Research Of A Kind Of Single-order Diffraction Grating Used To Laser-plasma Produced X-ray Diagnose

In this paper, we made a research on quasi-random rectangular holes self-supporting transmission grating to solve the bad diffraction influence leaded by support-mesh structures of the X-ray transmission grating. What’s more, we made a research on the single-order diffraction grating used to laser-plasma produced X-ray diagnoses.Black-white transmission grating, as an old dispersive element, was widely applied in practice. The transmission grating used for X-ray region often fabricated with support-mesh structures to realize self-support. However, the support-mesh structures always made a bad influence on the original diffraction pattern of the grating and make it complicated to apply. To solve this problem, in this paper we provided a method to realize a kind of totally self-supporting transmission grating by arrange the rectangular transmission holes in a high Z foil quasi-randomly. Theatrical analysis and experimental result both proved that the diffraction of the transmission grating can get rid of the bad influence of the support-mesh structures by using this new designed method. We also made a discussion about the optimization of the grating designing parameters. The signal to noise ratio of the grating diffraction can be improved by narrowing the length of the basic rectangular holes and increasing the transmission area.Transmission grating is widely used in laser-plasma produced X-ray diagnoses. The precision of the calculated data would be largely increased and thus the following data analysis is largely simplified while using single-order diffraction grating instead of traditional transmission grating. But unfortunately, the existed single-order diffraction gratings which used in X-ray region can’t realize self-support, easy to fabricate and with a high enough absolute efficiency of the first order to applied inpractice. In this paper, based on scalar dittraction theory, we designed a kind of quasi-single-order diffraction grating used in laser-plasma produced X-ray diagnose, which we name as inclined rectangular apertures gratings(IRAG). IRAG is totally self-supported and the absolute diffraction efficiency of the first order is approximately 3% which is reasonable for many practical applications. The simple structures of IRAG largely reduced the fabrication difficulty. We made the theoretical derivation and simulation of the diffraction of the IRAG. We fabricated a sample grating in visible region and a sample grating in X-ray region. Then we tested their diffraction patterns in visible light region and soft X-ray region respectively. The experimental results showed that IRAG can realize quasi-single-order diffraction along two special axes by suppressing the higher orders to a low enough level, which are in good agreement with the theoretical prediction. We also made an analysis of the experimental error which is mainly leaded by the fabrication error and then we calculated the precise influence of the fabrication error to the diffraction of the grating.Those two methodologies can profit applications of this kind of x-ray dispersive element in a wide field.