Update docs/source/models/lasers.rst

Co-authored-by: chillenzer <[email protected]>

Author: steindev

docs/source/models/lasers.rst

@@ -95,7 +95,7 @@ The result of this last integral can be read off from the known solution for the
 .. math::
   \hat E_x(x, z, \Omega) = &\
     \epsilon_\Omega
-    \left[ 1 + \frac{z^2}{z_\mathrm{R,x}^2} \right]^{-1/4}
+    \left[ 1 + \frac{z^2}{z_{\mathrm{R},x}^2} \right]^{-1/4}
     e^{-\left[
         x - \left( x_0 - \frac{c}{\Omega_0 w_{0,x}}\alpha z \right)
       \right]^2