Measurement error of thermal time constant of pyroelectric detector obtained from the cutoff frequency of its frequency response

The thermal time constant of the pyroelectric detector is usually determined from the cutoff frequency of its frequency response to sinusoidally modulated radiation. The method can provide reliable measurement results on condition that the thermal and electric time constants are significantly different. Literature does not give more specific suggestions of desired values of the factor n which is the ratio of the thermal to electrical time constants. In this study, the mathematical formula for determination of the measurement error of thermal time constant as a function of the factor n was derived.