How to access model variables ?

[lzago01]

First, a lot of congratulations for ray-optics, which I just discovered.
It is really huge.
A basic question, noting that I am yet not familiar with the json coding used here.
How does one access low-level model variables ?

For instance, take the triplet example from the doc.
pm.first_order_data() prints all first order data.
But how to I access and use a single variable, like efl, or bfl ?

[mjhoptics]

Hello @lzago01,
The first order data is maintained in the analysis results model. This is available via the optical model (usually assigned to a variable opm). Here is some sample code:

ar = opm['analysis_results']
ax_ray, pr_ray, fod = ar['parax_data']
fod.efl

The fod variable is the FirstOrderData object. The different items are defined in the documentation. The other items, ax_ray and pr_ray, are the paraxial axial marginal ray and paraxial principle ray.

When you make changes to an optical model, always call
opm.update_model()
before looking at any analysis results; they will be recalculated by update_model().

Thanks for your kind comments, feel free to ask further questions.
Regards
Mike Hayford