35 results about "Depolarization ratio" patented technology

The invention discloses a sea surface oil spilling detection method of a complete polarization synthetic aperture radar (SAR). The method comprises the following steps of: carrying out adaptive threshold value segmentation on a complete polarization SAR image to obtain complete polarization SAR images getting rid of the sea surface; selecting a training sample and a testing sample from the complete polarization SAR images getting rid of the sea surface; training an SVM (Support Vector Machine) detector, and normalizing polarization characteristic vectors of the detector, which comprise a scattering entropy H, a scattering angle alpha, a negative entropy A, a co-polarization ratio gamma, a cross polarization ratio eta, a depolarization ratio delta, a co-polarization phase difference phi HH-VV and a cross polarization phase difference phi HH-VV; and finally, detecting and identifying spilled oil and suspected objects by using the SVM and outputting a detection result. The method has thecharacteristics of high detection speed and low false alarm rate and is suitable for the sea surface oil spilling detection of the SAR.

The invention relates to a comprehensive polarization measuring device of argon fluoride (ArF) laser optical thin film elements. An ArF excimer laser, an ArF excimer laser beam expanding and collimating device, an iris diaphragm, a polarizer, a beam splitter and a sample platform of the comprehensive polarization measuring device are placed in sequence along a main optical axis; a reference lightpolarization detecting device is positioned on a reflected light path of the beam splitter; the sample platform is positioned on a transmission light path of the beam splitter; a transmission light polarization measuring device is fixedly mounted on a first rotatable supporting arm; a reflected light polarization detecting device is fixedly mounted on a second rotatable supporting arm; the sampleplatform, the first rotatable supporting arm and the second rotatable supporting arm are positioned in the same plane and are provided with the same rotation center; and the rotation center is positioned on the main optical axis. By adopting the comprehensive polarization measuring device, the polarization reflectivity, the transmissivity, the reflection depolarization ratio and the transmission depolarization ratio of the optical thin film elements in different shapes, which are positioned at different incidence angles, can be measured at the same time, and thereby the need of various ArF laser optical thin film elements on polarization performance assessment can be met to the maximum limit.

The invention discloses a time division multiplexing based single-detector all-fiber polarization lidar. The lidar adopts all-fiber link, utilizes a delay fiber to realize time division multiplexing, and uses a single detector to realize simultaneous detection of parallel polarization signals and vertical polarization signals in radar echoes. Detection of atmospheric depolarization ratio is realized with the single detector, and the liar has the advantages of low cost, system stability, relative eye safety, all-fiber link, compact structure and the like.

The invention discloses coherent laser radar for simultaneously detecting atmosphere wind speed and the depolarization ratio. The coherent laser radar mainly comprises a light source emitting module (L), polarization frequency mixing modules (S and P) and a signal processing module 15. Echo signals are divided into S polarization light and P polarization light through polarization beam splitters in the polarization frequency mixing modules (S and P), liner polarization local oscillator light is converted into circular polarization light through a quarter-wave plate, the circular polarization light is divided into S polarization light and P polarization light through the polarization beam splitters, and the S polarization light, the P polarization light and signal light in a corresponding polarization state are subjected to frequency beating. According to the scheme, the utilization rate of the echo signals of the coherent wind measuring laser radar can be increased, and the performance of the coherent wind measuring laser radar can be improved; the signals in different polarization states are measured, the depolarization ratio of aerosol is measured, and detection of the coherent wind measuring laser radar on the condition of the aerosol is achieved.

The invention discloses a cloud particle detecting system and method based on polarization detection. The system comprises a laser transmitting optical unit for generating polarized light, a forward scattering detecting unit and a backward scattering detecting unit, wherein the laser transmitting optical unit generates the polarized light by using a laser diode, a polaroid and a half wave plate; the forward scattering detecting unit is used for judging whether particles are recorded and sizes of cloud particles are obtained; and the depolarization ratio of the scattered light is obtained through the backward scattering detecting unit to determine a phase state of the particles. According to the method, information such as the size and the phase state of the particles is determined by the forward scattering detecting unit and the backward scattering detecting unit jointly, particle size spectrum distribution of cloud droplets and ice crystals is obtained, and then, solid water content and liquid water content in cloud are obtained.

The present invention discloses a coherent laser radar signal processing method based on a GPU. Based on a CUDA (Compute Unified Device Architecture) algorithm of the NVIDIA Corporation, the method employs GPU (Graphic Processing Unit) parallel computation to replace FPGA or DSP operation in a traditional coherent wind lidar, and the CPU is employed to perform storage and further processing of a power spectrum output by the GPU. Compared to a traditional coherent wind lidar, the GPU computation is faster in speed and lower in cost, can achieve real-time wind speed inversion or real-time time-frequency conversion. The power spectrum data is stored to conveniently perform further processing of the data by employing other algorithms to extract more useful information such as atmospheric visibility, an atmospheric depolarization ratio and the like.

