Analyses of Factors Having Effects on Detection Resolution of Mechanical Scanning Thermograph with Single Infrared Detecting Element.

The minimum detectable size, as a resolution, is one of the most important performance indices of thermograph. This index represents the ability as to how small size can be detected on the display screen, and smaller value indicates more precise measurement of an object to be measured. In case that temperature measurement is a purpose, identification of the minimum detectable size alone is insufficient. It is necessary to clarify the relationship between the size of an object to be measured and the temperature reading.This study pays attention to its point, and has quantitatively discussed the aberration of lens, the frequency response of signal processing amplifier and the defocus, respectively, as the major factors that deteriorate the performance indices of typical mechanical scanning thermograph. Then, the theoretical minimum detectable size and the temperature reading of the system have been comparatively studied, and the relation of them has been clarified with actual measuring values.