🚀 go-pugleaf

In article <1992Sep28.071622.3040@trl.oz.au> jdell@trl.OZ.AU (John Dell - Photonics) writes:

>Anyway, the problem (at last) is that we need to measure lowish temperatures
>now (of the order of 300-500 C) and we would like some recommendations of how
>to do this using optical pyrometry.  What have been peoples' experiences, how
>do you calibrate the system, what products are available, how accurate
>are they, how precise are they, do you look at the block or the semiconductor,
>have you had to worry about the window (ie do you need a sapphire window
>or will a standard window do and simply change the effective emissivity), 
>do you need to heat the window to prevent condensation of As, how do you
>limit the field of view .....? 

Last spring I worked with an Optical Pyrometer attempting to measure
(accurately) the maximum temperatures on Si using an Nd:YAG (1.06um)
beam, with very little success.  Although we were looking for
temperatures near 1600K, we still learned quite a bit about optical
pyrometry.

We found the biggest consideration to be how much area on the sample
that you need to see.  We needed a resolution such that the window that
the pyrometer saw was about 300um wide - which is very difficult to
attain.  The problems in viewing an area this small come from the fact
that the lens must be _very_ close to the sample.  Since we were trying
to look at the surface temperature, our situation was  a little
different than yours because we needed to look at the sample head on.

Our pyrometer was made by Inframetrics (I don't remember the model
number offhand) but we found it to be very accurate in other (larger
scale) situations.  Simply looking into a tube furnace revealed only a
2-3 degree difference between the pyrometer and the furnace controller;
Calibration was performed by Inframetrics.

Please send me email and I can dig up some old manuals and notes to give
you more information.


Ian D. Bjorhovde
ianbjor@gas.uug.arizona.edu  -or-  ianbjor@convx1.ccit.arizona.edu
Department of Materials Science & Engineering
University of Arizona, Tucson AZ