PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging
Optics and Photonics, Ch Stops, pupils and optical instruments
Problem
Two thin converging lenses share an axis in air, light travelling left to right. Lens 1 has focal length f1=100 mm and clear diameter 20 mm; lens 2, 50 mm to its right, has focal length f2=50 mm and clear diameter 10 mm. A small object stands on the axis 200 mm in front of lens 1, and a circular field ring 10 mm across is mounted in the plane of the final image. Rays are paraxial; use the thin lens equation under CV1 and this chapter's rule: image every rim into object space, then compare.
((a)) Find which rim is the aperture stop for the axial object point, and give the diameter and position of the entrance pupil and of the exit pupil.
((b)) Locate the final image and find the overall transverse magnification.
((c)) Decide which rim is the field stop, by finding for each candidate the object height h at which it clips the chief ray, and give the object height at the edge of the field.
((d)) Find the object height at which vignetting sets in, and say what part of the field, if any, is vignetted.