simulate op• Data kinds: none → sweep (an op determined by its arguments alone — it takes no image or data input)
• Call: import interferometry; interferometry.chromatic_confocal_simulate(surface_um=0.0, wavelength_start_nm=500.0, wavelength_step_nm=0.5, n_bins=401, dispersion_um_per_nm=0.2, reference_wavelength_nm=600.0, peak_fwhm_nm=4.0, peak_counts=1000.0, background=10.0, noise=0.0, seed=0) (or opsinterferometry.get("chromatic_confocal_simulate"))
Synthesise the confocal return spectrum of a surface at a known height.
A chromatic objective is built to have axial colour on purpose: each
wavelength focuses at a different height, so only the wavelength focused *on
the surface* passes the confocal pinhole. The spectrometer therefore sees a
peak whose wavelength is the height::
lambda_peak = reference_wavelength_nm
+ (surface_um - 0) / dispersion_um_per_nm
i.e. ``surface_um = (lambda_peak - reference_wavelength_nm) *
dispersion_um_per_nm`, which is what :func:chromatic_confocal_height`
inverts. The peak is modelled as a Gaussian of FWHM *peak_fwhm_nm* on a flat
*background* pedestal.
surface_um: true height (0 = the reference wavelength focuses
exactly on it). May be negative — unlike a
time-of-flight distance, a height is signed.
wavelength_start_nm / wavelength_step_nm / n_bins: the spectrometer axis.
dispersion_um_per_nm: the axial chromatic dispersion, height per
nanometre. This is the calibration constant and
the units are in the name for a reason: a
per-micrometre reading of it is a 1000x error in
the height.
peak_fwhm_nm: spectral width of the confocal response.
peak_counts / background: peak height above, and level of, the pedestal.
noise / seed: additive Gaussian sigma and its integer seed.
Returns a 1-D float64 spectrum of `n_bins` non-negative intensities
(clipped at 0, because a spectrometer cannot read negative light — and the
clip is stated here rather than left as a surprise).
Ground truth: with `noise=0 the "gaussian"` estimator recovers
*surface_um* exactly (measured 0.0e+00 to 3.6e-15 um over heights from
-15 to +18 um), at any peak width and even with the peak two bins from the
band edge, because the logarithm of a sampled Gaussian is exactly a parabola
and the three-point fit is *local* — there is no Hilbert transform here, so
the truncation failure that limits the coherence-scanning side does not exist
on this one (pinned in the tests).
Raises `ValueError`: non-real / non-finite / string / bool parameters, a
non-positive step / width / dispersion, negative *peak_counts* /
*background* / *noise*, *n_bins* outside `[3, MAX_SCAN_POINTS]`, and a
*surface_um* whose wavelength falls outside the spectrometer band (the
out-of-range case a real probe reports as "no surface").
• coherence_scanning family guide
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• coherence_scanning — py -3.11 examples/coherence_scanning.py
sweep as input)csi_envelope · csi_peak_position · chromatic_confocal_height
simulate)csi_signal_simulate · csi_stack_simulate
*Provenance: interferometry.py — INTERFEROMETRY operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.