| The temporal and spatial far-field power density distribution on the target is of vital importance for the study of intense laser atmospheric propagation effect, the evaluation of beam control ability and tracking and aiming ability. Widely used for far-field beam profile diagnosis, the method based array detectors is a research focus in the field of high power laser testing technologies. In this dissertation, to meet the measurement requirements of laser beam diagnosis for high energy continuous wave lasers and high power repetitively pulsed lasers, studies on key technologies of laser spot target instruments based on array detectors and beam parameters evaluations are carried out. Several major achievements accomplished are as follows.1. Theoretical analysis and numerical simulation are carried out for the propagation effects of high power laser beams in slant atmosphere path. Based on the self-developed numerical simulation program, and together with the practical field atmospheric optical parameters, profile characteristics of laser beams in the slant atmosphere path are studied with numerical method and analytical method. Effects of atmospheric conditions on beam intensity spatial frequency characteristics, scintillation characteristics, beam drift and expanding characteristics are analyzed. Quantitative relationship between different atmospheric optical conditions and the requirements for the measurement system is studied. And, practical performance indexes for the measurement system are determined.2. Series of key techniques related to high energy continuous wave laser beam profile diagnosis are studied. To meet the requirements of quantitative attenuation and sampling, high energy laser attenuation and sampling method based diffuse reflection is investigated. Spatial distribution of the transparent light field, angle characteristics and attenuation coefficient of the diffuse attenuation unit are calculated respectively. These results match the experiment well. Temperature characteristics of mid-infrared HgCdTe detector are studied both theoretically and experimentally. Temperature auto-compensation model for responsivity is built. A detector array with temperature auto-compensation is designed and developed. And, technical difficulties of high altitude environmental adaptability are solved. Surface treatment techniques of the high power laser proof materials are explored, satisfying the high power laser test requirements. An absolute responsivity collimation scheme with several light sources of different wavelengths is proposed. A system for measuring temperature characteristics of the HgCdTe detector is built with the temperature ranging from-60℃to40℃, settling the wide temperature range collimation difficulties of mid-infrared photo-detector. Mechanical structure of the CW high energy laser detector array is designed, meeting the different requirements of different application conditions and platforms. A laser spot target instrument on unmanned aerial vehicle target for measuring continuous wave high energy lasers is developed, featuring high resolution, wide dynamic range and high power laser protective capability. With this detector array, aiming ability of the high power laser system is accurately measured. The uncertainty of this system is less than lμrad.3. Techniques related to far-field beam profile diagnosis of repetition rate pulse lasers are studied. To measure the low repetition nanosecond pulsed laser,"temporal amplification" and "charge asynchronous integration" scheme is employed. Related technologies as nanosecond pulse signal temporal expanding amplification, self-trigged extraction, signal acquisition and processing are developed. Technical difficulties of online measurement of multi-channel nanosecond pulsed signals without synchronous triggers are solved. To measure the high repetition pulsed laser, technologies including information extraction of high repetition signal envelope and multi-channel pulsed signal acquisition are studied. An unmanned aerial vehicle airborne detector array for10kHz high repetition DPL laser is developed, realizing accurate measurement of laser beam power density on the airborne target.4. Evaluation methods for on-target beam parameters of high power lasers are studied. Evaluation of characterization parameters, which represent the propagation ability of the laser beam to the target, is studied and related factors are analyzed. To specify the effects of the performance indexes of a detector array on the evaluation of the beam parameters, an analysis method based on the combination of laser atmospheric propagation numerical method and beam profile statistical analysis method is developed. With the practical field atmospheric optical parameters, effects of the performance parameters (such as spatial resolution, sampling frequency, inconsistency of the sensitivity and linear dynamic range) of high energy laser spot target instrument on the on-target beam parameter evaluation are studied. Quantitative evaluation results are given with numerical simulation, further validating the rationality of the designed performance parameters of the instrument. |
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