An Basic Study for a Transmission Grating with Reduced 0th Order Light

研制了一种新型透射光栅。到目前为止，晶体和光栅已被用作x射线光谱仪的色散元件。晶体具有较高的光谱分辨率，但在某一波段的观测效率较低。反射光栅在钎焊波长附近具有良好的效率。但是为了将它应用于2kv以上的x射线，需要很大的面积。透射光栅是2kev以上x射线光谱仪中最有趣的装置之一。然而，透射光栅的最大缺点是对散射光的吸收效率低（每一阶为10.13%）。其效率低下的原因之一是不能引入透射光栅的钎焊角。为了提高对一阶光的传输效率，本文提出了一种新的透射光栅设计思路。在透射光栅中引入一个反射角，可以使0阶光减弱，一阶光增强。计算机模拟演示了这些性能。此外，在可见光下的实验也显示了这种新型透射光栅的栅格优势。

A new transmission grating is developed. So far crystals and gratings have been used fro a dispersive elements in spectrometers for X-rays. The crystals provide high spectral resolution, but the observation effeciency for a certain energy band is small. The reflective gratings have a good efficiency near the brazed wave length. But in order to apply it for the X-rays above 2 ke V a large area is required. The transmission grating is one of the most interesting device for the spectrometer for X-rays above 2 keV. However, the big disadvantage of the transmission grating is its inefficiency into the dispersed light (10.13% for each first order). One of the reason of the inefficiency is that the braze-angle could not be introduced for a transmission grating.In this research, I introduce a new idea for the transmission grating in order to improve the efficiency to the first order light. The introduction of one reflection in the transmission grating can resemble a braze-angle, and make the 0th order light reduced, and the first order light emphasized. Computer simulation demonstrated these performances. Furthermore, experiments using a visible light also showed the grate advantage of this new transmission grating.