Figure 9.

(a) Spot diagram with the black circle showing the Airy disk (1.95 µm) for the imaging system in the center and edge of the image field. (b) Cross section of the PSF shown in terms of the relative irradiance at y-axis. Relative intensity is approximately the same over the image field from the center to the edge. (c) Field curvature and percent of distortion are shown from left to right, respectively. Very small field curvature effect can be observed at the edge, which is about 4 µm, and the percent of distortion is negligible.