Research On Application Of Binary Optical Elements In Laser Beam Shaping

Laser technology has been widely used in many fields of contemporary society,and laser rangefinder and laser target designator based on it have played an important role in cutting-edge industry and military.The core component of the laser target designator is the laser transmitter,which transmits the laser continuously and stably to the target through laser shaped,but the uniformity of emitted beam from the laser transmitter is poor,and it's optical system does not meet the miniaturization requirements.Therefore,the miniaturization of laser transmitting optical system is studied by using binary optical theory,so that the emitted laser beam can meet the requirements of collimation and homogeneity.At the same time,the miniaturization of laser transmitting optical system is realized.In order to realize the miniaturization of the optical system of the transmitter of the laser target designator,a laser beam shaping system consisting of a four-fold spherical beam expanding system,a set of mirrors and a binary optical element group is designed in this paper.Firstly,the four-fold spherical beam expanding system is used to expand the laser beam with a specific waist size,and the divergence angle and diameter of the laser beam are changed to match the subsequent shaping binary optical elements.Secondly,based on scalar diffraction theory,an improved GS algorithm mathematical model including initial phase selection and amplitude adjustment is established,and the improved GS algorithm is used to design the homogenized binary optical element and the aligned binary optical element,so that the binary optical element with excellent performance can be obtained.Then,according to the theory of constant light power and geometric ray propagation,the objective function of beam shaping is established,the structure of Galileo binary optical elements is established,and the laser beam shaping system based on binary optical elements is designed by developing the application program in ZEMAX,so as to realize the overall design and evaluation of the system.Finally,the shaped beam measurement system is set up,and the measurement of shaped laser beam parameters is realized by CMOS method and image processing.The optical structure of the laser beam shaping system designed in this paper is: 42mm×36mm×36mm,and the uniformity of the shaped laser beam is 96.2%,and the semidivergence angle is 0.25 mrad.When the Q-switched 1064 nm YAG solid-state laser with 1.5mm of spot radius,semi-divergence angle of 2.44 mrad and optical pulse energy of 60 mJ is used as the light source of the shaping system,the experimental results show that the uniformity of the shaped beam is 80.15%,the semi-divergence angle is 0.31 mrad,and the pulse energy is 46.71 mJ.The optical structure of laser beam shaping system is small and the quality of emission beam is stable,which provides theoretical guidance for the application of binary optical elements in laser beam shaping.