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

1992 Fiscal Year Final Research Report Summary

• Project/Area Number: 03804009
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Astronomy
• Research Institution: Osaka University
• Principal Investigator: KITAMOTO Sunji Osaka University, Faculty of Science, Research Associate, 理学部, 助手 (70177872)
• Project Period (FY): 1991 – 1992
• Keywords: Transmission Grating / Spectroscopy / X-ray Spectroscopy / High Efficiency

Research Abstract

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.