Pixelized Device Control Actuators for Large Adaptive Optics

This technology can be used in military surveillance and relay mirrors, imaging for retinal disease, reconnaissance mapping, and missile detection and targeting.

A fully integrated, compact, adaptive space optic mirror assembly has been developed, incorporating new advances in ultralight, high- performance composite mirrors. The composite mirrors use Q-switch matrix architecture- based pixelized control (PMN-PT) actuators, which achieve high- performance, large adaptive optic capability, while reducing the weight of present adaptive optic systems.

The self-contained, fully assembled, 11×11×4-in. (≈28×28×10-cm) unit integrates a very-high-performance 8-in. (≈20-cm) optic, and has 8-kHz true bandwidth. The assembled unit weighs less than 15 pounds (≈6.8 kg), including all mechanical assemblies, power electronics, control electronics, drive electronics, face sheet, wiring, and cabling. It requires just three wires to be attached (power, ground, and signal) for full-function systems integration, and uses a steel-frame and epoxied electronics. The three main innovations are:

1. Ultralightweight composite optics: A new replication method for fabrication of very thin composite 20-cm-diameter laminate face sheets with good as-fabricated optical figure was developed. The approach is a new mandrel resin surface deposition onto previously fabricated thin composite laminates.
2. Matrix (regenerative) power topology: Waveform correction can be achieved across an entire face sheet at 6 kHz, even for large actuator counts. In practice, it was found to be better to develop a quadrant drive, that is, four quadrants of 169 actuators behind the face sheet. Each quadrant has a single, small, regenerative power supply driving all 169 actuators at 8 kHz in effective parallel.
3. Q-switch drive architecture: The Q-switch innovation is at the heart of the matrix architecture, and allows for a very fast current draw into a desired actuator element in 120 counts of a MHz clock without any actuator coupling.

This work was done by Gareth J. Knowles, Ross W. Bird, and Brian Shea of QorTek and Peter Chen of the Catholic University of America for Goddard Space Flight Center. For further information, contact the Goddard Innovative Partnerships Office at (301) 286-5810. GSC-15666-1