OPERATIONAxiolab 5 Illumination and contrast methods in transmitted light ZEISS05/2019 430037-7444-001 93(4) ConclusionsThe gray-white color appearing first in the brightposition in the above example (Fig. 4-8/1)corresponds to a path difference of 150 nmaccording to the Michel-Lévy color chart (Fig. 4-9).When the lambda compensator is brought into thebeam path, the non-birefringent "surroundings"of the synthetic fiber appear dark red, whichcorresponds to the path difference of thecompensator of 550 nm (1st order interferencecolor for the path difference of 550 nmcorresponds to 1 λ).If the polarization direction (nγ or nγ' ) of thebirefringent sample to be examined is parallel tothe principal polarization direction (nγ) of thelambda compensator, i.e. in the NE-SW direction,the path difference of the sample (e.g. gray-white:150 nm) and the path difference of the lambdacompensator (red: 550 nm) add up. This results ina color change of the sample from grayish white togreenish-blue (resulting path difference = 700 nm).If the polarization direction of the birefringent sample to be examined is perpendicular to the principalpolarization direction of the lambda compensator, i.e. in the NW-SE direction, the path difference of thesample (e.g. gray-white: 150 nm) is subtracted from the path difference of the compensator (red:550 nm). In this case, the interference color of the sample visibly changes from gray-white to orange(resulting path difference = 400 nm).NOTEThe Michel-Lévy color tables are available in the literature catalog no. 42-312.Fig. 4-9 Schematic diagram of the colorcharts developed by Michel-Lévy
