Deuterium lamps require filament power and anode-cathode voltage of at least 350 V to initiate the discharge and then, for best performance a carefully regulated discharge current. Until the deuterium lamp reaches thermal equilibrium, the radiated output varies. After approximately 10 to 15 minutes, the output will be almost completely stable. For applications requiring extreme stability, an additional 15 to 30 minutes of warm-up may be required. This is particularly important when using the 63345 Calibrated Lamp.