To: atm{at}shore.net
From: Jim Burrows 
Reply-To: Jim Burrows 


At 12:11 2003-02-17 -0500, James Lerch wrote:

>     A) Nearly every time I show the classic
>radial surface deviation graph to a new student, their eyes glaze over.  So
>my first thought was to chart the surface error over the Diameter of the
>mirror, instead of just the radius.

As our Pres sez, "Get used to it."   I think it's a
little (very little) bit dishonest - none of our tests give you asymmetric
information, so why plot it?

>     B) X axis labels.  Instead of  radial percent, I just displayed the zone
>center radiuses.  Compare the graph to your couder mask (or rings drawn on
>the back of the mirror blank) to help visualize the areas that need work
>while figuring (Does anyone want tick marks showing radial % or physical
>dimensions?)

A nice compromise is to put on physical dimensions (maybe with the big grid
marks), then some little different-colored ticks to show the zone radii.

>     C) Y axis labels.  Instead of marking off microns (or nanometers) I just
>put wave error reference lines.  (Does anyone really want to know the actual
>surface height in nanometers??)

I think waves are just confusing.  We have to know what's really on the
glass - save the waves for the optical evaluation - Strehl, and P-V in
small type for the reactionaries.

>     D) Y Axis Scaling.  Since having the option of a figuring history slide
>show was high on my "to-do" list.  I changed the Y-Axis
scaling options.
>The scaling function is now fixed to the following displays:
>         (i) 1/4 wave
>         ...

Nah, as above, forget the waves.  A very handy thing, following our guru,
Carl Zambuto, is to be able to see the deviations from parabolas with RoCs
different from the optical best-fit which might be better figuring goals
(usually shorter ROCs giving high centers).

         -- Jim Burrows
         -- mailto://burrjaw{at}earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84)

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