Laser Focal Spot Size Calculator

Use this calculator to get the size and location of your Gaussian laser beam waist at focus, as well as the Rayleigh range. Also try our Laser Focusability Calculator for a simpler calculator version.

Laser Parameters

Wavelength (nm): Required

Lens Focal Length (mm): Required

Gaussian Beam Propagation Factor:

Beam Divergence (Half angle) (mRed): Required

Beam Diameter at Aperture (d=2ω) (mm):

Beam Waist Diameter (d₀=2ω₀) (mm):

Distance from d₀ to Lens (mm): Required

Distance from d₀ and Exit Aperture (mm):

Distance from Exit Aperture to Lens (mm):

Adjust your parameters above and select 'Calculate' again to refine the values.

Calculation Results

zᵣRayleigh Length

s"Distance from lens to "new" Waist

d₀"New Beam Waist Diameter (After lens)

zᵣ"New Rayleigh Length

Notes:

Some of the input parameters are mutually dependent and the software will calculate them automatically when possible. A calculated parameter will be locked for editing. If you wish to unlock it, you must erase the value entered which caused it to be locked. Example: Fields A and B are mutually dependent. You enter a value in A and B is calculated and locked. You wish now to edit B. You must first delete A, upon which B will be erased an unlocked.
This calculator uses Sidney Self's equations for focusing spherical Gaussian beams.
Want to measure the actual beam size? Try a BeamTrack Power/Position/Size sensor, or a full-fledged beam profiler for a complete picture of your laser beam.