| oblique 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) |
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| erect illumination | An illumination in which the rays of light are directed downward, almost perpendicularly onto the upper surface of the object, which reflects the rays upward into the optical system. Synonym: erect illumination, vertical illumination. (05 Mar 2000) |
| Koehler illumination | <microscopy> Mode of microscope illumination in which the light source is imaged onto the condenser iris diaphragm and the field diaphragm (in front of the lamp collector lens) is imaged by the condenser onto the plane of focus of the specimen. With Koehler illumination, the aperture and field can be regulated independently to provide maximum resolution and optimum contrast. Also, a field with uniform illumination is obtained, circumscribed by the image of the field diaphragm. (05 Aug 1998) |
| 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) |
| 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) |