Journals >Journal of Infrared and Millimeter Waves
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2018
Volume: 37 Issue 5
18 Article(s)
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High output power THz quantum cascade lasers and their temperature dependent performance
LIN Tsung-Tse, WANG Ke, WANG Li, and HIRAYAMA Hideki
Quantum cascade lasers (QCLs) are promising high output power semiconductor-based terahertz (THz) sources with narrow linewidths and wide operating frequency. We have grown and fabricated THz-QCLs based on GaAs/AlGaAs superlattices under the guidance of a newly developed simulation tool based on the framework of Non-EqQuantum cascade lasers (QCLs) are promising high output power semiconductor-based terahertz (THz) sources with narrow linewidths and wide operating frequency. We have grown and fabricated THz-QCLs based on GaAs/AlGaAs superlattices under the guidance of a newly developed simulation tool based on the framework of Non-Equilibrium Green's Function (NEGF) method. The latest THz-QCLs demonstrated 270 mW peak power and 2.4 mW average power at 10 K, which is comparable to the highest reported value but with a size of more than 4 times larger than ours. Temperature dependence of the device performance are analyzed through the detailed calculations by using the NEGF method..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 513 (2018)
Preparation of large area and high performance flexible GaInP/GaAs/InGaAs tandem solar cells
ZHANG Meng-Yan, GUO Zhen, SUN Li-Jie, and CHEN Jie
Flexible high-efficiency III-V multijunction solar cells are being developed for use in unmanned Aerial Vehicles (UAVs), wearable devices and space applications. The solar cell epitaxial layers are grown on GaAs substrate by metalorganic chemical vapor deposition (MOCVD) and then are transferred to flexible substrates Flexible high-efficiency III-V multijunction solar cells are being developed for use in unmanned Aerial Vehicles (UAVs), wearable devices and space applications. The solar cell epitaxial layers are grown on GaAs substrate by metalorganic chemical vapor deposition (MOCVD) and then are transferred to flexible substrates by cold-bonding and epitaxial lift-off process (ELO). Through the design of ELO apparatus and a large number of experiments on the optimal parameter, GaAs solar cell structure can be effectively separated from 4-inch GaAs wafer without defects and degradation in performance. Recently, 30 cm2 large area flexible GaInP/GaAs/InGaAs 3-junciton solar cells on 50 μm polyimide film achieved a 1-sun, AM0 conversion efficiency of 31.5% with an open-circuit-voltage of 3.01 V, a short-circuit current-density of 16.8 mA/cm2, and a fill factor of 0.845. By using the very light PI substrate, the unit weight of the solar cell is only 168.5 g/m2 and the specific power is up to 2 530 W/kg..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 518 (2018)
Ultrafast terahertz modulation characteristics of organolead halide perovskite films revealed by time-resolved terahertz spectroscopy
ZHANG Bo, LYU Long-Feng, and SHEN Jing-Ling
Ultrafast terahertz (THz) modulation characteristics of organolead halide perovskite films (CH3NH3PbI3 and CH3NH3PbI3-xClx) were investigated on picosecond time scales using time-resolved THz spectroscopy. Upon photo-excitation, a transient decrease in THz transmission was observed. Compared with CH3NH3PbI3, CH3NH3PbI3Ultrafast terahertz (THz) modulation characteristics of organolead halide perovskite films (CH3NH3PbI3 and CH3NH3PbI3-xClx) were investigated on picosecond time scales using time-resolved THz spectroscopy. Upon photo-excitation, a transient decrease in THz transmission was observed. Compared with CH3NH3PbI3, CH3NH3PbI3-xClx showed a better modulation depth (10%) within the range of the photo-excitation powers used. The mechanism underpinning this photoconductive ultrafast response was determined by measuring the transmission properties and calculating the carrier density. The larger crystalline bulk of the CH3NH3PbI3-xClx film produced higher carrier densities than the CH3NH3PbI3 film. These results demonstrate that CH3NH3PbI3-xClx films are promising materials for developing high-performance THz modulators and ultrafast switchable THz photoelectric devices..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 523 (2018)
Minimization design of guard ring size of p-well/DNW single photon avalanche diode
YANG Hong-Jiao, and JIN Xiang-Liang
