Cryogenic Optical Refrigeration for Space Applications

ABSTRACT: Optical refrigeration is currently the only demonstrated all-solid-state cryocooling technology. Optical cryocoolers use laser light to cool small crystal or glass cooling elements. The cooling element absorbs the laser light and reradiates it at higher energy, an example of anti-Stokes fluorescence. The extra energy of the outgoing light comes from the thermal energy of the cooling element, which in turn becomes colder. This Phase I proposal, entitled Cryogenic Optical Refrigeration for Space Applications, directly addresses the deploying optical refrigerator for cooling infrared sensors aboard DoD space missions. ThermoDynamic Films LLC (TDF), in collaboration with the University of New Mexico (UNM), proposes to design fully functional prototype cryogenic optical refrigerators and improve the key components needed to make these refrigerators operate at lower temperatures and higher efficiencies. In particular, the proposers will develop new, higher-efficiency cooling materials and they will design and characterize the thermal links that connect the refrigerators to the sensors. The TDF/UNM collaboration is internationally recognized as the pioneer in the field of optical refrigeration. This collaboration is the only group of investigators to have demonstrated optical cryocooling, and it is vigorously advancing both the science and applied aspects of this revolutionary technology. BENEFIT: In many areas of national defense, scientific and laboratory analytic instruments, medicine and high performance electronics, it is necessary to cool instruments and devices to cryogenic temperatures (below -150°Celsius). Cryocoolers are essential components in the infrared (IR) systems that are used for defense applications such as surveillance and ballistic missile guidance. Cryocoolers are an important part of the U.S. governments priority of heightened homeland and international military security. Cryocoolers are also needed to cool superconductors in a host of medical and geological applications. With no moving parts, TDFs cryogenic optical refrigerators would not be subject to wear. Additionally, they do not utilize any fluids, which can leak and generally need replenishing. Additional advantages include the compactness of these refrigerators, total lack of vibrations, agility, high temperature stability, the absence of electromagnetic interference (EMI) and rapid cool down. These advantages are particularly compelling for aerospace applications, such as those for space-borne infrared sensors.