Invited paper
2023, 52(2): 20210870.
doi: 10.3788/IRLA20210870
Based on the background that picosecond pulse width laser with multi-pulses damaging the solar cells, we use three methods that are the surface morphology, voltammetry characteristics and electrolumi-nescence of solar cells to obtain the damage characteristics of solar cells with the laser before and after laser ablation. A three-junction GaAs solar cell with pulse width of 15 ps and wavelength of 1 064 nm is irradiated by picosecond pulsed laser. By changing the laser irradiation power through repetition frequency regulation, the damage characteristics of grid line and non-grid line of solar cell under laser irradiation are analyzed. The experimental results show that, although the laser spot is small, the material inside the battery has been damaged. It's mainly because the damage of the ordered structure of the material inside the battery is gradually increased. When the laser power is higher, the internal damage area is larger. When the gate line is irradiated by laser, the fusion of the gate line will greatly affect the absorption of the carriers by the solar cell, thus reducing the photoelectric conversion ability of the solar cell, and then affecting the electrical performance of the solar cell, so that the damage effect of the gate line is stronger than that of the non-gate line.
2023, 52(1): 20220748.
doi: 10.3788/IRLA20220748
Single photon lidar (also known as photon counting lidar) has detection sensitivity of single photon magnitude. Compared with traditional linear detection lidar, it can obtain longer detection distance, and it has become the frontier and development trend of lidar technology. However, the extremely high detection sensitivity also makes the single photon lidar highly susceptible to the interference of background noise photons in detection, which greatly reduces its performance in daytime and greatly limits its application scope. Based on the detection principle of single photon lidar, this paper briefly reviews its technical development, analyzes the requirements of all-time work for single photon lidar detection system, and a new spectral filtering technique is adopted to greatly improve the detection performance of single photon lidar in daylight. At the same time, this paper also proposed a general evaluation model, which can be very intuitive to evaluate the detection performance of various lidar systems.
2022, 51(7): 20220313.
doi: 10.3788/IRLA20220313
Aerosol deposition and diffusion mainly study the motion state, concentration migration and surface deposition process of aerosol particles in the atmosphere. The physical parameters mainly include the deposition flux, deposition velocity, concentration distribution and diffusion velocity of aerosol particles. Relevant research can provide a scientific basis for the optimization of aerosol generation and the evaluation and prediction of extinction effects. In this paper, three major methods for the generation of aerosols were summarized, the mechanism of aerosol particles settling and diffusing in the atmosphere was analysed, and the calculation, simulation and experimental measurement methods of aerosol settling and diffusing characteristic parameters were expounded. In view of the challenges in the study of aerosol deposition and diffusion, perspectives on future theoretical analyses, numerical simulations, experimental research and comprehensive applications are provided.
2022, 51(7): 20220221.
doi: 10.3788/IRLA20220221
Vortex beam is a kind of novel structured beam with helical wavefront and carries orbital angular momentum (OAM). Such structured field can find applications in many domains as large-capacity data transmission, remote detection, etc. The wavefront aberration occurs when the vortex beam propagates in a non-homogeneous medium as atmosphere turbulence, resulting in the OAM changing and go against practical applications. Therefore, it is necessary to compensate distorted vortex beams through adaptive optics. The recent advances on adaptive correction of distorted vortex beams was mainly reviewed. The current mature correction schemes were firstly introduced in brief, including wavefront sensing along with probe Gaussian beams, array detection along with phase retrieval algorithms, and so on. Then the deep-learning-based approaches were highlighted, as Zernike polynomial coefficients inversion, turbulence phase screen inversion, etc. The advantages and limitations of employing deep learning for distorted vortex beam compensation were also discussed. Finally, development trends of distortion compensation of vortex beams were prospected.
