time constant, <of a detector whose output varies exponentially with time>
time required for the output to change, after a step variation from one steady input to another steady input, by the fraction (1 − 1/e) of its total change in value, where the total change in value is the difference between the initial value and the final (asymptotic) value
Note 1 to entry: The time constant is expressed in seconds (s).
Note 2 to entry: This entry was numbered 845-05-59 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-1318 in CIE S 017:2011.