The D&S Scaling Digital Voltmeter, Model RD1, is the readout device for the Emissometer. The RD1 has a variable gain knob to set the voltage reading equal to the emittance of the calibration standard. Once this is done, the RD1 indicates emittance directly when the AE1 detector is placed on the material to be measured. The Model AE1 measures flat surfaces as small as 2.25 inches (5.7 cm) across. The optional Model AE-AD1 adapter is available for flat surface areas as small at 1.5” (3.8 cm) in diameter. The optional AE–AD3 adapter is available for flat surface areas as small as 1.0 inches (2.54 cm) across. The AE-ADP adapter for 1.5” (3.8 cm) samples is available for a number of special measurement applications as outlined in D&S Technical Note 11-2. Custom adapters can be designed for cylindrical surfaces or almost any other surface geometry.