Optical pyrometer having a cyclically moving detector

Claim 1

IN A TEMPERATURE MEASURING APPARATUS, A FIRST LENS ALONG AN OPTICAL AXIS AND FOCUSSING IN A FIRST PLANE, A FIRST IMAGE OF AN AREA OF A HEATED BODY WHOSE TEMPERATURE IS TO BE MEASURED, A FILAMENT HAVING A SHORT CALIBRATED PORTION POSITIONED IN SAID FIRST PLANE AND ADAPTED TO BE HEATED TO A KNOWN TEMPERATURE, A SECOND LENS POSITIONED IN AND ALONG SAID AXIS AND SPACED FROM SAID FIRST LENS, TO PROJECT ALONG SAID AXIS AND TO FOCUS IN A SECOND PLANE NORMAL TO SAID AXIS, A COMPOSITE IMAGE HAVING TWO CONTIGUOUS PORTIONS, NAMELY, SAID FIRST IMAGE AND THE CALIBRATED PORTION ONLY OF SAID FILAMENT, SUPERPOSED THEREOVER, A PHOTOELECTRIC CELL HAVING A LIGHT-SENSITIVE SURFACE POSITIONED IN SAID SECOND PLANE AND MOUNTED FOR MOVEMENT IN SAID SECOND PLANE TRANSVERSELY TO SAID AXIS AT AN ANGLE TO SAID CALIBRATED PORTION OF SAID FILAMENT, FIRST MEANS CONNECTED WITH SAID PHOTOELECTRIC CELL TO ALTERNATELY AND CYCLICALLY MOVE THE SAME AS AFORESAID, BETWEEN A FIRST POSITION WHEREIN SAID CELL IS ENERGIZED ONLY BY SAID FIRST PORTION OF SAID COMPOSITE IMAGE, AND A SECOND POSITION WHEREIN SAID CELL IS ENERGIZED BY SAID IMAGE OF SAID CALIBRATED PORTION ONLY OF SAID FILAMENT, AND SECOND MEANS IN CIRCUIT WITH SAID CELL FOR MEASURING THE OUTPUT THEREOF AS A FUNCTION OF THE DIFFERENCE IN TEMPERATURE BETWEEN THE HEATED BODY AND SAID CALIBRATED PORTION OF SAID FILAMENT.