spad op• Data kinds: countrate → countrate
• Call: import fullseye as fs; fs.ledger.spad_deadtime_correct(measured_hz, dead_time_ns=50.0) (to call the implementation directly, import photoncount; photoncount.spad_deadtime_correct(measured_hz, dead_time_ns=50.0); from the registry, opsphoton.get("spad_deadtime_correct"))
Recover the true photon rate from a dead-time-distorted measured rate.
The exact inverse of the non-paralysable law of spad_deadtime_apply::
n = m / (1 - m*tau)
A round trip apply -> correct is exact to machine precision (measured max elementwise relative error 6.0e-16 over 2000 rates spanning 1e3 to 5e7 Hz at tau = 50 ns, where the measured rate reaches 71.4% of the 20 MHz saturation rate).
There is deliberately no paralysable inverse. m = n*exp(-n*tau) is not injective — every measured rate below the maximum 1/(e*tau) corresponds to *two* true rates, one below and one above 1/tau — so returning one of them would be a fabrication dressed as a correction. Resolve the branch with an independent measurement (e.g. an attenuator step) and invert it yourself.
*measured_hz* is a 1-D array of measured rates in counts per second; *dead_time_ns* the dead time in nanoseconds (default 50, the same
placeholder spad_deadtime_apply uses — replace it with the datasheet value). Returns the corrected true rates as a float64 1-D array.
Raises ValueError: negative, non-finite or non-1-D *measured_hz*, a non-positive *dead_time_ns*, and — instead of returning inf or a negative rate — any measured rate at or above the saturation rate 1/tau, which no non-paralysable detector can ever produce.
• photon_timeresolved family guide
• 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.
• photon_timeresolved — py -3.11 examples/photon_timeresolved.py
countrate as input)spad)spad_deadtime_apply · tcspc_coates_correct
*Provenance: photoncount.py — PHOTON 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.