diff --git a/examples/optics/cavity_w_Rc.py b/examples/optics/cavity_w_Rc.py
new file mode 100644
index 0000000000000000000000000000000000000000..8a5f60b61ad3c3e2a1dd480001d5dc7be25f7000
--- /dev/null
+++ b/examples/optics/cavity_w_Rc.py
@@ -0,0 +1,54 @@
+"""
+---------------------------------------------------------
+Simple example to show the use of the utility functions:
+- cavity_w1w2_Rc1Rc2(Lambda, L, w1, w2)
+- cavity_info(Lambda, L, Rc1, Rc2)
+
+Andreas Freise 01.12.2014
+http://www.gwoptics.org/pykat/
+---------------------------------------------------------
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+from pykat.optics.fabryperot import *
+import numpy as np
+
+
+def main():
+	# wavelength
+	Lambda = 1064.0E-9
+	L = 3994.515
+
+	print("Advanced LIGO")
+	# attr ITMY Rc -1940.7
+	# attr ETMY Rc 2242.4
+	w1=0.053
+	w2=0.062
+	[g1, g2, Rc1, Rc2] = cavity_w1w2_Rc1Rc2(Lambda, L, w1, w2)
+	print("w1 = {0}, w2 = {1}".format(w1,w2))
+	print("g1 = {0}, Rc1 = {1}".format(g1,Rc1))
+	print("g2 = {0}, Rc2 = {1}".format(g2,Rc2))
+	print("g1*g2 = {0}".format(g1*g2))
+
+	print("A+")
+	# attr ITMX Rc -1852.9
+	# attr ETMX Rc 2174.3
+	w1=0.08
+	w2=0.094
+	[g1, g2, Rc1, Rc2] = cavity_w1w2_Rc1Rc2(Lambda, L, w1, w2)
+	print("w1 = {0}, w2 = {1}".format(w1,w2))
+	print("g1 = {0}, Rc1 = {1}".format(g1,Rc1))
+	print("g2 = {0}, Rc2 = {1}".format(g2,Rc2))
+	print("g1*g2 = {0}".format(g1*g2))
+
+	# cross check
+	[zr,w0,z1,wc1,wc2]=cavity_info(Lambda, L, Rc1, Rc2)
+	print("(cross check: w1 = {0}, w2 = {1})".format(wc1,wc2))
+
+		
+if __name__ == '__main__':
+	main()
+