Abstract: Heating/defrost constructions of a very low temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: Heating/defrost constructions of a very loW temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: Adjustment of the force that a stylus exerts on an object in a stylus profiler is accomplished by having a magnetic core, which is operably connected to the stylus and and mounted within an electromagnetic coil. The core moves relative to the coil as the stylus moves vertically. The coil creates a uniform magnetic field within the range of movement of the core. The core is elongated to be subject to uniform fields so that the force that the core-coil combination applies to the stylus is constant irrespective of the vertical position of the stylus.