these days, I always study the zemax for laser's gaussual beam analysis.

 

now, I have know how to do this:

(1). set wavelength. for our laser, the wavelength is 1064nm.

(2). set LED. for the example.

(3). set 'general'.'aperture type' is 'entrance pupil diameter'; 'aperture value' is ...;'apodization type' is 'Gaussian'; 'apodization factor' is ...

(4) from the '2D layout', we can see the light road system.

(5) 'analysis'-'physics optics'-'paraxial gaussual beam': in the 'settings', set the parameters,then you can find the results as follows.