Biomedical Engineering Reference
In-Depth Information
Figure. 8.2 shows a simple microscope setup with a coupled charge device (CCD) as the image sensor.
Lens 1 is focused on the sample. This lens is also called the objective lens. The magnified image is
projected on the CCD sensor, which is then transferred digitally to a computer for further processing.
The amount of light collected by the objective lens determines the brightness of the image. The
brightness of the recorded image is proportional to the square of the numerical aperture:
NA 2 (8.6)
where NA is the numerical aperture of the objective lens. The numerical aperture is determined as
I
N
NA
ΒΌ
n sin
a
(8.7)
FIGURE 8.2
Schematic concept of a simple microscope with a CCD sensor.
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