<title>Developmental thermography: triple aspect thermography</title>

In order to compensate for the weak points in conventional infrared plane scanning thermography (PST), the authors' efforts toward the technical development of new thermographic imaging since 1968 has led to the following three kinds of developmental thermography (DT): (1) triple aspect thermography (TAT), (2) multiple aspect thermography (MAT) and (3) panoramic thermography (PT). This paper presents the technique for TAT and discusses some aspects of this technique. In TAT a pair of plane surface mirrors are located at either side of a subject at a selected angle to the subject's median plane to reflect the infrared emission from each lateral surface of the subject into the thermocamera. The thermocamera scans the frontal surface directly and both lateral surface of the subject through the reflectors. Consequently, the thermograms of the three different aspects of the subject can be taken simultaneously and displayed in the CRT frame of the thermography in symmetrical arrangement. The viewing angle and coverage of the lateral images are variable according to the reflector angle to the subject's median plane. TAT enables us to observe thermal phenomenon over a wide coverage of a subject surface at one time, especially thermal trace with time on the three aspects of a subject.