User guide

This guide follows a retrieval from the measurement to a reported pulse: what a FROG trace records, how to prepare it, which physical model to fit, how to run and judge a retrieval, how to interpret and propagate the result, how to put an error bar on it, and how to keep the analysis reproducible. Each chapter collects the practical how-to pages and the physics and numerical background for one step.

If you are new to croak, begin with the introduction and your first retrieval. The examples provide runnable applications of every chapter.

Step	Chapter	Covers
1	Measurement fundamentals	the PNPS framework, interactions, units, grids and Fourier conventions
2	Preparing and checking data	loading files, cleaning and regridding, simulated scans, marginal checks
3	Modelling the measurement	thin and dispersive media, geometric smearing, focal and collection models
4	Retrieval and numerical methods	solver choice, the objective, gradients, regularisation, fitted parameters
5	Interpreting results	plots, ambiguities, durations, spectral checks, validation
6	Propagation and dispersion tuning	materials, gases, chirped and coating mirrors, compression
7	Uncertainty	bootstraps, the thickness systematic, analytic covariance
8	Saving and reproducible workflows	the GUI, HDF5 results, TOML sessions, replay and scripts
—	Glossary and references	terminology, notation and the literature

• Measurement fundamentals and conventions
• Preparing and checking data
• Modelling the measurement
• Retrieval and numerical methods
• Interpreting results
• Propagation and dispersion tuning
• Uncertainty
• Saving, sessions, and reproducible workflows
• Glossary and references