A New Approach for Fabricating Large Format Deformable Mirrors

Adaptive Optics(AO) is a technique that removes the blurring created by the atmosphere when using an astronomical telescope. High speed mirrors, included as part of the telescope, that can change shape (i.e. deformable mirrors) can enable this technique, resulting in a much sharper image. This project would look to develop a new approach to making such deformable mirrors. This integration would allow for the more routine use of AO in telescopes. A key task for this approach is the fabrication of thin curved glass “shells” that are part of the deformable mirror optics. The investigators will develop a more economical way of making these shells. The program will develop the approach for making shells up to 0.9 m in diameter. This will enable existing large telescopes to utilize such optics for use in astronomy. The project will involve a graduate student in the development work. This project will investigate a new approach for fabrication of the shells needed to use in Adaptive Secondary Mirrors. Typically, initially flat polished sheets of glass are formed into curves via heating. This approach would rely on an accurate negative form to slump the glass onto. This project would take a different approach by letting the glass slump freely within a support ring that is outside the final optical diameter of the shell. Such an approach allows for creation of shells over a variety of radii of curvature, simply by adjusting the peak temperature. To create an approximately parabolic shape, an additional force is required that is accomplished with a top weight with a given force just outside the optical diameter creates close to the desired shape. This ability to fabricate simpler and more robust large format deformable mirrors, will make such technology available to a wide range of telescopes of various aperture sizes. This fabrication approach can also be applied to other applications beyond astronomy that require large curved and deformable optics such as solar concentrated photovoltaic power systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.