Enter the beam diameter at two separate points and the distance between those two points into the calculator to determine the laser divergence.

## Laser Divergence Formula

The following equation is used to calculate the beam divergence.

  ϴ = 2*arctan (( Df - Di )/ 2L)
• Where  ϴ is the angle of divergence
• Df is the beam diameter at point f
• Di is the beam diameter at point i
• L is the distance between point f and point i

To calculate the laser divergence, take the arc tangent of the difference between the beam diameters at each point over 2 times the distance between point, then multiply by 2.

## What is a Laser Divergence?

Definition:

Laser divergence is the measure of the angle of a laser beam’s spread. A laser beam that has low divergence could be said to be “collimated”, which means it will maintain a narrow beam as opposed to spreading out.

If you’re using an optical instrument, such as an optical collimator, that requires a collimated beam of light, you have to make sure that the laser beam has low divergence.

## How to Calculate Laser Divergence?

To calculate the divergence of a laser, subtract the diameter at point f from the diameter of the beam at point i, then, divide by 2 times the distance between the 2 points.

Next, take the arc tangent of that value and then multiply by 2 to get the laser divergence.