A general purpose prism refractometer instrument was designed to measure the thermo-optic coefficient (change of index of refraction with temperature) of optical materials. The current wavelength range is from 350 nanometers to 15 micrometers. We have measured over a temperature range from 10K to 770K but currently limit the range to ~62K and up. The nominal uncertainties in index are n/104 and the temp coefficient is within 10% of value. Precision refractometry at room temperature in the visible is done with a Wild Model 79 precision spectrometer with visible line sources. The nominal uncertainties are less than 0.001% with this instrument. More detailed information can be found in the PDF document "Prism Refractometer at the University of Arizona". The procedure for sample preparation and typical measurement costs are in the PDF document "OSC Cyrogenic Refractometer - Prism Specifications." Equation fitting to data is also routinely done as an aid in the determination of the thermo-optic coefficients. A brief listing of dispersion equations is available (PDF).
Return to James M. Palmer home page.