RI with microscope

Learned something interesting about measuring RI with a microscope today....

I tried measuring a CZ cab that I had just finished and came up with 1.32.

I then polished a slice of the material and came up with 2.1.

Moral of the story ( I think) this does not work on lenses, only through a
flat surface.

js

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"Jack Schmidling"
Learned something interesting about measuring RI with a microscope today....

I tried measuring a CZ cab that I had just finished and came up with 1.32.

I then polished a slice of the material and came up with 2.1.

Moral of the story ( I think) this does not work on lenses, only through a
flat surface.


Interesting! Does it make a difference if the dome of the cab is pointing
towards the microscope,
or that the flat surface of the cab is the one that you are looking through
first?

Groeten,

Jaap

What about through the back of the cab?

Carl
1 Lucky Texan


Jack Schmidling wrote:
Learned something interesting about measuring RI with a microscope today....

I tried measuring a CZ cab that I had just finished and came up with 1.32.

I then polished a slice of the material and came up with 2.1.

Moral of the story ( I think) this does not work on lenses, only through a
flat surface.

js



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to reply, change ( .not) to ( .net)

"Jaap Bos"
Interesting! Does it make a difference if the dome of the cab is pointing
towards the microscope, or that the flat surface of the cab is the one
that you are looking through
first?

I apparently had a brain freeze. It never occurred to me to flip the stone
over. Haven't tried it yet but I assume it would work from the back (flat)
side.

js


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Jack Schmidling wrote:
Learned something interesting about measuring RI with a microscope today....

I tried measuring a CZ cab that I had just finished and came up with 1.32.

I then polished a slice of the material and came up with 2.1.

Moral of the story ( I think) this does not work on lenses, only through a
flat surface.

js


Don't know what microscope you're using. It is possible to measure
refractive index with even a cheap biological microscope, see
my take on it at:

http://www.mbstevens.com/mscope/crystals.html
....about halfway down the page.

Some of the material there may bear on your findings.
--
Cheers, ms http://www.mbstevens.com/

"m"

Don't know what microscope you're using. It is possible to measure
refractive index with even a cheap biological microscope, see
my take on it at:

I have several but your method requires known RI media. The direct method
requires nothing but a method of measuring the focus travel.

BTW, I just faceted a piece of Strontium titanate (Fabulite) and it really
is a beautiful gem.

What is really interesting is the piece of rough I started with. It was
about .5" in diameter and just a little longer. The top was polished and
the bottom ground. When one looks through this piece, the RI creates the
illusion that the piece is about half it's actual height. The effect is
really dramatic and everyone I showed it to noticed it immediately without
any coaching.

It makes my wife's diamond look dull and boring by comparison.

js


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Jack Schmidling wrote:
"m"

Don't know what microscope you're using. It is possible to measure
refractive index with even a cheap biological microscope, see
my take on it at:


I have several but your method requires known RI media. The direct method
requires nothing but a method of measuring the focus travel.

A cab would complicate any method because the curvature of its face
makes it into a lens; any point the light leaves or enters the curved
face is going to be impacting at a different angle than other points on
its curved surface.

The advantage for the immersion method -- for curved surfaces -- is that
if you can find a liquid with exactly the same RI
as the object being tested, the light will continue travelling in a
straight line no matter what the angles of incidence are.
(The method does consume some time, though!)

"m" schreef..
Jack Schmidling wrote:
"m"

Don't know what microscope you're using. It is possible to measure
refractive index with even a cheap biological microscope, see
my take on it at:


I have several but your method requires known RI media. The direct method
requires nothing but a method of measuring the focus travel.

A cab would complicate any method because the curvature of its face
makes it into a lens; any point the light leaves or enters the curved
face is going to be impacting at a different angle than other points on
its curved surface.

The advantage for the immersion method -- for curved surfaces -- is that
if you can find a liquid with exactly the same RI
as the object being tested, the light will continue travelling in a
straight line no matter what the angles of incidence are.
(The method does consume some time, though!)


Yes, your immersion method is very good. But the problem that Jack Smid has, he
is working with a
stone with a very high refractive index. And there is no liquid that can match
that RI, so he has
to go for the "dry" or "Duc de Chaulne's" method.for an RI-estimation.

Groeten,

Jaap

Jaap Bos wrote:


"m" schreef..
Jack Schmidling wrote:
"m"

Don't know what microscope you're using.
It is possible to measure refractive index
with even a cheap biological microscope,
see my take on it at:


I have several but your method requires
known RI media. The direct method requires
nothing but a method of measuring the focus
travel.

A cab would complicate any method because the
curvature of its face makes it into a lens;
any point the light leaves or enters the
curved face is going to be impacting at a
different angle than other points on its
curved surface.

The advantage for the immersion method -- for
curved surfaces -- is that if you can find a
liquid with exactly the same RI
as the object being tested, the light will
continue travelling in a straight line no
matter what the angles of incidence are. (The
method does consume some time, though!)


Yes, your immersion method is very good. But
the problem that Jack Smid has, he is working
with a stone with a very high refractive
index. And there is no liquid that can match
that RI, so he has to go for the "dry" or "Duc
de Chaulne's" method.for an RI-estimation.

Estimations of CZ's R.I. that I have seen range
between 2.14 and 2.20. If you'll have a look
at:

http://www.2spi.com/catalog/ltmic
cargille-standard.shtml

....you'll see that you can order
Cargill's EH series that goes to 2.11, or
its low temperature series FH melts, 2.12 to
2.21. The FH melts are used in the same
way as immersion liquids, but must be warmed
before the object is introduced.

"m" schreef ...
Jaap Bos wrote:


"m" schreef..
Jack Schmidling wrote:
"m"

Don't know what microscope you're using.
It is possible to measure refractive index
with even a cheap biological microscope,
see my take on it at:


I have several but your method requires
known RI media. The direct method requires
nothing but a method of measuring the focus
travel.

A cab would complicate any method because the
curvature of its face makes it into a lens;
any point the light leaves or enters the
curved face is going to be impacting at a
different angle than other points on its
curved surface.

The advantage for the immersion method -- for
curved surfaces -- is that if you can find a
liquid with exactly the same RI
as the object being tested, the light will
continue travelling in a straight line no
matter what the angles of incidence are. (The
method does consume some time, though!)


Yes, your immersion method is very good. But
the problem that Jack Smid has, he is working
with a stone with a very high refractive
index. And there is no liquid that can match
that RI, so he has to go for the "dry" or "Duc
de Chaulne's" method.for an RI-estimation.

Estimations of CZ's R.I. that I have seen range
between 2.14 and 2.20. If you'll have a look
at:

http://www.2spi.com/catalog/ltmic
cargille-standard.shtml

...you'll see that you can order
Cargill's EH series that goes to 2.11, or
its low temperature series FH melts, 2.12 to
2.21. The FH melts are used in the same
way as immersion liquids, but must be warmed
before the object is introduced.

Pity, your URL seems to be obsolete, at least I could not get info on the
High-RI Cargill
solutions.
But fluids of an RI 1.81, (as I recall from literature about refractometer
contact-fluids) do
contain e.g. phosphor and will spontaneously ignite when they are dry. Hardly
something to work
with in a non-lab environment.

Groeten,

Jaap