Choice of prisms

Choose the objective-side prism with the letter indicated in the top line of the objective en- graving, e. g. C for pupil position C, by rotating the turret.

Choose the condenser-side prism that corre- sponds to the magnification of the objective used, e. g. pos. 40 for objective 40x, by rotating the disc.

Setting ICT contrast

Turn the objective-side prism turret to the left and right (Fig. 67). Also adjust the contrast with the aperture diaphragm. Optimum contrast for specimens with parallel structures can be obtained by rotating the specimen. Colour contrast: Turn over the analyser, so that the lambda sign can be seen on the top.

Sources of error if ICT image quality is unsatisfactory

Embedding medium, specimen slide (petri dish) or specimens (e. g. crystals, fibres) are of birefringent material. The phase shifts caused by birefringence disturb the interference con- trast image. This can sometimes be remedied by rotating the specimen.

Fig.Ê 67Ê

Setting ICT contrast

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Leica DM IRB manual Choice of prisms, Setting ICT contrast, Sources of error if ICT image quality is unsatisfactory