beer_lambert_transmittance — OPTICS glassbody op

• Data kinds: signal → signal

• Call: import fullseye as fs; fs.ledger.beer_lambert_transmittance(path_mm, sigma_per_mm=0.01) -> 'np.ndarray' (to call the implementation directly, import glassmirror; glassmirror.beer_lambert_transmittance(path_mm, sigma_per_mm=0.01) -> 'np.ndarray'; from the registry, opsoptics.get("beer_lambert_transmittance"))

Usage

Beer–Lambert internal transmittance T = exp(−σ·L). The green cast of coloured and thick glass.

path_mm: optical path length in the medium [mm] (array allowed, non-negative).

sigma_per_mm: absorption coefficient [1/mm] (array allowed — varying it per wavelength gives colour).

Returns: internal transmittance (0–1). Interface reflections are not included (that is slab_transmittance).

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_optics — py -3.11 examples/glass_and_mirror_optics.py

• poc_pv_thermal_survey — py -3.11 examples/poc_pv_thermal_survey.py

• poc_thermal_radiometry — py -3.11 examples/poc_thermal_radiometry.py

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

emva_photon_transfer · emva_quantum_efficiency · emva_linearity_error · emva_snr_curve · emva_dark_current · cie_xyz_from_wavelength · spectrum_to_srgb · thin_film_reflectance

Same category (glassbody)

slab_transmittance · refract_rays · prism_min_deviation_deg


*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.