| Kohler illumination | <technique> The recommended type of optical microscope illumination in which the image of the lamp filament is focussed in the lower focal plane of the substage condenser. As opposed to collimated illumination in which the light emitting surface is imaged in the object. Collimated illumination requires even intensity across the light emitting surface but is preferable for certain types of microscopy. Kohler illumination gives even illumination on the object even if there are irregularities in the brightness of the light emitting surface. (18 Nov 1997) |
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| focal illumination | Illumination in which a beam of light is directed diagonally to an object so that it is brilliantly illuminated while the surrounding area is in shadow. Synonym: lateral illumination, oblique illumination. Kohler illumination, a method of illumination of microscopic objects in which the image of the light source is focused on the substage condenser diaphragm and the diaphragm of the light source is focused in the same plane with the object to be observed; maximises both the brightness and uniformity of the illuminated field. (05 Mar 2000) |
| lateral illumination | Illumination in which a beam of light is directed diagonally to an object so that it is brilliantly illuminated while the surrounding area is in shadow. Synonym: lateral illumination, oblique illumination. Kohler illumination, a method of illumination of microscopic objects in which the image of the light source is focused on the substage condenser diaphragm and the diaphragm of the light source is focused in the same plane with the object to be observed; maximises both the brightness and uniformity of the illuminated field. (05 Mar 2000) |