Question

On a given microscope, the numerical apertures of the condenser and low power objective lenses are 1.25 and 0.25 respectively. You are supplied with a filter that selects a wavelength of 520 nm.

a. What is the limit of resolution of this microscope?
b. Will you be able to distinguish 2 points that are 300nm apart as being separate, or will they blur into one?

Answer 1

Answer:

a. Resolving power (R) = 346.7 nanometers (nm)

b. No, because the resolving power is 346.7 nm

Explanation:

In microscopy, resolution or resolving power (R) refers to the minimum distance at which two distinct points can still be distinguished as separate entities. R can be calculated by the following equation:

Resolving power (R) = wavelength /(NAo + NAc), where NAo is the numerical aperture of the objective and NAc is the numerical aperture of the condenser. In the case above described:

R = 520 nanometers / (1.25 + 0.25) = 346.7 nanometers (nm)

In consequence, the resolving power of this microscope at 520 nanometers of wavelength is 346.7 nm, thereby two points separated by 300 nm will be too close to be distinguished as separated objects.