Onto Innovation Inc.
ENHANCED HEAT TRANSFER IN LIQUEFIED GAS COOLED DETECTOR

Abstract:

A horizontal Dewar flask is used with an optical metrology device, which may advantageously reduce the vertical height of the device. A thermal transfer member provides thermal transfer between a liquefied gas cooled sensor and liquefied gas in a chamber of the Dewar flask. To compensate for the loss of thermal transfer from the sensor as the liquefied gas evaporates and changes to a gaseous state, the thermal transfer member biases heat transfer to the liquefied gas that is at the bottom of the chamber. The thermal transfer member may have a larger surface area at a bottom portion of the thermal transfer member than the upper portion. For example, the thermal transfer member may include one or more projections that extend into the liquefied gas with greater density at the bottom of the chamber than at the top of the chamber.