Wojtanowski Jacek, Jakubaszek Marcin, Zygmunt Marek
Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland.
Sensors (Basel). 2020 Apr 30;20(9):2569. doi: 10.3390/s20092569.
In this paper, we present a novel configuration of an optical angle-of-incidence (AOI) sensor based on the application of a freeform mirror. The main challenge in designing this mirror was to provide a strictly linear transformation between AOI and the spatial position of the spot created on the linear detector array. Another two goals of this paper were to minimize stray light issues (improve the dynamic range) and create an intermediate focus and lateral shift in the detector position with respect to the plane of incidence. From an optical point of view, the designed mirror can thus be understood as the composition of three components: a high-numerical-aperture (NA) fully achromatic f-theta lens in one cross-section and a perfectly focusing lens, combined with a deviating prism in the second (orthogonal) cross-section. In comparison to the standard "shade" methods, the proposed approach allows a constant angular resolution to be maintained over the entire field of view. The mirror was designed on the basis of fundamental geometrical rules by numerically solving differential problems using an innovative scheme based on the minimization of the specific merit function. The proposed method was practically applied to design a freeform mirror for a 90°/120° field-of-view sensor, showing a satisfactory performance.
在本文中，我们基于自由曲面镜的应用，提出了一种新型光学入射角（AOI）传感器配置。设计此镜子的主要挑战在于在AOI与线性探测器阵列上产生的光斑的空间位置之间提供严格的线性变换。本文的另外两个目标是将杂散光问题降至最低（提高动态范围），并在探测器位置相对于入射平面产生中间聚焦和横向偏移。从光学角度来看，设计的镜子因此可以理解为三个组件的组合：一个在一个横截面中的高数值孔径（NA）全消色差f-θ透镜和一个完美聚焦透镜，以及在第二个（正交）横截面中的一个偏折棱镜。与标准的“遮光”方法相比，所提出的方法允许在整个视场中保持恒定的角分辨率。该镜子是根据基本几何规则设计的，通过使用基于特定优值函数最小化的创新方案对微分问题进行数值求解。所提出的方法实际应用于为90°/120°视场传感器设计自由曲面镜，表现出令人满意的性能。
