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Techno-Fusion large mirrors

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#1 Astronorm

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Posted 03 December 2014 - 11:11 AM

People asked me to post some pictures of the Techno-Fusion lightweight mirrors that I now produce, polish and coat.

 

Normand Fullum

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#2 Howie Glatter

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Posted 03 December 2014 - 11:31 AM

Wow, Normand ! Congratulations. How do you do that ?

 

   Something perverse inside of me wants you to make a video where the glass spacers are set up on the back plate before the top plate is on, and something knocks over a post on the edge, which starts a chain-reaction that propagates to the center.



#3 Bob S.

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Posted 03 December 2014 - 11:35 AM

Wow Norm, Those are beautiful to look at. I once owned an 18" Stabilite cellular mirror figured by Pegasus that cooled very quickly. However, I was always just a bit concerned about the possibility of the vertical supports delaminating. Additionally, I had heard that cellular mirrors with thin reflecting surfaces created a problem for opticians with print through. Furthermore, making mirror supports for large cellular mirrors has got to be an incredible challenge to prevent astigmatism?

 

How have you tamed the three above-mentioned gremlins? I am sure that many of us are very interested in those three aspects of your new mirrors.

 

Thanks, Bob S.



#4 Astronorm

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Posted 03 December 2014 - 12:00 PM

Hi Bob, 

I am happy to say that I solved those problems. Over the last 3 years, I worked with Laval University and we did our homework :-)

First, The fusion is made in the kiln and it's impossible to delaminate the parts once they are fused, It's not glued together it's like they are welded together. We tested the fusion points with 30 lbs at 6" away from the fusion point before the parts broke. But they didn't brake the fusion point, they broke all around it and half way inside the plate!

Second, I solved the print through problem also but I won't tell my secret!! See the picture of a 50" under Foucault testing. If there was any Print Through, they would be very very apparent.

Third, I use a 54 floating points system under the mirror and a special Wiffle Tree that support the 2 plates at the same time for a very good lateral support.

 

 

Regards

Normand

 

 

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#5 Bob S.

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Posted 03 December 2014 - 06:50 PM

Normand, Finally, a large cellular mirror that might just be a game changer!!!

 

Thanks very much for addressing each and every question. Having been a cellular mirror owner in the past and being a very picky consumer, these were really burning questions related to your new venture. The Foucault image looks beautiful to my relatively untrained eyes. Sounds like you also have solved the mounting issues. The only large cellular of yours that I know of in another scope manufacturer's product requires the removal of the mirror for transport. Is this also the case with your mirror cell/scope?  I am wondering if you are fighting much propensity for astigmatism with your mirror and mirror cell? Those apparently have been pretty tricky issues for 50" monolithic mirrors in a more vertical position in the scopes. Is it possible that some of the gravity issues encountered by monolithic mirrors are mitigated by your much lighter weight celluar mirrors? BTW, how much does the 50" Techno-Fusion weigh? Thanks again for letting us pick your brain. You have no need to worry about me stealing any of your secrets. I have never made a mirror before or for that matter a telescope<g>.

 

Bob S.


Edited by Bob S., 03 December 2014 - 07:10 PM.


#6 Astronorm

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Posted 03 December 2014 - 07:12 PM

Bob, You are right about the monolithic mirrors. There own weight is mostly the cause of the astig. The fact the my 50" Techno-Fusion weight only 350 lbs. but still has the 6 to 1 ratio structure gives them the maximum rigidity, a solid mirror of that size would weight thousands of pounds.

 

Normand



#7 Bob S.

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Posted 05 December 2014 - 07:49 PM

Normand, How did you arrive at the mirror cell design? Are there any guidelines for the mounting of cellulars this large? How has the mirror performed closer to horizontal in California? I see that the scope is surrounded by pretty high walls which suggests that you were not planning on having the mirror/scope too horizontal.

Bob



#8 Astronorm

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Posted 05 December 2014 - 09:30 PM

Bob, The mirror is not cellular, it's a Techno-Fusion. In a cellular mirror, the back of the mirror is open and need a specially made cell that will contact the mirror ribs at at specific place because the mirror is less rigid. In my Techno-Fusion design, the back of the mirror is closed, only the sides are open, this make a much more rigid mirror. I use a 54 floating points under the mirror and a Wiffle tree for the edge support. You are right for this telescope, my customer had given me the walls height, so I design the scope accordingly but the wiffle tree was design to support the mirror all the way to vertical. The same mirror cell and wiffle tree is usedd on the polishing machine and optical bench.

 

Normand



#9 Bob S.

