Date: Fri, 20 May 2005 10:33:05 -0700

Author: Martin Simon

Subject: Re: Large Parabolic Mirrors


I had a nice 18" diam concave glass mirror that we used
to demonstrate image formation with a mirror but it broke
into two pieces. After partially successful repair, there
is a crack in the middle and because alignment is not perfect,
creates two offset images. The nice thing is that you can
cover half the mirror to see the effect on the image, and
the contribution from each half of the mirror is very clear,
since each half creates a slightly offset image.

I wanted to replace the mirror with a good quality
whole mirror of a similar size. I bought the mirror you mention
from Arbor, which looks the same as the Pasco mirror. However,
the quality of the image formation is not nearly as good as my
old broken mirror which I still use for that purpose. The image
is too fuzzy and never comes to a sharp focus. If you look
in the mirror, it looks like there are two different curvatures
which would explain the bad focus.

I am still looking for a good replacement mirror.

Martin Simon

Gerald Zani wrote:

>I found them at Pasco and Arbor but they may not be parabolic:
>Does anyone have these mirrors?

From Fri May 20 13:46:01 2005