- Do problems 4 and 6 from section 7 of the notes..
- What is the maximum diameter a 1-meter focal length spherical reflector may have (at infinite conjugate) without exceeding an OPD of one-quarter wavelength (from spherical aberration) for a wavelength of 0.5 mm? What is the maximum half-field-angle this same mirror may cover without exceeding an OPD of one-quarter wavelength from coma?
- Given the following singlet lens description
# *rd**th**ap**rn*1 48 3.6 7.5 BK7 2 -32 7.5 where

*ap*is the aperture height,*rd*is the radius of curvature,*th*is the center thickness, and*rn*is the glass.- Enter the lens into OSLO. Replace the radius of the second surface with a paraxial axial angle solve of -0.2. This maintains the focal length of the lens as you vary the radius of the first surface. Find the resulting focal length.
- Calculate the Seidel spherical aberration as a function of the bending factor. You can do this by varying the radius of curvature of the first surface, calculating the spherical aberration, and then computing the bending factor from the reported curvatures. Plot the spherical aberration as a function of the bending factor. What lens shape minimizes the spherical aberration?
- Find the field of view at which the spot size is three times that on-axis at paraxial focus. You can do this by setting a nominal field of view (say 5 degrees) and then calculating the spot size as a function of the fractional field.
- For the lens that minimizes spherical aberration, find the Seidel image aberrations if the lens thickness is zero (thin lens) and compare to those for the given lens thickness (thick lens).

- Design a thin f/16 landscape lens (zero coma and astigmatism) for a focal length of 50 mm and half-field of view of 8-degrees. Use BK7 as the glass. Choose a bending factor as described in the notes. Plot the fourth-order wavefront aberrations as a function of stop position (keeping the f/number fixed). Use this plot to determine the optimum stop position for this landscape lens. You may use OSLO or MATLAB to assist in the calculations.

Maintained by John Loomis,
last updated *30 Nov 2005 *