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Compound achromatic microscope, stand ‘Laborlux’

Maker

LEITZ

Country

Germany

Signature

Ernst Leitz / Wetzlar / 435491

Category

Microscopes

Optical 1

Compound

Optical 2

Achromatic

Size of the microscope (h x b x d)

iwith attached illumination unit: 40 × 22 × 45 cm

Inventory number

SM 12

Description

The T-shaped base plate and the limb of the Laborlux microscope are cast of aluminium, which has a black enamelled finish. Behind a microscope lamp can be attached, in the foot also the mirror which can be rotated around its axis by means of a little handle bar.
The stage is fixed to the limb, this microscope has a simple mechanical stage. Below the stage the Berek-type condenser with diaphragm and a front lens that can be folded away. The focal length of the complete condenser is 18.51 mm, without the front lens the focal length is 53.86 mm.
On top of the limb the fine and the coarse adjustment, acting on a dovetailed block to which various nosepiece changers and eyepieces can be attached. With this microscope go a quadruple nosepiece changer and a binocular eyepiece. A lens in the optical path corrects for the small mechanical tube length, as Leitz objective lenses are corrected for a 170 mm body tube.
There are two eyepieces ‘Zeiss’ KPL 8×, they must be a later addition. Their focal length is 31.14 mm and their magnification is 8.03×.
In the nosepiece changer are four objective lenses ‘1 3½:1 A 0.10’; ‘3 10:1 A 0.25’; ‘6L 45:1 A 0.65’ and ‘Oel 100:1 A 1.30 no. 231605’. They were investigated using the Bleeker microscope with a body tube of 170 mm, the ‘1’ and the ‘3’ with a 10× Huygenian eyepiece, the ‘6L’ and the immersion objective with a 5× Huygenian eyepiece.

Objective 1 (3½:1) 3 (10:1) 6L (45:1) Oel (100:1)
Focal length (mm) 31.68 16.49 4.18 1.90
Magnification 35.42 102.34 226.3 511.7
Numerical aperture 0.094 0.26 0.68 1.36
Resolving power (µm) 4 1.6 < 0.8 < 0.8

Objective lens ‘1 3½:1 A 0.10’ is spherically slightly overcorrected, its field is flat.
Objective lens ‘3 10:1 A 0.25’ is well corrected, it only shows some zonal aberrations.
Objective lens ‘6L 45:1 A 0.65’ is spherically overcorrected, however the other aberrations are well corrected. It resolves the diatom Pleurosigma angulatum into dots.
Objective lens ‘Oel 100:1 A 1.30’ is spherically undercorrected, its field is rather curved but the other aberrations are well corrected. It resolves the Surirella gemma diatom into lines, the dots are just not visible.