Many thanks to you, Hwang. May I have source code for http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=521 The same issue as I asked you before. How can I change some words such as Photon Energy, Light Intensity (in side the simulation's window) into other language rather than English so that my students can use your simulation much easier? Thanks for your help Benson