OPERATION
ZEISS
Illumination and contrast methods in reflected light …
Axioscope 5/7/Vario
112
430035-7344-001
03/2018
4.3
Illumination and contrast methods in reflected light microscopy
4.3.1
Setting up reflected light brightfield microscopy using the KÖHLER method
(1) Application
Reflected light brightfield microscopy is the easiest and most commonly used optical microscopy method.
It is used to examine optically opaque specimens or samples as e.g. cut material or wafers.
For an imaging result which is as true to the specimen as possible, we must not only consider the so-
called direct bundled beams but the indirect ones as well, i.e. the beams which diffract and scatter on the
sample details. According to ABBE, the image is truer to the specimen when the fraction of the indirect
bundled beams is larger.
The cone of light emerging from the reflected light illuminator is reflected on a color-neutral beam
splitter before it passes through the objective which is focused on the specimen surface (so-called
condenser function). The objective collects the light reflected on the specimen and creates, with the tube
lens, the microscopic intermediate image. This image can then be examined visually or documented
objectively.
(2) Instrumentation
−
Axioscope with pre-installed LED 10 W illuminator or optionally used with HAL 100 halogen lamp
mounted at the back of the upper part of the stand
−
ACR P&C brightfield reflector module for reflected light in the reflector turret
−
Upper part of the stand with HAL 100/HBO 6-positions HD, DIC with aperture and field diaphragm
sliders or upper part of the stand with HAL 100/HBO 6-positions HD, DIC and 2x 14x40 mm stop
slider
(3) Setting the reflected light brightfield
−
The microscope is in the correct operational
mode according to section
−
The microscope is switched on.
•
When the halogen illuminator is used: Switch
on the HAL 100 halogen illuminator on the
external power supply unit (
1
).
•
Move the toggle switch (Fig. 4-14/
3
) to the
RL
position for reflected light.
•
Adjust the light intensity with the control
button on the external power supply unit
(
2
).
•
Put a high-contrast reflected light sample on the
microscope stage.
•
Swing in the 10x objective on the nosepiece (
6
).
•
Focus the sample with the focusing drive (
5
). Try to focus away from the sample to avoid any
collision between the objective and sample.
Fig. 4-14
External power supply unit for
HAL 100