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Posted 05 December 2014 - 11:13 PM

Bob, The mirror is not cellular, it's a Techno-Fusion. In a cellular mirror, the back of the mirror is open and need a specially made cell that will contact the mirror ribs at at specific place because the mirror is less rigid. In my Techno-Fusion design, the back of the mirror is closed, only the sides are open, this make a much more rigid mirror. I use a 54 floating points under the mirror and a Wiffle tree for the edge support. You are right for this telescope, my customer had given me the walls height, so I design the scope accordingly but the wiffle tree was design to support the mirror all the way to vertical. The same mirror cell and wiffle tree is usedd on the polishing machine and optical bench.

 

Normand

Normand, Thanks for the info. I am beginning to get a much better picture in my mind of how your large Techno-Fusion mirrors are working. Is the back side of the Techno-Fusion then completely flush level so that it rides equally on all of the pads? I am imagining that you have to have different length supports for the front plate to be able to get a fairly dished out parabola? Thirdly, is there a price list for these mirrors on your website? I have been talking with a friend who is considering his options on a very large mirror for a permanent Newtonian setup. Sorry for all the questions about this Techno-Fusion mirror but it really seems intriguing and also kind of scary at the same time. The scary part is that when one invests large sums in a mirror, they want/need to know that it will hold up and stand the test of time.  Bob. S.


Edited by Bob S., 05 December 2014 - 11:20 PM.


#10 Astronorm

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Posted 06 December 2014 - 08:06 AM

Hi Bob,

Very understandable to ask questions, I would do the same thing :-) The back of the mirror is convex, the same amplitude than the front because the mirror is slumped on a mould to the F ratio. That way, the top plate doesn't have to be grinded at the center and the 2 plates are of the same thickness every where. The 54 floating points of the cell takes care of this and adjust itself accordingly. The Clam shape of the entire structure of the mirror make it even more rigid than if it was a flat  back plate. I don't have a price list on my web page because every large mirror is made to order with the specs of the customer. Just let me know the size and focal ratio that your friend is looking for and I can give you a price.

 

Normand



#11 Bob S.

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Posted 06 December 2014 - 09:23 AM

Norm, Now I pretty well understand how you went about making these very interesting mirrors. If the scope you have set up in California shows  tight star images with little to no astigmatism, then you have a real winner on your hands. Thanks for sharing the particulars of the mirrors/scope. The person who is interested is I am sure reading this thread and thinking about his options. Bob S.



#12 Astronorm

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Posted 06 December 2014 - 10:35 AM

Hi Bob,

My customer can testify that the star image s very pinpoint. Of course you will need a Paracorr for the F/3.5 system but any system would at the F ratio. 

As for the prices, I was at the SPIE convention in Montreal last summer and the was the Schott company on site with a 50" cellular blank made of Zerodur. The price tag on the BLANK only was 5000,000. Euro!!!! About $750,000.!!!  OK it is zerodur but for someone that is looking for a visual telescope with this aperture , I could make 3 to 4 entire telescopes for the price of 1 blank!!....... The structure of my Techno-Fusion mirrors is made to speed up the cooling time to about 30 minutes, for Borosilicate of that diameter, it's pretty good I think!! :-)

 

Normand



#13 Bob S.

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Posted 06 December 2014 - 01:15 PM

Normand, I think I only have one last question (really probably have more but don't want to hog all of the questions ;>). How does one build the mirror cell for a Techno-Fusion so that it can uniformly support the backside of a large mirror like the 50" with the significant concavity in the back?


Edited by Bob S., 06 December 2014 - 03:01 PM.


#14 Astronorm

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Posted 06 December 2014 - 09:11 PM

Hi Bob,

If you look at the picture at the begening of thisd tread, you will see the 54 floating points cell. It works just like a 27 points by balancing the triangles on 3 collimation points. The back of the mirror is convex but the floating points adjust automaticaly to match the back of the mirror.

 

Normand



#15 Alan A.

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Posted 16 December 2014 - 12:53 AM

Hi Normand,

 

Congratulations on completing this mirror.  Its an impressive project and could be a game changer for those of us interesting in getting into a really large optic.

 

Perhaps I missed it, for the 50" diameter mirror how thick is each plate? And the material is plate glass or borosilicate?

 

Thanks,

 

Alan

 

PS - my vote is that Bob S. obtains one of these beauties  and invites us over for a star party!


Edited by Alan A., 16 December 2014 - 12:53 AM.


#16 Astronorm

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Posted 16 December 2014 - 07:22 AM

Hi Alan

 

The top plate is 28mm and the back plate is 15mm all made of birosilicate.

