DE8905951U1 - Illumination device on a microscope - Google Patents

Description

Description: 89019 G Illumination device on a microscope

The innovation concerns an illumination device on a microscope with which light dark field conditions can also be set for lenses with a small image scale.

The system condensers used in microscopy generally allow the setting of perfect dark field conditions for objectives up to an image scale of approx. 5x. The dark field is either created with the help of a special dark field condenser or by inserting diaphragms with annular openings near the aperture diaphragm plane via a revolver in the condenser. However, for objectives with a smaller image scale of 2.5x or 1.25x, it is difficult to create a homogeneous dark field. This is because the relatively large fields of these objectives must be evenly illuminated without direct light falling into the objectives.

A wide variety of proposals have been made to solve this problem, but they all require a relatively high level of effort. For example, in the applicant's application brochure "Darkfield Microphotography", printing note A 41-170.1-d, it was suggested to remove the condenser completely for this purpose and instead attach a ring diaphragm to the condenser carrier, adjust this to suit the field diaphragm by adjusting the height of the condenser carrier with the field diaphragm closed, open the field diaphragm, place a frosted glass on the field diaphragm, adjust the height of the condenser carrier again and then even move the lamp collector until the most homogeneous and bright illumination is achieved. Apart from the fact that this adjustment is relatively complicated, the frosted glass causes a relatively high loss of brightness.

Furthermore, in Zeiss Information No. 27, Issue 9k (1982) on pages 18-19, a transmitted-light dark-field illumination device is described, which is also suitable for lenses with a low image scale. However, the entire illumination device is replaced by a fiber-optic ring lamp. Adapting this illumination device, which was actually intended for brightfield microscopes, to the upright tripods of "normal" microscopes requires major modifications, so that a quick change between brightfield and darkfield illumination is no longer possible.

DE-OS 31 05 571 describes a condenser for transmitted light dark field illumination that can be adapted to lenses with different apertures. But apart from the fact that the document does not say up to which image scale the condenser can be used, a central diaphragm placed near the aperture plane must be adjustable in height and an additional optical system is required that creates a strongly divergent beam path at the location of the aperture diaphragm.

The aim of this innovation is to create an illumination device for microscopes which requires only minor changes or adjustment work to set light dark field conditions for objectives with a small image scale, based on known and available bright field illumination devices.

This task is carried out in accordance with the characteristics of the Claim 1 is solved by the fact that the device consists of a Condenser with fold-out front lens and a

near the aperture in the microscope base, the central part of the

Central diaphragm shading the illumination beam

consists.

In contrast to the state of the art, the central diaphragm required to create dark field conditions is not inserted near the aperture diaphragm in the condenser, but rather is positioned near the diaphragm, which is normally the light field diaphragm. With the front lens of the condenser folded out at the same time, a homogeneous dark field can be created with these simple measures, even for lenses with a magnification of 1.25x and 2.5x.

Since the light field diaphragm in upright microscopes is often arranged horizontally in the base of the stand, the center plate required for setting the dark field can simply be a glass, plastic or metal plate that is inserted into the corresponding recess in the light field diaphragm holder. No further modifications or adjustments are required.

The innovation is explained in more detail below in an exemplary embodiment based on Figures 1-3 of the attached drawings.

Figure 1 Shows the structure of a conventional

Illumination device on a microscope in section along the optical axis;

Figure 2 shows the lighting device modified according to the innovation for dark field illumination/ also in section along the optical axis;

Figure 3 shows the central aperture (15) shown in Figure 2 top view.

The light illumination device for upright microscopes shown in simplified form in Figure 1 has the following structure: A field diaphragm (10) with an adjustable diameter is mounted horizontally in the base (9) of the microscope.

Arranged horizontally. The light field diaphragm (10) is covered by a glass plate (13) in the holder (11) for the light field diaphragm. The holder (11) protrudes upwards at the edges of the glass plate (13) and thus forms a recess (14) above the glass plate (13).

The condenser (5) is mounted on its carrier (15) beneath the table (3) of the microscope. This condenser (5) has a two-part optical system consisting of a front lens (7) and a second lens (8). The fnAnf I Î&eegr;&ogr;&ogr; -ic-*· mi f -iWror Î&Ggr; aee iin Î&eegr; (A) aiie A Î &ogr; m Cf rah I onnann

foldable. The condenser shown can be obtained from the applicant under the number 44 53 40.

An objective (2) with a relatively large magnification is attached to the microscope revolver marked (1). The diagram in Figure 1 shows the field illumination beam path for this objective.

In Figure 2, the illumination device is modified so that a lens (12) also attached to the turret with a small magnification of 1.25x provides perfect

Qun|(o[f;M-Re(jingijnn;n apnaKen. &Ggr;) a 7 ij je* d 1 S FTOHt &Igr;&Idigr;&Ggr;!55 d &bgr; S Condenser (5) folded out of the beam path.

After folding out the front lens of the condenser (5), the field diaphragm (10) is no longer imaged in the object plane by the remaining lens (8) of the condenser, but rather further above next to the lens (12). It is therefore possible to shade the lens opening with a central diaphragm near the field diaphragm (10).

For this purpose, the central diaphragm (15) shown in the top view in Figure 3 is placed on the cover glass (13) of the luminous field diaphragm (10). This central diaphragm has a central, opaque coating (16) with a diameter of approx. 10-14mm and

I I ff · t · ·

: its external dimensions are adapted to the recess (14) in I the holder (11) of the light field panel (1Q) so that it S* centers itself there when placed on it.

$ The diameter of the opaque aperture (16) on the '£ 6 lasp plate (15) must be selected so that no direct light enters the lens. For different lenses, for example with the image scale 2.5x and 1.25x

(I Under certain circumstances, different diameters may also result. It may therefore be advisable to provide several such glass plates (15) ^ with different sizes of the ZsritrsLblnd CIo)-

which can be exchanged as needed.

Claims (2)

Protection claims: 1. Illumination device on a microscope for setting light-darkfield conditions for objectives (12) with a small image scale, characterized in that the device consists of a condenser (5) with a fold-out front lens (7) and a central diaphragm (15/16) near the diaphragm in the microscope base (light field diaphragm 10) which shades the central part of each illumination beam. 2. Lighting device according to claim 1, characterized in that the frame (11) of the cover (10) has a recess (14) and the central cover is a glass, plastic or metal plate (15) inserted into the recess.