In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap. To 1/10 wave and to 1/20
wave. I wanted to see the interference fringes but a monochromatic
light source is needed for sharp lines and I don't have the typical
sodium light source used for this purpose. But I do have a green laser
pointer which is pretty monochromatic. So I shined the laser through a
piece of frosted glass and onto the flats and it worked great. Now I'm
gonna check me some surface plates to see just how flat they are,
albeit in small areas. The largest flat is 3 1/8 diameter x 3/8 thick,
another is 1 1/8 dia. x 1/4, and the last is 1 inch square x 1/4
thick. The canada balsam I bought so I could re-cement some older
lenses.
Eric
















+

fired this volley in
:

In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap.

Neat! I've ground a few for diagonal mirrors within 1/8th wavelength,
and that was both a chore and a joy. Seeing absolutely straight
interference lines on both axes on a reference and work piece of which
you made both is a real treat!

I don't know if I'd have the patience now. It seems like money's now not
so much an issue as time!

I've ground primary mirrors, too, and that's even more time-consuming.

Lloyd

replying to etpm, passerby wrote:
Building a telescope or something? Just curious what use can an optical flat
be around the shop. Nothing I can think of here measures in _nanometers_ ...

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wrote:
In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap. To 1/10 wave and to 1/20
wave. I wanted to see the interference fringes but a monochromatic
light source is needed for sharp lines and I don't have the typical
sodium light source used for this purpose. But I do have a green laser
pointer which is pretty monochromatic. So I shined the laser through a
piece of frosted glass and onto the flats and it worked great. Now I'm
gonna check me some surface plates to see just how flat they are,
albeit in small areas. The largest flat is 3 1/8 diameter x 3/8 thick,
another is 1 1/8 dia. x 1/4, and the last is 1 inch square x 1/4
thick. The canada balsam I bought so I could re-cement some older
lenses.
Eric

How do they sell balsam, and how do you use it? I know what it is, in a
finished optical group, but not the detail in how they bond the elements
with no bubbles etc. How do you uncement lenses?

On Mon, 25 Jan 2016 19:18:02 +0000, passerby
wrote:

replying to etpm, passerby wrote:
Building a telescope or something? Just curious what use can an optical flat
be around the shop. Nothing I can think of here measures in _nanometers_ ...
Mostly the flats are just for fun. But I can and will check the
surface plates and gauge blocks.
Eric

On Mon, 25 Jan 2016 20:33:26 +0000 (UTC), Cydrome Leader
wrote:

wrote:
In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap. To 1/10 wave and to 1/20
wave. I wanted to see the interference fringes but a monochromatic
light source is needed for sharp lines and I don't have the typical
sodium light source used for this purpose. But I do have a green laser
pointer which is pretty monochromatic. So I shined the laser through a
piece of frosted glass and onto the flats and it worked great. Now I'm
gonna check me some surface plates to see just how flat they are,
albeit in small areas. The largest flat is 3 1/8 diameter x 3/8 thick,
another is 1 1/8 dia. x 1/4, and the last is 1 inch square x 1/4
thick. The canada balsam I bought so I could re-cement some older
lenses.
Eric

How do they sell balsam, and how do you use it? I know what it is, in a
finished optical group, but not the detail in how they bond the elements
with no bubbles etc. How do you uncement lenses?
The balsam comes as random chunks and powder. It should be washed with
clean water, allowed to dry, then heated until it melts. Then xylene
is mixed in until the resultant mixture is about as thick as molasses.
This mixture is then placed on one lens and the other lens is placed
on the first lens, pressed gently to squeeze out the excess, and the
balsam is then allowed to dry. Lenses glued this way can be uncemented
by gentle heating to soften the balsam or can be soaked in xylene.
Eric

On Saturday, January 23, 2016 at 2:28:44 PM UTC-5, wrote:
In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap. To 1/10 wave and to 1/20
wave. I wanted to see the interference fringes but a monochromatic
light source is needed for sharp lines and I don't have the typical
sodium light source used for this purpose. But I do have a green laser
pointer which is pretty monochromatic. So I shined the laser through a
piece of frosted glass and onto the flats and it worked great. Now I'm
gonna check me some surface plates to see just how flat they are,
albeit in small areas. The largest flat is 3 1/8 diameter x 3/8 thick,
another is 1 1/8 dia. x 1/4, and the last is 1 inch square x 1/4
thick. The canada balsam I bought so I could re-cement some older
lenses.
Eric

A) do you know about this place? http://surplusshed.com/ If not, then you should. They have really good prices on optics and other fun stuff (gears and the like). They have periodic sales that give amazing prices.

B) I haven't done any of this since I was a kid, but am I mistaken in remembering canada balsam smelling like a New England forest? We (dad & I) used it to mount specimens and cover slips on microscope slides, IIRC.

On Tue, 26 Jan 2016 15:44:43 -0800 (PST), rangerssuck
wrote:

On Saturday, January 23, 2016 at 2:28:44 PM UTC-5, wrote:
In yesterday's mail was a package for me containing some canada balsam
and a few optical flats. The flats weren't originally made as flats
and aren't as thick as the real thing. But the surfaces of the glass
are still flat and the flats were cheap. To 1/10 wave and to 1/20
wave. I wanted to see the interference fringes but a monochromatic
light source is needed for sharp lines and I don't have the typical
sodium light source used for this purpose. But I do have a green laser
pointer which is pretty monochromatic. So I shined the laser through a
piece of frosted glass and onto the flats and it worked great. Now I'm
gonna check me some surface plates to see just how flat they are,
albeit in small areas. The largest flat is 3 1/8 diameter x 3/8 thick,
another is 1 1/8 dia. x 1/4, and the last is 1 inch square x 1/4
thick. The canada balsam I bought so I could re-cement some older
lenses.
Eric

A) do you know about this place? http://surplusshed.com/ If not, then you should. They have really good prices on optics and other fun stuff (gears and the like). They have periodic sales that give amazing prices.

B) I haven't done any of this since I was a kid, but am I mistaken in remembering canada balsam smelling like a New England forest? We (dad & I) used it to mount specimens and cover slips on microscope slides, IIRC.
A) Where do you think I got the optics from?
B) Yes.
Eric