The 67030 Blackbody Source is a highly uniform, temperature stable source of infrared radiation. These sources emit blackbody radiation by multiple reflection, absorption and re-emission of the thermal energy. The thermal energy of the cavity is provided by a ceramic sealed 110 VAC heater coil that uniformly heats the stainless steel cavity cylinder to temperatures from 50 °C to 1050 °C. 1 inch (25.4 mm) diameter cavity opening.