In order to further diminish the size of SPAD detector, the guard ring size of p-well/DNW (deep n-well) SPAD was designed based on a 0.18 μm CMOS Image Sensor (CIS) technology and SPADs of varied guard ring sizes were fabricated. The measured results show that, the guard ring with its size decreased to 0.4 μm is still In order to further diminish the size of SPAD detector, the guard ring size of p-well/DNW (deep n-well) SPAD was designed based on a 0.18 μm CMOS Image Sensor (CIS) technology and SPADs of varied guard ring sizes were fabricated. The measured results show that, the guard ring with its size decreased to 0.4 μm is still effective in preventing premature edge breakdown (PEB), and the guard ring size does not have a significant impact on the dark count rate (DCR) and the photon detection probability (PDP) of p-well/DNW SPADs. The SPADs achieve a low DCR and a broad spectral response, and the DCR is 638 Hz at 25℃ with a PDP peak of 16% at 530 nm for 20 μm diameter active area structure..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 527 (2018)
Enhance absorption based on the resonance of localized surface plasmon modes in a metamaterial absorber
ZHANG Zhen-Ya, LIU Xiao-Li, and WEN Xiao-Dong
In this paper, we present a single peak absorption characteristic of high performance metamaterial absorber in 150~165 THz region. The designed absorber contains two arrays: a dual metallic particles array and a dual air holes array. The damping constant of metal layer is optimized in simulations. It is found that the In this paper, we present a single peak absorption characteristic of high performance metamaterial absorber in 150~165 THz region. The designed absorber contains two arrays: a dual metallic particles array and a dual air holes array. The damping constant of metal layer is optimized in simulations. It is found that the maximum absorption rate 96% can be obtained when using 2.3 times of damping constant in simulations. The absorption peak is excited by the localized surface plasmon (LSP) modes resonance. In order to reveal the resonant electromagnetic mechanism and research the effects of structural parameters variations on the resonant absorption peak, two sets of simulations were carried out. It was found that with increasing the vertical distance V, the absorption peak is enhanced and a new absorption band is achieved when V = 160 nm. In the second simulations, for the increase in horizontal distance H, the absorption peak is also enhanced and another new absorption band is achieved when H=190 nm. Electric field intensity distribution results show the excitation of LSP modes and the coupling effect between LSP modes lead to the absorption peak enhanced phenomenon..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 533 (2018)
On board adaptation of temperature of the FY-4 meteorological satellite radiation imager
WANG Gan-Quan, SHEN Xia, WANG Wei-Cheng, WANG Bao-Yong, and HU Bing-Ting
FY-4 is a geostationary three-axis stable platform meteorological satellite. The radiation imager loaded on it is affected by the dramatic daily and periodic changes of the external heat flow. The temperature of key components such as the scanning mechanism and the main optical system fluctuates over 40°C per day.FY-4 is a geostationary three-axis stable platform meteorological satellite. The radiation imager loaded on it is affected by the dramatic daily and periodic changes of the external heat flow. The temperature of key components such as the scanning mechanism and the main optical system fluctuates over 40°C per day. How the optical and supporting structures adapt to severe environmental temperature changes and ensure good image quality is an international problem in the design of remote sensing instrument systems for geostationary triaxial stabilization platforms. The matching design of various materials and the adoption of appropriate supporting structure forms are good strategies to avoid and reduce the deformation of the optical machine and the degradation of imaging quality caused by large temperature fluctuations. The on-orbit data indicates that the radiation imager overcomes the adverse effects of large temperature difference between day and night. The diffuse plaques of sensitive stars cover only one pixel, and the noon and midnight results are not much different..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 540 (2018)
Channel selection of atmosphere vertical sounder (GIIRS) onboard the FY-4A geostationary satellite
YANG Yu-Han, YIN Qiu, and SHU Jiong
Channel selection experiments for the retrieval of temperature have been carried out using the data obtained by GIIRS (the hyperspectral vertical detector equipped on the FY-4A geostationary satellite). According to information capacity, using line-by-line radiative transfer model, channels are selected by step-by-stepChannel selection experiments for the retrieval of temperature have been carried out using the data obtained by GIIRS (the hyperspectral vertical detector equipped on the FY-4A geostationary satellite). According to information capacity, using line-by-line radiative transfer model, channels are selected by step-by-step iterative method. Finally, sensitive channels using for retrieval of temperature profile are selected, 56 channels in global and 58 in FY-4A’s detection range. The selected channels have small correlation with each other, and they have higher information capacity, which can be used as the representative channel set for temperature profile retrieval research and data assimilation..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 545 (2018)
