Posts of the Category: Techniques
Here I explain the handling of the microscope and different methods to enhance contrast.
Determining Size in Microscopic Images
Our Biology curriculum in school requires students to be able to calculate the size of cells and other structures from light micrographs, which have a scale bar. It’s probably more interesting for students to actually take the light micrographs themselves. It is not difficult to determine the size of cells and other structures in light [...]
How to prevent Air Bubbles in Wet Mounts
The statistics feature of my blogging software allows me to see what readers are searching for, and one of the questions that keeps reappearing over and over again is the question on how to prevent air bubbles in wet mounts. I have already published a video on how to correctly make a wet mount (temporary [...]
Testing the Hand Microtome
A few days ago I ordered a microtome. Here is a video showing you the different parts: Now it’s time to test the device. The first sample is a carrot. It can be cut into the right shape to fit into the specimen holder of the microtome and it is sufficiently solid to allow for [...]
Making a wet mount microscope slide
This post explains how to make a wet mount. Video included!
Fixing specimens for making permanent slides
Before specimens can be processed for making permanent slides, they may need to be fixed. This step kills the specimen and preserves the structures. It also prepares the specimen for staining. There is no one single method to fix a specimen, too much depends on the nature of the specimen itself and on the subsequent [...]
The hemocytometer (counting chamber)
The hemocytometer (or haemocytometer or counting chamber) is a specimen slide which is used to determine the concentration of cells in a liquid sample. It is frequently used to determine the concentration of blood cells (hence the name “hemo-”) but also the concentration of sperm cells in a sample.
How to obtain the best resolution with your microscope
The resolution that a microscope is capable of achieving is probably the single most important factor that determines the quality of a microscopic image. Without a sufficiently high resolution, magnification is not possible without loss of quality. Read the following introductory post: . There are a variety of different factors that determine the achievable resolution. [...]
Cover glass thickness and resolution
The thickness of the cover glass can have a significant impact on the resolution. The effect is highest with high-numeric aperture aperture (high magnification) objectives, and barely noticeable when using objectives of a low numeric aperture. Types of cover glasses Cover glasses come in all sorts of different sizes. I already wrote a post about [...]
The effect of the mounting medium on specimen and image quality
The mounting medium can have a significant effect both on the image quality and on the specimen itself. I tried a little experiment by observing pollen from a plant (in this case the buttercup, Ranunculus), mounted in five different ways: Air-mounted, with no cover glass Air-mounted, with a cover glass Mounted in water (temporary mount) [...]
Köhler illumination to reduce reflections
The Köhler (or Koehler or Kohler) field diaphragm is located above the light source. It is responsible for controlling the width of the light beam (but not its intensity). The light source of a microscope without Köhler illumination will illuminate the whole specimen, which may be the source of stray light and excessive heating of [...]