Fig. 1. Infrared thermal imager test system

Fig. 2. Source of light filling the entrance pupil at a point on the target hole

Fig. 3. Geometric relation of blackbody source, target, and entrance pupil

Fig. 4. Edge concentric rings selected from targets with different sizes

Fig. 5. Measurement results of ring temperature of different targets under different distances between targets and blackbody source

Fig. 6. Temperature uniformity on blackbody source surface

Fig. 7. Temperature uniformity on target surface