An overview on linear hyperspectral unmixing
YUAN Jing, ZHANG Yu-Jin, and GAO Fang-Ping
Hyperspectral imaging acquires precise spectral information about the scene radiance that is exploited from efficient earth exploration in remote sensing. However, because of the limited spatial resolution, mixed pixels widely exist in the obtained hyperspectral data. It severely hinders the application of hyperspectraHyperspectral imaging acquires precise spectral information about the scene radiance that is exploited from efficient earth exploration in remote sensing. However, because of the limited spatial resolution, mixed pixels widely exist in the obtained hyperspectral data. It severely hinders the application of hyperspectral data. Hence, hyperspectral unmixing (HU) has become an essential task for HSI analysis. The most commonly model used for the mixture formation is a linear process or non-linear process. As linear mixing model (LMM) has clear physical meaning and is amenable to mathematical treatment, it has received widespread attention. To tackle the unmixing challenge, a number of linear algorithms have been proposed effectively. However, unmixing is a challenging, ill-posed inverse problem because of observation noise, environmental conditions, endmember variability, and data set size. The paper provided a comprehensive review of the state-of-the-art model in spectral unmixing. These models are discussed according to the following four categories: matrix decomposition, archetype analysis, bayesian method and sparse regression. In addition, both advantages and defects of these models are presented. Finally, a perspective on future research directions for advancing spectral unmixing methods is offered..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 553 (2018)
Calibration technique of spectral radiation for an infrared trap detector
ZHANG Lei, and LIN Zhi-Qiang
The quantification of remote sensing information requires spectral radiometric calibration technology support with high accuracy. This technology can ensure the comparability, accuracy and long-term stability of sensor data acquisition. Now, the calibration technique traced to the cryogenic absolute radiometer is the tThe quantification of remote sensing information requires spectral radiometric calibration technology support with high accuracy. This technology can ensure the comparability, accuracy and long-term stability of sensor data acquisition. Now, the calibration technique traced to the cryogenic absolute radiometer is the trend of development. In order to improve the accuracy of infrared absolute spectral response, a gold-plated hemisphere reflector is added to a thermopile detector. So an infrared trap detector is developed as the standard transfer detector. The spectral response linearity, spatial response uniformity and stability of an infrared trap detector are tested by electric substitution technology. The authors also have established an infrared radiometric calibration system based on the cryogenic absolute radiometer. The combined relative uncertainty in the spectral responsivity of this detector from 1.1~3.0 μm is below 1%. The application of infrared trap detector to radiometric calibration can improve the calibration accuracy of sensors through its shorter calibration chain..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 572 (2018)
Analytic exploration of AM/PM conversion characteristics of high power millimeter-wave traveling wave tubes using Eulerian hydrodynamic analysis
QIU Hai-Jian, HU Yu-Lu, HU Quan, ZHU Xiao-Fang, and LI Bin
Based on the phase expansion nonlinear Eulerian beam-wave interaction theory model of millimeter-wave traveling wave tubes, Eulerian large-signal analytic solutions of electric field and AM/PM conversion are obtained by the method of successive approximation. Then, the Eulerian large-signal analytic solutions are compaBased on the phase expansion nonlinear Eulerian beam-wave interaction theory model of millimeter-wave traveling wave tubes, Eulerian large-signal analytic solutions of electric field and AM/PM conversion are obtained by the method of successive approximation. Then, the Eulerian large-signal analytic solutions are compared to a Lagrangian beam-wave interaction theory model and traditional Eulerian nonlinear models. All the simulations are conducted on a set of millimeter-wave traveling wave tube parameters which are based on a single pitch section of a Q-Band traveling wave tube. It is found that the gain, phase and AM/PM conversion of Eulerian large-signal analytic solution agree well with Lagrangian beam-wave interaction theory model before saturation occurs. The maximum error of gain is less than 8.5% near saturation. The Eulerian large-signal analytic solution gain more accuracy than traditional Eulerian models. The present Eulerian large-signal analytic solution can describe saturation effects which is caused by electron overtaking that cannot be found by traditional Eulerian analysis. Results validate the correctness and effectiveness of our Eulerian large-signal analytic solution and the analytic solution of AM/PM conversion..