fiber op• Data kinds: none → table (an op determined by its arguments alone — it takes no image or data input)
• Call: import fullseye as fs; fs.ledger.fiber_mode_field_diameter(core_radius_um=4.1, v_number=2.2) (to call the implementation directly, import fiberoptics; fiberoptics.fiber_mode_field_diameter(core_radius_um=4.1, v_number=2.2); from the registry, opsoptics.get("fiber_mode_field_diameter"))
Mode field diameter (MFD) of LP01 in µm —— the 1/e² diameter of the Gaussian with the largest overlap with the exact field.
> The detailed description below is the original text — the summary and the headings are translated.
厳密: LP01 の固有値 (u, w) から場 E(r) = J0(ur/a)/J0(u)(r ≤ a)、K0(wr/a)/K0(w)(r > a)を作り、ガウス exp(−r²/w₀²) との重なり |∫E·G r dr|² / (∫E² r dr ∫G² r dr) を最大にする w₀ を黄金分割で探す(MFD = 2w₀)。
近似: Marcuse 1977 の w₀/a = 0.65 + 1.619 V^{−3/2} + 2.879 V^{−6}(この同じ定義への当てはめ式)。もう 1 つの定義 Petermann I(2 次モーメント、w² = 2∫E² r³ dr / ∫E² r dr)は裾の指数関数を重く数えるので大きく出る —— 定義が違えば MFD は 10 % 違う(V = 1.2)ことを隠さないため両方返す。
返り値: dict(mfd_um, mfd_marcuse_um, relative_difference, mfd_petermann1_um, overlap, u, w)。
Every optics op validates its input before computing (nothing slips through silently):
• Units are baked into the argument name — _mm / _um / _deg / _mrad. Confusing mm with µm does not crash; it yields a plausible-looking wrong answer, so the name prevents it. Nothing here guesses the unit from the magnitude.
• Strings raise ValueError — float('50') succeeds, so an unparsed configuration value would slip through as a length (measured: thin_lens('50', '200') returned a plausible 66.667 mm). bool is refused too, as the implicit promotion True == 1.
• complex / masked arrays raise ValueError (real-valued slots only; silently dropping the imaginary part or peeling off the mask is refused). NaN/Inf raises ValueError on every input.
• Division by zero and its relatives are refused by name: focal length 0, radius of curvature 0, refractive index <= 0, a fully opaque aperture (all zeros, so the normalisation is 0/0), a PSF whose sum is <= 0, a Stokes vector with S0 = 0, and an object sitting at the front focal point (the image is at infinity).
• Only two ops return a non-finite value, and both state it as a contract: depth_of_field returns far_mm = inf beyond the hyperfocal distance (that is what the hyperfocal distance means), and gaussian_beam returns wavefront_radius_mm = inf at the waist (the radius of curvature of a plane wavefront). Both also return a finite companion (far_is_infinite / curvature_per_mm). Any other silent NaN/Inf is detected internally and raises ValueError — "float64 overflowed" and "the answer is infinite" are different claims, so the first is never returned wearing the face of the second.
• Size caps: generated grids are capped by optics.MAX_GRID (4096); supplied fields/PSFs/apertures by optics.MAX_FIELD_ELEMENTS (2^24); ABCD element chains by optics.MAX_SYSTEM_ELEMENTS (1024); Zernike by MAX_ZERNIKE_TERMS (512) / MAX_ZERNIKE_ORDER (40) / MAX_ZERNIKE_BASIS (2^25). This closes, fail-closed, the paths where a small argument triggers a huge internal allocation (measured: n_max=40 × 4096² needs 108 GB).
• Physically impossible states are refused too: a Stokes vector with degree of polarisation > 1, negative transmittance, negative intensity, and invalid Zernike indices such as n-|m| odd.
• 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.
• poc_fiber_light_guide — py -3.11 examples/poc_fiber_light_guide.py
table as input)abcd_matrix · wavefront_stats · sfr_from_edge · paraxial_trace · seidel_coefficients · spot_stats · tolerance_analysis · wavefront_from_opd
fiber)material_group_index · material_gvd · fiber_numerical_aperture · fiber_v_number · fiber_lp_modes · fiber_bundle_coupling
*Provenance: fiberoptics.py — OPTICS 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.