19 laser illuminator with tuned parallel beams for checking dish shape

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polgyver

Creative Tinkerer
Original poster
Pub Member / Supporter
Sep 21, 2010
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Toronto
Today I assembled, after many delays, a structure made of 3/4" aluminum square tubing, which contains 19 small lasers. There are 5 horizontal bars connected to vertical longer bar. I assumed that the front surfaces of 5 bars can be treated as a straight flat plane. The 19 lasers, set in plastic holders, were precisely tuned to shine perpendicularly to their bases.
The distance between lasers, and also between bars, can be easily changed to fit dishes of different size.
Each bar has its own set of 2 AA batteries, locked inside, which can be switched on and off by turning small screw.
The parallel beams of red light from lasers can be reflected back to LNBF "face" by using small mirrors with magnets, placed on dish's surface, where the mirrors could be easily shifted to illuminated spots.
I have a few dishes which do not provide good "Q" when pointed to satellites, so I suspect their shape is not truly parabolic. I hope to be able to re-shape these dishes for better "Q".
Three photos follow :
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I am speechless :hatsoff polgyver you are crazy...... in good sense of this word :bow
But seriously.... OK, you find out that dish is in bad shape, and what is next? I do not think it is easy to bring it back to original shape, and if you manage to do it than after some time it will warp again. That is problem of dishes made of tin.
 
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The parallel beams of red light from lasers can be reflected back to LNBF "face" by using small mirrors with magnets, placed on dish's surface, where the mirrors could be easily shifted to illuminated spots....
Great project. I have always wondered how close my small dish is to a true parabola. Also a great way to find the exact focal point.

I have lots of thin mirror sheeting left over from a solar cooker experiment. Then you could see where all the beams converge at the same time. Just glue it to the dish with some spray-on contact adhesive. I'll send some to you free for the asking. If you want it just let me know your dish diameter and send me a PM with your mailing address.
 
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Cool!
Guess iot works better than always having to track the sun, and an artifical point source would always be too close if bright enough.
 
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This project is a continuation of earlier one, posted on this forum 4 years ago:
7 laser illuminator with 14 small mirrors reveal Wavefrontier flaws
I abandoned it for so long... but, finally, decided to continue with more lasers and simplified design.
Thanks, N6BY, for offering your mirrors, but I still have about 50 small mirrors from other projects.
Today, after a few days of vacation, I attempted to continue with the project, obviously started too late,
and got discouraged with bad quality photos and mosquito bites...
Surely, I have to learn more about taking photos in difficult light conditions.
I added LNBF, attached 19 small mirrors to a good dish, hoping to see 19 small red reflections from mirrors on LNBF "face".
The laser stand was set at an 36.6 degree, which is correct for 97 W in Toronto.
The CNC TV program was received with Q = 38 % earlier, but, after placement of laser stand in front of dish, the Q dropped to 30 %.
5 photos follow:thumb_IMG_6409_1024.jpg thumb_IMG_6412_1024.jpg thumb_IMG_6413_1024.jpg thumb_IMG_6414_1024.jpg thumb_IMG_6415_1024.jpg
 
I think I would get a spray can of of chrome paint and chrome the dish.
I've messed with mirrors using double face tape and it's a bitch on a large dish.

Then, strip the paint when alignment is done.
 
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I can not stop admire your effort!
Thank you, RimaNTSS, for support... it is encouraging to get "likes" from experienced members like you and Titanium and others who themselves have many "likes"...
Today I examined one of dishes to be straightened, and tried to fix it, but not done yet ... (like you predicted).
9 photos are below :
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I think I would get a spray can of of chrome paint and chrome the dish.
I've messed with mirrors using double face tape and it's a bitch on a large dish.

Then, strip the paint when alignment is done.

This is interesting idea, providing the chrome paint would fill in the coarse, uneven surface of the dish (see 2-nd photo of my earlier post).
I tried, much earlier, to "paste" pieces of aluminum cooking foil over the dish's surface, its shiny side up, using water, and later, honey, to make
it stick longer to the dish, but the light reflections from the tape were not well defined.
I have small mirrors with magnets, and they are easy to add and slide over the dish's surface.
Cheers, polgyver
 
This is interesting idea, providing the chrome paint would fill in the coarse, uneven surface of the dish (see 2-nd photo of my earlier post).
I tried, much earlier, to "paste" pieces of aluminum cooking foil over the dish's surface, its shiny side up, using water, and later, honey, to make
it stick longer to the dish, but the light reflections from the tape were not well defined.
I have small mirrors with magnets, and they are easy to add and slide over the dish's surface.
Cheers, polgyver
My offer to send you some free mirror sheeting is still good. The only problem I can think of is accidentally letting the dish set out in the sun because it could easily melt your LNBF! :eeek
 
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