Index Instruments pioneered digitial refractive index instruments in the 1980’s and still lead the field in build quality, performance and price.


Index Instruments - logoSnells Law of refraction

Index’  range of refractometers extends from hand-held optical refractometers to bench/lab models or research units with the highest specification.


While most of us reference Refraction to air or water, fundamentally, Refractive Index is defined as the factor by which the wavelength and the velocity of the radiation are reduced with respect to their vacuum values. The speed of light in a medium is v = c/RI, where c is the speed in vacuum. Similarly, for a given vacuum wavelength, the wavelength in the medium is divided by RI. This implies that vacuum has a refractive index of one. Refractive index of materials varies with the wavelength. This is called dispersion; it causes the splitting of white light in prisms and rainbows, and chromatic aberration in lenses. In opaque media, the refractive index is a complex number: while the real part describes refraction, the imaginary part accounts for absorption.

Index Instruments have developed RI testing systems for special applications that provide opticians, surgeons and manufacturers of devices new capabilities.

Hand held Refractometer     Compact portable digital refractometers   General Purpose digital refractometer TCR High Performance refractometer

Optical Activity who manufacture polarimeters is a related company of Index Instruments.

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Index Instruments Products Index technologies
Hand held refractometers  GR1 for gas (anesthetics or petroleum)
Digital hand held refractometers  Contact Lens refractometer
General purpose refractometers  Corneal Hydrometer for use in surgery
Peltier controlled refractometers  RI Calibration Standards
High specification refractometers