随着社会经济的高速发展, 环境污染和生态破坏日益严重, 突发性环境污染时有发生。 利用光谱技术测量有害气体的浓度, 可以对空气进行实时监测。 在弱吸收条件下, 利用多次反射池可以增加有效光程, 从而提高吸收光谱的探测灵敏度。 基于Herriott型多光程池的结构, 提出了一种紧凑型多光程池。 该光学器件由多个圆环形凹面反射镜螺旋封闭构成, 入射光沿着环形镜的径向和轴向同时传播, 形成有规律的放射状分布, 光线在吸收池中的反射轨迹呈螺旋路径, 光斑呈螺旋形分布。 实现了入射光和出射光的分离, 从而增加了光路的可调空间。 由于吸收池中的反射次数与螺旋的圈数成正比, 可以根据实际需要选择合适的光程。 另外, 该反射池的主体是一个圆筒, 具有稳定的机械性能和一定的抗震性。 利用ABCD矩阵变换分析了系统的稳定性, 通过模拟发现光束通过透镜后, 焦点会聚在圆筒中心附近, 能使入射光斑在池中收敛, 并讨论了反射次数与螺旋圈数的关系。 还研究了在不同入射角条件下的旋光特性, 发现线偏振光的旋转角度与入射角度成正比。 当入射角相同时, 旋转角度随着反射次数的增加而增大。

With the rapid development of social economy, the environmental pollution and the ecological destruction are continuously deteriorating while sudden environmental pollution incidents occur frequently. Real-time monitoring harmful gases of the air take advantages of spectroscopic techniques for concentration measurement. Multipass optical cells are -widely used in absorption spectrometry technique to improve gas detection sensitivity under the condition of weak absorption. This paper proposes a spiral-torus type multipass optical device base on the structure of Herriott type cell. The optical device consists of multiple torus concave mirrors in a spiral way. Incident light propagates along with radical and axial direction in winding staircase pattern. The faculae on the inner wall present a spiral-type. The entrance and exit apertures are separated due to the spiral trace of optical rays, which increases the accessible adjustment of the apparatus. The effective optical length can be adjusted based on the proportional relationship to the reflective times. This device is characterized with easy adjustment and excellent mechanical performance due to its cylindrical structure. Based on ABCD matrix, the stability of the system was analyzed and the relationship between the number of reflections and the incident angle were discussed. With optical simulation software, we designed a device for separating polarized light, and the characteristics of its rotation was studied.