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 578 (2018)
Study and modeling of infrared polarization characteristics based on sea scene in long wave band
ZHANG Jing-Hua, ZHANG Yan, and SHI Zhi-Guang
According to the surface micro-element bidirectional reflectance distribution function (BRDF), the polarization effect of the object’s surface is analysed. Based on infrared polarization characteristics in long wave band, a model combining the infrared reflected effect and emitted effect is developed to calculate the pAccording to the surface micro-element bidirectional reflectance distribution function (BRDF), the polarization effect of the object’s surface is analysed. Based on infrared polarization characteristics in long wave band, a model combining the infrared reflected effect and emitted effect is developed to calculate the polarization degree. The simulation result of this model indicates that the degree of polarization is determined by the value of the ratio of emitted radiation to reflected radiation. With the use of RadThermIR, the emitted radiation and reflected radiation of the sea surface and ship targets can be obtained. Based on radiation results and the proposed polarization calculation model, the polarization degree of the ship and sea water surface in different time and different detected angle is simulated. Experiments were conducted to measure the polarization degree in sea scenarios. The experimental data are consistent with the simulated results, which validates the effectiveness of the proposed model..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 586 (2018)
Optical phase transition properties of vanadium dioxide thin film characterized by noise spectra
SHANG Ya-Xuan, LIANG Ji-Ran, LIU Jian, ZHAO Yi-Rui, and JI Yang
The reflectance of thermochromatic material vanadium dioxide (VO2) and its fluctuation (noise spectrum) were measured simultaneously during the semiconductor-metal phase transition via self-built experimental system. The noise spectra were measured by a Data-Acquisition Card with real time fast Fourier transforms (FFTsThe reflectance of thermochromatic material vanadium dioxide (VO2) and its fluctuation (noise spectrum) were measured simultaneously during the semiconductor-metal phase transition via self-built experimental system. The noise spectra were measured by a Data-Acquisition Card with real time fast Fourier transforms (FFTs-DAC), showing the same phase-transition temperature (55℃) of the sample as that measured via reflectance measurement. A significant noise peak (around 15~20 MHz) was found in high temperature regime (the metal phase), while being almost flat in low temperature regime (the semiconductor phase). Such a noise peak also reflects that the low-temperature semiconductor phase and the high-temperature metallic phase have different crystal structures. Noise spectroscopy may be widely used to study phase-transtion materials..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 595 (2018)
A directional thermal radiance model for row crop canopy impact of sensor footprint
LI Kun, QIAN Yong-Gang, WANG Ning, MA Ling-Ling, QIU Shi, LI Chuan-Rong, TANG Ling-Li, CHEN Zhi-Ming, and WANG Guo-Zhu
The direction of thermal radiance is one of the key problems in thermal infrared remote sensing retrieval and product validation. Aiming at row crop, a directional thermal radiance model is built by considering the sunlit/shaded leaf, sunlit/shaded soil, multiple scattering and field of view. The accuracy and sensitiviThe direction of thermal radiance is one of the key problems in thermal infrared remote sensing retrieval and product validation. Aiming at row crop, a directional thermal radiance model is built by considering the sunlit/shaded leaf, sunlit/shaded soil, multiple scattering and field of view. The accuracy and sensitivity of the model are discussed and the results show that the model can not only explain the row crop structure and hot spot effect well, but also be suitable for simulating the thermal radiance of continuous canopy. Compared with the FRA97 and the FovMod model, the directional distributions of directional brightness temperature are in good agreement. The root mean square error is 0.18 K and 0.36 K respectively..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 599 (2018)
