sensorchar op• Data kinds: signal × signal → table
• Call: import fullseye as fs; fs.ledger.emva_photon_transfer(mu_y, var_y, mu_y_dark, var_y_dark, mu_y_sat) (to call the implementation directly, import sensorchar; sensorchar.emva_photon_transfer(mu_y, var_y, mu_y_dark, var_y_dark, mu_y_sat); from the registry, opsoptics.get("emva_photon_transfer"))
Derives the system gain K and the dark noise σ_d from the photon transfer curve (Eqs. 50, 53, 54).
*mu_y*, *var_y*: mean and temporal variance per exposure step (mu and var_temporal of emva_pair_statistics). *mu_y_dark*, *var_y_dark*: the same quantities for dark images. *mu_y_sat*: mean at saturation (measured at the exposure where 0.1–0.2 % of the pixels reach the maximum value).
K is the slope of the straight line (with intercept) fitted to σ²_y − σ²_y.dark against μ_y − μ_y.dark. Points used: 0–70 % of saturation (right after eq. 50). σ_d = √(σ²_y.dark − 1/12)/K (eq. 53). ★Below σ²_y.dark < 0.24 DN² quantization noise dominates and it cannot be estimated, so sigma_d is None and sigma_d_upper = 0.40/K (eq. 54) is returned.
Returns {"K", "offset", "sigma_d", "sigma_d_upper", "sigma_d_valid", "n_points", "residual_rms", "used"} (used is a boolean per point: used in the fit or not).
Raises ValueError: lengths differ / fewer than 3 points in 0–70 % / slope not positive / var_y_dark negative.
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_emva1288_sensor — py -3.11 examples/poc_emva1288_sensor.py
table as input)abcd_matrix · wavefront_stats · sfr_from_edge · paraxial_trace · seidel_coefficients · spot_stats · tolerance_analysis · wavefront_from_opd
sensorchar)emva_pair_statistics · emva_quantum_efficiency · emva_linearity_error · emva_snr_curve · emva_sensitivity_threshold · emva_dynamic_range · emva_dark_current · emva_spatial_nonuniformity
*Provenance: sensorchar.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.