Bolometer
![Spiderweb bolometer for measurements of the cosmic microwave background radiation. Image credit: NASA/JPL-Caltech.](/Images/godic/202501/01/JPL_Spiderweb_Bolometer4707.jpg")
![Conceptual schematic of a bolometer. Power, P, from an incident signal is absorbed by the bolometer and heats up a thermal mass with heat capacity, C, and temperature, T. The thermal mass is connected to a reservoir of constant temperature through a link with thermal conductance, G. The temperature increase is ΔT = P/G. The change in temperature is read out with a resistive thermometer. The intrinsic thermal time constant is τ = C/G.](/Images/godic/202501/01/Bolometer_conceptual_schematic.svg4707.png")
A bolometer (Greek, βολόμετρον or bolometron; βολο- meaning of thrown things; and -μετρον, measurer) is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.