OPERATIONAxiolab 5 Illumination and contrast methods in transmitted light ZEISS05/2019 430037-7444-001 97NOTEFor a high-contrast image with higher-magnification objectives (from approx. 20x) theillumination aperture must be reduced to a value between 0.15 and 0.20, i.e. the aperturediaphragm must be closed accordingly.The effect of the lambda/4 plate (Fig. 4-10/4) can be undone by either swiveling it out of thebeam path or turning it with the lever (Fig. 4-10/3) into one of its two click-stop positions.(4) Sample differentiation between gout and pseudo-gout• Move two polarizers to the dark position (the analyzer is oriented NORTH-SOUTH, while the polarizeris oriented EAST-WEST).• Swivel in the lambda plate and, if a rotary lambda plate is available (e.g. 445226-0000-000), set theoscillation direction to 45° (γ, stop position).• Select crystal needles that are oriented in the gamma direction (see marking on the lambda plate).(5) Analysis• If the crystal needles oriented parallel to the gamma direction of the lambda plate are yellow, and thecrystal needles lying at a right angle to the gamma direction are blue, the crystals are monosodiumurate crystals (gout).• If the crystal needles oriented parallel to the gamma direction of the lambda plate are blue, and thecrystal needles lying at a right angle to the gamma direction are yellow, the crystals are calciumpyrophosphate crystals (pseudo-gout).This analysis is also possible using a polarizer with a fixed lambda plate which can be placed on theluminous-field diaphragm. In that case, the lambda plate does not have to be rotated.
