KLC K1148 Babinet Soleil Compensator

A Babinet Soleil Compensator ( BSC ) is placed between two crossed polarizers ( axes perpendicular to each other ) in such a way that the linear input polarization from the first polarizer is at 45 degrees to the fast axis of the compensator. Viewing through the second polarizer in a white light source, a black cross ( Null ) is observed at zero reading of the micrometer. This is zero retardation reading of the BSC. An unknown retardation to be measured is introduced between BSC and the polarizer. The BSC micrometer is turned until the black cross ( Null ) is observed again. The micrometer reading is an indirect measure of unknown retardation. A calibration chart is provided with each BSC which gives retardation in waves at a specific wavelength vs the micrometer reading.