The change of field of view (FOV) which is caused by the image defocus of laser communication terminal introduced in the process of assembly will have a great interference to the link energy budget. In view of the problem, the method of measuring the FOV is proposed to calculate the defocus amount of receiving system. On the premise of the sensitivity of the detector is satisfied by the received energy, the relationship among the defocus receiving energy, defocus amount and FOV are derived by the theoretical analysis and calculation. With the link distance is 1km, the defocus amount of 0.27mm is calculated under the FOV of 0.965mrad which is measured by experimental test. The maximum FOV from 2km to 4km can be reversed further. At the same time, the test experiment platform was designed and the FOV of the laser communication terminal was measured. Compared with the theoretical calculation results, the maximum error is less than 55μrad, which is conformed to the error allowable range. Conclusion: By the method of measuring the FOV of the system, the defocus error which is caused by assembling can be calculated, so the maximum FOV of the system in different link distance can be simulated. The method not only solves the problem that the defocus amount is difficult to measure, but also provides theoretical guidance to increase the FOV of laser communication by introducing the image defocus.
With the problem of small field of view, high precision and difficulty in alignment for portable laser communication, the method and device based on measuring field of view in portable laser communication are designed and proposed. By calculating the link energy under the specified communication distance, the energy range of extensible field of view can be obtained. A high precision measuring device is designed. The actual test was carried out. The result shows that the receiving field of view for portable laser communication is 0.63mard under the condition of 1km communication distance and the sensitivity of detector -30dBm. The field of view for portable laser communication can be accurately measured by the test method and device. The test device can extend the measuring range of small field of view in different fields.
The influence of the alignment error in laser communication is analyzed. The link energy model with the position deviation at the image surface is established, and on the basis of this model, the spot deviation and the receiving optical axis deviation caused by the angular deviation of the optical axis are discussed and analyzed. Under the conditions of initial transceiver parameters, the link energy and the allowable maximum angle deviation with the distance of 0~2km are further calculated. The model formula of alignment error can be applied to analysis and discussion under the father distance. It has a theoretical guiding significance for the field laser communication test.
Demanding for the closed communication among urban buildings, a solution for close range laser communication is proposed. The functional composition of the system is demonstrated and analyzed and the parameters of the system are reasonably allocated. The system design is used with independent optical aperture. The energy model under the inherent error of transceiver is analyzed and calculated. On the basis, the actual communication test was carried out, the specific test operation process is given and the measured data are obtained. The deviation between the average data and the theory is not more than 0.58dB. The correctness of the theoretical energy model is verified. The energy model can be used to guide the design of remote distance communication terminal. At the same time, the successfully development and communication test can be effectively accelerated the application of civil communication for urban buildings.
In order to analysis and design the Czerny-Turner structure spectrometer with the high resolution and high energy reception, various astigmatism methods of the Czerny-Turner structure are reported. According to the location of plane grating, the astigmatism correction methods are divided into two categories, one is the plane grating in divergent illumination, another is the plane grating in parallel illumination. Basing on the different methods, the anastigmatic principle and methods are analyzed, the merits and demerits of the above methods are summarized and evaluated. The theoretical foundation for design of broadband eliminating astigmatism Czerny-Turner spectrometer and the reference value for the further design work are laid by the summary and analyzing in this paper.
With urgent demand for an integrated information network and development of free-space laser communication technology, research on high-rate laser communication networking technology is vital. This study analyzed the technical difficulties related to space laser communication networking and proposed a laser communication networking solution. A wide-angle beam expander and dual-rotating prism group were incorporated into a multiaccess optical laser communication antenna. The wide-angle beam expander collects signal light from different directions; the dual-rotating prism group tracks different targets simultaneously. This paper presents an overall scheme allowing multiaccess free-space laser communications based on the optical antenna described and the associated relay optics and transceiver subsystems.
In order to break through the laser communication technology of one point to multipoint, which is the difficult problems for laser communication. The networking solutions of the antenna structure of three concentric spheres are proposed. Being with the advantages of simple structure, small size and light weight, the antenna structure of three concentric spheres can be applied to short-distance space laser communication. The feasibility of the system can be realized from two aspects, the analysis of link and the analysis of the precision index. On this basis, the whole optical system can be determined by the corresponding optical system design. Under the condition of permitting of link energy, the optical system of antenna structure of three concentric spheres with mobile field azimuth angle of 120°and the pitching angle of 20°is completed. The parameters can meet the requirements in the subsystem of the communication receiving optical path, the communication transmitting optical path and the communication tracking optical system. The results indicate that the antenna structure of three concentric spheres can be applied to the laser communication networking under the short-distance space.