 

Normand

P,S. get a few friends together and buy one for the group!!!  :-)



#17 Bob S.

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Posted 16 December 2014 - 05:36 PM

 

Alan

 

PS - my vote is that Bob S. obtains one of these beauties  and invites us over for a star party!

Alan, I only play a doctor with peoples' psyches. You are the real doctor who deals with something more than the mind most of the time so pony up some of that dough and buy one of Normand's Techno-Fusion scopes. I promise to come look through yours and will even buy you a fancy dinner. Bob S.


Edited by Bob S., 16 December 2014 - 05:38 PM.


#18 Astronorm

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Posted 16 December 2014 - 06:50 PM

He guys, I am sure I can get the owner of the 50" Fullum Folded Newtonian installed not to far from San Jose to let you go over and try it!!! Than you can decide if you want a 50" or a 60" F/3.5 Folded Newtonian!!! :-)

 

Normand

P.S. Seriously, if you want to try it, let me know ......:-)



#19 Alan A.

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Posted 16 December 2014 - 10:08 PM

Hi Normand,

 

Thank you for the kind offer.  I actually am planning on acquiring a scope in the 40-60" range but am not in the market yet.  I hope the owner of this 50" or perhaps some of his guests will be able to share some observing reports here on CN.  I expect these reports will be quite spectacular.  

 

Best,

 

Alan

 

PS - Bob - I got a big grin reading your response,  but I thought you knew me better than that.  Trying to ply me with food and wine instead of a good astronomy book...  :)



#20 Bob S.

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Posted 20 December 2014 - 10:36 AM

Normand,

I saw that you had described the front plate on the Techno-Fusion mirrors as being 28mm thick. Are you using a solid piece of plate glass for the front and rear surfaces? Additionally, if the front and back plates are made of plate glass, are the vertical ribs also made of a similar material so that you do not have coefficient of expansion challenges between dissimilar materials? Thanks, Bob S.



#21 Astronorm

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Posted 20 December 2014 - 11:06 AM

Hi Bob

 

I use Borosilicate (Pyrex) for the mirror material, not plate glass. I get very large sheets of Borosilicate 15mm thick. Then I WaterJet cut to the diameter needed. So all the mirror parts, even the posts come from the same sheets. The first operation is to fuse 2 plates together for the top plate. Than I fuse all the posts with the top and bottom plate. The third time in the kiln is to slump the entire structure to the F/3.5 ratio. The top plate is 28mm, not 30mm because I still have to smooth out the surface after the slumping.

 

Have a nice day

Normand

P.S. Keep asking questions Bob, I don't mind :-) I have no secrets other than the Fusing and Polishing technique !!  :-)



#22 Astronorm

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Posted 20 December 2014 - 01:52 PM

To whoever it might interest, I will give a 10% discount on a large telescope from 40" to 60" Folded Newtonien if the order and a small deposit is done before the end of 2014 !!!!!!!  :shocked:  

It's my Christmas present to the Astronomy Community!!

 

Normand

P.S. Let me know if you want to know how much you could save.........!



#23 GShaffer

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Posted 20 December 2014 - 02:10 PM

So not only are you an extraordinary telescope maker but also a sneaky salesman too :)

#24 Bob S.

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Posted 20 December 2014 - 03:34 PM

So not only are you an extraordinary telescope maker but also a sneaky salesman too :)

 

And a darn good one I might add that can speak either French or English fluently. I just called Normand to get a sense of how much these huge scopes cost and what his 10% pre-2015 deposit discount represents. The full scopes are a bit over $3k/inch which seems pretty reasonable given how much work goes into making these behemoths. Normand told me that they take about a year to a year and half to make depending on what options you want on them. The really nice thing that Normand mentioned was that you collimate these scopes as you would any Newtonian. Normand uses a tertiary mirror that resides in the focuser to accomplish the folded design. He has a high-end very seasoned astrononomical equipment manufacturer that helped him develop and make the tertiary mirror system. Other than a lack of a track record for these mirrors, it sure looks like they may offer persons wanting ultra-large aperture a pretty interesting alternative to conventional slab mirrors which essentially don't generally get much larger than about 42". Bob S.


Edited by Bob S., 20 December 2014 - 04:34 PM.


#25 Astronorm

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Posted 20 December 2014 - 04:24 PM

Hi Bob,

If you want some references names and address of some of my Techno-Fusion mirrors owners, just send me a personal Email at : telescopesnormandfullum@videotron.ca and I will forward their Email. I know their is not to many people yet but it's a brand new technology.

 

Normand

 

PS You should see M42 in a 50".................... :lol:




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