raytracing 1.0.2

Simple optical ray tracing library to validate the design of an optical system (lenses positions and sizes, focal lengths).

RayTracing

This code aims to provide a simple ray tracing module for calculating various properties of optical paths (object, image, aperture stops, field stops). It makes use of ABCD matrices and does not consider aberrations (spherical or chromatic). It is not a package to do "Rendering in 3D with raytracing".

The code has been developed first for teaching purposes and is used in my "Optique" Study Notes (french only), but also for actual use in my research. I have made no attempts at making high performance code. Readability and simplicity of usage is the key here. It is a single module with only a few files, and only matplotlib as a dependent module.

The module defines Ray , Matrix, MatrixGroup and ImagingPath as the main elements. Matrix and MatrixGroup are either one or a sequence of many matrices into which Ray will propagate. ImagingPath is also a sequence of elements, with an object at the front edge. Specific subclasses of Matrix exists: Space, Lens, ThicklLens, and Aperture. Finally, a ray fan is a collection of rays, originating from a given point with a range of angles.

Installing

There are several ways to install the module:

1. Simplest: pip install raytracing
2. If you download the source of the module, then you can type: python setup.py install
3. From GitHub, you can get the latest version (including bugs) and then type python setup.py install
4. If you are completely lost, copying the folder raytracing (the one that includes __init__.py) from the source file into the same directory as your own script will work.

Getting started

You need matplotlib, which is a fairly standard Python module. If you do not have it, installing Anaconda is your best option. You should choose Python 3.7 or later.

The simplest way to import the package in your own scripts after installing it:

from raytracing import *

This will import Ray , and several Matrix elements such as Space, Lens, ThickLens, Aperture, DielectricInterface, but also MatrixGroup (to group elements together) and ImagingPath (to ray trace with an object at the front edge) and a few predefined other such as Objective (to create a very thick lens that mimicks an objective).

You create an ImagingPath, which you then populate with optical elements such as Space, Lens or Aperture. You can then adjust the imaging path properties (object height for instance) and display in matplotlib.

This will show you a few examples of things you can do:

python -m raytracing

In your code, (such as the test.py or demo.py files included in the source), you would do this:

from raytracing import *

path = ImagingPath()
path.append(Space(d=10))
path.append(Lens(f=5, diameter=2.5))
path.append(Space(d=12))
path.append(Lens(f=7))
path.append(Space(d=10))
path.display()

You may obtain help by typing (interactively): help(Matrix), help(Ray),help(ImagingPath)

python
>>> help(Matrix)
Help on class Matrix in module raytracing.abcd:

class Matrix(builtins.object)
 |  Matrix(A, B, C, D, physicalLength=0, apertureDiameter=inf, label='')
 |  
 |  A matrix and an optical element that can transform a ray or another
 |  matrix.
 |  
 |  The general properties (A,B,C,D) are defined here. The operator "*" is
 |  overloaded to allow simple statements such as:
 |  
 |  ray2 = M1 * ray
 |  or
 |  M3 = M2 * M1
 |  
 |  The physical length is included in the matrix to allow simple management of
 |  the ray tracing. IF two matrices are multiplied, the resulting matrice
 |  will have a physical length that is the sum of both matrices.
 |  
 |  In addition finite apertures are considered: if the apertureDiameter
 |  is not infinite (default), then the object is assumed to limit the
 |  ray height to plus or minus apertureDiameter/2 from the front edge to the back
 |  edge of the element.
 |  
 |  Methods defined here:
 |  
 |  __init__(self, A, B, C, D, physicalLength=0, apertureDiameter=inf, label='')
 |      Initialize self.  See help(type(self)) for accurate signature.
 |  
 |  __mul__(self, rightSide)
 |      Operator overloading allowing easy to read matrix multiplication
 |      
 |      For instance, with M1 = Matrix() and M2 = Matrix(), one can write
 |      M3 = M1*M2. With r = Ray(), one can apply the M1 transform to a ray
 |      with r = M1*r
 |  
 |  __str__(self)
 |      String description that allows the use of print(Matrix())
 |  
 |  backwardConjugate(self)
 |      With an image at the back edge of the element,
 |      where is the object ? Distance before the element by
 |      which a ray must travel to reach the conjugate plane at
 |      the back of the element. A positive distance means the
 |      object is "distance" in front of the element (or to the
 |      left, or before).
 |      
 |      M2 = M1*Space(distance)
 |      # M2.isImaging == True

Examples

You can run the module directly with python -m raytracing or look at the examples directory.

You can run demo.py to see a variety of systems, illuminator.py to see a Kohler illuminator, and invariant.py to see an example of the role of lens diameters to determine the field of view.

Licence

This code is provided under the MIT License.