Orateur
Description
In the ANR DISPERS project, we use a physics-first approach to simulate spectroscopy instruments. Each physical stage of the instrument, such as optics, source catalogs, detector response, and calibration, is modeled based on physical principles wherever possible. Machine learning is only used to complement these models where physics alone is insufficient or too expensive. These model components are integrated through Simcraft, a modular simulation framework built around interchangeable, pluggable physical model components. We present three such components, each of which addresses one stage of the simulation.
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Synthetic catalog generation samples from AION, a multimodal transformer foundation model (Parker, Lanusse, Shen et al., arXiv:2510.17960, 2025), replacing hand-tuned parametric distributions with catalogs that inherit realistic cross-modal correlations (fluxes, morphology, spectra). Grew from foundation-model benchmarking at the AstroInfo 2025 hackathon into a package via a CentraleDigitalLab student project.
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PSF modeling pairs a physics-based forward simulator (aperture geometry, Zernike aberrations, polychromatic sources) with ML models inverting the problem: Zernike/wavefront-error coefficients estimated directly from a PSF image, without a dedicated wavefront sensor. We combine a discriminative CNN regressor (Sauniere, Gillard & Zoubian, SPIE 2024) with a DDPM diffusion model that also reconstructs the PSF with calibrated uncertainty (SPREAD; Sauniere et al., in prep. for AAS/AJ).
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Instrument calibration couples a geometrical-optics dispersion model with an ML residual corrector as an interpretable Chebyshev-polynomial alternative. Benchmarked against a published on-ground result (Gillard et al., 2025, arXiv:2506.08378): preliminary results are the same order of magnitude but do not yet match its accuracy.
All three are validated against Euclid/NISP ground-test data as a case study, but the approach, physical model plus targeted ML correction, and the simulation framework, generalizes beyond this instrument.