Deformable Mirror for Spaceflight

The specific objective of this IRAD is adapting a precision glass slumping technology that GSFC has developed for making grazing incidence mirrors for making normal incidence mirrors. These mirrors, extremely thin (0.2mm) and lightweight (0.5 kg/m2), will be sent to Dr. Keith Patterson at JPL and colleagues at Caltech who will attach precision actuation mechanisms on their backs to adjust their focus and other characteristics, making them fully diffraction-limited at 500nm wavelength. The requirements on the mirror substrate are: They must be no more than 0.2mm thick, because of both a desire to have a lightweight mirror and the fact that the actuation mechanism has a very limited dynamic range, which is inversely proportional to mirror substrate thickness. They must be diffraction-limited at all but the lowest spatial frequencies. In practice, this means that any deviation from the mathematic prescription must be well below 20 nm. This is because the actuation mechanism is not effective in removing errors with spatial periods shorter than about 20mm.