Abstract: A cryogenic heat exchanger, such as a pulse tube cryogenic heat exchanger, is provided wherein the chilled heat transfer connection point can be conveniently disposed at an "apex." The heat exchanger has a bridging chamber with a first opening and a second opening. Disposed within the bridging chamber is a plurality of fins disposed longitudinally between the first opening and the second opening so as to partition the bridging chamber into a plurality of parallel longitudinal channels of equal cross-section. The first opening and the second opening are disposed at an angle to one another, so that a heat transfer gas flowing through the heat exchanger, changes direction within the bridging chamber.

Abstract: A cryogenic cooler of the pulse tube type is provided wherein the reservoir is disposed within the compressor housing. The invention provides the high efficiencies associated with orifice pulse tube cryogenic coolers, but is more compact and is generally lighter in weight than conventional pulse tube cryogenic coolers.

Abstract: A photolithographic etching process for accurately and uniformly fabricating wire screen disks of varying complex geometries for cryogenic cooler regenerators. The photolithographic etching process includes the steps of applying a photoresist to a sheet of wire screen, developing the photoresist in the form of one or more desired disk shapes, and then etching the developed sheet of wire screen to form the wire screen disks. The etching process of the present invention produces wire screen disks with solid edges, thus ensuring that the wire screen disks fit properly in the regenerator. Also, these edges have no loose or bent wires which can break off and potentially damage the compressor and other moving parts of the cryogenic cooler. The etching process of the present invention can be used to fabricate wire screen disks with varying complex geometries, thus allowing for the construction of cryogenic coolers having complex, but more efficient, configurations.