Patent ID: 8687184

Claim:
A method for validating path length and optical characteristic of a fibre optic probe, the method comprising the steps of: (a) providing a fibre optic probe reference cell ( 8 ) comprising a base wall ( 11 ), first and second opposed upstanding walls ( 12 ) and further walls, which further walls are perpendicular to the opposed upstanding walls, each further wall having an optical window ( 13 , 15 ), the cell further comprising a top wall ( 14 ), which top wall ( 14 ) is provided with a further optical window ( 16 ), which further optical window ( 16 ) is adapted to permit transmission of light to and from a fibre optic probe ( 1 ), which walls ( 11 , 12 , 14 ) define a chamber ( 10 ), wherein the chamber ( 10 ) is provided with a reference material and wherein the base wall ( 11 ) comprises a reflector ( 19 ) adapted to reflect incident light from a fibre optic probe ( 1 ) back to said fibre optic probe ( 1 ); (b) connecting the fibre optic probe reference cell ( 8 ) to the fibre optic probe ( 1 ) comprising a fibre optic cable ( 2 ) having a first input optical fibre ( 5 ) and a second output optical fibre ( 6 ), which first input and second output optical fibres ( 5 , 6 ) extend to a sampling end ( 4 ), said fibre optic cable ( 2 ) being connected at an end to an analyzer adapted to process the first input optical fibre ( 5 ) and the second output optical fibre ( 6 ); (c) transmitting light through the first input optical fibre ( 5 ) into the chamber ( 10 ) to interact with the reference material; (d) transmitting incident light back to the fibre optic probe ( 1 ) to determine path length of the fibre optic probe reference cell ( 8 ) and absorption characteristics of the reference material; (e) calibrating the fibre optic probe ( 1 ) based on the path length of the fibre optic probe reference cell ( 8 ) and the absorption characteristics of the reference material; and (f) validating the calibration step by determining the path length of the fibre optic probe reference cell ( 8 ) and the absorption characteristics of the reference material in a spectrophotometer.