Tutorial 2 - Lens Export

This notebook demonstrates how to create and export a lens geometry using the diffinytrace package.

The workflow includes:

• Setting up a B-spline surface for the lens geometry.

• Converting the lens to a CAD solid.

• Exporting the lens as an STL file for use in CAD software

import sys
import os
import gc
import tqdm
sys.path.insert(0, os.path.abspath(".."))
device = "cuda:0"
results_folder = "results/"
results_folder += "lens_export/"
try:
    os.mkdir(results_folder)
except:
    pass

Diffiny trace uses an older version of cadquery with which it is pretty easy to directly talk to open cascade. With this approach it is possible to export bspline lenses without fitting optical lens surfaces

the function dit.export.cad.lens_to_solid returns an object that is understood by open cascade

import diffinytrace as dit
import torch

aperture_radius_detector = 12.
bspline_surface1 = dit.Bspline(aperture_radius_detector,[3,3],[10,10])
with torch.no_grad():
    bspline_surface1.coeff.data = torch.randn_like(bspline_surface1.coeff.data)*7.
lens_transform = dit.transforms.Identity()

lens_thickness = 20.
surface1 = dit.Plane()
lens1 = dit.Lens(lens_transform,lens_thickness,surface1,bspline_surface1,dit.materials["PMMA"],aperture_radius_detector,is_square=True)
solid = dit.export.cad.lens_to_solid(lens1,20)
solid

c:\Users\marti\anaconda3\envs\working\Lib\site-packages\torch\functional.py:505: UserWarning: torch.meshgrid: in an upcoming release, it will be required to pass the indexing argument. (Triggered internally at C:\actions-runner\_work\pytorch\pytorch\pytorch\aten\src\ATen\native\TensorShape.cpp:4383.)
  return _VF.meshgrid(tensors, **kwargs)  # type: ignore[attr-defined]

Although below a resolution and tol is defined bspline surfaces are always exported exactly with no fitting of nurbs surface to geometry. However other lens surfaces will be approximated

dit.export.cad.export_lens(results_folder+"lens.stl",lens1,resolution = 200,tol=0.001)

It’s also possible to export lenses with round apertures.

aperture_radius_detector = 12.
bspline_surface1 = dit.Bspline(aperture_radius_detector,[3,3],[10,10])
with torch.no_grad():
    bspline_surface1.coeff.data = torch.randn_like(bspline_surface1.coeff.data)*7.
lens_transform = dit.transforms.Identity()

lens_thickness = 20.
surface1 = dit.Plane()
lens1 = dit.Lens(lens_transform,lens_thickness,surface1,bspline_surface1,dit.materials["PMMA"],aperture_radius_detector,is_square=False)
solid = dit.export.cad.lens_to_solid(lens1,20)
solid

dit.export.cad.export_lens(results_folder+"lens_round.stl",lens1,resolution = 200,tol=0.001)