spad op• Data kinds: countrate → countrate
• Call: import photoncount; photoncount.spad_deadtime_correct(measured_hz, dead_time_ns=50.0) (or 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
:func: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 :func: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.