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Science Forum Index » Optics Forum » Guy Macon on cleaning optics
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| Guy Macon |
 Posted: Wed Apr 16, 2008 8:27 pm |
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David Weinshenker wrote:
Quote: Hmmm... if I were searching up someone's usenet posting history,
I would be more interested in posts that they authored than those
where someone else merely mentioned their name in the subject line...
I believe the Google "group search" page does have input boxes for
searching on different fields of the message. (At least it did the
last time I looked; I use the "google groups" interface as little
as possible: have they just mashed the message search feature
in with the general webpage search now?)
Indeed it does. Alas, employers don't do searches on Google Groups.
To do that, they have to fgo past Images, Maps, News, Shopping,
and Gmail, clock on more from the dropdown list and select groups.
and that's if they have scripting turned on. Without scripting, they
have to pick groups as the 29th choice in a list of 41 choices.
Instead, the employer just uses Google web search, and there he
finds a bunch of Usenet posts stolen by websites that pretend that
it is original content.
--
Guy Macon
<http://www.guymacon.com/> |
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| Phil Hobbs |
| Posted: Wed Apr 16, 2008 9:16 pm |
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Guy Macon wrote:
Quote: Phil Hobbs wrote:
Old fashioned washing with detergent, followed by a few deionized water
rinses, is better than most methods unless the glass or coatings are
especially prone to weathering. Mag fluoride coatings are fine in
water, but cryolite (soft AR coatings) aren't. If you're
ultrasonicating, be careful to mount the optics by the ground
edges--sitting a lens on its side in an ultrasonic bath is an expensive
mistake.
I have to say, ultrasonic cleaning scares me. Cavitation is very'
erosive of a wide variety of surfaces.
Mag fluoride is pretty hard stuff, fortunately. Lenses generally
survive very well, as long as you don't lay them on their sides. I've
never had a problem with damaging one.
Quote:
I have always used Collodion, and it is quite cheap. Putting down
multiple thin layers makes for quicker curing, but I temnd to leave
it on at least overnight, and often over a long weekend. after a
couple of days the natural shrinkage lifts the edges for you, and
it comes off really easy. The cheesecloth does absorb a fair amount.
with a more expensive product I would consider using ripstop nylon
instead.
but with Opticlean I usually use ordinary 3M white PVC tape, which isn't
quite sticky enough but works well and is very clean itself.
Do you cover the whole surface, make a criss-cross pattern, or just
use a strip to pull, not to avoid all possibility of the filk ripping?
I usually use a big wide strip of tape--3M sells white PVC tape in
3-inch widths. You have to cover the entire surface with the tape, or
the film rips. That isn't too serious usually, since this particular
tape is so clean--you can just stick another piece down and peel it off,
without worrying whether you're completely on the polymer or not.
People use plain Scotch tape for cleaning fibre ends, which works fine
for dust but not for fingerprints. Opticlean works for both.
Cheers,
Phil Hobbs |
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| Richard J Kinch |
| Posted: Thu Apr 17, 2008 11:48 pm |
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Guy Macon writes:
Quote: Reputation Defender will do it for a nominal charge, ...
Until somebody comes up with Anonymous Reputation Ruiner. |
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| David Weinshenker |
| Posted: Fri Apr 18, 2008 12:09 am |
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Guy Macon wrote:
Quote: David Weinshenker wrote:
Hmmm... if I were searching up someone's usenet posting history,
I would be more interested in posts that they authored than those
where someone else merely mentioned their name in the subject line...
I believe the Google "group search" page does have input boxes for
searching on different fields of the message. (At least it did the
last time I looked; I use the "google groups" interface as little
as possible: have they just mashed the message search feature
in with the general webpage search now?)
Indeed it does. Alas, employers don't do searches on Google Groups.
To do that, they have to fgo past Images, Maps, News, Shopping,
and Gmail, clock on more from the dropdown list and select groups.
and that's if they have scripting turned on. Without scripting, they
have to pick groups as the 29th choice in a list of 41 choices.
Instead, the employer just uses Google web search, and there he
finds a bunch of Usenet posts stolen by websites that pretend that
it is original content.
Hmmm... if I do a website search on my name, it mostly comes
up with stuff regarding an identically-named Professor of Human
Genetics at some college in the southeastern USA. I suspect that
anyone that I would consider offering to work for would be able
to realize that that wasn't me, even if it "came up at the top
of a web search on my name". One might equally suspect they would
equally well be able to determine that the sort of "search result"
you describe had little relevance to the sort of thing they were
interested in, rather than giving blind credence to "the fact that
someone saying nasty things about you on the internet" (which it how
it sounds like you think such a "search result" would be interpreted).
-dave w |
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| Jeroen Belleman |
| Posted: Fri Apr 18, 2008 7:30 am |
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Charles Manoras wrote:
Quote:
Of course "real opticians" clean their optics by passing it gently but
firmly over the skin of their forearms (on the smooth side!), I have seen
this done many times, especially during the polishing process.
Then there was that scientist, (was it Robert Wood?), who cleaned
optical instruments by pushing his cat through.
Jeroen Belleman |
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