Re: ATM An $18.00 Null Test

[Scott Rychnovsky <srychnov@chem.ps.uci.edu>]

>I have discovered that one can null test almost any paraboloidal (or other
>conic section) mirror using a single lens in front of the knife edge and a
>good quality diagonal mirror.  The idea is the following, best told by an
>example:
>

Dave,

Isn't this, in essence, the Dall Null test?  If I remember right, the
limitations are that your reference lense must be close to perfect, or it
is not worth the bother.  I don't know that those Edmund lenses are that
good.

The Dall null test is discussed in the ATM volume 1, and there is a later
article in Sky and Telecscope.  I believe these articles discuss the
placement of the lense and slit.  I do not have them in front of me, but I
will look up the articles and give you references if you are interested.

Scott
--
Scott Rychnovsky
srychnov@chem.ps.uci.edu