OPERATIONZEISS Illumination and contrast methods in reflected light … Axioscope 5/7/Vario112 430035-7344-001 03/20184.3 Illumination and contrast methods in reflected light microscopy4.3.1 Setting up reflected light brightfield microscopy using the KÖHLER method(1) ApplicationReflected 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 thesample details. According to ABBE, the image is truer to the specimen when the fraction of the indirectbundled beams is larger.The cone of light emerging from the reflected light illuminator is reflected on a color-neutral beamsplitter before it passes through the objective which is focused on the specimen surface (so-calledcondenser function). The objective collects the light reflected on the specimen and creates, with the tubelens, the microscopic intermediate image. This image can then be examined visually or documentedobjectively.(2) Instrumentation− Axioscope with pre-installed LED 10 W illuminator or optionally used with HAL 100 halogen lampmounted 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 diaphragmsliders or upper part of the stand with HAL 100/HBO 6-positions HD, DIC and 2x 14x40 mm stopslider(3) Setting the reflected light brightfield− The microscope is in the correct operationalmode according to section 6 5 7 H 3.− The microscope is switched on.• When the halogen illuminator is used: Switchon the HAL 100 halogen illuminator on theexternal power supply unit (658HFig. 4-14/1).• Move the toggle switch (Fig. 4-14/3) to the RLposition for reflected light.• Adjust the light intensity with the controlbutton on the external power supply unit(659HFig. 4-14/2).• Put a high-contrast reflected light sample on themicroscope stage.• Swing in the 10x objective on the nosepiece (660HFig. 4-15/6).• Focus the sample with the focusing drive (661HFig. 4-15/5). Try to focus away from the sample to avoid anycollision between the objective and sample.Fig. 4-14 External power supply unit forHAL 100
