mattyfatz
Pooh-Bah
Reged: 12/27/06
Posts: 1070
Loc: R E N O
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I've seen this question ( how do I clean my mirror?) asked a hundred times in the two years I've been here at CN. for every answer there is someone foiling it.
Let me ask this; How do the major observatories clean their optics? Do they even bother? With all the fires in the West this seaon I suspect the major US observatories are looking at the same problem. What is their solution?
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*****MATTY******
All sorts of stuff
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colinsk
scholastic sledgehammer
Reged: 01/17/08
Posts: 899
Loc: CA
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Here is some information I collected and posted for holographers:
http://www.holowiki.com/index.php/Cleaning_Mirrors
It includes the procedures from one observatory.
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Mahalo.
Coulter 10.1" Dobsonian
Coronado PST
TV-76
Lunt LS60TDS50FTBF1200- On Order 
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John Jarosz
I'm being watched...
Reged: 04/25/04
Posts: 2150
Loc: Chicago area, IL
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Air compressors with filters may stop oil & crud.
Remember that when compressed air is released the rapid expansion of the air causes it to cool. If there is water vapor in the compressed air you may find it deposited as water drops on the surface you are blowing off. Commercial building systems often have a drier so the compressed air has a very low dew point.
Canned air is no better - you are risking your optics with their quality control.
I'd use a bulb type blower to keep all this water stuff to a minimum.
Giotto Blower
John
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6" F4.6(w/Paracorr) GEM reflector, 8" F11 Dall Relay Scope
6" F5 RFT Refractor, Garrett Gemini 20x80 LW
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Chriske
Kijkerbouw Urania
Reged: 08/15/04
Posts: 1843
Loc: Boechout, Belgium
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Quote:
I've seen this question ( how do I clean my mirror?) asked a hundred times in the two years I've been here at CN. for every answer there is someone foiling it.
Let me ask this; How do the major observatories clean their optics? Do they even bother? With all the fires in the West this seaon I suspect the major US observatories are looking at the same problem. What is their solution?
Hi,
I don't think the pro's with their large mirrors clean optics. If they do, it is in preparation for a new layer of alu.
The complete procedure can be seen on the Palomar site. Lots of pictures on 'how to' and some movies to if I'm not mistaken. Very interesting.
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Chris
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photonovore
Moonatic
Reged: 12/24/04
Posts: 2465
Loc: tacoma wa
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The popular methods used by professionals (large observatories) are: 1) water flushing, 2) compressed air or nitrogen, 3) CO2 flushing. The last seems the preferred method vis a vis efficiency and lack of negatives. From the Subaru telescope (Mauna Kea Observatory) folk: "When liquid CO2 (-56.6C) is released out through a fine nozzle, it suddenly expands without exchanging heat (adiabatic expansion), becoming a mix of gaseous CO2 and dry ice. If we blow this mixture at the primary mirror, the dry ice wraps around the dust and both dust and ice are blown away from the mirror by the gaseous CO2. This method is called "CO2 Cleaning."
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Mardi
AR-5 ldx75 refractor, 80mm f/11 refractor, 6" eq3 RFT, ETX-70.
Whitepeak Lunar Observatory Website
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sarastro
sage
Reged: 08/12/04
Posts: 314
Loc: Seattle
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Quote:
I never use canned or compressed air. Every astronomer should have a Giotto's Rocket Air.
I have one of these. It's inexpensive, works great and never runs out of air! 
I expect most camera stores will have them in stock.
Roger
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Fiske
Carpal Tunnel
Reged: 03/14/04
Posts: 1935
Loc: Missouri / United States
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So, no one participating on this thread has actually seen any grado blown on a mirror from an air compressor? Interesting. 
I'm waiting now for someone to ask where they can get a CO2 flushing system to clean their XT-8...
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Fiske Miles
Nikon 8x42 LX / 12x50 SE Binos
Mini Borg 60ED, TV-101, AT80Ach, XT-8, C11/CI-700, 22-Inch Dob
Way too many Nagler eyepieces
http://www.fiskemiles.blogspot.com/
www.fiskemiles.com
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jcjr
professor emeritus
Reged: 01/06/08
Posts: 563
Loc: TN, USA
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Wonder if a welding CO2 tank and some appropriate regulator would do it? Have no idea. I know nothing of welding equipment. Just wondering if the rapid expansion from a welding tank would give the CO2 blizzard?
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CPC 1100, C102SLT, SV F80, Meade 70 & 60 AZT
Q70 38mm, Pan24, Meade 5K 18mm UW, Axiom LX 15mm, Nagler 13T6, Axiom LX 10mm, Expanse 20mm, 9mm, 6mm, BO/TMB 5mm, 2.5mm
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Fiske
Carpal Tunnel
Reged: 03/14/04
Posts: 1935
Loc: Missouri / United States
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You go, Guy!!
