Abstract: A two-piece spring probe in electrical contact with a piece of testing equipment is used for probing an object to be tested. The two-piece spring probe includes a coiled compression spring and a conductive element. The coiled compression spring has a non-uniform outer diameter and is used to electrically contact the object. The conductive element is directly connected to the coiled compression spring and in electrical contact with the testing equipment.

Abstract: A cascade refrigeration system includes first and second cooling devices. The first cooling device includes a first compressor, a condenser, an expansion device, an evaporator having first and second passages independent from and not communicating with each other, and a first conduit interconnecting the first compressor, the condenser, the expansion device and the first passage. The second cooling device includes a second compressor, a heat exchanger, and a second conduit interconnecting the second compressor, the second passage and the heat exchanger. A circulation switching device includes a switching mechanism connected to the first conduit downstream of the condenser and upstream of the expansion device.

Abstract: An evaporator includes a casing and a plurality of circulation units disposed on the casing. Each of the circulation units includes a flow path formed in the casing, an inlet formed in the casing for entry of one of refrigerants into the casing and fluidly communicating with the flow path, and an outlet formed in the casing spaced apart from the inlet for exit of the one of the refrigerants out the casing and fluidly communicating with the flow path. The circulation units are independent from each other and do not fluidly communicate with each other.