duration of exposure
time difference between the end time,
Note 1 to entry: For a single pulse, the exposure duration is the duration between the half-peak power point of the leading edge and the corresponding point on the trailing edge. For a train of pulses (or subsections of a train of pulses), the exposure duration is the duration between the first half-peak power point of the leading pulse and the last half-peak power point of the trailing pulse.
Note 2 to entry: The exposure duration is expressed in seconds (s).
Note 3 to entry: This entry was numbered 17-415 and 17-355 in CIE S 017:2011.