Powermeters and 2D beam imaging systems on the Novosibirsk terahertz free electron laser

Two types of powermeters for the Novosibirsk terahertz free electron laser (NovoFEL) are considered in this paper. The first one is an expositional etalon device on the basis of a heat isolated sapphire plate. The calorimeter is shown to have a constant emissivity of 0.74 in the entire generation range of NovoFEL. The second device is a CW calorimeter with a special absorption cone with an Al₂O₃ ceramic coating made by a gas dynamic method. Two 2D beam imaging systems with 152 mm times 152 mm workspace are presented. The first one is a thermofluorescent screen with an optical video camera, and the second one is a scanning ID line of thirty piroelectric detectors. Small beams and objects will be investigated by a commercial Pirocam III piroelectric camera with 12 mm times 12 mm workspace.