Patent ID: 8193496

Claim:
A method of visually detecting a gas leak of any one or more chemicals of a group of predetermined chemicals, the gas leak emanating from a component of a group of components in different locations, the method comprising: aiming a passive infrared camera system towards the component, wherein the passive infrared camera system comprises: a lens, a refrigerated portion defined by the interior of a Dewar flask, the refrigerated portion comprising therein: an infrared sensor device; and a single filter configuration comprising at least one fixed optical bandpass filter, each filter fixed along an optical path between the lens and the infrared sensor device, wherein at least part of the aggregate pass band for the single filter configuration is within an absorption band for each of the predetermined chemicals and wherein the aggregate pass band for the single filter configuration is at least about 200 nm; and a refrigeration system adapted to cool the refrigerated portion, the refrigeration system comprising a closed-cycle Stirling cryocooler; filtering an infrared image associated with the area of the gas leak under normal operating and ambient conditions for the component with the at least one optical bandpass filter; receiving the filtered infrared image of the gas leak with the infrared sensor device; electronically processing the filtered infrared image received by the infrared sensor device to provide a visible image of the gas leak under variable ambient conditions of the area around the leak; and visually detecting the leak based on the visible image under the variable ambient conditions.