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Fiske Miles
Nikon 8x42 LX / 12x50 SE Binos
Mini Borg 60ED, TV-101, AT80Ach, XT-8, C11/CI-700, 22-Inch Dob
Way too many Nagler eyepieces
http://www.fiskemiles.blogspot.com/
www.fiskemiles.com
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colinsk
scholastic sledgehammer
Reged: 01/17/08
Posts: 899
Loc: CA
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I use CO2 to clean things all the time. I have never had a problem from the dry ice that occasionally forms. However, I still end up having to use compressed air on occasion as I don't always have CO2 at home.
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Mahalo.
Coulter 10.1" Dobsonian
Coronado PST
TV-76
Lunt LS60TDS50FTBF1200- On Order
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Owen
sage
Reged: 06/21/07
Posts: 319
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Sounds like a use for a re-fillable CO2 fire extinguisher to me - just lose the 'horn'... 
Owen
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jcjr
professor emeritus
Reged: 01/06/08
Posts: 563
Loc: TN, USA
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Thats a great idea, Owen. If CO2 fire extinguishers condense enough dry ice for Steve McQueen to conquer The Blob, then they would surely be good enough for a measley 8" mirror!
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CPC 1100, C102SLT, SV F80, Meade 70 & 60 AZT
Q70 38mm, Pan24, Meade 5K 18mm UW, Axiom LX 15mm, Nagler 13T6, Axiom LX 10mm, Expanse 20mm, 9mm, 6mm, BO/TMB 5mm, 2.5mm
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Mr Magoo
scholastic sledgehammer
Reged: 11/05/05
Posts: 895
Loc: Franklin, Indiana
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I advocate using Nitrous Oxide in a very small room. After the first few minutes of use, you won't care what damage it's doing to your optics. 
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Ken
Franklin, IN
Member, Indiana Astronomical Society
B.S.A. Astronomy Merit Badge Counselor
6" f/10 Dob
Vintage Sears Discoverer 4-6305A 60mm
Vintage Manon 60mm (The Marsha Scope)
Criterion RV-6
My CN Photo Gallery
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photonovore
Moonatic
Reged: 12/24/04
Posts: 2465
Loc: tacoma wa
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Quote:
So, no one participating on this thread has actually seen any grado blown on a mirror from an air compressor? Interesting.
We have a compressor in our garage--for mechanical work (we have eight motorcycles). The thought occurred to me to use it to blow off optics a long time ago--but after seeing what a nice test blast did to a fresh piece of white paper i gave it up! Water and oil mostly it looked like, quite a mess; i'm told that this stuff typically accumulates in the tank & hose in ordinary garage compressors and one needs a filter gizmo at the hose end to effectively capture it. So yes, i've seen gunk coming from air compressors-- just not on my optics.
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Mardi
AR-5 ldx75 refractor, 80mm f/11 refractor, 6" eq3 RFT, ETX-70.
Whitepeak Lunar Observatory Website
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Fiske
Carpal Tunnel
Reged: 03/14/04
Posts: 1935
Loc: Missouri / United States
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Mardi:
The salient point here is that seeing a compressor, used in a garage to service 8 motorcycles, without even a line filter, discharge oil and water is not an argument for NEVER using an air compressor of any type on optics.
And so far, no one who has contributed to this thread has mentioned any problem when using an air compressor on optics, while a number of contributors routinely use them with no trouble.
Hmmmmm.
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Fiske Miles
Nikon 8x42 LX / 12x50 SE Binos
Mini Borg 60ED, TV-101, AT80Ach, XT-8, C11/CI-700, 22-Inch Dob
Way too many Nagler eyepieces
http://www.fiskemiles.blogspot.com/
www.fiskemiles.com
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photonovore
Moonatic
Reged: 12/24/04
Posts: 2465
Loc: tacoma wa
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Fiske,
I wasn't making any blanket argument against using compressed air to clean optics.
I would, however, certainly advise checking the output of *any* air compressor for absolute purity and cleanliness before using it to clean any optic. I personally would not use any but an oil-less type compressor to clean optics. One sees this type more often in labs and art studios than in home garages, where the oil lubricated compressor type is most common (the two wheeled types made by Sears and everyone else)--and the latter are almost never equipped with a line or any other filters. They are potential trouble. Most all mechanic shops purposefully inject oil into the compressor airstream to lubricate their airtools, so that is no alternative-- though i am sure one that has been tried--by someone...
I find people much more willing to relate success stories-- than stories detailing their embarrassments. That's a well known problem with anecdotal evidence.
Point is, it is a very good idea to know just what kind of "compressed air" one is using---before one uses it on optics. That is probably something we can all agree on.
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Mardi
AR-5 ldx75 refractor, 80mm f/11 refractor, 6" eq3 RFT, ETX-70.
Whitepeak Lunar Observatory Website
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