LCTF机载高光谱相机光学系统设计

Optical System Design of LCTF-Based Airborne High Spectral Resolution Camera

针对无人机载设备结构及重量受限的特点,基于液晶可调谐滤光器件,设计了一种用于无人机载的高光谱成像光学系统.系统拥有46个通道,工作光谱范围为可见光到近红外(0.45~0.9μm),光谱分辨率10nm,焦距81.25mm,相对孔径1/2.5,全视场角12°,最大畸变量不大于0.12%,在航高5 000m时,地面像元空间分辨率0.4m,地面幅宽1km×0.87km.系统采用液晶可调谐滤光器整体嵌入式设计,在无渐晕设计条件下,得到的光学系统成像质量优良,均方根最大弥散斑直径不超过5μm,成像器件极限分辨情况下的各视场调制传递函数值均不小于0.54.用Zemax的多重结构特性定义和热分析功能,模拟了系统成像质量,最终确定系统整体温控25℃±5℃、液晶可调谐滤光器件温控35℃±1℃的方案.在无人机升限范围内(3~6km),飞行速度引起的系统像移小于像元尺寸,无需对像移补偿.

Considering that the space and weight of unmanned airborne equipment is limited, an unmanned airborne high spectral imaging optical system on the basis of liquid-crystal tunable filter liquid crystal tunable filter, which has 46 channels. The working spectrum of the system covers the visible light to near-infrared light （0.45 ~0.9 μm）, the spectrum resolution is 10 nm, the focal length is 81.25 mm, relative aperture is 1/2.5, the full viewing field angle is 12°, the maximum distortion is less than 0.12 %, the ground pixel resolution is 0.4 m, the ground breadth is 1 kmX 0.87 km with 5000m of flight level. The liquid crystal tunable filter overall embedded design is adopted and the aberration produced by liquid crystal tunable filter is revised. The imaging quality of the system is excellent under the no vignetting design condition, the root-mean -square diameter of maximum dispersed spot is less than 5 μm, the modulation transfer function of every viewing field is more than 0.54 under the sCMOS Nyquist frequency situation. Zemax multi-configuration and thermal analysis were used to simulate the imaging quality of system. 25 ℃ ± 5 ℃ of system temperature control scheme and 35 ℃±1 ℃ of liquid crystal tunable filter temperature control scheme was confirmed. In the range of 3 km^6 km aviation altitude, the system doesnrt need image motion compensation.