lockin op• Data kinds: image2d → video
• Call: import fullseye as fs; fs.ledger.lockin_ring_synthesize(height, zenith_deg, n_sources, multipole, frames_per_period, n_periods, albedo=None, noise_sigma=None, seed=None) -> 'np.ndarray' (to call the implementation directly, import lockin; lockin.lockin_ring_synthesize(height, zenith_deg, n_sources, multipole, frames_per_period, n_periods, albedo=None, noise_sigma=None, seed=None) -> 'np.ndarray'; from the registry, opsoptics.get("lockin_ring_synthesize"))
A Lambertian relief lit by a ring of modulated sources -> image sequence (T, H, W).
height is a height map in pixel units (normal = (-h_x, -h_y, 1) / norm). n_sources point sources sit at zenith angle zenith_deg from the camera axis and equally spaced azimuths theta_s; source s emits (1 + cos(2 pi k / frames_per_period - multipole theta_s)) / n_sources in frame k, i.e. the modulation phase runs around the ring multipole times (multipole 1 = a dipole pattern, 0 = all in phase). Pixels follow albedo * max(0, n . l_s) summed over sources, shadows included. The sequence has frames_per_period * n_periods frames and is demodulated with lockin_demodulate(video, 1.0, frames_per_period). White noise of standard deviation noise_sigma needs an explicit seed (no hidden random state).
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_lockin_imaging — py -3.11 examples/poc_lockin_imaging.py
video as input)lockin_demodulate · lockin_amplitude · lockin_phase · lockin_separate · pixel_shift_merge · pixel_shift_motion_mask
lockin)lockin_demodulate · lockin_amplitude · lockin_phase · lockin_noise_floor · lockin_walsh_codes · lockin_separate · lockin_ring_normals · lockin_thermal_wave
*Provenance: lockin.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.