Abstract: A large area pyroelectric joulemeter for measuring the pulsed beam output of a laser. The joulemeter employs a pyroelectric detector element with front and rear conductive surfaces forming electrodes, a relatively massive mounting block with relatively high thermal conductivity and an epoxy adhesive for securing the detector element to the mounting block, the epoxy having relatively high thermal conductivity so that heat can be quickly dissipated out of the detector element. An internal recess in the mounting block accommodates a trimming capacitor and resistor for adjusting the voltage sensitivity of the detector assembly to a constant value. The detector assembly is removably installed within an outer housing having a main base portion and a removable bezel.