Building and interacting with models

Before you can perform simulations of your optical system you must first build a model of it. Finesse includes a variety of tools and features to make it straight forward to build models ranging from simple single Fabry-Perot cavities to full gravitational wave interferometers.

We offer two ways in which you can build a model. Firstly using KatScript, which is a declarative domain specific language we have developed for building models of interferometers. This removes the complexity of dealing with Python and keeps you focused on the physics of your model. Secondly, we offer a full Python application programming interface (API) that can also be used for building a model for those wishing to use a more programmatic object-orientated interface.

Neither is better or worse, however most of the examples in the documentation will be shown using KatScript. Any feature in KatScript has an equivalent in the Python API, however not all features in Finesse are guaranteed to have an equivalent KatScript option. This will likely be true for newer or more complex features that users would only really use from a Python interface.

The Python API section also details how you can interact with your model once it has been built. It allows you to easily amend and update the model and parameters.

• KatScript
  • Quick reference
  • A quick example
  • Language fundamentals
    • Whitespace and comments
    • Types, names, and keywords
    • Numbers
  • Components and detectors
  • Commands and analyses
  • Ports and nodes
  • Paths
  • Expressions and references
    • Supported operators
    • Supported expression functions
    • References
    • Keywords
  • Arrays
  • Generating KatScript from a model
  • Registering custom KatScript directives
• Python API
• Symbolics
  • Referencing parameters
  • Preserving intent
  • two-arg vs N-arg operators
  • Basic simplification