and the device comprises a laser emission unit, an X-axis movable laser reflector, an X-axis and Y-axis movable laser reflector, a dynamic shaping module and a focusing galvanometer system. The laser emitting unit, the X-axis movable laser reflecting mirror, the X-axis and Y-axis movable laser reflecting mirror, the dynamic shaping module and the focusing galvanometer system are all fixed to a support at the top of the supporting table. According to the invention, based on a specially designed laser, laser beam phase space distribution is adjusted by using a variable optical path to realize beam shaping, a laser beam can be changed into a rectangular flat-topped light spot, and the size of the rectangular light spot is adjusted through the size of the optical path. And the focal length of the laser beam and the size of the flat-topped light spot can be dynamically adjusted, and uniform machining on microelectronic device packaging, wafer surfaces and optical element surfaces is achieved.

A zero-optical-path-difference double-frequency heterodyne grating ruler comprises a light source, a signal detecting and processing system, a polarization splitting prism, a first quarter-wave plate, a rectangular prism, a second quarter-wave plate, a third quarter-wave plate, a total reflection mirror, a long-strip prism, a reference grating and a 45-degree-placed polaroid. The two measuring light paths of the system always keep zero optical path difference, so that the measuring precision can be ensured, and the environmental stability of the system is also remarkably improved. And a high-precision and high-robustness measurement scheme is provided for precision equipment such as a photoetching machine and a precision motion platform.

According to the open pit coal mine methane emission monitoring equipment, the pretreatment device, the sampling air pump and the CH4 analyzer are arranged through the mounting column, and the stability of the mounting column is ensured through the base of the triangular structure support. The pretreatment device is a three-stage progressive filtering unit, dust and steam in the open pit coal mine gas can be removed, and the obtained sample gas can be cleaner and drier and is appropriate in temperature. By utilizing suction force generated by the sampling air pump, air enters an optical cavity of the CH4 analyzer after being treated by the pretreatment device. The CH4 analyzer further comprises a laser and a CH4 optical analysis module, the laser emits a laser beam with a specific wavelength to the optical cavity, and multiple reflections are formed in the optical cavity, so that the effective optical path of the laser beam reaches a preset range; the CH4 optical analysis module measures the concentration of methane in the sample gas by detecting the light intensity change of the laser beam after the laser beam passes through the optical cavity containing the sample gas. According to the scheme, the methane emission condition of the open pit coal mine can be accurately monitored.

The invention discloses a two-photon interference method. A built two-photon interference system comprises a light source device, a first adjusting branch, a second adjusting branch, a coupling device and a detection device. The light source device is capable of outputting a first single-photon signal and a second single-photon signal. Based on the established two-photon interference system, the optical path of a second single-photon signal can be adjusted through a second adjusting branch, and the polarization state of a first single-photon signal can be adjusted through a first adjusting branch, so that the two single-photon signals meet interference conditions, and the coincidence counting rate of two beams of optical signals output by a coupling device can be obtained through a detection device. And two-photon interference can be simply and quickly realized.

The invention relates to the technical field of optical detection, in particular to an asymmetric spherical cylindrical surface optical multi-pass cell and a calculation method thereof. The invention provides an asymmetric spherical and cylindrical surface optical multi-pass pool, which comprises a spherical reflector and a cylindrical reflector, and the spherical reflector and the cylindrical reflector are both concave reflection, are oppositely arranged and are coaxial; at least one of the two reflectors is provided with a light hole. According to the invention, Lissajous light spot pattern distribution can be realized without rotating the reflector, the utilization rate of the mirror surface is high, and long optical path can be realized. And the relative rotation angle of the two reflectors in the optical axis direction can be kept, the stability of light spot patterns is guaranteed, namely the stability of the light reflection and propagation space path is guaranteed, and therefore the light absorption efficiency is improved.