Re: [Phys-l] refraction lab

[Bernard Cleyet <bernardcleyet@redshift.com>]

You probably want to use speculum which is softer than most and has  
high reflectivity.

http://en.wikipedia.org/wiki/Speculum_metal

I discover one may purchase concave blanks:


http://www.classicscience.com/speculum/speculum_metal1.html



One must use several "pastes" starting w/ what? 80 grit and ending up  
w/ several hundred before polishing w/ cerium or rough.  At least  
that's what I did when I ground glass blanks for telescopes.

On further googling I discovered detailed instructions for this  
nearly dead technology*.

http://www.europa.com/~telscope/mudge.txt


* Not so w/ glass.  I recently attended a SoCal Physics Technicians  
meeting at El Camino College.  One large room is dedicated to  
grinding and figuring mirrors,. including several sophisticated  
Foucault testers.

Here's a list:

http://stellafane.org/tm/mc/other.html


bc wonders if Edmund still sells telescope making kits.



On 2008, Apr 28, , at 19:09, Paul Lulai wrote:

> A fairly common method- use knox gelatin and jello molds.  cut the  
> lens, use it, eat it later.
> I've wanted to do a 'build optics' day.
> I've done the gelatin molds.  The one I am missing is mirrors.   
> I've read (Dr. Falco of Arizona University) that one can make  
> mirrors by using two bars of metal and a paste btn the surfaces.   
> Continued rubbing will make one side concave, the other convex.  I  
> don't know where to get the appropriate pastes.
>
> Have a good one.
>
>
> Paul Lulai
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