Index: /trunk/Mars/msimreflector/MFresnelLens.cc
===================================================================
--- /trunk/Mars/msimreflector/MFresnelLens.cc	(revision 19613)
+++ /trunk/Mars/msimreflector/MFresnelLens.cc	(revision 19614)
@@ -260,4 +260,8 @@
     // Positive Fresnel Lenses ... are usually corrected for spherical aberration.
 
+    // Tim Niggemann:
+    // The surface of the lens follows the shape of a parabolic lens to compensate spherical aberration
+    // Draft angle: psi(r) = 3deg + r * 0.0473deg/mm
+
     // sin(omega) = R / sqrt(R^2+f^2)
     // tan(alpha) = sin(omega) / [ 1 - sqrt(n^2-sin(omega)^2) ]