How to Choose the Best Microscope for Your Needs
A microscope is a device that magnifies small objects and reveals details that are invisible to the naked eye. Microscopes are used for various purposes, such as scientific research, education, hobby, and industry. But how do you choose the best microscope for your needs?
There are many factors to consider when buying a microscope, such as the type, the magnification, the resolution, the illumination, the features, and the budget. In this article, we will explain each of these factors and give you some tips on how to find the perfect microscope for you.
Type of Microscope
The first thing to decide is what type of microscope you need. There are two main types of microscopes: optical and electron. Optical microscopes use light to form an image of the object, while electron microscopes use a beam of electrons to do so.
Optical microscopes are more common and affordable than electron microscopes. They are suitable for observing living or non-living specimens that are transparent or opaque. Optical microscopes can be further divided into compound and stereo microscopes. Compound microscopes have one or more objective lenses that provide high magnification and resolution, but have a narrow field of view and depth of field. Stereo microscopes have two objective lenses that provide lower magnification and resolution, but have a wider field of view and depth of field. Compound microscopes are ideal for viewing thin sections of cells and tissues, while stereo microscopes are ideal for viewing three-dimensional objects such as insects and minerals.
Electron microscopes are more expensive and complex than optical microscopes. They are suitable for observing very small or detailed structures that are beyond the limit of optical microscopes. Electron microscopes can be further divided into scanning and transmission electron microscopes. Scanning electron microscopes (SEM) scan the surface of the specimen with a focused electron beam and produce a three-dimensional image of its topography. Transmission electron microscopes (TEM) pass a beam of electrons through a thin section of the specimen and produce a two-dimensional image of its internal structure. SEMs are ideal for viewing surface features such as pores and cracks, while TEMs are ideal for viewing ultrastructure such as organelles and molecules.
Magnification and Resolution
The next thing to consider is how much you want to enlarge the object and how clear you want to see it. These two aspects are related to the magnification and resolution of the microscope.
Magnification is the ratio between the size of the image and the size of the object. For example, if a microscope has a magnification of 100x, it means that the image is 100 times larger than the object. Magnification depends on both the objective lens and the eyepiece lens of the microscope. To calculate the total magnification, you need to multiply the magnification of the objective lens by the magnification of the eyepiece lens.
Resolution is the ability of the microscope to distinguish two points that are close together as separate points. For example, if a microscope has a resolution of 0.2 micrometers (Âµm), it means that it can separate two points that are 0.2 Âµm apart. Resolution depends on both the wavelength of the illumination source and the numerical aperture (NA) of the objective lens. To calculate the theoretical resolution, you need to divide the wavelength by twice the NA.
The higher the magnification, the larger the image; but it does not necessarily mean that it is clearer or more detailed. The higher the resolution, the clearer and more detailed the image; but it does not necessarily mean that it is larger or more visible. Therefore, you need to balance both magnification and resolution when choosing a microscope.
The third thing to consider is how you want to light up your object. Illumination is essential for microscopy because it determines how well you can see your object.
There are two main types of illumination: transmitted and reflected. Transmitted illumination means that light passes through