Torch Lens Maker

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Hello! I'm Victor, the author of this project.
I'm looking for funding to be able to keep working on it. If you can, please consider donating or sponsoring.
Thank you! ❤️

Roadmap ​

This is a big list of things I'd like to do with Torch Lens Maker. Feel free to come discuss it on GitHub.

Documentation ​

  • Write a lot more documentation!
  • Integrate pdoc to generate reference documentation
  • Add "download this notebook" button
  • Document sign and axis convention
  • Fix rendering of build123 models
  • Add page discussing total internal reflection, blocked rays and sequential mode
  • Add "try it live" functionality with pyodide / jupyterlite / etc.
  • Document lens inner vs outer thickness
  • Custom nbconvert markdown template for clearer text output cells: https://stackoverflow.com/questions/56229030

Examples ​

  • Non rotationally symmetric example
  • Petzval lens
  • https://en.wikipedia.org/wiki/Rapid_Rectilinear
  • Optimizing surface and position jointly
  • Astigmatism example
  • Regularization example
  • tlm.parameter() on inner / outer thickness
  • https://pbr-book.org/3ed-2018/Camera_Models/Realistic_Cameras
  • Hubble space telescope repair mission
  • Grazing-incidence reflection X-ray telescope
  • Microscope
  • Binoculars
  • Periscope
  • Explanation of depth of field in photography
  • Custom nn.Module to group a subsequence / parameters
  • Anchors demo / kinematic chain demo
  • Avoiding "negative collisions" during optimization with regularization
  • Thin lens equation

Surfaces ​

  • Cubic Bezier Spline
  • Linear Spline
  • Implicit version of SphereR
  • Convert between surface types by fitting samples
  • Improve Outline support
  • use rtol / atol in contains() instead of bare tol
  • rename samples() epsilon argument to clarify what it does
  • implementation of parabola without Sag but direct solve of the quadratic collision equation
  • Non axially symmetric surfaces
  • Replace Surface.testname() by __str__()
  • In sag surface make sure there is an inner where() for safe backwards when masking

Materials ​

  • Load data from material database

Lenses ​

  • Cemented lenses class
  • Anchors for lenses

Optical modeling ​

  • make focal elements "collide" rays and update them, so that end= works as with other elements
  • research composing distance functions https://iquilezles.org/articles/distfunctions/, could be useful to model astigmatism and viewing glasses for example
  • different ray category for non colliding with surface and total internal -> better blocked visualization
  • tlm.parameter() on surface diameter
  • tlm.parameter() on index of refraction
  • F-number calculation
  • Aperture detection and sampling marginal rays
  • AbsolutePosition: Fixed absolute positioning
  • ChromaticFilter: Filter rays based on wavelength
  • OpticalSurface
    • add error_on_no_collision option, by default drop
    • add error_on_negative_collision, by default allow
  • Collision detection: detect convergence before max iter with tolerance parameter
  • Zoom lenses: sampling dimension for mechanical configuration
  • Diffuse reflection / partial reflection (analogy to NN dropout)
  • Utility function to get available dimensions of a model

Optimization ​

  • More tweaking options for loss function: radial weighting, wavelength weighting, etc.
  • LR scheduler
  • Caching of best minimum
  • Optimization with 3D rays (image loss math)
  • Per parameter learning rate adapted to parameter scale. Example: one parabola coefficient, one distance
  • detect when optimization leads to parameter out of domain with nice error message for example, setup an impossibly short focal length with a spherical lens
  • detect when optimization reaches a point where there are no rays exiting the system, make a nice error message
  • better plotting of parameters during optimization (vector shaped parameters, eg piecewiseline)
  • Plot of surface shape evolution during optimization
  • Regularization and loss functions: Negative collision regularization (regularization on t value of collision)
  • Constraints on parameters:
    • Min / Max constraint on coordinate
    • Min / Max constraint on derived coordinate: distance from principal axis (radial)
    • Combine absolute positioning and relative positioning with constraints to make absolute with constraints
    • Implement constraints with reparameterizaion or gradient projection

Analysis ​

  • Virtual optical element to visualize ray distribution
  • Debug optical element
  • Show airy disk in spot diagram
  • Ray error plot: Loss as a function of 1 or 2 variables, histograming on a variable / show ray distribution over some variables
  • Loss plot, plot loss function of 1 or 2 variables
  • Sequence analysis:
    • Number of valid rays at each stage
    • Angular aperture/spread of beam at each stage
  • Focal length measurement
    • principal points, optical center, etc.
    • be able to measure focal lengths in different ways that make sense for optics (front, back, etc: choose a reference point on the lens
    • position a lens relative to its center, or other points on the lens: front, back, center, nodes, etc.
  • Find intermediate/virtual images
  • Measure optical aberations and concepts: coma, astigmatism, petzval field curvature, etc...

Manufacturing ​

  • Implement 3D export for SphereR
  • Export full stack

TLMVIEWER ​

  • Better rendering of Aperture
  • Better rendering of ImagePlane
  • Better rendering of surfaces in 3D
  • Rename end= argument
  • Smart non-zero default for end= argument if no focal element
  • improve default sampling dict for show() function
  • lens cosmetic edge
  • Show/Hide cosmetic edges
  • dont show legend div if title is empty
  • default bbox zoom for 3D view
  • Support multiple scenes (2D / 3D / more)
  • add option for light sources: draw rays a bit before their origins to see them better
  • Group elements:
    • Support arbitrary grouping of elements
    • Support tags in elements
    • Side bar with tree view of model
    • Toggle buttons in tree view of model
    • Toggle buttons for tags
  • Animate rays
  • Animate camera
  • Slider to display a % of total number of rays
  • Display stack info per layer (number of rays, aperture diameter, etc.)
  • Camera selection button
  • Set camera view button (XY / XY / XZ)
  • Display scale bar
  • Surface tooltip (material / type / parameters)
  • Fullscreen button
  • Support object and base coordinate color rendering for rays in 3D (use 2D colormaps?)
  • Better handle of window resize with threejs onWindowResize()
  • "tlmviewer loaded" should show version
  • clean up code layout in tlmviewer.py / render_sequence
  • clean up code in scene.ts
  • fix visible inner disk when rendering two half spheres

Testing ​

  • optical elements unit tests: lens maker equation setup a stack, call forward, check loss value aginst expected check loss is differentiable, and gradient is finite
  • test_local_collide: add tangent test cases specific to surfaces*
  • Fix collision tests with rays that have V_X == 0
  • same sign for offset in generators for sphere and sphereR

Advanced topics ​

  • Enforce mypy --strict and ruff
  • Think about float128 support
  • GPU performance benchmark
  • Reduce number of project dependencies (scipy, colorcet at least)