The steady-state load curve, defined as the steady-state relation between the voltage across the bolometer and the current through it, is obtained theoretically for a bolometer whose sensitive material is a semi-conductor. The derivation is based on two physical postulates: (1) The resistivity varies with the absolute temperature T according to the factor eτ/T, where τ is a constant which depends on the nature of the semi-conductor; (2) the bolometer has a steady-state temperature rise above the ambient temperature which is proportional to the power dissipated in the bolometer by the current passing through it. The results are expressed in terms of a parameter x = T0/τ, where T0 is the ambient temperature, and indicate that there is a maximum in the voltage versus current curve when the value of x is less than
; this prediction is fully confirmed by experiment. Five sets of curves are presented which indicate the form of the relations among the voltage across, the current through, the resistance of, and the power dissipated in, the bolometer.
© 1946 Optical Society of America
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