Multiple beam generation and adaptive control plays an important role in the laser propagation applications. The existing approaches are usually mechanical, so they have many limitations in terms of accuracy, bandwidth, and flexibility. In this paper, a kind of dynamic multiple beam forming method based on the fiber laser phased array (FLPA) is proposed. In this method, the FLPA based on the multi-objective optimization algorithm is employed, which can theoretically generate any number of outgoing beams, and dynamically adjust the power of each beam. The numerical simulation experiments based on a 19-cell FLPA were conducted. The results show that two stable outgoing beams of FLPA can be generated after about 200 iterations, and the power distribution error of the two beams can reach less than 4%. In addition, the two beams can also be combined into one after about 50 iterations.
A mathematical model of the diffraction efficiency change with the ambient temperature for the double-layer harmonic diffractive elements (HDE) is presented, and its effects are analyzed in this paper. The double-layer HDE structure is investigated and the optimization procedure is based on the equation of diffraction efficiency of the double-layer HDEs. By selecting appropriate design wavelength, the average diffraction efficiency of the system is reaching 99% in working wavelength and working temperature, which improves the image contrast and the image quality significantly. A set of dual-wavelength infrared optical system is designed based on dual-wavelength 320x240 element cooled thermal IR focal plane arrays detector. By introducing double-layer HDEs and aspheric surfaces, the chromatic aberration and the off-axis aberration are well corrected and the system structure is simplified. The system working in the wave band of 3.7~4.8μm and 7.7~9.5μm and with the F number of 2 is consisted of 8 elements and has 100% cold shield efficiency. The image quality evaluating results show that the performance of the dual-wavelength infrared optical system is very well in
temperature from -40C° to +60C°.
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