Virtual OBJECT Ray Tracing

[Stuart Leinoff <leinoffs@ACC.SUNYACC.EDU>]

Brian McInnes Wrote in response to:

> For the case of light traveling from left to right, a virtual image
> will be located to the right of an optical device (lens or mirror).

Stu, either you or I have lost the plot here.

Brian McInnes


I was AGHAST when I read my own post on ray tracing.

I wrote "virtual image" at every place I meant "virtual object"

(Brian is right; I think I've lost more than "the plot" though; "the dimensia" is breathing down my neck)

The post should have read as follows:

One more point may be made about virtual OBJECT ray tracing in addition to the well presented explanations so far.

For the case of light traveling from left to right, a virtual OBJECT will be located to the right of an optical device (lens or mirror).

The correct image location can be obtained if we simply ray trace the image of that virtual object as if the light proceeds from right to left TO the optical device, but we change the "type" of the optical device; that is we treat a converging lens as if it were a diverging lens (and vice versa) in the "right to left" ray tracing. The same reversal would be done with a mirror as well.

I wrote a note on this with the appropriate math and ray tracing diagrams for TPT a number of years ago. (Vol 29/Number 5 p.275; May 1991)

I hope this makes more sense now!

Stu Leinoff
Adirondack Community College