From: "James Lerch" 
To: 
Cc: "ATM List" 
Reply-To: "James Lerch" 


Greetings All,

UPS was able to safely return Charlie's mirror to me today, no new data
inside the box, only the interferometry report I've already posted.

So, in the never ending quest to figure out what going on with Robo, I
played with a Ronchi grating for a little while this evening, and made an
interesting animation..

Here's the setup:

Charlie's 12.5" F/4.49 mirror
80 LPI ronchi grating (need to make/buy something better) USB 640*480 CCD (no Lens)
Laser Diode from laser pointer

A Static stand was made to support the CCD and Laser diode like this:

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/StaticStand.jpg (49kb)

Close up of the CCD and Laser Diode layout:

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/CCD_Laser.jpg (55KB)

Next, Robo2 was slid underneath this setup, and the 80lpi ronchi grating
was secured to the knife edge (knife edge was for support only..)  The
whole setup looked like this:

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/Ready.jpg (55KB)

The idea was only the Ronchi screen would move during this test, the CCD
and light source were completely stationary.

Once all this was assembled:
#1 I set the mirror at ROC
#2 Temporarily placed the lens back on the camera
#3 Aimed the camera and centered the mirror in the video display
#4 Removed the lens from the camera
#5 Tediously aimed and aligned the mirror so the CCD was outside Roc, and the
image filled the CCD chip
#6 Laterally moved the Ronchi grating into place
#7 Longitudinally position the Ronchi Grating so it worked like a knife edge
and
nulled the inner portion of the mirror, and called this the 0 Position (RoC)

Here's an animation of what I called the 0 position (animated lateral
ronchi screen motion in different sizes and formats)

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_0Pos.avi (938KB)
http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_0Pos_med.avi (305KB)

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_0Pos.gif (2MB)
http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_0Pos_med.gif (639KB)

At this point I moved the platform towards the mirror 0.4" and called
this the minus 0.4 position, created a Ronchi image, moved the platform
away from the mirror 0.05" and repeated the process thru RoC until I
arrived at the + 0.85" position.  (Lots of work...)

After processing all the images (each still image was created from 178 frame AVI
which was stacked and summed since the live image was fairly dim as I was hoping
to keep the laser diode in the non lasing mode...)  Anyway here's the animation,
All are the same except for size and format:

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi.avi (2.5MB)
http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_med.avi (882KB)
http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_Small.avi (574KB)

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/A_Ronchi_sm.gif (1.2MB)

Hopefully later today after I get some sleep I'll have a chance to try and
make a comparison between my images and Jim Burrow's diffract.  If anyone
wants to get a head start, the raw images can be found as a Zip file here:

http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/Raw.zip ( 11 MB !!!!!)

Or individually here:
http://lerch.no-ip.com/atm/2ndTry/A_Ronchi/

All the raw files have the following naming convention
Testxxx_TimeHHMMSS_Pos_xxx where negative position is inside RoC.

Since this test looks kind of promising but has lots of diffraction
effects, I'll probably do a similar series of Ronchi images using a normal
setup.

I also hope to be able to print some higher LPI Ronchi screens, or if that
fails, purchase some....

Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

--- BBBS/NT v4.01 Flag-5