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


Greetings All,

I've "Wasted a Whole Day" and it all Vladimir's fault 

Earlier today Vladimir wrote while replying to Jeff,

"If you are at it you can make third image by removing the lens and
let the lensless camera came so close to the KE that CCD will be filled
with light and make another shot and post it as well."

So I broke out my Vesta web cam and started playing.

First I tried imaging a mirror under Foucault with just the bare CCD, no
joy, what you got was a very defocused version of the image below,  that
does weird stuff while you cut the knife in/out and move the knife
longitudinally

http://lerch.no-ip.com/atm/SPPCCD/slit_focused.jpg  (8KB)

Next I made a Pinhole to replace the slit (actually it was the slit, with
another slit perpendicular to it) and tried again.  This time I got
something:

http://lerch.no-ip.com/atm/SPPCCD/Pin_CDD_Zone.jpg (47KB)

However, the image was pretty dim and grainy, the image above is the
composite of 100+ images that were stacked and summed, and its still not
pretty

Since I had an image, I tried the Flip and Diff trick to see what I'd get. 
Hmm interesting:

http://lerch.no-ip.com/atm/SPPCCD/Pin_CDD_Flip_Diff.jpg

At this point I realized to get anywhere with a bare CCD and no optics, I really
needed a brighter point source (my existing green LED is a 10,000 MCD that
came with a warning about not looking into the light! )

So I grabbed one of my many cheap laser pointers, popped out the internal
lens, and taped it to my platform.

Next I tried to see what I could see, here's some results:

http://lerch.no-ip.com/atm/SPPCCD/Knife_in_out.avi  (246KB video)
http://lerch.no-ip.com/atm/SPPCCD/OutSide.jpg    (17KB)
http://lerch.no-ip.com/atm/SPPCCD/Inside.jpg   (17KB)

OK, now we're getting somewhere, but there are a few obstacles.  Since the
CCD moves with the knife, as you move Longitudinally, the image size
changes pretty quick.  Placing a mask on the mirror makes for HORRID
diffraction (even worse than the inside / outside ROC images).  And the
diffraction caused as the knife cuts in only makes things worse.

One Last Trick, and this one has promise I think.  I grabbed an 80 LPI
Ronchi and started playing.  Here's one Inside ROC:

http://lerch.no-ip.com/atm/SPPCCD/Paul_Ronchi_Inside.jpg  (22KB)

and this one which was 0.56" further away than above, and outside ROC

http://lerch.no-ip.com/atm/SPPCCD/Paul_Ronchi_In+056.jpg (19KB)

Obviously the Ronchi grating wasn't all that great, but when compared to
Jim Burrows Diffract, there is an amazing resemblance...

Well, that's what I did today :)  BTW, here's one last pick of the setup up (and
yes, I need to replace the rusty razor blades!)

http://lerch.no-ip.com/atm/SPPCCD/Setup.jpg (51KB)

All in all, it was an interesting way to spend a Sunday :)

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"

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