2022, 51(7): 20210866.
doi: 10.3788/IRLA20210866
Compared with the visible to short wave infrared spectrum, hyperspectral remote sensing imaging in the infrared spectrum has unique application advantages, especially in resource exploration, surface environment monitoring, atmospheric environment monitoring and military reconnaissance. Although the infrared hyperspectral imagers are mainly airborne at present, the domestic and foreign institutions have never given up promoting the spaceborne application of infrared hyperspectral remote sensing. Therefore, based on the detailed analysis of the design, implementation and specifications of the primary infrared hyperspectral imagers, this paper first summarizes the characteristics, existing problems and solutions of the current infrared hyperspectral imagers from the three key indexes of spectral resolution, spatial resolution and radiometric resolution. That is, breaking through the technologies of fine spectroscopy, high-sensitivity detectors, low-temperature optics and background radiation suppression are the main technical problems to be solved in the development of infrared hyperspectral imagers in the future. Based on the above, the application of infrared hyperspectral imaging in long distance gas detection is overviewed, and its unique advantages are also analysed. Finally, the development direction of infrared hyperspectral remote sensing imaging is depicted.
2022, 51(6): 20220321.
doi: 10.3788/IRLA20220321
Sodium laser guide stars (LGS), known as artificial stars, can be used to detect and correct wavefront aberrations induced by atmospheric turbulence, which can significantly improve the adaptive-optical telescope's imaging quality. Due to the limited corrected field of view of single LGS, multiple sodium LGS, created by exciting sodium atoms in the Earth's mesosphere via multiple yellow laser beams, is developed to yield high-resolution imaging in a much larger field-of-view, which has important applications in the fields of precision astronomical observation and space target detection. The successful implementation of microsecond-pulse sodium guidestars constellation via 100 W level pulsed sodium laser was reported, based on a small angle precise polarized combining and splitting technology. At Lijiang Observatory, four-ways~20 W/beam yellow laser beam with kHz repetition-rate and hundred-μs pulse width were projected up to the sky through one launching telescope, and generated a distinctive four-point grouping on a 40" field of view with variable configurations of linear, parallelogram, rhomboid and square. The spot size of each guide star was about 3.25" and the corresponding brightness was around 8 magnitude in V band. The sodium return signal could well avoid Rayleigh light interference by the pulse synchro controlling technology to deliver higher spatial resolution. This could serve as a technical reference for multi-conjugate correction systems on large-aperture astronomical telescopes.
2022, 51(6): 20220249.
doi: 10.3788/IRLA20220249
Compared with the traditional multispectral imaging detection, polarized multispectral imaging detection can detect more information of the detected object surface such as roughness and moisture content, which brings great convenience to target detection. However, at present, it is mainly used for target detection and not widely used in target classification. BP neural network is a typical neural network commonly used at present. Neural network can establish the start-to-end mapping. On the premise that the training sample set is large enough, the trained neural network with good consequences is an efficient, accurate and high-speed tool. Firstly, the polarized multispectral images of typical ground objects were obtained by using the polarized multispectral imaging detection system based on rotating polarizer and filter, and after the images were preprocessed, the data set could be established; Secondly, the neural network was trained on this data set. The trained neural network could process the unknown polarized spectrum images and realize the classification of several typical ground objects; Finally, the effect of neural network classification was evaluated and compared with several other typical classification methods. It was found that the neural network method has better classification accuracy and effect. Compared with the typical maximum likelihood classification algorithm, its overall classification accuracy could be improved from 91.7% to 94.2%, and the Kappa coefficient could be improved from 0.851 to 0.898. The results show that the polarized multispectral image classification method based on neural network has certain research significance for improving and optimizing the existing data processing methods of polarized multispectral images.
2022, 51(6): 20220274.
doi: 10.3788/IRLA20220274
The technical bottleneck of realizing the three-dimensional optical information transmission of space-air-ground-sea is to solve the problem of laser uplink and downlink transmission under the dynamic sea surface conditions of air-sea sea-air cross-media. This paper mainly used the blue-green laser in the seawater environment as the carrier and proposed a numerical research method for the downlink transmission of the blue-green laser through the air-sea dynamic across the medium sea surface. The effects of atmospheric sea mist, sea surface wind speed, and particle distribution in seawater on the down-transmission scattering properties of blue-green lasers were discussed in detail. The variation of blue-green laser transmittance with transmission angle under different wind speeds, and the transmittance of blue-green laser downlink transmission under different atmospheric sea mist visibility, different chlorophyll concentrations, and different bubble concentrations were numerically calculated. The results showed that when the blue-green laser is transmitted in seawater, the effect of bubbles on laser attenuation increases with the increase of wind speed and decreases with the increase of transmission depth; the transmission rate of the blue-green laser through the atmospheric sea surface and seawater gradually increases with the increase of visibility of sea mist in the atmosphere at the offshore surface. With the increase of transmission distance, the influence of chlorophyll increases gradually, and the transmittance of blue-green laser decreases. The work in this paper provides theoretical and technical support for the cross-media wireless optical transmission and communication of blue-green lasers uplink and downlink across the air-sea and sea-air.
