Patent ID: 9594016
Date: 2017-03-14
CPC Classifications: G01J,G01N,Y10T

Claim:
1. A method of deriving a photometric measure of a liquid disposed in a chamber between first and second chamber walls, the second chamber wall comprising one or more diffractive reflective surfaces, the method comprising: directing a first light beam having a first wavelength through the first wall and liquid to a first location on the one or more diffractive reflective surfaces to cause the first light beam to be diffracted such that a first selected order beam of a first selected diffraction order is reflected at or in the first wall towards the second wall, the reflected first selected order beam being diffracted at a second location on the one or more diffractive reflective surfaces such that a first other order beam of a first other diffraction order, different from the first selected diffraction order, exits the chamber through the first wall; detecting the first other order beam to derive a first signal relating to the first other order beam; and deriving the photometric measure using the first signal.