This calculator will help you to compute the thermal lens focal length

www.simtrum.com

$f=\frac{2kAP}{dn/dT}$

$A=\pi r^2 $

Thermo-optical coefficient $dn/dT$ ,heat conductivity $k$ ,Pump light radius $r$ ,Thermal power $P$


Input
Thermo-optical coefficient,dn/dT:
-/mk

heat conductivity, $k$:
W/mK
Pump light radius, $r$
$\mu m$
Thermal power, P
W



Output
focal length , f:
mm