2022, 51(6): 20210949.
doi: 10.3788/IRLA20210949
The new spaceborne photon counting radar can acquire high-precision three-dimensional information of ground and ground targets, but its measurement accuracy is greatly affected by noise. Aiming at the difficulty of signal extraction of single-photon laser data in areas with inconsistent background noise and large slope area, this paper proposed a single photon point cloud denoising algorithm based on multi-feature adaptive. It was different from the traditional circular or elliptical filtering kernel, and used the parallelogram filtering kernel which was more in line with the characteristics of single photon point cloud data, and signals were adaptively identified by slope, spatial density and noise rate. The ICESat-2 single photon point cloud data located in the glacier area of Qinghai-Tibet Plateau was selected to carry out the point cloud denoising test and verification, and the study area had a large slope and broken terrain. Compared with the official denoising results of ATL03 and ATL08, the proposed algorithm has better performance in areas with inconsistent background noise level and large slope area.
2022, 51(5): 20210916.
doi: 10.3788/IRLA20210916
A Combined Atmospheric Radiation Transfer (CART) software was developed, which could be used to calculate the spectral transmittance and background radiation (including ambient scattered solar radiation and thermal radiation) of the atmosphere from visible to far infrared wavelength bands based on atmospheric parameters. The multi-dimensional variations of atmospheric transmittance and background radiation in a certain wavelength-band with zenith angle and distance were paid special attention by researches in optical engineering area. Thus, it was necessary to quickly calculate the scene atmospheric optical characteristics. The newly two-dimensional scene fast computing function of atmospheric radiative transfer by using CART was mainly introduced. According to the characteristics of discrete coordinate method (DISORT) which could simutaniously output the radiance at various zenith angles and azimuth angles, the program to calculate the multiple-scattered atmospheric radiance was designed at each direction (azimuth and zenith angles) simultaneously, which greatly improved the calculation efficiency. As the atmospheric transmittance and heat radiation change slowly with space position, sampling calculation and spline interpolation were adopted to save the calculation time greatly while keeping the calculation accuracy. For a scene with more than 10000 times calculations, the speed was 2-3 orders of magnitude faster than before. It will be usefull in the calculation of atmospheric radiative transfer scenarios in practical engineering applications.
2022, 51(4): 20211113.
doi: 10.3788/IRLA20211113
Digital readout of infrared focal plane array (IRFPA) orients its development. Compared with traditional analog IRFPA, digital IRFPA has many advantages. The critical technique of digital IRFPA is the digital readout integrated circuit (DROIC). The design and implementation of the 1280 × 1024, 10 μm DROIC was introduced in detail in this paper. The DROIC was tested and the results showed its noise was 157 μV, the power consumption was 165 mW when frame rate was 50 Hz, and the column fix pattern noise was 0.1%. The DROIC interconnected short-wave infrared detector through flip chip successfully and completed imaging. The images had good resolution and rich details. The test results and images’ effect indicated that the DROIC has some features, such as low noise, wide transmission bandwidth and good resistance to interference and so on, and contributes to the development of IRFPA’s performance.
2022, 51(4): 20220004.
doi: 10.3788/IRLA20220004
The exciton polaritons in the semiconductor microcavity driven by light is a hot research field in physics and optics in recent years, and the superposition quantized vortex of the Bose-Einstein Condensates (BEC) driven by light in the microcavity has subversive potential application value in the field of quantum sensing. An accurate mathematical model via Runge-Kutta Difference and FDTD finite element method was constructed to characterize the time-space evolution of the quantum vortex gyrotron polariton system. On this basis, the influence of some key parameters related to pump light, signal light and semiconductor microcavity materials on the evolution characteristics of the quantum vortex gyroscope exciton polariton condensate was studied. For the pump light and signal light, the light intensity and geometric size of the annular spot were considered. Meanwhile, the effect of the microcavity material on the exciton polariton system was converted into the effect of the effective mass on the BEC system through mathematical transformation. By scanning a lot of parameters, some key factors affecting the performance of the quantum vortex gyroscope were obtained, including the geometric parameters and intensity of the pump light, the related influence of the pump light and the signal light, and the material properties of the semiconductor microcavity. The relationship between material properties and superposition state evolution of quantum vortex gyroscope was calculated by characterizing the relationship between effective mass and properties of different microcavity materials, and the range of reasonable values for effective mass was found to be narrow. These works provided an important reference for the engineering prototype development of the quantum vortex gyroscope.
