[quote author=Fu-Kwun Hwang link=topic=1156.msg4454#msg4454 date=1245653034]
Could you provide the URL of the examples ?
[/quote]
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1140.0


[quote author=Fu-Kwun Hwang link=topic=1156.msg4454#msg4454 date=1245653034]
I think if you use thin lens approximation in the simulation, the thickness of the lens is only visual effect.

If you want to simulate effect due to thick lens, you need to use Snell's Law to calculate all the refractions occurs at the boundary of lens. You are welcomed to check out [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=46.0]Thick Lens[/url]

If you want to show how the thickness of a lens affect the focus, that is another story!

Many drawing in Physlet optical bench is only an approximation.
Please check out the attached image. It assumed thin mirror and thin lens case.
The space in the simulation is not the same as real world.
The mirror and lens will be almost like a thin/short line if you want to draw it according to real dimension.
[/quote]

Yes! i only want a visual effect, like physlet ones.

I google and found your thick lens http://www.compadre.org/OSP/document/ServeFile.cfm?ID=8257&DocID=886
but the function to draw the polygon that represents the lens is complicated. I doubt i can copy it over to make it work.