Cryogenic cooler

Claim 1

A thermal energy device comprising: (a) a scanning means for scanning energy emanating from a scene; (b) a detector array for receiving the scanned energy and generating electrical signals representative of the energy emanating from the scene; (c) electro-optical means connected to the detector array for producing a visible representation of the energy emanating from the scene; and (d) a closed cycle cooler for cooling the detector array to its operating temperature, said cooler including a housing, a compressor piston and a regenerator/displacer piston, a piston connecting rod, a crankshaft, bearings mounted between the connecting rod and crankshaft, a motor operatively connected to the crankshaft for reciprocating the pistons, and a noise reducing means, the compressor piston including a head dividing the housing into a crankcase working volume and a working volume, walls of the compression piston head and housing forming coaxially aligned spring retaining recesses in the piston head and housing, the noise reducing means including a preloaded spring mounted in the coaxially aligned recesses for providing a driving force to the compression piston at bottom dead center while minimizing the driving force at top dead center for maintaining engagement of the connecting rod and crankshaft with the bearings whereby operating noise is substantially reduced.