THE PERFECT MICROSCOPE ILLUMINATION
A high quality illumination is regarded as a key issue for a perfect information transfer from specimen to target (human eye/camera chip). The illumination angle, definable by the condenser diaphragm, directly affects the resolution power of the microscope system. The final illumination setup should create a homogenous image background with a high dosage of sample details “on top”.
The human eye compensates illumination defects and pretends depth of focus. On the contrary, the microscope camera is brutally honest to a suboptimal setup and reveals any deficit in illumination. No coincidence that August Karl Johann Valentin Koehler (1866-1948) developed an optimized microscope illumination while working on photomicrography problems.
Following A. Koehler, a perfect microscope illumination has to fulfill the following requirements:
The illumination aperture (=angle) should be adaptable to the NA (=opening angle) of the objective in use.
In order to reduce stray light, the illuminated object area should be definable.
Illumination aperture and illuminated area should be adjustable independently.
Illumination for each image point has to be identical.
Aperture diaphragm (1) and Field Diaphragm (2) are the important variables of the microscope illumination and enable the user to follow Koehler’s requirements.
HOW TO DO A PROPER KOEHLER SETUP?
The first 4 steps have to be taken by using the field diaphragm:
Focus on sample by focus drive. Close Field Diaphragm (3)
Focus image of Field Diaphragm by adjusting condenser height (4)
Center image of Field Diaphragm by using condenser centering screws (5)
Open Field Diaphragm for complete field (6)
THE FINAL ADJUSTMENT
The final adjustment has to be done with the aperture diaphragm (7).
Especially unstained specimen (native smears, water samples) require a stronger closure of the aperture diaphragm to achieve contrast, while stained histological sections are less demanding.
The chart (8) may help to understand the consequences of the aperture diaphragm setup.
Using the aperture diaphragm will balance the image parameters (contrast, resolution, depth of field, brightness), always depending on the sample characteristics. Please do not use the condenser diaphragm to reduce the image brightness. The light setting in most cases is too high to observe delicate structures, be careful not to outshine them.
Follow August Koehler, and you will install best preconditions for your maximal understanding of the sample.
The BA310 is designed for the rigors of daily routine work in the demanding applications of universities, clinics, laboratories, and many other life sciences or medical applications requiring quality optical performance. BA310's full Kohler configuration provides maximum illumination quality for even the most demanding samples. Additional contrast methods like Phase contrast, polarization, and darkfield and discussion/teaching devices ensure that the BA310 offers long term functionality to all user levels.
The Motic’s established BA410 flagship model displays the highest level of optical performance. A complete set of Plan Apochromatic lenses is now available for maximum demands in color reproduction and resolution. The BA410E allows a profound diagnosis in pathology, hematology, and cytology with their requirements for best color fidelity. Increased numerical apertures provide an expanded resolution power for a more detailed specimen evaluation.
Panthera C2 is a new world-class level cased in a revolutionary technical future-orientated solution, now accessible for life sciences. Stunning Ultra Contrast Optics for best insights, convincing performance of the dual-slide holder for one-hand operation, and intelligent light management with an LED “Feedback indicator”: a setup ready to smoothen your daily workflow.
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