prism_min_deviation_deg — OPTICS glassbody op

Data kinds: signalsignal

Call: import glassmirror; glassmirror.prism_min_deviation_deg(wavelength_nm=550.0, apex_deg=60.0, glass='N-BK7') -> 'np.ndarray' (or opsoptics.get("prism_min_deviation_deg"))

Usage

A prism's angle of minimum deviation [deg]. It varies with wavelength through the dispersion of real glass — that is why you see a rainbow.

> The detailed description below is the original text — the summary and the headings are translated.

wavelength_nm: スカラまたは配列 [nm]。データ入力なので第 1 引数

(2026-09-04 の敵対的検証で判明: 台帳は「先頭 N 個が宣言 in 型のデータ」という

規約なのに、この op だけ apex_deg を先頭に置いていた。波長の配列が

apex_deg に入り float(配列)素の TypeError を投げていた ―― 規約に

揃えるのが正しい直し方で、番人を足すのは対症療法)。

apex_deg: 頂角 A [deg]。glass: raytrace.glass_catalog の硝材名、または屈折率の数値。

返り値: 最小偏角 δ_min = 2·asin(n·sin(A/2)) − A(Hecht §5.5)。n·sin(A/2) > 1 の

波長は光が出られない(全反射)ので NaN。

検算: N-BK7・A=60° で d 線(587.6 nm)の δ_min ≈ 38.9°、F 線(486.1)と C 線(656.3)の

差(角分散)が Abbe 数から予想される向き(短波長ほど大きく曲がる)になる。

Family-wide input contract (fail-closed)

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.

Detailed usage guide

optics_imaging family guide

References (sample data, literature)

• 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.

Runnable examples (verified samples that actually call this op)

glass_and_mirror_opticspy -3.11 examples/glass_and_mirror_optics.py

Ops the type connects to (they accept signal as input)

cie_xyz_from_wavelength · spectrum_to_srgb · thin_film_reflectance · fresnel_dielectric · fresnel_conductor · metal_optical_constants · beer_lambert_transmittance · slab_transmittance

Same category (glassbody)

beer_lambert_transmittance · slab_transmittance · refract_rays


*Provenance: glassmirror.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.