- Home
- Glass and Refractive Index
- What is the "Reference Temperature"?
What is the "Reference Temperature"?
- By Mark Nicholson
- Published 28 October 2005
- Glass and Refractive Index
-
Rating:
Summary and References
Summary
- The refractive index of air (a blank entry in the material column) is always exactly 1.0 at all wavelengths at the system temperature and pressure.
- If the glass reference temperature and pressure of 1.0 atmosphere does not match the surface temperature and pressure, ZEMAX must adjust the index using the method described.
- There are 3 important temperatures and pressures:
- The system temperature and pressure is the air temperature and pressure that has an index of exactly 1.0, and wavelengths are measured in this air.
- The surface temperature and pressure is the environment in which a particular glass is used.
- The reference temperature defines the air to which the index given by the dispersion formula is relative. It also defines the media in which the wavelength argument of the dispersion formula is measured.
References
ZEMAX User's Manual, Chapter 19, "Thermal Analysis"
Related Articles
2 Responses to "What is the "Reference Temperature"?" 
|
said this on 23 Jan 2006 9:02:53 AM PDT
In the Zemax user manual (p. 512) there is the expression that gives the refractive index variation with the temperature.
Such expression, developed by Schott Glass
Technologies, is an accurate approximation only from -40 to 80 Celsius.
What is the behaviour of refractive index at lower temperatures?
It's strange but I couldn't find anything even in letterature!
|
Author)|
said this on 23 Jan 2006 11:16:33 PM PDT
Hi Pierangelo,
Its a good point. AFAIK, there is no commonly accepted formula below this temperature. In these cases, you must make measurements and enter the index directly. - Mark
|