First laboratory demonstration of iEFC for high-contrast imaging at small angular separation on ELT scales

@misc{sallard2026first,
  title = {{First laboratory demonstration of iEFC for high-contrast imaging at small angular separation on ELT scales}},
  author = {Charles Sallard and Patrice Martinez and Alain Spang and Kian Milani and Lyu Abe and Mathilde Beaulieu and Carole Gouvret and Aurélie Marcotto and Julien Dejonghe and Olivier Preis},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.37120},
  eprint = {2609.37120},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.37120},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - First laboratory demonstration of iEFC for high-contrast imaging at small angular separation on ELT scales
AU  - Charles Sallard
AU  - Patrice Martinez
AU  - Alain Spang
AU  - Kian Milani
AU  - Lyu Abe
AU  - Mathilde Beaulieu
AU  - Carole Gouvret
AU  - Aurélie Marcotto
AU  - Julien Dejonghe
AU  - Olivier Preis
PY  - 2026
DA  - 2026/09/29
PB  - arXiv
DO  - 10.48550/arxiv.2609.37120
UR  - https://arxiv.org/abs/2609.37120
AB  - Implicit electric field conjugation (iEFC) is an efficient, model-free wavefront control technique for dark hole creation. Its model-free nature, relying on calibration with real data rather than a synthetic model of the instrument, makes it uniquely versatile and highly attractive. It has been successfully demonstrated in a variety of environments, both in the laboratory and on-sky, using different experimental platforms and coronagraphs. A common characteristic of these demonstrations is that the resulting DHs exhibit moderate to large inner working angles and wide fields of view, often extending over several tens of λ/D. Here, we report the first demonstration of iEFC at small angular separations, achieving a DH spanning 1 to 4 λ/D on a segmented pupil in H-band under laboratory conditions. This combination of aggressive IWA and reduced FoV highlights the uniqueness of the SPEED facility (segmented pupil experiment for exoplanet detection). SPEED is a high-contrast imaging testbed designed for extremely large telescopes (ELTs), developed in the context of the ELT/PCS instrument (planetary camera and spectrograph), currently in pre-phase A. Its small-IWA coronagraph, an APCMC (apodized pupil complex mask coronagraph), and its multi- and out-of-pupil-plane deformable mirror (DM) architecture are specifically optimized for DHs at very small IWAs, down to the diffraction limit. Our results demonstrate (i) that widely separated out-of-pupil DMs are well suited to generating DHs with IWAs down to 1 λ/D, and (ii) the effectiveness of iEFC, when combined with the SPEED wavefront control architecture, for high-contrast imaging with segmented telescopes. Ultimately, these results pave the way toward meeting the stringent high-contrast requirements of ELT-class instruments, opening new opportunities for exoplanet detection at unprecedented angular resolutions.
ER  -