Radiation bolometer

Claim 1

A RADIATION RESPONSIVE DEVICE FOR MEASURING THE TEMPERATURE OF A FURNACE COMPRISING A CASING ADAPTED TO BE SUPPORTED ON THE WALL OF THE FURNACE AND HAVING AN OPENING IN ONE END THEREOF ADAPTED FOR ALIGNMENT WITH AN OPENING IN THE WALL OF THE FURNACE, A LENS POSITIONED IN SAID CASING OPENING FOR FOCUSING RADIATION WITHIN SAID CASING, A SUPPORTING BLOCK TOTALLY ENCLOSED WITHIN SAID CASING HAVING A HIGH HEAT STORAGE CAPACITY, MEANS FOR SUPPORTING SAID BLOCK IN HEAT INSULATED RELATIONSHIP WITH THE WALLS OF SAID CASING, A RADIATION SENSITIVE DEVICE POSITIONED WITHIN SAID BLOCK COMPRISING A SMALL TUBULAR EVACUATED GLASS ENVELOPE HAVING A THERMALLY RESPONSIVE RESISTANCE ELEMENT MOUNTED THEREIN, A HOUSING CLOSELY FITTED OVER SAID ENVELOPE, MEANS FOR SUPPORTING SAID RADIATION SENSITIVE DEVICE AND SAID HOUSING THEREFOR IN HEAT INSULATED RELATIONSHIP WITHIN SAID BLOCK, AN ELECTRIC HEATING ELEMENT POSITIONED IN SAID BLOCK, A THERMOSTAT RESPONSIVE TO THE TEMPERATURE CONDITION OF SAID BLOCK FOR CONTROLLING SAID HEATING ELEMENT TO MAINTAIN THE TEMPERATURE OF SAID BLOCK SUBSTANTIALLY CONSTANT, AND ALIGNED OPENINGS IN SAID BLOCK AND HOUSING RESPECTIVELY TO SUBJECT SAID RADIATION SENSITIVE DEVICE TO THE RADIATION FOCUSED BY SAID LENS.