Multiple laser communication is the key point of integrated space-ground network system, and it is the necessary prerequisite of realizing the network communication link between multiple satellites. In this paper, current situation and the development status of multiple laser communication are introduced, then optical principles and methods of multiple laser communication are discussed, and advantages and disadvantages are compared and analyzed with different multiple space laser communication system. The systems were classified according to different principles, including the simple principle type, exchange points type, RF and laser combined type, field expanding type and large field communication type. Then we look into the future of multiple laser communication systems, and the result shows that the paraboloid of revolution type has great potential in the future's laser communication space network ,for it’s large communication range and high energy efficiency. It can be used to communicate between the aircraft platform, airship platforms and satellite platforms. Which laid the foundation for the future development of the laser communication space network.
We present three rotation symmetric planar metamaterials and consist of 3, 4 and 6 split resonant rings (SRRs) respectively, proved that they are polarization-insensitive. The modulation characters constructed by the three planar metamaterials are also studied and compared to demonstrate that the structure with more even rotation symmetry is much more beneficial to be polarization-independence. Furthermore, the influencing rules of the electrodes on the polarization character of metamaterials are obtained. The polarization character can be converted by tailoring the electrodes which provides a guide to construct and design novel terahertz polarimetirc devices for potential applications.
Thermal properties of diffractive optical element and method of design athermal hybrid infrared optical system are introduced. Athermal LWIR hybrid infrared optical system for no cooled staring detector is designed. The system consists of three lenses, the effective focal length is 100mm，the relative aperture is 1:1,the wavelength spectrum is 8~11μm, the field view is 14° and the total optical length is just 140mm. The result shows that the modulation transformation function at 17lp/mm is greater than 0.6 between -40-60°C，which prove that the system can work correctly at a large temperature range.
The laser detection and identification is based on the method of using laser as the
source of signal to scan the surface of ocean. If the laser detection equipment finds out
the target, it will immediately reflect the returning signal, and then through receiving
and disposing the returning signal by the receiving system, to realize the function of
detection and identification. Two mediums channels should be though in the process
of laser detection transmission, which are the atmosphere and the seawater. The
energy loss in the process of water transport, mainly considering the surface reflection
and scattering attenuation and internal attenuation factors such as seawater. The
energy consumption though atmospheric transmission, mainly considering the
absorption of atmospheric and the attenuation causing by scattering, the energy
consumption though seawater transmission, mainly considering the element such as
surface reflection, the attenuation of scattering and internal attenuation of seawater.
On the basis of the analysis and research, through the mode of establishment of
atmospheric scattering, the model of sea surface reflection and the model of internal
attenuation of seawater, determine the power dissipation of emitting lasers system,
calculates the signal strength that reaches the receiver. Under certain conditions, the
total attenuation of -98.92 dB by calculation, and put forward the related experiment
scheme by the use of Atmospheric analog channel, seawater analog channel. In the
experiment of the theory, we use the simulation pool of the atmosphere and the sea to
replace the real environment where the laser detection system works in this kind of
situation. To start with, we need to put the target in the simulating seawater pool of 10
meters large and then control the depth of the target in the sea level. We, putting the
laser detection system in position where it is 2 kilometers far from one side, secondly
use the equipment to aim at the target in some distance. Lastly, by launching and
detecting the signal of returning wave, identify the effect of the image produced by
Objective: In the field of computer vision, the technology for the automatic recognition of coded pattern plays an important basic role in the camera calibration process of intrinsic and extrinsic parameters, the binocular image matching process and the three-dimensional reconstruction process. Therefore, in the measurement processing, the successive rate for the automatic recognition of coded pattern must be guaranteed. Method: According to analyzing the geometric information of the coded pattern (the mixed type) and basing on the existing recognition method, a new automatic recognition method is proposed, which is the effective method to solve the multi-points recognition in single image by taking the multi-feature information of the coded pattern as the recognition criteria. Result: Both the new recognition method and the old recognition method are used in identifying the one hundred coded pattern which have been actually collected. The experimental result shows that, not only the new recognition method can achieve accurate identification of coded pattern with the recognition accuracy rate of 100%, but also its processing speed is 2.38 times faster than that in the old recognition method. Conclusion: It is obvious that there are many advantages in the new automatic recognition method, including the high effective recognition, the faster executive speed and independent on the auxiliary decoding process information. The new recognition method of multi-criteria combination can provide a strong guarantee for the realization of every aspect in the work of photogrammetry.
The intelligent control of simulation target with infrared imaging target in the indoor and outdoor
environment can effectively and quantitatively evaluated the parameters such as the minimum resolution
temperature difference（MRTD）and spatial resolution of airborne forward looking infrared, infrared detection
and tracking, infrared alarm, and etc.
This paper focused on introducing the working principles of the intelligent control simulation target of
Infrared imaging target, studying the thermal radiation characteristics of the infrared target surface material,
analyzing the influences of the infrared radiation energy distribution, and developing the intelligent control
simulation target with IR imaging target for hardware-in-the-loop simulation test. The intelligent control
simulation target which area was 5 ㎡ and concluded 44 infrared targets including two kinds of infrared
targets ,0.25ｍ×0.25ｍ, and 0.25m×0.5m, achieved 1℃～10℃ temperature simulation of target and the
background, and temperature control precision better than 0.5℃. Field test requirements were achieved by