envelope op• Data kinds: sweep → signal
• Call: import fullseye as fs; fs.ledger.csi_envelope(signal, remove_bias=True) (to call the implementation directly, import interferometry; interferometry.csi_envelope(signal, remove_bias=True); from the registry, opsinterferometry.get("csi_envelope"))
Coherence envelope of a z-scan interferogram (analytic-signal magnitude).
dsp.envelope computes |hilbert(x)| for any 1-D signal and is called here verbatim, so the two can never drift apart. The one thing added is the one thing an interferogram needs and a generic signal does not: removal of the intensity pedestal. An interferogram is a + b*V(z)*cos(...) with a > 0, and the analytic-signal magnitude of that is not b*V — the DC term passes through the Hilbert transform untouched and dominates.
Measured on the module's reference scan (a = 0.5, b = 0.4, envelope sigma 1.2 um, surface centred): with the bias removed the envelope matches the analytic b*V(z) to 1.83e-07; without it, the error is 0.5 — the entire pedestal — and the recovered "envelope" never goes near zero. dsp.envelope called directly on the same raw interferogram gives that identical 0.5, which is the honest statement of what this operator adds. That is why remove_bias defaults to True; False is available for a scan whose pedestal you have already removed some other way, and it is your statement that you did.
signal: 1-D scan intensities ((n,), n >= 3).
remove_bias: subtract the scan mean before the transform.
Returns a 1-D float64 envelope of the same length.
Raises ValueError: a non-1-D, empty, too-short (< 3), non-finite, complex or masked *signal*, a *signal* over MAX_SCAN_POINTS elements (checked before the float64 promotion), or a non-bool *remove_bias*.
• 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
signal as input)—
envelope)—
*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.