A hybrid algorithm based on the simulated annealing algorithm and the iterative algorithm is proposed for the design of diffractive optical element (DOE) to shape the laser beams. The algorithm has the global optimization ability of simulated annealing algorithm as well as the local optimization ability of iterative algorithm. Comparisons between the hybrid algorithm and other two optimization algorithms show that the hybrid algorithm has satisfactory convergence property and design accuracy. Numerical simulation results demonstrate that the diffraction efficiency of the DOE is higher than 94% and non-uniformity is less than 1%. Therefore, this algorithm can be well applied in the field of beam shaping.
As the improvement of Astronomy technology, the size of the space optical system is developing toward huge type. However, the capability of the carriers of the space optical systems, which has got rid in the way of the development of the space optical system, is limited. To solve this problem, a self-deployable baffle is discussed, a method of the deployment utilizing elastic strain energy is advanced, and a new deployable baffle is designed in this paper. The baffle here consists of three or more sleeves, and each diameter of the sleeve is different in order to make the whole structure contract easily. The baffle is staying in contraction state until it is in the state of working. It is able to deploy into working state as required in a very short time. Well moving stabilization and high precision of deployment are ensured in this new style of deployable baffle. In order to reduce the mass of the baffle, every sleeve in the system uses the structure of thin board. As a result of the use of sleeve structure, the inner faces of the baffle are varied in each sleeve. To prove it is still effective in the optical system, professional software of ASAP is used to test its behavior. All the analysis and emulation prove that the baffle in working state is able to resist the stray light from the outside of the Field of View (FOV), improve the quality of the imaging, and meet the requirements of the optical system.
A design method of diffractive optical element is presented for converting a single modal Gaussian beam into a flat-top
beam in the far field of the source. The design is based on geometrical method and modified Gerchberg-Saxton method.
Geometrical method derives from the conservation of energy and the constant optical path length. This method could
supply initial phase distribution of the modified Gerchberg-Saxton method. To find the optimization design results, the
modified Gerchberg-Saxton method is important to choose the feedback factor to increase the convergent speed. In
addition, tolerances and limitations of such elements result in a reduction of the diffraction efficiency and as a result of
stray light. Further study indicates that deviation of the laser wavelength, incident beam, and observation plane can
greatly influence flat-top beam shaping quality. On the basis of theoretical and experimental results, limitations for the
application of diffractive beam shaping elements are investigated.
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