Creating a Geometry
The Geometrical Optics interface supports interaction with any geometric entity. The geometry can be constructed from built-in primitives like circles and line segments, loaded from various CAD formats, or constructed with parts from the Ray Optics Part Library. Rays can interact with both deformed and undeformed geometries, for example, when an object undergoes thermal expansion.
Part Libraries
In ray optics models, it is often necessary to set up geometry sequences consisting of entities that are more complex than simple geometry primitives such as spheres, cones, blocks, etc. Instead it might be necessary to insert lenses with different thicknesses and radii of curvature, off-axis conic mirrors, and parabolic concentrators. The entity shapes might need to be resolved to extremely high precision. This can be conveniently accomplished using the Part Libraries for the Ray Optics Module.
The Ray Optics Module Part Libraries contain fully parameterized sequences of geometry instructions that produce more complex shapes frequently required for geometrical optics simulation, including the following:
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Spherical lenses and mirrors,
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Conic lenses and mirrors,
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Aspheric lenses and mirrors (even, odd, and Q-type),
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Doublet and triplet lenses,
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Cylindrical lenses,
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Beam splitters,
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Polygonal mirrors,
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Prisms,
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Circular and rectangular annuli, and
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Retroreflectors.
For example, you can load the Spherical Lens 3D part into a model and then specify the radii of curvature of each lens surface, along with the lens thickness and diameter.
Parts can include predefined selections that make it easy to apply boundary conditions or material properties to multiple entities at the same time. Some parts also include multiple variants, or different sets of inputs that you can choose between. For example, you could either specify the off axis distance or off axis angle for a conic mirror.
In addition, many parts automatically define work planes so that the parts and other features can more easily be positioned and oriented with respect to each other.
Many Ray Optics tutorials use the Part Library to create their geometry sequences. To learn more, see the following models:
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Newtonian Telescope: Application Library path Ray_Optics_Module/Lenses_Cameras_and_Telescopes/newtonian_telescope
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Petzval Lens: Application Library path Ray_Optics_Module/Lenses_Cameras_and_Telescopes/petzval_lens
Part Libraries in the COMSOL Multiphysics Reference Manual.
Ray Tracing in an Imported Mesh
It is possible to compute ray trajectories in an imported mesh. The mesh can be imported from a COMSOL Multiphysics file (.mphbin for a binary file format or .mphtxt for a text file format) or from a NASTRAN file (.nas, .bdf, .nastran, or .dat).
If the mesh is imported from a COMSOL Multiphysics file, the imported mesh always uses a linear geometry shape order for the purpose of modeling ray-boundary interactions, even if the model used to generate the mesh had a higher geometry shape order.
If the mesh is imported from a NASTRAN file, the ray-boundary interactions may be modeled using either a linear or higher geometry shape order. If Export as linear elements is selected when generating the NASTRAN file, or if Import as linear elements is selected when importing the file, then linear geometry shape order will be used.