| Wavefront sensor is the important constituent part of the adaptive optical system. It is a feedback element used for real-time detection of the wavefront aberration of the system. It mainly includes Hartmann-Shack sensor, pyramid sensor, shearing interferometer, and curvature sensor, etc., among which Hartmann-Shack sensor has been used most widely due to its excellent comprehensive characteristics.Holographic wavefront sensor is a kind of wavefront sensing method newly proposed in recent years, and it uses multiplexing holographic element to load various aberration modes and utilizes the approximate linear relationship between the output signal and the aberration amplitude of various modes so as to directly obtain the wavefront aberration. Based on optical methods the holographic wavefront sensor has realized the complicate matrix computation process of traditional wavefront sensors and thus greatly reduced the amount of computation.In the future it is possible to transform the current adaptive optics system driven by computer software to a kind of adaptive optics system with super high band width formed by pure hardware electronic circuit. Compared to Hartmann-Shack sensor, the holographic wavefront sensor still has advantages like not being sensitive to scintillation but able to work in environment with strong turbulence and scintillation. In the future it could be possibly applied to the detection on targets in low angle of elevation by ground-base optoelectronic telescope, optical communication horizontal transmission system in free space, and high energy laser weapon system, etc.This article makes deeper researches on holographic wavefront sensor through theoretical analysis, numerical simulation, and experimental verification. In addition, it also establishes a holographic adaptive optics system by combining the holographic wavefront sensor with 21-element deformable mirrors and conduct primary exploration on the prospect of its application into engineering. Based on the aforementioned work, this article multiplexes the holographic wavefront sensor and the wavefront corrector into a signle liquid crystal light modulator, proposes the concept of dynamic holographic adaptive optics system, establishes related theoretical models, and verifies the feasibility through numerical simulation and experimental verification. The major content of this article includes the following aspects:1. Basic conception and system composition of adaptive optics technology are introduced in this paper, development history of adaptive optics system is reviewed, and its main application fields are summarized; meanwhile, the basic principles of several currently used wavefront sensors are analyzed, as well as characteristic and limitation of various wavefront sensors are summarized; besides, fundamental principles of holography are introduced briefly, background of holographic wavefront sensing method is analyzed, and its development history is also reviewed; finally, the current situation of holographic wavefront sensing method at home and abroad is described.2. The theoretical model of holographic wavefront sensing method is also deduced according to scalar diffraction theory in this paper; response sensitivity changes of sensor is analyzed through numerical method with different aberration bias and detection aperture parameters; furthermore, amplitude type hologram is established with the method of optical micro printing, holographic wavefront sensor is set up combing CCD detector, the feasibility of holographic wavefront sensing method is verified through experiments, and preliminary open-loop correction experiment is conducted by utilizing liquid crystal spatial light modulator as wavefront correction components.3. Main classification and research status of wavefront corrector are introduced briefly in this paper, numerical model of 21-element deformable mirror based on Gaussian response function model is established, and aberration correction effect of 16 low Zernike modes is analyzed, so as to analyze the closed-loop correction performance of holographic adaptive optics system on static aberrations; moreover, closed-loop correction performance of holographic adaptive optics system is analyzed through experiment on the basis of self-developed 21-element deformable mirror, so that calibration frequency is superior to 200 Hz and RMS value of wavefront residual error after closed-loop correction is superior to 0.1λ; And finally, the application of holographic adaptive optics system in broadband light illumination system is analyzed through numerical analysis and experiment measures.4. Foreign research situation of compact adaptive optics system is analyzed, and the concept of dynamic holographic adaptive optics is put forward; meanwhile, the basic principles of dynamic holographic adaptive optics system are described, and the theoretical model is established so as to numerically simulate closed-loop calibration process of static aberrations; at last, experimental facility is set up based on liquid crystal spatial light modulator and the system feasibility is verified through experiments. |
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