根据太赫兹探测成像用户的需求，设计了一种适用于太赫兹波段的光学系统。其焦距 为50 mm，F数为1，工作波段为50 ～ 100 μm，接收器为非致冷型IRM160A红外探测器，全视场角为11.9°。该系统 采用共轴式结构，由3片球面透镜和1片CCD保护玻璃组成，并使用了Topas COC新型材料。另外还引入了1个非球面， 以实现系统结构简单、重量轻和成本低的目标。设计结果表明，当截止频率为10 cy/mm时，该光学系统的调制传递函 数接近衍射极限，各个视场的点列图均方根半径均远小于艾里斑半径，并具有良好的成像质量，因此能够满足太赫 兹光学系统的总体设计要求。

According to the requirements of THz imaging detection, an optical system suitable for the THz waveband is designed. The optical system has a focal length of 50 mm, a F number of 1, an operation waveband from 50 m to 100 m and a full field of view of 11.9°. Its receiver is an uncooled IRM160A infrared detector. In the system, a coaxial structure consisted of three spherical lenses and a piece of glass for protecting a CCD is used. A new material Topas COC is used. In addition, to meet the requirements of simplicity, low weight and low cost, an aspheric surface is also introduced. The design result shows that at a cut-off frequency of 10 cy/mm, the optical system has a modulation transfer function close to the diffraction limited curve. In each field of view, the RMS radii of the spot diagrams are far less than the airy disk radius. Its imaging quality is good. So it can meet the overall design requirements of a THz optical system.