1) Measuring device 2) Measuring instrument 3) Measuring system 4) Measuring instrument 5) Optical device 
instrument measuring refraction of light
• (n.) A contrivance for exhibiting and measuring the refraction of light.
An instrument used to measure salinity by refraction, the amount light deflects from a straight line through a medium.
(from the article `instrumentation`) ...rely on instrumentation for monitoring chemical, physical, and environmental properties, as well as the performance of production lines. ...
(re″frak-tom´ә-tәr) an instrument for measuring the refractive power of the eye. an instrument for determining the indexes of refraction of various substances, particularly for determining the strength of lenses for spectacles.
An instrument used to measure the degree of refractionwith a gemstone. One of the primary tests to identify gemstonematerial.
Instrument that measures the refraction of light when it enters through a different dimension, such as from air to water or from air into a crystal.
Re`frac·tom'e·ter noun [ Refraction + -meter .] (Opt.) A contrivance for exhibiting and measuring the refraction of light. 
Type: Term Pronunciation: rē′frak-tom′ĕ-ter Definitions: 1. An instrument for measuring the degree of refraction in translucent substances, especially the ocular media. Synonyms: objective optometer, refractionometer See: refractive index
Small hand-held device that can be used for determining how concentrated or dilute a urine sample is (a measurement referred to as urine specific gravity).
[n] - measuring instrument for measuring the refractive index of a substance
noun measuring instrument for measuring the refractive index of a substance