R and D program on bimorph mirrors at the ESRF

The very low emittance of new synchrotron sources and the increasing number of micro-focusing applications make the production of highly stable and well defined beams increasingly necessary. The use of flexible mirrors whose curvature can be changed while maintaining a correct figure appeared to be a very attractive solution. For over two years, the ESRF has been developing a new approach which consists of making an X-ray mirror from an active material such as piezoelectric ceramics. With respect to conventional bender this concept, already used in astronomical and laser applications, has the advantages to be mechanics free, very compact and relatively cost effective. This paper presents the status of the ESRFs developments in this field. First, theoretical and technical descriptions of the system are given. Experimental tests of various configurations confirmed the potential of this concept. For example, two 150mm long bimorph mirrors set into a Kirkpatrick-Baez geometry gave a focused spot of 10microm (vertical) x 20microm (horizontal). Finally, the developments of in-situ control systems (strain gauges, optical devices), necessary to fully exploit the capabilities of these active optics, are discussed