The invention discloses an atmosphere laser remote sensing method based on polarization modulation and polarization laser radar. According to the invention, by use of specially designed polarization modulation light signals as detection light, back scattering light of a to-be-detected target includes two paths of orthogonal polarization echo signals and respectively carries carriers and positive first-order sideband signals. Thus, a receiving end detects reflection echoes only by use of a detector. By measuring frequency and power of beat frequency electrical signals in the echo signals, real-time measurement can be performed on wind speed information and depolarization ratio information in the atmosphere simultaneously. The invention discloses a polarization laser radar. Compared with theprior art, by ingeniously designing detection of optical signals, it can be achieved that real-time accurate measurement can be performed on wind speed and depolarization effects of to-be-detected atmosphere; only one set of detectors can be required; and the system structure is quite simple and the achieving cost is quite low.

The invention discloses a calibration method for a polarization laser radar and belongs to the technical field of laser radar calibration. The calibration method for the polarization laser radar is based on the light leakage ratio of a polarization beam splitter (PBS). The calibration method is used for correcting the depolarization ratio of the polarization laser radar. According to the method, the photomultipliers of two channels are exchanged, depolarization ratios under two situations are calculated, so that the gain ratio G of the two photomultipliers is calculated; and the value of a light leakage ratio a is calculated according to the depolarization value of standard atmospheric molecules; and the gain ratio G and the light leakage ratio a are both system constants and will not change due to weather, so that the two calibration constants can be used for correcting a depolarization ratio in subsequent observation. With the method of the invention adopted, the calibration work ofthe polarization laser radar system can be effectively and accurately carried out.

The invention relates to the field of optical systems, and particularly discloses a radar system which is characterized in that a transmitting assembly transmits a path of signal light and a path of local oscillation light, the signal light enters a light guide assembly, the local oscillation light enters a receiving assembly, and the light guide assembly divides one path of the signal light into the receiving assembly and divides the other path of the signal light to be transmitted to the outside. And the light reflected by the outside is guided to enter the receiving assembly. The receiving assembly divides light returned from the outside into first polarization component light and second polarization component light, the first polarization component light and the second polarization component light are mixed with the local oscillation light to obtain a first measurement result and a second measurement result, and the signal light is divided into the first polarization component light and the second polarization component light to obtain a third measurement result and a fourth measurement result correspondingly. And a processing device obtains wind field information of the external atmosphere and obtains depolarization ratio information of the external atmosphere according to the measurement result. According to the invention, atmospheric wind field information and atmospheric depolarization ratio information can be detected at the same time, and the measurement accuracy can be improved.

The invention discloses an optical path system for measuring the forward and backward scattering and depolarization ratio of a single particulate matter. The optical path system comprises an incidentlight collimation and depolarization module, a laser calibration detection module, a single particle scattering module, a backward polarized light detection module, a forward scattered light measurement module and a light splitting lens, the incident light collimation and depolarization module, the light splitting lens, the single particle scattering module and the forward scattered light measurement module are sequentially installed, and the laser calibration detection module and the backward polarized light detection module are oppositely arranged on the opposite faces of the light splittinglens. The optical path system is simple in structure and high in stability, by establishing the reasonable combination of a collimating lens and a condensing lens, the optical path system is reasonably designed, and the optical path system is suitable for being widely applied to the pollutant monitoring of the monitoring stations, so that the detection level of the atmospheric pollutant physicalproperties is greatly improved.

The invention provides a depolarization gain ratio correction method for a laser radar. The method comprises the following steps: (A1) obtaining a vertical component EP(h) and a horizontal component ES(h) of a laser radar echo signal; (A2) obtaining parameters; (A3) analyzing the parameter epsilon(h): if the parameter epsilon(h) is not related to the height h when h is greater than h0, and the h0is the height of the atmospheric boundary layer, entering the step (A5); if the parameter epsilon(h) when h is greater than h0 is related to the height h, executing the step (A4); (A4) adjusting a transmitting light path and a receiving light path of the laser radar, and entering the step (A1); (A5) correcting the depolarization gain ratio k to be the depolarization ratio of the atmospheric molecules when h is greater than h0, wherein epsilon1 is the average value of the parameters when h is greater than h0. The method has the advantages of simplicity, convenience and the like.

The invention provides an optical simulation system and method for characterizing the irregular degree of particulate matter, and relates to the technical field of atmospheric monitoring, and the optical simulation system comprises an incident light module, a scattering measurement cavity and an intensity detection module; the incident light module, the scattering measurement cavity and the intensity detection module are coaxially arranged; and a forward scattered light measurement module and a backward scattered light depolarization ratio measurement module are arranged in the scattering measurement cavity, and the forward scattered light measurement module and the backward scattered light depolarization ratio measurement module are arranged at an angle with the laser emission direction. According to the design, through calculation of a strict T-Matrix optical model, the position of the optical lens is reasonably arranged, and through repeated measurement and calculation in a laboratory, a high instrument signal-to-noise ratio is guaranteed. By establishing a reasonable lens group arrangement sequence and adopting the combination of the collimating lens and the condensing lens, a design target of effectively detecting the irregularity degree of environmental particulate matters in real time is achieved, data are transmitted to a remote monitoring center in real time, and the detection level of the irregularity degree of atmospheric pollutants is improved to a certain extent.