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JPL's Micromesh Bolometer

Taking some lessons from nature, the Jet Propulsion Laboratory (JPL) designed a novel "micromesh bolometer" to measure minute temperature variations in the cosmic microwave background, which provides a snapshot of the universe about 300,000 years after the Big Bang. In a design reminiscent of a highly efficient spider's web, JPL's bolometer uses the least amount of material possible for optimal performance.

Replacing solid crystalline materials used by conventional bolometers, JPL's web-shaped grid reduced the material needed by 99%. The silicon nitride supporting material for the balometer is only one micron thick, several microns wide, and up to ten thousand microns long. (A micron is roughly the thickness of a single strand in a spider's web, on 100 times finer than a human hair.) These features were etched onto the bolometer using advanced micromachining and photolithography techniques at JPL's Microdevices Laboratory.

By absorbing millimeter-wave radiation from the cosmic microwave background, the bolometer measures the changing temperature of the micro web with a tiny thermometer made from specially developed Germanium. Changes in the thermometer indicate the amount of radiation detected. The bolometer measures minute temperature variations (a 100-millionth of a degree or 0.0001 C) in the cosmic microwave background. An Italian-designed cooling system also chills the sensor to three-tenths of a degree above absolute zero, giving the bolometer the high level of sensitivity needed to create the BOOMERANG maps.

The Microdevices Laboratory is a state-of-the-art research and technology-development facility in the Center for Space Microelectronics Technology (CSMT) at JPL. Funding for the bolometer came from JPL's Technology and Applications Programs (TAP) Directorate. JPL is managed by the California Institute of Technology on behalf of NASA