Design and development of a cryogenic high-accuracy refractometer

We present the development of a demonstration prototype for a compact and relatively cheap system capable to measure the refraction index of glasses, between 0.4 to 1.7 micron, at room and cryogenic temperatures (T=100-300 K), with an absolute precision of few parts of 10-5. The basic concept is the measurement of the deviation angle of monochromatic light passing through a prism sample placed in the cryogenic chamber. The precision of the measurements depends on many factors, in particular the angle measurement and the thermal stability, therefore the system can control its alignment. The main issue is the trade-off between the simplicity of the set-up and the precision of the refractive index measurement.

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