fullseye

csi_design — INTERFEROMETRY design op

• データ種: なし → table(引数だけで決まる op —— 画像やデータの入力を取らない)
• 呼び出し: import fullseye as fs; fs.ledger.csi_design(wavelength_um=0.6, bandwidth_um=0.1, z_range_um=12.0, width_px=640, height_px=480, min_visibility=0.3, step_divisor=8.0) (実装を直接呼ぶなら import interferometry; interferometry.csi_design(wavelength_um=0.6, bandwidth_um=0.1, z_range_um=12.0, width_px=640, height_px=480, min_visibility=0.3, step_divisor=8.0)、台帳から引くなら opsinterferometry.get("csi_design"))

使い方

The axial limits of a coherence-scanning setup, from the source spectrum.

The counterpart of :mod:visiondesign for the vertical axis: closed-form answers to the questions asked before any hardware is bought — how localised is the coherence peak, how finely must the scan step, how many planes is that, and how much memory does the stack need.

Returned dict:

• coherence_length_um — (4 ln2 / pi) * lambda^2 / delta_lambda, the FWHM of |gamma(OPD)| for a Gaussian source (Born & Wolf 7.5.8). This is a property of the optical path difference. Verified in the tests against a direct numerical Fourier transform of the Gaussian source spectrum, at three (lambda, delta_lambda) settings, agreeing to 6 significant figures.
• envelope_fwhm_um — half of that: the width of the envelope along the scan axis, because the double pass makes OPD = 2z. This is the one to hand to :func:csi_signal_simulate / :func:csi_stack_simulate, and the two are reported separately precisely because collapsing them into one name called “coherence length” is a clean factor-of-two error in every height the module produces. (It was one during development, and the numerical check above is what caught it.)
• envelope_sigma_um — envelope_fwhm_um as a Gaussian sigma.
• fringe_period_um — lambda/2. The double pass halves it, and this is the number that makes phase-shifting ambiguous above lambda/4.

• max_z_step_um — lambda/4. The Nyquist ceiling on the scan step; :func:csi_peak_position and :func:csi_height_map refuse at or above it. It is a rejection bound, not an operating point — the accuracy is already gone well before the refusal. Measured on a tilted plane (lambda 0.6 um, bandwidth 0.12 um, ceiling 0.15 um, no noise at all, so every number below is method error):

  ========== =========== =========== step [um] bias [nm] RMSE [nm] ========== =========== =========== 0.0375 0.09 0.22 0.0750 (rec) 0.09 0.26 0.1000 -0.07 0.39 0.1200 0.39 2.90 0.1400 -4.75 134.64 0.1499 -1.89 18.38 ========== =========== ===========

  A step of 0.14 um is accepted and returns heights that are wrong by 500x the recommended step’s error, with a worst pixel at 198 nm. Note also that the last two rows are not monotone: 0.1499 is better than 0.1400. The error near the ceiling is an aliasing beat between the fringe period and the step, not a smooth degradation, so “just under the limit” cannot be made safe by nudging the step. Use recommended_z_step_um; the bias only stays in the 0.1 nm range up to about lambda/6.

• recommended_z_step_um — lambda/step_divisor (default lambda/8, the usual 90-degree-per-plane choice), reported only if it is below the ceiling.
• capture_range_um — the height interval over which the fringe contrast stays above min_visibility of its peak, 2*sigma*sqrt(2 ln(1/min_visibility)). Outside it a surface produces fringes too faint to locate, whatever the scan range is.
• planes_per_envelope — how many scan planes fall inside envelope_fwhm_um at the recommended step. Below ~4 the three-point estimators have nothing to fit.
• n_planes / stack_elements / stack_megabytes — the scan you are about to run and the float64 stack it produces, plus stack_within_cap against :data:MAX_STACK_ELEMENTS. This is the number people discover after waiting for the scan.
• phase_unambiguous_step_um — lambda/4, the largest surface step phase-shifting interferometry can measure without a fringe-order error. It is here so the two families can be compared in one place: coherence scanning has no such limit inside the scan range, and that is the entire reason to pay for the scan.

What this deliberately does not return is a vertical repeatability — a “resolution” in nanometres. That number depends on the signal-to-noise ratio and on which of :data:ESTIMATORS you use, the estimators do not even rank the same way with and without noise, and an attempt to verify the textbook “two surfaces closer than the coherence length are unresolved” criterion against this module’s own forward model failed: two reflectors 0.4 coherence lengths apart still produce two envelope maxima, because the two interferograms interfere with each other and the envelope of a sum is not the sum of the envelopes. Rather than assert a formula that its own tests contradict, this operator returns only quantities it can verify, and the measured estimator table lives in the module docstring.

Raises ValueError: non-real / non-finite / string / bool parameters, a non-positive wavelength / bandwidth / range, a bandwidth_um at or above wavelength_um (a source whose spectrum reaches zero frequency is not a quasi-monochromatic source and the coherence-length formula does not apply to it), a min_visibility outside (0, 1), a step_divisor below 4 (which would recommend a step at or past its own Nyquist ceiling), and pixel counts outside [1, 65536].

詳しい使い方ガイド

• coherence_scanning ファミリ ガイド

参考(サンプルデータ・文献)

• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。
• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。
• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• coherence_scanning — py -3.11 examples/coherence_scanning.py
• poc_interferometry_step — py -3.11 examples/poc_interferometry_step.py

型が繋がる次の op(table を入力に取れる)

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同カテゴリ(design)

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Provenance: interferometry.py — INTERFEROMETRY operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.

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