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5. Definitions
Working distance
Distance between sample and front lens mount
Numeric aperture
A mathematical relationship, directly related to the (NA)
of the aperture ratio and the resolution power of the
object lens.
The NA is the product of the sine of half the aperture
angle of an object lens and of the refractive index of the
medium through which light enters the object lens.
This is an especially important constant for high-perfor-
mance object lenses.
Resolution power
The capacity of the object lens to separate the fine lens
structures of the sample. The resolution power of a
microscope lens is measured by how two adjacent dots
can be separated. (line structures in the object can be
seen as a set of points). The resolution power of micro
scope lens is defined as follows:
The wavelength range of visible light is between 400 µm
and 700 µm.
The resolution power increases when the light wavelength
decreases. The higher the resolution power of the object
lens, the finer the structure of the object can be resolved.
Depth of sharpness
Distance between the upper and lower limit of the image
sharpness which is determined by the optical system.
Structures lying outside this limit appear out of focus and
can only be sufficiently seen when using low magnifying
lenses. A low depth of sharpness is a special disadvan-
tage in microphotography.
Field of view number
The number that specifies the diameter of the field in the
eyepiece (diaphragm) in mm.
Diameter of field of view
The actual sample field in mm. The diameter of the field
of view of a microscope eyepiece in mm is calculated as
follows:
5. Definitions
A=0.61 wavelength
NA
6. Accessories
/ 6.1 Object lenses/ 6.2 Eyepieces
6.1 Object lenses
As a standard, the microscope is equipped with achro-
matic lenses 4x, 10x, 40x and 100x (oil).
A 20x achromatic object lens is also available for a
200x total magnification, a 60x achromatic lens for a
600x magnification. In order to achieve improved
magnification of the perimeters of the field of view, the
achromatic lenses can be replaced by flat field achro-
matic lenses.
The flat field achromatic lenses are also available in
4x, 10x, 20x, 40x and 100x (oil).
Object lens data:
Vergrößerung
NA
Arbeitsabstand
4x
0.10
17.04 mm
10x
0.25
8.05 mm
20x
0.40
2.10 mm
40x
0.65
0.32 mm teleskopisch
100x
1.25
0.13 mm Öl-Immersion
6.2 Eyepieces
As a standard, the microscope is equipped with one or
two 10x wide-field flat field eyepieces. This results in a
total magnification of 40x, 100x, 400x and 1000x.
When using of one or two 16x eyepieces you can
achieve total magnifications of 64x, 160x, 640x and
1600x.
A 10x pointer eyepiece accessory is available for
measuring and pointing to samples.
A pointer is directed to the centre is in the image
(see fig. 1). By using the scales on the XY stage, it is
possible to measure the distances.
Another accessory for measuring samples is the micro-
meter eyepiece (see fig. 2)
The micrometer eyepiece has a 15x magnification
which achieves a total magnification of 60x, 150x,
600x and 1500x.
6. Accessories
Abb. 1
Abb. 2
Magnification
of the lens
Field of view number of the eyepiece
Field of view on the object side in mm
=
