Enter the wavelength (um) and the numerical aperture into the Calculator. The calculator will evaluate the Resolving Power. 

Resolving Power Formula

e = .61 * L/NA


  • e is the Resolving Power (um)
  • L is the wavelength (um)
  • NA is the numerical aperture

To calculate Resolving Power, divide the wavelength by the numerical aperture, then multiply by .61.

How to Calculate Resolving Power?

The following steps outline how to calculate the Resolving Power.

  1. First, determine the wavelength (um). 
  2. Next, determine the numerical aperture. 
  3. Next, gather the formula from above = e = .61 * L/NA.
  4. Finally, calculate the Resolving Power.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

wavelength (um) = 0.55

numerical aperture = 0.9

FAQ – Resolving Power Calculation

What is Resolving Power?

Resolving Power is a measure of the ability of an optical system to distinguish between closely spaced object points. It is often used in microscopy, photography, and astronomy to describe the clarity of an image.

Why is the numerical aperture important in calculating Resolving Power?

The numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. A higher NA allows for a higher resolving power, meaning the system can distinguish finer details.

How does wavelength affect Resolving Power?

The wavelength of light used in an optical system affects its resolving power. Shorter wavelengths can resolve finer details than longer wavelengths. This is why ultraviolet light, with its shorter wavelength, is used in some microscopy techniques to achieve higher resolution.

Can Resolving Power be improved by changing the numerical aperture?

Yes, increasing the numerical aperture (NA) of an optical system can improve its resolving power. This is because a higher NA allows the system to collect light from a wider range of angles, which contributes to a finer resolution. However, there are practical limits to increasing NA, such as lens design and light diffraction.