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Study On Laser Warning Based On Bi-material Microantilever Array

Posted on:2015-05-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:B LiFull Text:PDF
GTID:1228330422493333Subject:Instrument Science and Technology
Abstract/Summary:PDF Full Text Request
Laser technology has been widely used in industrial, medical, biological and otherfields, especially in military field, for its strong directivity, good monochromaticity, highbrightness and high energy. In the early1980s, laser range finders and the laser radartracking recognition systems have been equipped in forces, promoting weapons andequipment capacity of aerospace aircraft, surface ships and ground vehicles. In recent years,with the rapid development of laser technology, a variety of high-power and high-energylaser equipments have been created, leading to the role of the laser weapon from previoustarget recognition and target tracking into the target hit and destroyed. Many countries areengaged in the research of laser warning system in view of the increasing laser weaponthreats. However, the existing laser warning systems cannot satisfy the high accuracy, widespectrum, wide field and high sensitivity requirements. This paper proposes a new laserwarning system based on Micro-electromechanical Systems (MEMS) to overcome theshortcomings of the existed systems.The purpose of this subject is to develop a new type of laser warning system, to solvethe disadvantages existing in some products. We use micro-cantilever Focal Plane Array(FPA), whose detection ability is significantly better than that of the existing warningdetector especially in the identification of a narrow pulse laser. In addition, the use ofcylindrical lens optical system can realize multiple wavelength laser warning. And laserorientation method of double line array ensures the larger the alarm field and improves theorientation precision of the whole system.In this paper, basic theory, algorithm structure, technical scheme and system realization of laser warning system based on MEMS technology has been studied deeply. We set up the experimental system based on PC and conduct the optical design, hardware development, thermodynamic analysis and image processing, which has made full preparations for the development of the laser warning system based on MEMS technology. The specific researchwork mainly includes:First, the method of laser warning based on microcantilever array was studied, and its feasibility analysis was performed. The working features and the types of laser weaponswere summarized. Through analyzing the structure, characteristics and thermal mechanicalworking performance of microcantilever, its basic parameters, such as detected laser type,spectrum range and detection sensitivity, were attained. We made a laser warning systembased on area microcantilever array, and set up an experiment to test its ability.Second, a non-imaging orientation method based on dual-line array was proposed.Incident lights were divided into meridional ray and sagittal ray via the cylindrical mirroroptical system, and the meridian and sagittal angle data could be separately obtained by twodetectors, then the orientation of incident laser could be calculated though the establishedmathematical models. Experiments showed that this method has great capacity oforientation for the incident laser in its field of view (FOV), and the orientation accuracy hasbeen efficiently improved.Third, theoretical researches and structure design for the cylindrical mirror opticalsystem were in the work. According to the performance of microcantilever cell, vectoralgorithm was used to analyze the geometrical optical properties of the cylindrical mirroroptical system, and the initial optical structure that suitable for the microcantilever arraywas obtained through ray tracing. The initial optical structure was optimized by using theoptics calculation software called ZEMAX, and then we got the two-piece-type cylindricalmirror optical system. The simulation results showed that the FOV of this system couldattain20°, the MTF could be7lp/mm, and the wavelength range is1.064μm~3.8μm, whichcompletely meet the demands of the laser warning system based on microcantilever array.Fourth, propose a method that use damage threshold of the detectors as the evaluationcriterion of the system performance. Most of the laser warning systems use the detectionsensitivity to the beacon laser as the evaluation criterion, without consideration of thethreshold when high energy (high power) laser weapon acting on laser warning system. Inorder to measure and analyze the laser damage threshold of our microcantilever, somedamage experiments about pulse laser and continuous wave laser were done, and the resultsshowed that narrow pulse laser has the largest damage threshold on the microcantilever, andthe laser energy could not be more than160mJ/cm2.For laser warning system based on MEMS technology, its key detectors is microcantilever focal plane array (FPA). The detection and discrimination to the incidentlaser are realized via optical readout method, and the wavelength, type and incidentorientation of the incident laser could be judged at the same time. This system solves thedisadvantages of the former laser warning system, such as single wavelength, small FOVand low directional sensitivity, in particular for the unable warning of narrow pulse laser.Due to the application of microcantilever focal plane array (FPA) based on MEMS, thevolume of the detector is much smaller than the traditional detectors, while the opticalreadout method ensure that this system could perfectly avoid the effects of stray light andlaser light scattering in the progress of data acquisition.
Keywords/Search Tags:laser warning, microcantilever array, optical design, energy threshold
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