Shape-Shifting Mirrors

Prototype of the new glue-free deformable mirror. (Source: JTEC)

A team of researchers from JTEC Corpora­tion and Osaka Uni­versity developed a bimorph deformable mirror that allows for precise shape modi­fication and usage under vacuum, a world first. Because piezo-actuators and a mirror substrate in conven­tional deformable mirrors were bonded with epoxy glues, this caused problems such as organic gas emission in a vacuum chamber and denatured bonding materials due to chamber cleaning at high tempera­tures. Thus, the use of a deformable mirror was performed only in ambient atmo­spheres.

The team led by Kazuo Yamauchi invented a method for bonding PZT actuators to a mirror substrate without using epoxy glues to develop a glue-free bimorph deformable mirror, allowing for usage of deformable mirrors under vacuum. They developed a technique to bond PZT actuators to a mirror substrate by using inorganic silver nano­particles. They confirmed that the emission rate of organic gas was at an acceptable level: the vacuum chamber was not conta­minated by the gas while main­taining the same level of operability as that of conven­tional mirrors.

They also confirmed that the bonding and bending charac­teristics were almost the same before and after heating at 200°C, which is necessary for cleaning procedures. These results verified practical usage of this mirror under vacuum. This group’s achieve­ments will permit a maximal use of 100-1,000 times brighter X-rays provided by fourth-generation syn­chrotron radiation faci­lities than that of current third-generation faci­lities.

This mirror will be used in X-ray experi­ments and soft X-ray systems, both of which need a high vacuum environment, for the fourth-generation large syn­chrotron radiation faci­lities in which precision optics under vacuum are indis­pensable. “Our bimorph deformable mirror will be used in a variety of appli­cations – not only for X-ray radiation systems, but also for controlling space tele­scopes and high intensity lasers,” says Yoshio Ichii. (Source: Osaka U.)

Reference: Y. Ichii et al.: Development of a glue-free bimorph mirror for use in vacuum chambers, Rev. Sci. Inst. 90, 021702 (2019); DOI: 10.1063/1.5066105

Link: Dept. of Precision Science and Technology, Graduate School of Engineering, Osaka University, Osaka, Japan

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