光学显微镜成像方式及投影冷光源的分频合成探讨

Discussion on Optical Microscope Imaging Modes and Composion of Cold Light Source Device Using Frequency Splitting

传统显微镜光源主要包括卤素灯光源、纯水过滤热射线光源、LED光源等，由于卤素灯光源含有大量760~1400 nm区段的红外线，纯水过滤热射线光源滤除红外线不彻底且水会导致透射光线的部分散射，LED光源在500 nm波长附近的光照强度不足、波形存在缺陷，容易灼伤样品或使成像质量受限，都难以满足需要采用大功率冷光源进行无损、高质量显微观察成像和测试的要求。本文在总结光学显微镜的成像方式、光源类型及各类光源优缺点的基础上，提出了采用三棱镜-凸透镜组分频合成冷光源的新思路。该思路首先利用三棱镜将卤素灯光源光谱按频率顺序打开，然后选择可见光区域内的光谱，用凸透镜组校正可见光方向后，再由三棱镜将这些可见光合成不含热射线的冷光源。理论和砂岩荧光薄片实际测试效果表明，该方法既可完全排除热射线，从而使样品免遭受破坏，又保持了完整的可见光光谱，解决了大功率冷光源红外线生热和光谱存在缺陷的难题，这为采用大功率冷光源的光学显微镜投影高质量成像提供了新的方法及切实可行的依据。该套分频合成光源的装置主要配置为：玻璃材质的同规格的三棱镜与凸透镜各两个，卤素灯光源一个。结构简单，可在需使用大功率冷光源进行无损成像和测试等方面获得广泛的应用。

Halogen lamps, pure water filtered heat rays and LED are the main conventional light sources for the optical microscope. Halogen lamp light source contains a lot of infrared rays from 760 to 1400 nm. The pure water filter incompletely filters out infrared rays, which results in scattering of some transmission light. For the LED light source, around the 500 nm wavelength, the light intensity is weak and the waveform is incomplete, which can cause samples to burn or can affect the final imaging quality. Therefore, conventional light sources are not suitable cold light sources for non-destructive and high-quality imaging microscopic observation and testing. Based on the comparison of imaging modes and the light source types, the advantages and disadvantages of different light sources are discussed. A new idea to obtain a cold light source through prisms and convex mirror groups is proposed. The idea is firstly to open the spectrum of the halogen lamp light source in order of frequency through the prism, then choose the visible spectrum, finally adjust the light direction through convex mirror groups and then compound the cold light without heat rays through the prism. Theory and practical application results by studying fluorescence in thin sections of sandstone showed that the cold light obtained by this method not only completely filters out heat rays, but also retains the whole visible spectrum. This method provides a feasible foundation for the projection imaging of a high-power cold light source microscope. The whole device includes two prisms and convex mirrors, and one halogen lamp and is especially suited for non-destructive imaging.