Refractometric device

Abstract

An immersion-type refractometric device for measuring the concentration of solutions including a probe having a curved measuring surface on the immersible tip. A light source directs a diverging light beam internally through the probe body toward the measuring surface. In one embodiment, light reflected from the measuring surface is received by a light-reflecting surface on the probe tip and directed through the probe body toward a photosensitive element connected to a measuring circuit which provides an output signal indicative of solution concentration. In another embodiment, the photosensitive element is located in the probe tip and receives reflected light directly from the measuring surface. When a linear output is desired over a range of solution concentrations, the measuring surface is curved to produce incidence angles of the reflected light varying from a minimum corresponding to the critical angle when the solution concentration is at the lower limit of the predetermined range to a maximum corresponding to about 1.25 times the critical angle when the solution concentration is at the upper limit of the predetermined range. When a switching function is desired, the curvature of the measuring surface is contoured so that the incidence angles are substantially constant across the measuring surface.

Dependencies are inferred from the claim text.