光学极大望远镜大切分数量积分视场像切分方法的研究

The coming ten years is important period as a milestone in the developing history of the international astronomical optical equipment. Astronomical scientists will give their welcome to several ground based optical giant telescopes, which enable to observe further and fainter. Integral field spectrograph becomes one of their first-light instrumentations due to its advantage at the aspect of spatial and spectral resolution. Image slicer becomes the first choice of the giant telescopes under the construction since fiber bundle style integral field unit can’t figure out the problem about low duty ratio and random transmission noise, micro-lens array style can’t make balance between 2-D slicing image and spectral coverage. Image slicer with a large amount of integral field units is a kind of feasible method to seek more clearly (high spatial resolution) and wider (large field of view) observation but require more in design and manufacture. To achieve the purpose of high spatial and spectral resolution and diffraction-limit imaging, we plan to optimize its design method with some consideration, including simultaneously polishing technique, less optical parts, athermal supporting structure, stray light suppression and so on, and try to expand the integral field in spatial direction by using an asymmetric focal ratio transferring system.

未来十数年是国际天文光学装备发展史上具有里程碑意义的一个时期，天文科学家将迎来数架地基光学极大望远镜，有能力观测更远、更暗的天体。积分视场光谱仪在空间、光谱分辨率方面的兼容特点，使之成为未来光学望远镜的首选终端仪器之一。由于致密光纤束无法解决低占空比、随机传输噪声等问题，微透镜阵列无法解决二维像切分与光谱覆盖相矛盾的问题，在建的光学极大望远镜均选择像切分器作为积分视场单元的器件。面对看得清（高空间分辨率）与看得广（大视场）两种极端追求，大切分数量积分视场像切分器成为最大限度满足需求的一种实现手段，同时对设计与制造方面提出更多、更高的要求。计划研究多镜同时磨抛、减少光学件数量、使用抗温变支撑结构、设置消光结构等方法来优化像切分器设计方案，使用非对称光束的前端变焦比系统来扩大空间方向上的积分视场，达到高空间分辨率、大视场和衍射极限成像的研究目的。

天文积分视场光谱观测可获得扩展天体的三维光谱数据，包括空间和光谱信息，有助于研究星系形成与演化、恒星形成普遍机制、研究超大质量黑洞等。像切分器是积分视场单元的三种实现形式之一，具有重构狭缝、焦面占空比高、光谱覆盖范围大等优点，但结构复杂、制造难度大。通过大切分数量积分视场像切分方法研究，形成较为系统的像切分器设计体系。以TMT-IRIS为研究对象，提出一种单级像切分方案，并尝试一种两级像切分方案，扩展器件在更多切分数量方面的设计方向。初步构建一套光学模型+机械模型+杂散光分析的初步研究方法，有助于像切分器光学性能的深入研究。更多关注像切分器的制造工艺与方法研究，基于国内光学加工条件开展的器件国产化试制取得与预期相符的阶段性结果，有助于了解和掌握制造细节，有助于改进和完善像切分器制造工艺方案。调研非对称光束整形技术在积分视场光谱及高分辨率光谱方面的应用情况，提出相关的光学方案。