DEVELOPMENT AND APPLICATION OF SOFT X-RAY INTERFEROMETER

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13450034
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied physics, general
• Research Institution: THE UNIVERSITY OF TOKYO
• Principal Investigator: MOMOSE Atsushi THE UNIVERSITY OF TOKYO, GRADUATE SCHOOL OF ENGINEERING, ASSOCIATE PROFESSOR, 大学院・工学系研究科, 助教授 (20322068)
• Co-Investigator(Kenkyū-buntansha): KOYAMA Ici-iro THE UNIVERSITY OF TOKYO, GRADUATE SCHOOL OF ENGINEERING, RESEARCH ASSOCIATE, 大学院・工学系研究科, 助手 (90323526)
• Project Period (FY): 2001 – 2002
• Keywords: Soft X-rays / Synchrotron Radiation / Interferometer / Fourier Spectroscopy

Research Abstract

Interferometry, which is indispensable in modem science and technology, has been quite successfully developed in the visible light region. In the region of soft X-rays whose wavelength is much shorter than that of visible light, however, interferometry is underdeveloped, and few researches into the metrology taking advantage of wave nature are reported. It is dear that a variety of applications would be opened up when a soft X-ray interferometer is developed. However, the short wavelength of soft X-rays and poor quality of optical elements for soft X-rays have obstructed the development of soft X-ray interferometry. We have experience of constructing and operating interferometers for hard X-rays whose wavelength is further shorter than that of soft X-rays. We proposed this research project as an expansion of our activity into the soft X-ray region. In the hard X-ray region, crystal optical elements are available, and therefore interferometers were operated in spite of the hard-X-ray wa velength (ca. 0.1 nm). Although problems characteristic of soft X-rays, such as that crystals are not available, and that an interferometer has to be constructed in vacuum, are pointed out, we consider that the development of a soft X-ray interferometer can be within our scope basing on our achievement in the hard X-ray region.
We constructed a Mach-Zehnder type interferometer for 13-nm synchrotron soft X-rays employing free-standing Ru/SiN films for beam splitters. We selected this configuration because its operation is comparatively easy and a variety of applications are expected. We found that only two accurate tuning stages are required in order to align four optical elements, and fabricated a prototype comprising accurate petitioners driven by piezoelectric actuators. Furthermore, because the plan for alignment is important, we devised a method that depends on the visibility of visible laser.
Experiments using soft X-rays were canned out at the Photon Factory, High Energy Accelerator Research Organization. Unfortunately, we have not observed interference yet. We consider that vibration and/or deformation of optical elements would be responsible for current results. We will continue experiments, devising to get rid of the problems. Once interference is observed, we have a plan to add a mechanism for changing optical path lengths and to move on the development of soft X-ray Fourier interferometry to realize innovative energy resolution in the field of soft X-ray spectroscopy.