lensfile op• Data kinds: table → table
• Call: import fullseye as fs; fs.ledger.lens_file_write(prescription=None, system=None, path=None, encoding: 'str' = 'ascii') -> 'dict' (to call the implementation directly, import lensfile; lensfile.lens_file_write(prescription=None, system=None, path=None, encoding: 'str' = 'ascii') -> 'dict'; from the registry, opsoptics.get("lens_file_write"))
Write a prescription as .zmx text that lens_file_read and design programs read (table).
*prescription* is the dict from lens_file_read (None: the bundled example). *system* — optional — is an edited raytrace.lens_system (for example the output of lensopt.optimize_lens): its radii, thicknesses, conics, aspheric terms and media replace the prescription's surfaces while the fields, wavelengths, aperture type, comments and still-valid solves are kept (a solve whose value was edited is dropped from the output and listed in dropped_solves). The stop size is written as the system aperture: an entrance-pupil diameter (ENPD) recomputed from *system* when the prescription used ENPD or FNUM.
*path* (optional) writes the file; *encoding* "ascii" (default, plain text that diffs well) or "utf-16" (with byte-order mark, what current design programs save). Media: an (n_d, V_d) pair or a plain index becomes a model glass, a catalogue name or .agf record its name with n_d / V_d on the line; a custom Sellmeier medium without a catalogue name is refused (a reader could not resolve it). *system* may also be a raytrace3d.noncoaxial_system (the prescription is then optional): its break and return elements become COORDBRK surfaces (order flag 0 / 1 for the tracer's "xyz" / "zyx" breaks), an entrance-pupil diameter is recomputed from the stop radius.
Refused: a beamsplitter surface, a per-surface decenter / tilt (put a break around it), a tilted image or object plane, a return across an odd number of reflections or one that would need a negative thickness. A coaxial raytrace.lens_system with tilted / decentred surfaces is still refused.
A *system* (or a prescription's system) that carries configurations is written as a multi- configuration file: configuration 1 as the surface blocks, then MNUM and one row per varying thickness / curvature / glass / aspheric parameter and configuration (see the module help for what is refused); the result then also has n_configurations and rows (row counts per operand).
Returns {"text", "path", "n_surfaces", "encoding", "dropped_solves"}.
Example::
p = lens_file_read("triplet.zmx")
best = lensopt.optimize_lens(p["system"])["system"]
lens_file_write(p, system=best, path="triplet_reoptimised.zmx")
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_lens_file_roundtrip — py -3.11 examples/poc_lens_file_roundtrip.py
• poc_zoom_configurations — py -3.11 examples/poc_zoom_configurations.py
table as input)abcd_matrix · wavefront_stats · sfr_from_edge · paraxial_trace · seidel_coefficients · spot_stats · tolerance_analysis · wavefront_from_opd
lensfile)lens_file_read · lens_file_system · lens_file_report
*Provenance: lensfile.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.