P120FB11: Render at 1:1 instead of 4:1. The Red Pick-off Mirror Structure is the lower mirror, intercepting the white Target plane. The Target has four quadrants, Red, White, Blue, and Green, the 1st through 4th quadrants as you look at the face of the target. The fiducial marks at the center are 0.05 mm wide by 1 mm long. Note the 45 degree mitered finishes at the center. The fiducial colors, from the east, CCW, are magenta, gray, cyan, and yellow. The Target is inverted in this AutoVision rendered image.