diff --git a/python/optics.py b/python/optics.py
index 9dde059..1eb33b7 100644
--- a/python/optics.py
+++ b/python/optics.py
@@ -722,7 +722,8 @@ def example_layer():
     plt.subplot(1, 4, 4)
     plt.imshow(I, extent=(D[3], D[2], D[1], D[0]))
     plt.title("I")
-    
+
+# simulate a PSF incident on a 2-layered sample    
 def example_psflayer():
     #specify the angle of accepted waves (NA if n = 1)
     sin_angle = 0.7
--
libgit2 0.21.4