Patent ID: 7477394
Filing Date: 2009-01-13
Classification: G01N

Abstract:
1. A method for measuring a property of a liquid under test, the method comprising the steps of: a) contacting a liquid under test against a substantially planar transparent partition spaced a predetermined distance from a transparent window, the partition having a predetermined index of refraction; b) directing a ray of interrogating radiation having a predetermined wavelength through the transparent window and the partition into the liquid; c) allowing radiation reflected from the liquid to undergo total internal reflection within the partition while simultaneously preventing evanescent coupling of that reflected radiation into the window, the prevention of evanescent coupling itself being accomplished by: d) collecting at least some of the radiation passing through the partition, the partition having a maximum thickness dimension sized such that lateral propagation of radiation due to total internal reflection within the partition is minimized so that substantially all of the radiation reflected from a liquid being interrogated exits the partition within a predetermined lateral distance along the plane of the partition.