Calculate focused spot size - Gaussian FWHM

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SUMMARY

The calculation of the focused spot size, specifically the Gaussian Full Width at Half Maximum (FWHM), is approximated using the formula 2*wavelength*f/(pi*d0), where 'f' represents the focal length of the lens and 'd0' is the diameter of the collimated beam before the lens. For precise derivation, consulting laser optics textbooks, particularly "Principles of Optics" by Born and Wolfe, is recommended. The discussion emphasizes that while the formula is straightforward, understanding the underlying principles may require deeper exploration of optical theory.

PREREQUISITES
  • Understanding of Gaussian beam propagation
  • Familiarity with focal lengths in lens systems
  • Knowledge of basic optics terminology
  • Access to laser optics textbooks, specifically "Principles of Optics" by Born and Wolfe
NEXT STEPS
  • Research Gaussian beam propagation and its mathematical representation
  • Study the derivation of the Gaussian FWHM formula in laser optics
  • Explore the impact of lens focal length on spot size
  • Examine practical applications of Gaussian beam calculations in optical systems
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Optical engineers, physicists, and anyone involved in laser technology or optical system design will benefit from this discussion.

eliasds
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http://www.calctool.org/CALC/phys/optics/f_NA

Does anyone know how they calculate the spot size (Gaussian FWHM) at this website?

For a plane wave, the focused spot size it approx=2*wavelength*f/(pi*d0)
f=focal length of lens
d0=collimated beam diameter before lens

but how do you calculate the spot size of a gaussian?
 
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If you're asking how to derive the formulas used on the website, you'll have to look it up and wade through the details on your own - laser optics textbooks often go through it, and I bet it's in Born and Wolfe in one form or another, but generally it's a relatively simple and approximate formula that you just use.
 
Anyone else have a more detailed answer?
 

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