finesse.utilities.misc.changed_params¶

finesse.utilities.misc.changed_params(subs: dict)[source]¶

Temporarily change model parameters within a context.

This is a convenience function for providing a pattern of changing parameters temporarily, inside a context, without needing to make deep-copies of a Model. Usage of this function should be confined to with contexts.

Parameters: subs : dict

Dictionary of temporary parameter subsitutions. Expects a dict of Parameter to float value mappings.

Examples

In this example a simple Fabry-Perot cavity is created and this function is used to inspect how some cavity properties vary when temporarily changing parameters.

import finesse
import finesse.components as components

from finesse.utilities import changed_params

IFO = finesse.Model()
IFO.chain(
    components.Laser("L0"),
    components.Mirror("ITM", Rc=-10),
    components.Space("CAV", L=1),
    components.Mirror("ETM", Rc=10),
)
IFO.add(components.Cavity("FP", IFO.ITM.p2))

print(f"Initial FP.g = {IFO.FP.g}")
print(f"Initial FP.gouy = {IFO.FP.gouy}\n")

# Temporarily change ITM.Rcx to -15 m and ETM.Rcy to 9 m
with changed_params({IFO.ITM.Rcx: -15, IFO.ETM.Rcy: 9}):
    print(f"Temporary FP.g = {IFO.FP.g}")
    print(f"Temporary FP.gouy = {IFO.FP.gouy}\n")

# Check that params have been reset by looking at cavity again
print(f"Final FP.g = {IFO.FP.g}")
print(f"Final FP.gouy = {IFO.FP.gouy}")

Initial FP.g = [0.81 0.81]
Initial FP.gouy = [51.68386553 51.68386553]

Temporary FP.g = [0.84 0.8 ]
Temporary FP.gouy = [47.15635696 53.13010235]

Final FP.g = [0.81 0.81]
Final FP.gouy = [51.68386553 51.68386553]