Refractive index measurement of liquids over a broad spectral range

摘要

Techniques described herein generally relate to a refractometer. Using electromagnetic energy, the refractometer can accurately measure refractive index of a liquid without bulky precision optics. By empirically determining a relationship between the refractive index of a liquid sample and a measured reflected power from a resonant structure when in contact with the liquid sample, the refractive index of a liquid can be determined by measuring this reflected power. Furthermore, using multiple light sources of different frequencies, the refractive index of the liquid sample can be determined over a very broad spectral range, for example from ultra-violet to far infrared.

主权项

1. A method to measure refractive index of a liquid sample that is in contact with an optical surface that includes a resonant structure, the method comprising:
while the resonant structure is in contact with the liquid sample, illuminating the resonant structure with light that has a first optical power in a frequency band; measuring light that is reflected off the resonant structure and has a second optical power in the frequency band; and determining a refractive index value of the liquid sample based on the first optical power, the second optical power, and a reference optical power.