Evaluation: Difference between revisions
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==Counts per mm<sup>2</sup>== | ==Counts per mm<sup>2</sup>== | ||
There are multiple situations where a finding will be quantified in terms of amount per mm<sup>2</sup>. To make such calculations, you need to know the size of the area you see in the microscope. It is usually possible to look up what theoretically would be the area, but the most reliable way of knowing is to use a calibration slide (basically a translucent ruler with 0.1 mm line resolution or smaller, which may cost about $15) to measure the diameter of your view. The area is then calculated as: | |||
There are multiple situations where a finding will be quantified in terms of amount per mm<sup>2</sup>. To make such calculations, you need to know the size of the area you see in the microscope. It is usually possible to look up what theoretically would be the area, but the most reliable way of knowing is to use a calibration slide (basically a translucent ruler with 0.1 mm line resolution or smaller) to measure the diameter of your view. The area is then calculated as: | |||
*Area in mm<sup>2</sup> ≈ (diameter in mm)<sup>2</sup> x 0.79 | *Area in mm<sup>2</sup> ≈ (diameter in mm)<sup>2</sup> x 0.79 | ||
<gallery mode=packed heights=220> | |||
File:Calibration slide.jpg|A calibration slide. | |||
File:Micrograph of a calibration slide, showing the diameter of the field of view.jpg|Micrograph of a calibration slide, showing the diameter of the field of view. Each square is 0.05 mm wide, and each line represents 0.01 mm, making the diameter of the field of view 0.55 mm in this case. | |||
</gallery> | |||
Sometimes "high power field" (HPF) is used for area, but it has a substantially different area for different microscopes, for example: | Sometimes "high power field" (HPF) is used for area, but it has a substantially different area for different microscopes, for example: | ||