Rayleigh length calculator

What is the Rayleigh length?

The Rayleigh length (z_R) is the distance along the beam axis from the beam waist where the cross-sectional area of the beam increases by a factor of e². It represents the distance over which a laser beam remains approximately focused.

How to use the calculator

1. Enter the wavelength (λ) of your laser beam in micrometers (µm). This is typically provided in the laser specifications.
2. Enter the beam diameter (d) at a specific cross-section in millimeters (mm). This is usually measured as the diameter at 1/e² intensity level.
3. Click the "Calculate" button to compute the Rayleigh length.
4. The result will be displayed in millimeters (mm).

Practical Applications

The Rayleigh length is important in various applications including laser cutting, drilling, and optical communications where beam quality and focus need to be controlled.

Example

If you have a laser with a wavelength of 0.5 µm and a beam diameter of 2 mm at the 1/e² intensity level, the Rayleigh length would be calculated as follows:

z_R = π(2 mm)² / (0.5 µm) = π(4 mm²) / (0.0005 mm) ≈ 25.13 mm