Enter the center of the range of wavelengths and the total range of the wavelengths into the Coherence Length Calculator. The calculator will evaluate the Coherence Length. 

Coherence Length Formula

The following two example problems outline the steps and information needed to calculate the Coherence Length.

COL = λ^2 / (2*dλ)
  • Where COL is the Coherence Length ( )
  • λ is the center of the range of wavelengths 
  • dλ is the total range of the wavelengths 

To calculate the coherence length, square the center of the range, then divide by 2 times the total range.

How to Calculate Coherence Length?

The following example problems outline how to calculate Coherence Length.

Example Problem #1:

  1. First, determine the center of the range of wavelengths.
    • The center of the range of wavelengths is given as: 3.
  2. Next, determine the total range of the wavelengths.
    • The total range of the wavelengths is provided as: 4.
  3. Finally, calculate the Coherence Length using the equation above: 

COL = λ^2 / 2*dλ

The values provided above are inserted into the equation below and computed.

COL = 3^2 / (2*4) = 1.125

Example Problem #2: 

For this problem, the variables required are provided below:

center of the range of wavelengths = 10

total range of the wavelengths = 20

Test your knowledge using the equation and check your answer with the calculator..

COL = λ^2 / 2*dλ = ?