Differential spectral imaging system for biological and environmental monitoring

利用干涉仪的透射光谱、CCD的RGB单元的灵敏度光谱和物体的反射光谱，通过光谱模拟对波长差成像过程进行了理论分析。利用上述光谱计算得到的波长差图像上每个像素的颜色，并重建模拟图像。以非洲菊花瓣为例，模拟图像与真实波长差图像非常接近。其他类型的调制差分成像系统已经开发；荧光和偏振调制成像系统。荧光调制成像系统即使在正常明亮的室内也能提供清晰的荧光图像，如叶绿素和印章。偏振调制成像系统选择性地将透明图像和反射图像从显示在玻璃窗上和透过玻璃窗的图像中分离出来。差分光谱成像系统采用窄带通滤光片（干涉滤光片）和双视图光学元件，可以通过不同的光路从一个物体同时观察两个图像，从而改进为实时系统。该系统甚至可以对运动物体或光谱特征随时间变化的物体进行微分光谱成像。使用该系统监测了人体血液脱氧的变化。当手腕的血流通过绑带停止时，靠近手表面的静脉必须充满脱氧血红蛋白。该系统对脱氧血红蛋白的扩散变化进行了可视化观察。

The wavelength-differential imaging process has been theoretically analyzed by spectral simulation using the transmission spectra of the interferometer, sensitivity spectra of RGB cells of CCD and reflection spectrum of an object. The color of each pixel on the obtained wavelength-differential image is calculated using the spectra shown above and simulated image is reconstructed. For an example of gerbera petals, the simulated image was very close to the real wavelength-differential image.Other types of modulated differential imaging system has been developed; fluorescent-and polarization-modulation imaging system. The fluorescent-modulation imaging system provided clear fluorescent images such as chlorophyll and stamp on note even in normal bright room. The polarization-modulation imaging system selectively separated a transparent image and a reflection image from the image shown on and through a glass window.The differential-spectral imaging system has been improved into a real-time system using narrow band-pass filters (interference filters) and the dual view optics by which one can observe simultaneously two images through different optical paths from an object. The new system can even take the differential-spectral images of moving objects or objects which change their spectral characteristics with time. Change of deoxidization of human blood has been monitored over time using the system. When the blood stream of a wrist is stopped by banding, the vein near the surface of the hand must be filled with deoxyhemoglobin. The system has visualized change of the spread of deoxyhemoglobin.