APPARATUS AND METHOD FOR MONITORING AND REGULATING CRYOGENIC COOLING.

摘要

An apparatus and method for monitoring and/or controlling cryogenic cooling by measuring the opacity of the vapor cloud (113) generated from a cryogenic cooling device (112). The opacity is determined by measuring the reduction in intensity of a light beam (127) passed through the vapor cloud (1 13). The opacity measurements are used to control an operating parameter of the system, such as the cooling rate of the cryogenic cooling device (1 12). The opacity measurements may be normalized to compensate for variables, other than temperature of the workpiece (119) and cooling rate, which may affect the opacity of the vapor cloud (113).