On the other hand, if your interest lies in the structure of a particle, a close up is needed and the observed area must be closer to 2-3 microns, if not smaller.ĭesktop scanning electron microscopes are becoming more and more popular due to the potential that they offer for a price that is now comparable to that of a high-end light microscope. Also taking into account empty space between particles, a field of view of 25-30 microns is enough for such sample. This means that if you, for example, have particles with an average size of 1 micron and you want to count them, it is ok to have 20 particles per image, rather than wasting time by imaging one particle at a time. But if you have a close up of a face, small details such as hairs, spots on the skin and the color of the eyes can be observed. This is already enough for you to recognize the persons in the image. In a picture with your best friends, normally a face covers 5-10% of the surface of the space. Once again, this is quite a tricky question, but it can easily be answered with an example. What is the required field of view to image your samples? With modern instruments, objects in the range of few hundred picometers can be imaged – and that is the average size of an atom. This value typically ranges between some millimeters (a bug) to few microns (the hair of a bug) and a couple of nanometers (the molecular macrostructure of the exoskeleton). The field of view defines the size of the feature to be imaged. What is the field of view of a microscope? The formula of magnification also changes accordingly: What scientists use is a couple of parameters that describe the actual imaged area (field of view – the area that the microscope points at) and how sharp this image is (resolution). Magnification is thus a relative number and it is of no practical use in the scientific field. This means that if I print a picture of an apple that fits on a standard printer sheet and I print it again to fit on a poster that will be used to cover a building, the magnification value will change dramatically.Ī more scientific example can be applied to microscopy: when storing a digital image of the sample, resizing the image causes the magnification number to become ostensibly wrong. But the thing is, although the sample will not change its size, the picture can be printed in an infinite number of different sizes. The first object is obviously the sample. The modern definition of magnification is the ratio between two measurements, which implies that two objects are needed for a correct evaluation of the value. How to calculate microscope magnification
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