Considering the lens in Problem 6.29, determine its focal length and the location of the focal points with respect to its vertices V₁and V₂.

Data from Prob. 6.29

Figure P.6.29 shows two identical concave spherical mirrors forming a so-called confocal cavity. Show, without first specifying the value of d, that after traversing the cavity two times the system matrix is

Then for the specific case of d = r show that after four reflections the system is back where it started and the light will retrace its original path.

2d 2d 20(1-2) 2d 1 1 2 Figure P.6.29 4 3 M2 M1 |R|=|R2]=r