Treffer: The DeepFMKit python package: A toolbox for simulating and analyzing deep frequency modulation interferometers.

Deep Frequency Modulation Interferometry (DFMI) is an emerging laser interferometry technique for high-precision metrology, offering picometer-level displacement measurements and the potential for absolute length determination with sub-wavelength accuracy. However, the design and optimization of DFMI systems involve a complex interplay between interferometer physics, laser technology, multiple noise sources, and the choice of data processing algorithm. To address this, we present DeepFMKit, a new open-source Python library for the end-to-end simulation and analysis of DFMI systems. The framework features a high-fidelity physics engine that rigorously models key physical effects such as time-of-flight delays in dynamic interferometers, arbitrary laser modulation waveforms, and colored noise from user-defined 1/ fα spectral densities. This engine is coupled with a suite of interchangeable parameter estimation algorithms, including a highly-optimized, frequency-domain Non-linear Least Squares (NLS) for high-throughput batch processing of experimental data, and multiple time-domain Extended Kalman Filter (EKF) implementations for sample-by-sample state tracking, featuring both random walk and integrated random walk (constant velocity) process models. Furthermore, DeepFMKit includes a high-throughput experimentation framework for automating large-scale parameter sweeps and Monte Carlo analyses, enabling systematic characterization of system performance. DeepFMKit's modular, object-oriented architecture facilitates the rapid configuration of virtual experiments, providing a powerful computational tool for researchers to prototype designs, investigate systematic errors, and accelerate the development of precision interferometry. Program Summary Program Title: DeepFMKit CPC Library link to program files: https://doi.org/10.17632/v5cnpt2whh.1 Developer's repository link: github.com/mdovale/DeepFMKit Licensing provisions: BSD 3-clause Programming language: Python 3.9 and higher Nature of problem: Deep Frequency Modulation Interferometry (DFMI) is an increasingly important technique for high-precision optical metrology. The learning curve for modeling DFMI systems is very steep, as even a basic simulation requires implementing complex, non-linear physics, advanced digital signal processing for time-delays, and specialized parameter estimation algorithms. There are many researchers who must develop bespoke, time-consuming, and error-prone simulation toolchains by combining disparate libraries. The existing general-purpose optical design packages or specialized interferometry simulators are not tailored for DFMI's unique signal generation and signal processing needs. Solution method: DeepFMKit serves as a complete computational laboratory for DFMI. Due to its fully integrated, object-oriented design and a high-level Python interface, DeepFMKit has a significantly flatter learning curve compared to building custom simulation and analysis pipelines from scratch. The package covers the entire experimental workflow, featuring an intuitive approach for configuring the instrument's physics and noise properties, offering a suite of interchangeable readout algorithms for analysis of real or simulated data, and providing integrated tools for data handling and visualization. A ready-to-use infrastructure for automating large-scale parameter sweeps and Monte Carlo studies is also provided. [ABSTRACT FROM AUTHOR]