Design of a 166 GHz high power source based on power-combined technology
MENG Jin, ZHANG De-Hai, JIANG Chang-Hong, and YAO Chang-Fei
Ice clouds measurement technology plays an important role in improving the accuracy of the weather forecast and monitoring extreme weather phenomena and so on. Considering the physical dimension and shape distribution of ice-cloud particles, the problem of ice-clouds detecting could be solved by using terahertz passiveIce clouds measurement technology plays an important role in improving the accuracy of the weather forecast and monitoring extreme weather phenomena and so on. Considering the physical dimension and shape distribution of ice-cloud particles, the problem of ice-clouds detecting could be solved by using terahertz passive remote sensing instrument. As an important detecting channel, the 664 GHz RF front-end of receiver mainly includes a 664 GHz sub-harmonic mixer, a 332 GHz doubler and a 166 GHz high power source. Based on the design of terahertz doubler, a 166 GHz high power frequency multiplying source has been realized by using two way power-combined technologies. The measured results show that the output power of above-mentioned source is more than 46 mW in 164~172 GHz and the highest output power is 59 mW at 168 GHz. The above-mentioned research could solve the problem of lacking of the G band high power source in the LO chain, and provide technical support for the design of terahertz system working at higher frequency..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 608 (2018)
Research on the method of updating instrument line shape function of on-orbit fourier ultrahigh resolution spectrometer
WANG Jun-Feng, YE Han-Han, YI Wei-Ning, CHEN Zhen-Ting, FANG Xue-Jing, and DU Li-Li
Instrument line shape function (ILS)is one of the important physical characterization parameters of the fourier spectrometer, which affects the accuracy of the spectrometer. With the high-precision demand for remote sensing applications such as space measurement and atmospheric detection, how to measure and update the Instrument line shape function (ILS)is one of the important physical characterization parameters of the fourier spectrometer, which affects the accuracy of the spectrometer. With the high-precision demand for remote sensing applications such as space measurement and atmospheric detection, how to measure and update the ILS of the on-orbit spectrometer in real time is an important means to improve the accuracy of on-orbit ultrahigh resolution spectrometer. This paper used Fourier spectrometer as an example, according to the principle of ILS, used the characteristics of the measured solar spectral calibration data of the on-orbit ultrahigh resolution spectrometer, which have independent Fraunhfer line and less influenced by atmospheric aerosols, to monitor and update the ILS of the on-orbit ultrahigh resolution spectrometer. In this paper, the Kurucz solar spectrum model is used as the reference spectrum, the characteristic peaks of the measured solar calibration spectra and reference spectra are selected in the corresponding band, by adjusting the slit model of the spectrometer, the characteristic peak residuals are iteratively compared to calculate the ILS parameters of the instrument. Finally, after making a convolution between the updated ILS and the theoretical limb spectrum, we compared the results with the measured limb calibration spectrum. The error range is-6%~8%. These results show that this method can provide a reference for supervising and updating the ILS of on-orbit ultrahigh resolution spectrometer..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 613 (2018)
Retrieval algorithm of phycocyanin concentration in inland lakes from Sentinel 3A-OLCI images
MIAO Song, WANG Rui, LI Jian-Chao, WU Zhi-Ming, SHI Lei, LYU Heng, LI Yun-Mei, ZHAO Shao-Hua, and LIU Si-Han
Cyanobacteria is the dominant algae species in inland eutrophic water bodies, and the phycocyanin (PC) is its unique pigment which can be used as an indicator of its presence. Therefore, the retrieval of PC concentration by remote sensing is of great significance to early warning of cyanobacteria bloom. In this paper, Cyanobacteria is the dominant algae species in inland eutrophic water bodies, and the phycocyanin (PC) is its unique pigment which can be used as an indicator of its presence. Therefore, the retrieval of PC concentration by remote sensing is of great significance to early warning of cyanobacteria bloom. In this paper, the Random Forest retrieval Model for estimating PC concentration based on the sentinel 3A-OLCI bands was developed using in