METHOD AND DEVICE FOR MEASURING THE FOCAL DISTANCE OF A THERMAL LENS

摘要

The invention relates to a method for measuring the focal distance of a thermal lens (26) located in an analyte (23), comprising providing an optical excitation beam (21.1) extending through the analyte (23) and forming the thermal lens therein, emitting a coherent optical probing beam (22.1) extending through the analyte (23) and propagating substantially perpendicular to the optical excitation beam (21.1), and intercepting the coherent optical probing beam (22.1) with a detector (24) after the former has passed through the analyte (23). The method further comprises focussing the optical excitation beam (21.1) upstream or downstream from the optical lens (26) so that said thermal lens (26) is crossed by only a fraction (22.1a) of the probing optical beam (22.1), acquiring an interferential image using the detector (24), and processing the interferential image for calculating the focal distance of the thermal lens (26). The invention can be used for the physical and chemical analysis of the analyte (23).