2022, 51(4): 20210985.
doi: 10.3788/IRLA20210985
In the process of high temperature thermal experiment in aerospace, metallurgical casting and other industrial fields, it is necessary to obtain the high temperature on the shelter surface of the test piece quickly and accurately under the condition of high concentration of diffuse medium. The traditional radiation temperature measurement methods include band radiation method, brightness method, colorimetric temperature measurement method, multi-wavelength temperature measurement method and so on, which is the main measurement method to realize high temperature measurement. Due to the effect of medium particles, diffuse medium will produce various spectral scattering, absorption and emission effects, which will bring great interference to the accurate measurement of high temperature and lead to deviation of measurement results. It is necessary to improve classical radiation thermometry. Several main radiation thermometry methods under the condition of diffuse medium were discussed, including experimental data inversion method, thermal radiation calculation method, multi-channel split window method, information recovery calculation method, and neural network calculation method. The advantages and disadvantages of various methods were analyzed, and the challenges and development trends of radiation thermometry methods under the condition of diffuse medium were summarized.
2022, 51(4): 20210942.
doi: 10.3788/IRLA20210942
High throughput materials fabrication and characterization techniques are key to the transformation from materials genome approach to advanced materials R&D and manufacturing practice. Here the authors reported the application of the terahertz (THz-TDS) mapping of the electrical conductance of Cu alloy sample matrix fabricated using high throughput solid state synthesis method. Fast detection of 144 Cu alloy thin films on a single materials library chip were achieved. The mapping technique was based on an algorithm derived from Tinkham equations and Fresnel formula. The THz conductance acquired from alloy thin films of either uniform or continuous gradient thickness agreed semi-quantitatively with those determined with four-probe method. Distinctive conductance differences among the 144 Cu alloy samples were obtained within one batch. Further analysis of the changing trends in the microstructures and semi-quantitative compositions of representative samples against their electrical conductance revealed a clear composition-structural-function relationship. This study demonstrated that THz-TDS may be a powerful tool for fast high throughput screening of Cu alloy materials library chip, and facilitate the R&D procedure substantially.
2022, 51(3): 20210941.
doi: 10.3788/IRLA20210941
The new generation of aerospace remote sensing instruments are developing towards high spatial resolution, high energy resolution, and high time resolution. Its core components are high-performance large-scale small-pixel short-wave infrared InGaAs focal plane detectors. The latest research progress in the design and fabrication of high-density InGaAs detector arrays was reported, and hybrided with matching Si-CMOS readout circuits to form a focal plane. The breakthroughs in dark current and noise suppression of high-density small-pixel detectors , megapixel focal plane flip chip interconnection and other key technologies were focused. The new flip chip interconnection technologies such as high flatness chip surface shape control, indium bumps convex morphology and high consistency control, and high-density flip chip interconnection control were solved. Developed 10 μm pitch 2560×2 048 focal plane detectors, which D* was better than 1.0×1013 cm·Hz1/2/W, the response non-uniformity was better than 3%, the effective pixel rate was better than 99.7%, and the dynamic range was better than 120 dB. This focal plane was used for laboratory demonstration imaging, and the picture was clear.
