天文望远镜数字全息式自适应光学技术研究

Adaptive optics has greatly attracted astronomers' interests because of its successful application in astronomical imaging in the past several decades. In order to obtain more information of the universe, they want to get images from telescopes with higher resolution in shorter wavelengths. However, it is almost impossible to achieve this goal through increasing the number of actuators of wavefront correctors and shortening the working cycle of wavefront correctors and wavefront sensors. Digital holographical adaptive optics is a novel technique, which could overcome the astronomical turbulence and improve the image quality of telescopes through manipulating the amplitudes and phases of waves. All the procedures of digital holographical adaptive optics are finished by digital methods, so there is no need of wavefront sensors and wavefront correctors. Now there is almost no wavefront correctors and wavefront sensors could used in astronomy to improve quality of telescope at visiual wavelength or shorter wavelength, and this problem could not solve in short time. However, to obtain high resolution images of universe at shoter wavelenth is extremely expected for all of the astronomers'. So the digital holographical adaptive optics is extremely suitable to develop in astronomy.

随着天文观测的深入，天文学家对天文望远镜自适应光学技术的需求越来越高，希望在短波段，校正大气湍流扰动，提高望远镜成像质量。然而，在短时间内，通过增加波前校正器的促动器数量，提高波前校正器和波前传感器的工作频率，突破现有自适应光学技术瓶颈，实现短波段的自适应光学校正，是不现实的。数字全息式自适应光学技术是一种新型的自适应光学技术，通过操作光波的振幅和相位，实现动态像差校正，改善天文望远镜成像质量。因而，天文望远镜数字全息自适应光学技术完全不需要波前校正器和波前传感器等硬件，而是完全采用数字办法处理，是一种十分具有发展潜力的自适应光学技术。该自适应光学技术非常切合我国天文自适应光学技术的现状，它的发展可以弥补我国在制造高性能波前校正器和波前传感器方面的不足，为我国新型天文自适应光学技术的发展提供理论基础和技术储备。

自适应光学技术可以校正大气湍流，提高地基天文望远镜的分辨率，是地基大口径天文望远镜必备的光学仪器之一。然而，自适应光学系统的成像分辨率严重依赖核心元件的性能，如变形镜和波前探测器。这些元件的研制成本都很高，也导致自适应光学系统的研制成本很高。本项目以数字全息自适应光学技术在天文观测方面的应用展开，针对传统天文自适应光学技术，成本高，研制周期长，更新换代困难等问题，提出利用数字全息技术校正大气湍流，实现高分辨率成像的方法研究。本项目开展的研究内容如下：全息图重建和像差校正算法的研究；数字全息方法进行湍流校正能够达到的分辨率极限；数字全息自适应光学系统的设计和模拟仿真；实验光路的搭建及原理验证；同时针对数字全息自适应技术的一些缺点，提出了相应的解决方案；数字全息技术用于天文望远镜拼接镜面共相问题的研究；倾斜镜控制方法的研究等。本项目的研究进一步完善了数字全息自适应技术的理论基础，验证了该技术的可行性，为该技术应用于实际观测提供了理论基础和实验经验。