From: "Jim Miller" 
To: 
Reply-To: "Jim Miller" 


spikes produced by a vane are always perpendicular to the vane and symmetric.

jtm

----- Original Message -----
From: "Bill Kocken" 
To: ; 
Sent: Wednesday, July 16, 2003 11:23 AM Subject: Re: ATM Spider design



I don't think you'll have any unusual problem.  Your diffraction spikes
should look like the squashed X that your spider looks like.  I tend to
think that each straight spider vane produces 2 spikes, one that follows
the vane and another on the opposite side of the secondary obstruction.  A
3 vane spider thus produces 6 spikes.  A 4 vane spider actually produces 8
spikes, but you only because the opposite sides produce coincident spikes.
Your design should do this.

Curved spiders and offset spiders produce diffraction, but not straight spikes.

Bill Kocken


>From: "Russell Jocoy" 
>Reply-To: "Russell Jocoy" 
>To: atm{at}shore.net
>Subject: ATM Spider design
>Date: Tue, 15 Jul 2003 21:21:01 -0400
>
>
>("atm{at}shore.net")
>
>    Hello all again,
>
>             I have made my own spider out of extruded aluminum
1"x 1/16"
>thick. My question to the list
>is if my spider veins are not at  90 degree angles does this cause an image
>problem. My anchoring
>position is more like a squashed X.    I have seen curved spiders, but I
>don't see how any tension
>can be applied. I have heard that the diffraction spikes are eliminated by
>the curved supports.
>         Am I clogging areas by squashing my supports.. Here are the
>dimensions
>   Diameter of cage.... (9.5")
>  The "X" is squashed to 4.5" between supports on each
side leaving  about
>11" (on the diameter
>measurement) on the opposite gap..something like this........
>
>                                                              *
>     *
>                                                                 *
>  *
>                                                                     *    *
>                                                                        *
>                                                                     *
>*
>                                                                 *
>    *
>                                                              *
>       *
>
>                          Russ Jocoy
>("atm{at}shore.net")
>                                                                 *
>  *
>
>_________________________________________________________________
>The new MSN 8: advanced junk mail protection and 2 months FREE*
>http://join.msn.com/?page=features/junkmail
>
>

_________________________________________________________________
Protect your PC - get McAfee.com VirusScan Online
http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963

--- BBBS/NT v4.01 Flag-4