Leica DM IRB manual Centring the aperture diaphragm, Centring the field diaphragm

Centring the aperture diaphragm

Turn a low to medium objective magnification 10x/20x into the light path and focus a specimen with the coarse and fine drive.

Remove an eyepiece from one of the two eyepiece tubes and look into the empty tube or move the Bertrand lens into the light path.

Regulate the light intensity so that the rear objective pupil (rear lens surface of the ob- jective) can be clearly seen.

Using the adjustment button (72.1), open the aperture diaphragm nearly to the edge of the pupil.

Centre the aperture diaphragm to the edge of the pupil with the centring screws (72.2).

The aperture diaphragm influences the reso- lution, contrast and field depth of the micro- scope image. Image quality greatly depends on how carefully it is set. It may not be used for regulating the image intensity.

Centring the field diaphragm

Turn a low to medium objective magnification 10x/20x into the light path and focus a specimen with the coarse and fine drive.

Open the field diaphragm almost as far as the edge of the field of view.

Using the centring buttons (72.4), centre the field diaphragm to the edge of the field of view.

The field diaphragm is imaged on the surface of the specimen, framing the illuminated field. Normally, the field diaphragm is opened until it just disappears out of the field of view.

When imaging reduced picture diagonals such as in photomicrography or TV microscopy, the field diaphragm can be narrowed to frame the picture format, enhancing the image contrast.

The aperture diameter of the field diaphragm remains the same for all objective magnifi- cations.

Fig.Ê 72ÊApertureÊ and field diaphragmÊ

1 Aperture diaphragm adjustment, 2 Aperture diaphragm centring screws, 3 Field diaphragm adjustment, 4 Field diaphragm centring screws

1

4 2

3

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