Re: [Goptical] focal spot size

[Richard Graham]

Hi,

I see no one has replied to this for some time.

Goptical just does ray tracing and what you are seeing seems to be the
expected result to me. If your source is a point source that is what
will be modelled, there is no reason to expect a gaussian beam. I don't
believe there is a way to define a gaussian beam in goptical. What is
the physical system you are trying to model?

If what you want to get is the 1/e radius of your spot then you should
be able to just calculate this from the encircled intensity plot.

--
 Richard

On 04/03/2013 05:02 AM, Gregory Vieux wrote:
> Hi,
> 
> I am wondering if there is a way, using spot analysis, to get the focal
> spot size as defined for a Gaussian beam.
> My system is defined by a point source at infinity, a 3 mm radius
> aperture and a f=250 mm plano-convex lens. When using get_max_radius()
> or get_rms_radius() I obtain results of the order of 3 um, which is not
> possible considering Gaussian optics.
> Moreover, when reducing the aperture size, the focal spot size is
> decreasing when it should be increasing.
> I am wondering if the problem is coming from defining the source as a
> point source.
> 
> Any advice is welcome.
> 
> Thanks,
> 
> Gregory Vieux
>