Full-field imaging-based instantaneous hyperspectral absolute refractive index measurement

Multispectral refractometers typically measure refractive index (RI) at discrete monochromatic wavelengths via a serial process. We report on the demonstration of a white light full-field imaging-based refractometer capable of instantaneous multispectral measurement of absolute RI of clear liquid-gel samples across the entire visible light spectrum. The broad optical bandwidth refractometer is capable of hyperspectral measurement of RI in the range 1.30-1.70 between 400 and 700 nm with a maximum error of 0.0036 units (0.24% of actual) at 414 nm for an η = 1.50 sample. We present system design and calibration method details as well as results from a system validation sample.