Membrane optics is a flat lens that employs plastic in place of glass to diffract rather than reflect or refract light. Concentric microscopic grooves etched into the plastic provide the diffraction.[1]
Glass transmits light with 90% efficiency, while membrane efficiencies range from 30 to 55%. Membrane thickness is on the order of that of plastic wrap.[1]
DARPA plans to use membrane optics as part of its Membrane Optical Imager for Real-Time Exploitation (MOIRE) program. The program uses lightweight polymer membranes for a 20m (70feet) foldable plastic orbital telescope capable of seeing a 1m (03feet) object from 36000km (22,000miles) away. Membrane grooves range from 4 to hundreds of micrometers in width.[1]
According to DARPA, glass-based optics in satellites are reaching the point where larger mirrors exceed the lifting power of existing rockets. MOIRE is planned to be one-seventh the weight of a comparable glass-mirrored device.[1]
Individual membranes would be mounted on foldable metal petals. Once in geostationary orbit, the satellite would unfold. The membrane lens occupies one end and a sensor suite the other.[1]
The device would be the largest telescope ever built – twice the size of the ground-based twin 10sp=usNaNsp=us Keck telescopes. It could see about 40 percent of the Earth's surface and could image a 10x area at a 1sigfig=1NaNsigfig=1 resolution and generate videos at one frame per second.[1]
A ground-based prototype consists of a section of a 5m (16feet) wide device that created the first images with membrane optics.[1]