Re: Double concave mirror toy

[kowalskil <kowalskil@MAIL.MONTCLAIR.EDU>]

I think that an author of a message should not assume
that everybody who reads it if familiar with all messages
of the current thread. It is impossible to give each thread
as much time as it deserves. Some important things should
be repeated or summarized to avoid misinterpretations. In
reading Tom's message that you quoted, Scott, I assumed
that you were referring to a real image formed in any
way, not in a particular setup under discussion.

I have no classes today but came to school to observe what
I think is impossible. I was going to create a sharp image of
the frosted light bulb on the paper screen, remove the screen
and send the laser pointer beam through the area where the
real image (no longer visible) is located. Before investing
any time let me ask you this question. Do you think the light
from my laser pointer will be partially reflected in the area
of the real image? I do not think this to be possible but I
met you last year and I know that you are serious. Therefore
I will set up the optical bench as soon as I hear from you.

After reading messages which appeared in the last hour or
two I expect the "do not bother" reply. But I will be more
than happy to stop grading and conduct an easy experiment,
if you think I might learn something unexpected.
Ludwik Kowalski

Scott Goelzer wrote:

> Wow, so many questions:
> best to see it for yourself (worth 40$)
>
> My observations:
> When the image of the pink pig supplied with the demo is visible above the
> hole in the top of the clam shell mirrors, a pen laser is aim directly at
> the image. The result is that the laser appears to illuminate the image as
> if the pig were actually there. With clean mirrors, it is most convincing.
> I have not measured exact angles, but I would estimate that viewing (and
> illumintating ) between  30 to 60 degrees produces the best results. Looking
> down the hole at the pig while someone else is holding the laser and viewing
> the illusion make it very easy to envision the light path.
>
> Apologies to Tom if I said too much (or little)
>
> Scott
>
> *****************************
> S.Goelzer
> Physics Teacher
> Coe - Brown Northwood Academy
> Northwood NH 03261
> 603-942-5531 ext43
> sgoelzer@coebrownacademy.com
> *****************************
>
> on 5/7/02 2:38 PM, Ludwik Kowalski at kowalskiL@MAIL.MONTCLAIR.EDU wrote:
>
> > Tell us more about this. The real image of what? How
> > was that image produced? The real image where (or on
> > what)? Was the reflected beam only a tiny fraction of
> > the incident beam or was it a big fraction? How was
> > the incident laser beam directed with respect to rays
> > making the real image? How was the reflected beam
> > directed? What happens when the real image becomes
> > fuzzy? Does the reflected beam disappear when the
> > light producing the real image is turned off?
> > Ludwik Kowalski
> >
> > Scott Goelzer wrote:
> >
> > > Just did this! How cool. Took most everyone in the department by surprise.
> >
> > > > Try shining a laser pointer on the real image.  Ask students why something
> > > > you can't touch seems to reflect light.
> > > >
> > > > Tom Bross