侧面遮拦式日晕光度计的杂散光理论分析

提出了一种侧面遮拦结构的日晕光度计,在镜筒内通过设置多层挡板结构逐层抑制处于内视场的挡板边缘衍射光,同时采用倾斜布置的上挡板结构抑制处于外视场的入射窗口边缘衍射光和侧壁散射光.建立数学模型对这些杂散光抑制挡板进行了仿真计算,结果表明,优化各挡板的几何参数后,日晕光度计的设计视场可达3.5～10个太阳半径,视场内的杂散光水平均可低于10-8平均太阳亮度.相对于高山天文台的日晕光度计在4～8个太阳半径的视场内总杂散光达到10-2平均太阳亮度,该日晕光度计扩展了可观测视场,并使杂散光抑制提高了一个量级.

Theoretical Stray Light Analysis of Side-baffled Sky Brightness Photometer

A sky brightness photometer with a side-baffled structure,which adopts multibaffles to suppress diffracted stray light layer-by-layer in the inner field of view,is proposed.In addition,specially designed upper baffles block both scattered and diffracted stray light in the outer field of view.A mathematical model is established to simulate the baffles,and calculated results show that the field of view of the photometer can be designed to be 3.5～ 10 solar radii by optimizing the geometric parameters of the baffles.The stray light in the full field of view can be suppressed effectively to less than 10-8 of the mean solar brightness.Compared with the High Altitude Observatory,which has a sky brightness monitor with a field of view of 4 ～ 8 solar radii and a stray light level of 10-7 of the mean solar brightness,the proposed photometer expands the observable field of view and improves the stray light suppression level by over an order of magnitude.