SE308410B - - Google Patents

Abstract

1,014,769. Recording temperature. BARNES ENGINEERING CO. March 23, 1964 [April 11, 1963], No. 12089/64. Heading G1J. [Also in Division H4] In order to determine the temperature of an object by the intensity of infra-red radiation it emits, an infra-red camera is arranged to provide an image of the object together with an image of a calibrated temperature source which is positioned next to the object so that the depth of greyness of the image corresponding to the objects temperature is compared alongside the image of the calibrated source. As shown in Fig. 1, the infra-red camera 10 comprising a rotatable plane mirror 12 and a parabolic mirror 14 is so arranged in front of an object and calibrated source 60 that an infrared detector 18 which detects the infra-red radiation from a part of the field of view provides an A.C. current of such amplitude that a light source 36 fed with this current produces on a photographic plate 42 an image whose greyness is proportional to the intensity of the infra-red radiation. The calibrated temperature source may consist of a number of individual sources in the form of hot plates which are each heated electrically to known temperatures. Alternatively it may consist of a single hot source whose infra-red radiation corresponds to the highest temperature of the object, and by then suitably filtering different parts of the source or, as shown, by suitably alternating the current produced by the hot source radiation, images whose greyness correspond to known lower temperatures may be obtained. The calibrated temperature source may be provided with means (Fig. 4, not shown) for identifying different thermal pictures taken with the infra-red camera.