2022, 51(3): 20210821.
doi: 10.3788/IRLA20210821
The signal-noise ratio, dynamic range and sensitivity of long-wavelength (LW) infrared detector are limited by the charge capacity of digital readout integrated circuit (ROIC), which restricts the development and application of LW infrared imaging systems. The comparison and analysis of analog pixel and digital pixel ROIC technology were presented in this paper, the research status and main architectures of digital pixel focal plane array (FPA) were introduced. The 384×288 (25 µm) and 256×256 (30 µm) digital-pixel ROICs were designed with pulse frequency modulation scheme, and the designed comparator improved the power efficiency and robustness. Based on this, the digital LW FPA detector modules were designed with HgCdTe detector arrays, which measurement results were compared and analyzed with related works. The measured peak noise equivalent temperature difference are 3.4 mK and 1.9 mK, respectively, and the dynamic range achieves 96 dB. It’s confirmed that the digital pixel technology significantly improves the sensitivity and dynamic range of LW IRFPA, which manifests that this technology is a promising way to improve the performance of infrared detector.
A new method to improve the height measurement accuracy of the integrated navigation system of one-dimensional laser Doppler velocimeter (LDV) and single-axis rotation inertial navigation system (INS) is explored in this paper. The attitude output after base tilt compensation of the single-axis rotation INS is used to provide a high-precision attitude reference for the LDV. The height measurement principle of the one-dimensional LDV with dual-beam differential structure is studied, and the base tilt compensation method of single-axis rotation INS is analyzed. On the basis of theoretical analysis, on-vehicle experiments are carried out to verify the effectiveness of the designed height measurement method. Two groups of 35-40 min on-vehicle tests are completed. The maximum error of height measurement in the first group is −2.67 m, and the standard deviation is 1.0094 m; The maximum error of the second group of height measurement is 1.68 m, and the standard deviation is 0.5880 m, reaching the expected target that the continuous dynamic height measurement accuracy is better than 3 m under the vehicle condition. The related research proves the effectiveness of the height measurement method based on integrated navigation system of single-axis rotation INS and one-dimensional LDV.
2022, 51(12): 20220713.
doi: 10.3788/IRLA20220713
With higher demand and technological development to promote the working speed of aerial vehicles, the mobility and flexibility of aerial optical imaging have become more prominent, but the technical difficulty of achieving high-quality, high-resolution imaging is also extremely challenging. The complex interaction between aircraft and high-speed airflow produces aero-optical effects, and light waves or beams are subject to strong interference when passing through complex flow fields and optical windows, which has attracted many scientists to carry out multidisciplinary cross-fertilization of related research work, and a large number of research results have been achieved, providing strong support for experimental testing and engineering practice. In this paper, starting from the calculation of aero-optical flow field and optical window, the research progress of aero-optical transmission effect is reviewed in detail, the corresponding calculation methods are summarized, and the thinking and suggestions of aero-optical transmission effect calculation for aerial optical imaging are given based on the current technological development trend.
2022, 51(12): 20220781.
doi: 10.3788/IRLA20220781
The optical resonant cavity can not only enhance the interaction between the laser and matter, but also suppress the noise of the laser, which is an important tool for research on precision measurement, quantum optics, etc. Stable locking of laser and optical resonant cavity resonance is the key to its application. However, the locking effect will be affected by factors such as mechanical vibration, temperature changes, etc in the actual environment. The fuzzy algorithm is applied to the PDH (Pound-Drever-Hall) technology, so that the three parameters of the proportional-integral-differential controller can be adjusted according to the changes of the external environment to obtain the optimal parameters in real time, which effectively improves anti-interference ability of optical resonator locking. If outside interference is still so great that the lock is lost, the system can make it re-lock automatically. The system effectively improves the practicality of the optical resonator, and provides a technical basis for the application of the optical resonator in precision measurement and quantum optics experiments.
2022, 51(12): 20220667.
doi: 10.3788/IRLA20220667
Infrared detection technology plays a key role in many important fields, such as satellite reconnaissance, military guidance, astronomical observation, medical detection, and modern communications. Type-II superlattices, as a new generation of infrared detection materials after HgCdTe detectors, have unique advantages in terms of stability, manufacturability, and cost. The barrier-type InAs/InAsSb type-II superlattice infrared detectors are one of the most promising type-II superlattice infrared detectors. Their key performance has been steadily improved in recent years but is still constrained by factors such as low absorption coefficient, difficult heteroepitaxial growth, and large dark current. Herein, this article reviews the development history of III-V type-II superlattices, analyzes the different barrier structures, key properties and development trends of barrier-type InAs/InAsSb type-II superlattice infrared detectors, and points out the potential key problems and future development directions of barrier type InAs/InAsSb type-II superlattice infrared detectors.
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