Numerical Aperture (N.A.)
The numerical aperture is a key factor to the performance of objective lens (resolving power, focal depth and brightness). The N.A. is determined by the following formula:
The visual field brightness (B) of the microscope is determined by the following formula in relation to the objective lens magnification (M). The larger the N.A. and the lower the objective magnification, brightness will increase in the factor of the second power.
Numerical Aperture (N.A.)
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