在高精度的点源透射比测试中, 测试环境中背景杂散光的影响不可忽视。为了提高点源透射比的测试精度, 研制了一种可有效抑制背景杂散光的高性能光陷阱系统。依据点源透射比测试理论和光辐射能量传输理论, 给出了光陷阱主要设计参数与点源透射比测试误差的定量数学关系; 提出了背景杂散光各级散射路径全面可控的光陷阱设计思路, 大大增加了背景杂散光到达成像视场前的散射次数; 通过多种光陷阱模型的仿真比对实验, 验证设计思路和模型的优越性。实验结果显示: Φ20 m的光陷阱系统可使口径Φ2 m、外形尺寸约2.8 m×3.5 m×11 m的光学系统的点源透射比测试误差达到1.49×10-10, 较相同实验室空间下未使用光陷阱的测试系统降低了约4个数量级, 较相同实验空间下国外现有光陷阱方案降低了两个数量级, 可用于大型太空望远镜的高精度点源透射比测试。

The influence of background stray light can not be ignored in the high precision PST test. In order to improve the precision of the PST test, a high performance light trap system which can effectively suppress the background stray light was developed. The quantitative mathematical relationship between the main design parameters and the test error of PST was given based on the theory of the PST test and the theory of optical radiation transfer. The design idea of the light trap was proposed, which was fully controllable in the scattering path and greatly increased the scattering times to the imaging field of view. Through the simulation comparison experiment of some light trap models, the superiority of the design ideas and the model was verified. The result show that, when a light trap with diameter of 20 m is used for the PST test to an optical system with diameter of 2 m and size of 2.8 m×3.5 m×11 m, the testing error can be as small as 1.49×10-10, it is reduced by about 4 orders of magnitude compared with the test system without light trap under the same experimental space, and reduced by about 2 orders of magnitude compared with the existing light trap schemes under the same experimental space. The light trap can be used to the high precision PST for the large space telescope.