Application reflected lighting device for lighting light background and a black background

摘要

1493099 Bright and dark field microscope illumination ERNST LEITZ WETZLAR GmbH 19 Aug 1976 [20 Sept 1975] 34585/76 Heading G2J A system for providing both bright field and dark field illumination comprises a light source 5, brought to a focus in the plane of adjustable aperture stop 8, a fully reflecting annular mirror 13, by means of which the dark field illuminating beam passing through the periphery of lenses 9 and 10 is directed to annular lens 17 after which it is brought to a focus at image plant 18, which occurs in front of the objective 3, second annular lens 19 contained in the objective then directing the dark field illuminating beam on to mirror 24 and thus to object plane 21, whilst the bright field illumination, if movable stop 12 is removed, is directed by the centre portion of lens 9 and 10 on to partially reflective mirror 14 and thus to the objective 3 and to the objective plane 21. Movable annular stop 11 may be used to cut-off the dark field illuminating beam, and optical separation of the dark field and light field beam may be achieved at annular lens 17 by means of cylindrical diaphragm 22 and suitable design of mount 23. The reflective/ transmissive ratio of mirror 14 is preferably chosen so that the brightness of the dark field and bright field is the same, alternatively this may be achieved by means of a semi-transparent grey filter positioned in the path of the bright field illumination when stop 12 is removed.