A black-body source of radiation covering a wavelength range from the ultraviolet to the infrared

A black-body source of radiation of emissivity close to 1 over the wavelength range 02-5 μm is provided by electrically heating a graphite tube in an argon atmosphere. The tube has a conically indented graphite plug located midway along its length, forming a black-body cavity with radiation emerging axially through a 2 mm diameter aperture near one end. The source can attain radiance temperatures of 3000 K and hence provides a valuable background source for temperature measurements by absorptivity-emissivity methods and also provides a useful standard for radiation calibration purposes from the ultraviolet to the infrared.