situ data collected from Taihu Lake, Dianchi Lake and Hongzehu Lake. The results of the importance analysis of input variables in random forest demonstrated that the seventh band(674 nm), the eighth band(665 nm) and the ninth band (620 nm) have significant impact on the PC estimation. The accuracy assessment showed that the Mean Absolute Percentage Error(MAPE) of this PC retrieval model is only 34.86% with the Root Mean Square Error(RMSE) of 38.67 μg/L. The comparison between the mode developed by this paper and other models, i.e., Simis semi-analytic algorithm and PCI exponential model was extensively conducted, and it was found that compared with other two models, the MAPE was improved by 85.65% and 15.65% respectively, and the RMSE was improved by 26.08 μg/L and 19.86 μg/L respectively. The atmospheric correction accuracy was further analyzed using the in situ samples and synchronous satellite image, and the result showed that the Management Uint Mathematical Model (MUMM) method can be successfully used for the OLCI image. The atmospheric corrected spectral curves are consistent with the measured spectral curves, and the MAPEs of 8 bands are all less than 30% at the wavelength range between 560 and 779 nm. The random forest model developed for estimating PC concentration in this paper can be successfully applied to Sentinel 3A-OLCI images, which provides a new algorithm for remote estimation of phycocyanin concentration in inland lake..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 621 (2018)
Nonlinear spectral unmixing for hyperspectral imagery based on bilinear mixture models
YANG Bin, WANG Bin, and WU Zong-Min
Nonlinear spectral unmixing for hyperspectral remote sensing images can overcome the shortage of linear unmixing methods that failing in explaining the nonlinear mixing effect in more complex scenarios. Meanwhile, bilinear mixture models and their corresponding algorithms are the hot topic of related researches. A nonlNonlinear spectral unmixing for hyperspectral remote sensing images can overcome the shortage of linear unmixing methods that failing in explaining the nonlinear mixing effect in more complex scenarios. Meanwhile, bilinear mixture models and their corresponding algorithms are the hot topic of related researches. A nonlinear spectral unmixing algorithm based on the geometric characteristics of bilinear mixture models was proposed. By representing the models’ nonlinear mixing terms as the linear contribution of one extra vertex concentrating the common nonlinear mixing effect, solving the complex bilinear mixture models was converted to do the simple linear spectral unmixing. Further, a traditional linear spectral unmixing algorithm was adopted to estimate the abundances directly in an iterative way. Experimental results on simulated and real hyperspectral images indicate that the proposed algorithm can overcome the collinearity effect and the adverse impact caused by fitting too many parameters, and improve both unmixing accuracy and computational speed..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 631 (2018)
Dispersion correction in large-length range finding of frequency modulation continuous wave (FMCW) based on phase compensation
SHI Chun-Zhao, ZHANG Fu-Min, PAN Hao, QU Xing-Hua, and HE Ming-Zhao
In this paper, based on the principle of range finding of FMCW, the range finding system of the double light path FMCW was constructed and improved and the optical fiber delay line was added in the measuring optical path to expand the measuring distance to 65 m. The influence of dispersion in equal optical frequency reIn this paper, based on the principle of range finding of FMCW, the range finding system of the double light path FMCW was constructed and improved and the optical fiber delay line was added in the measuring optical path to expand the measuring distance to 65 m. The influence of dispersion in equal optical frequency resampling was also researched and the resampling model with dispersion and optical fiber delay line was deduced in this paper. Therefore, the dispersion correction method that used frequency amplitude to adjust the phase compensation coefficient in large-length range finding of FMCW was proposed. The experiments show that the optical fiber delay line is added within the range of 45~65 m and the dispersion is corrected effectively. After dispersion correction, the maximum error between the range fining at 65.165 m and the measuring value of interferometer is less than 500 μm. The standard error is 246 μm and the frequency spectrum resolution reaches 123 μm, quite close to the theoretical resolution. These results provide feasible reference for the large-length range finding of FMCW..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 5, 642 (2018)
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