Abstract: A deformable membrane assembly comprises an at least partially flexible fluid-filled envelope, one wall of which is formed by an elastic membrane that is held around its edge by a resiliently bendable supporting ring, a fixed support for the envelope and selectively operable means for causing relative movement between the supporting ring and the support for adjusting the pressure of the fluid in the envelope, thereby to cause the membrane to deform. The bending stiffness of the ring varies round the ring such that upon deformation of the membrane the ring bends variably to control the shape of the membrane to a predefined form. The moving means comprise a plurality of ring-engaging members that are arranged to apply a force to the ring at spaced control points.

Abstract: A deformable membrane assembly 1 comprising a fixed support; a fluid-filled envelope, one wall of which is formed by an elastic membrane 8 that is held under tension around its edge by a flexible membrane supporting member 2, 10, the membrane supporting member being coupled to the fixed support at a plurality of discrete control points 120 round the supporting member by respective engaging members for controlling the position of the membrane edge relative to the fixed support at the control points, and the member being unconstrained between said control points; and a selectively operable pressure adjuster for adjusting the pressure of the fluid within the envelope, thereby to adjust the shape of the membrane; wherein at least three control points are provided which are situated round the membrane edge at spaced locations on the member that are selected to increase the energy of the lowest order out-of-plane bending modes of the supporting member in response to loading through tension in the membrane that do n

Abstract: The present invention provides a deformable membrane assembly 1 comprising an elastic membrane 8 that is held under tension around its edge by a bendable membrane supporting member 2,10, a body of fluid in contact with one face of the membrane, the pressure of the fluid being controllable for adjusting the shape of the membrane, and one or more bending controllers 24 acting on the supporting member 2, 10 to control the bending of the supporting member in response to loading through tension in the membrane. The bending stiffness of the membrane-supporting member 2, 10 varies round its extent to control the profile of the edge of the membrane 8; etc. upon actuation. A variety of different types of bending controllers are disclosed which permit out-of-plane bending of the supporting member 2, 10 but prevent or control in-plane bending or deformation of the supporting member.