michelson_dc_readout — OPTICS cavity 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.michelson_dc_readout(power_w: 'float' = 1.0, arm_length_m: 'float' = 1.0, wavelength_nm: 'float' = 1064.0, *, dc_offset_rad: 'float' = 0.1, strain: 'float' = 0.0) -> 'dict' (to call the implementation directly, import cavityoptics; cavityoptics.michelson_dc_readout(power_w: 'float' = 1.0, arm_length_m: 'float' = 1.0, wavelength_nm: 'float' = 1064.0, *, dc_offset_rad: 'float' = 0.1, strain: 'float' = 0.0) -> 'dict'; from the registry, opsoptics.get("michelson_dc_readout"))

Usage

Antisymmetric-port power, strain sensitivity and shot-noise limit of a Michelson offset by φ₀ from the dark fringe.

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

Parameters

power_w : float

ビームスプリッタに入る光量 P_in [W]。

arm_length_m : float

腕の長さ L [m] (単純 Michelson。共振器の利得は cavity_strain_transfer で別に掛ける)。

wavelength_nm : float

波長 [nm]。

dc_offset_rad : float

暗縞からのオフセット位相 φ₀ [rad] (0 < φ₀ < π)。

strain : float

ひずみ h(腕の差 ΔL = hL)。

Returns

dict

p_out_w = P_in sin²((φ₀ + 4πhL/λ)/2)、slope_w_per_strain = dP/dh

= P_in sin(φ₀ + 4πhL/λ)·2πL/λ、shot_noise_w_per_rthz = √(2ħω P_out)、

h_shot_per_rthz = 散射雑音/傾き、h_shot_limit_per_rthz = φ₀ → 0 の極限

(1/2L)√(ħcλ/πP_in)、phase_total_rad。

Notes

散射雑音限界は小さなオフセットで h_shot = (1/2L)√(ħcλ/πP_in)/cos(φ_total/2)、φ → 0 で極限値に収束する(オフセットを下げるほど光量は減るが感度の比は変わらない —— DC 読み出しが成り立つ理由)。tests は傾きを有限差分で独立に求めて突き合わせる。

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)

• poc_gw_detector_pseudo_simulation — py -3.11 examples/poc_gw_detector_pseudo_simulation.py

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

abcd_matrix · wavefront_stats · sfr_from_edge · paraxial_trace · seidel_coefficients · spot_stats · tolerance_analysis · wavefront_from_opd

Same category (cavity)

fabry_perot_response · cavity_strain_transfer · pdh_error_signal · quantum_noise_budget


*Provenance: cavityoptics.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.