Hi guys,
I am looking for the spectral reflectance of several materials
(polished, normal incidence).
metal: gold, aluminium, silver, nickel, copper
dielectric: rutile, diamond, calcite, glass
The purpose is to illustrate their optical properties, more precisely
the behaviour of Fresnel reflections. Does someone know where I can
find such info? online resource? book?
Thanks in advance
Enrique
Enrique,
By "Fresenel reflection" you mean the specular relection from a
smooth surface, as opposed to diffuse reflection?
Depending on the wavelength you are interested in,
you might also try books on radiation heat transfer,
such as Siegel and Howell. Also, there is a lot of
information in the Infrared Handbook, (Wolfe and Zissis, eds.)
and its successor, The Infrared & Electro-Optical Systems
Handbook, a 7 volume set of books edited by Zissis.
Olin Perry Norton
That is right, I mean first-surface reflections.
I am interested in the visible light range, i.e. 300-700nm.
Could I find the dielectrics I am looking for in them? rutile,
diamond, calcite, glass
Thanks anyway.
Enrique
[snip]
Dear Enrique,
You probably know this, but just in case, remember that
there are formula that let you calculate the reflection
coefficient if you know the index of refraction.
So, you might try looking for refractive index data
in addition to data on reflectance. Particularly
for a common optical material like glass, refractive
index data should be readily available.
(Incidentally, the word "glass" covers a lot of territory.)
If you pick a particular type of optical glass, the manufacturer
should have plenty of data available on the refractive index.
Look at
formatting link
example.
Schott BK7 is a common optical glass. If you Google
"refractive index Schott BK7" (without the quotes)
you will find a lot of information.
I tried Googling "rutile refractive index" (without quotes)
and found this: "Refractive indices of rutile as a function
of temperature and wavelength," J. Rams, A. Tejeda, and
J. M. Cabrera, Journal of Applied Physics (1997)
Volume 82, Issue 3, pp. 994-997.
"The Infrared & Electro-Optical Systems Handbook,"
Volume 4, "Electro-Optical Components," edited by
William D. Rogatto, in Table 1.52 on page 46 gives
the refractive index of diamond from 480 nm to 656 nm.
Calcite will be a challenge. It is birefringent, so you
may have to rederive the formula for the calculation of
the reflection coefficient from the refractive index.
Olin Perry Norton
Thanks a lot for the answer, it is so helpful!
Yes, but I was not so sure about myself, so I would have preferred to
get data from proper sources.
However, I followed your advice, and got the refractive indices of
glass and rutile from the sources you mentioned. I computed the
spectral reflectance myself, and they look correct! I am very pleased,
thanks a lot.
"The Infrared & Electro-Optical Systems Handbook,"
Let's forget about calcite then. I have not looked at the book for
diamonds, but I will. I could also replace them with other dielectrics.
Do you know any whose spectral reflectances/refractive indices are
readily available?
Thanks again
Enrique
[
Dear Enrique,
People who design optics must have access to compendia of
refractive index data that include all commonly used optical
materials. I'm not one of these people, so I can't really
tell you the best place to look.
The Melles Griot web site I referred you to earlier and
the web sites of optical glass manufacturers (like Schott)
have tables of refractive index data for the materials
they sell.
I'm not sure what your intended application is. If you
want a selection of different materials with different
reflectivities, you might be able to use different types
of optical glasses.
They are readily available, not too expensive, and you can buy
them already polished and optically flat. Using an amorphous
material like glass would also eliminate the problem of
anisotropy and having to determine how you're oriented
relative to the crystal axes.
There seems to be an enormous literature on the refractive
indices of various materials. I searched for refractive index
on the NIST web site and came up with:
Shannon, Robert D., et al., "Refractive index and dispersion of
fluorides and oxides," Journal of Physical and Chemical Reference
Data, Vol. 31, 2002, pp. 931-970.
Google is tremendously helpful for finding this type of information.
I randomly picked sodium chloride as a common chemical compound and
Googled "refractive index sodium chloride" (without the quotes) and
immediately found a table of refractive index values.
"The Infrared & Electro-Optical Systems Handbook,"
Volume 4, "Electro-Optical Components," edited by
William D. Rogatto has tables of refractive indices
of many different materials, especially those used
as infrared windows and lenses.
Olin Perry Norton
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