title: Real-time differential refractometry without interferometry at a sensitivity level of 10(-6).
abstract: We present a refractometer based on the principle of total internal reflection that can sensitively record, in real time, the refractive index of fluids over a wide range of refractive indices. The device uses a divergent laser beam and a linear diode array, and has no mechanical or optical moving parts, enabling us to achieve the measurement of a refractive index at a sensitivity level of 10(-6). Our refractometer does not rely on interferometry, thus enabling the device to be compact, portable, and inexpensive. To the best of our knowledge, this is the first time a noninterferometric device that performs real-time differential refractometry with a sensitivity of better than 10(-5) has been demonstrated in the literature. We show that our experimental results agree very well with Fresnel theory. We establish a theoretical limit on the sensitivity of this class of refractometers.
authors.affiliation: Department of Physics, Miami University, Oxford, OH 45056-1866, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: McClimans
authors.forename: Charles
authors.initials: C
authors.lastname: LaPlante
authors.forename: David
authors.initials: D
authors.lastname: Bonner
authors.forename: Samir
authors.initials: S
authors.lastname: Bali