Temperature Variation concerns: Toxicology NH4H2PO4 (Ammonium dihydrogen phosphate, ADP) Atmospheric refraction near the ground produces mirages. YbF3 (Ytterbium trifluoride) The final sample we tried was engine oil and this shows the impact even more so. Sr (Strontium) We also tried a beverage, in this case cranberry juice. Peter Marriott – Refractometer Product Manager Rudolph Research Analytical Also see video: Refractometer, Temperature Correction & Control with a Rudolph J457 We are going to look at the effects of changing temperature on refractive index measurement and if Temperature Correction can compensate for temperature variances or if actual temperature … The refractive indices of the studied oils and the uncertainty in their values are calculated at λ=0.589. As a common approximation, terrestrial refraction is considered as a constant bending of the ray of light or line of sight, in which the ray can be considered as describing a circular path. GaP (Gallium phosphide) ZnO (Zinc monoxide) CsF (Cesium fluoride) In all cases, the refractive index decreased monotonically with increasing wavelength. Once a temperature coefficient is known, the temperature corrected refractive index can be calculated from an actual refractive index reading by the following formula: RITC = ((RT-AT)*TC)+RI Where: RITC = Refractive Index Temperature Corrected RT = Reference Temperature AT = Actual Temperature as Read on Instrument TC = Temperature Coefficient Of Sample RI = Actual Refractive Index As Read On Refractometer Example: Calibration … This is again just the variance from what we would call room temperature, 20C – 25C. B. Murray, T. C. Narayan, J. N. Munday. Ca (Calcium) CaWO4 (Calcium tungstate) Once the measurement is completed we wipe away the sample to prepare for the next measurement making sure the refractometer’s sample well is completely cleaned and nothing is left to potentially contaminate the next measurement. HfO2 (Hafnium dioxide, Hafnia) The complex refractive index of a material at temperature T is given by, $$ n + ik = (n_{ref} + \Delta n) + i(k_{ref} + \Delta k) $$. Ar (Argon) Temperature Correction is of little value when measuring anything other then sucrose & water based samples. The standard measurement temperature for refractive index values given on test certificates is 22°C. Sn (Tin) ENDMEMO . The coefficient of refraction is directly related to the local vertical temperature gradient and the atmospheric temperature and pressure. Dynamic optical properties of metal hydrides, ACS Photonics 5, 4677-4686 (2018)(Numerical data kindly provided by Kevin Palm), [CSV - comma separated] We will use distilled water, cranberry juice, ethyl glycol (Antifreeze) and engine oil. AgBr (Silver bromide) Temperature control is required depending on sample type. Ta (Tantalum) AlSb (Aluminium antimonide) Using Temperature Correction helps a little but we are still left with an error that is almost in the third decimal place. Then push the "TEMPERATURE" button to get the temperature reading (on the built-in thermometer). AgCl (Silver chloride) Calculate the refractive index of the medium. Copyright © 2020 Elsevier B.V. or its licensors or contributors. If the dispersion is also a problem (in case of broadband high-resolution observations), atmospheric refraction correctors (made from pairs of rotating glass prisms) can be employed as well. CuO (Copper monoxide) LiCl (Lithium chloride) SrMoO4 (Strontium molybdate) Be (Beryllium) where temperature T is given in kelvins, pressure P in millibars, and height h in meters.