Low Pressure Sodium Vapor Lamp provides light at 589 nm and 589.6 nm, useful for wavelength calibration or resolution regulation. When the lamp is turned on, it initially emits dim pink light to warm the Sodium metal; then it turns into the common bright orange color as the Sodium metal vaporizes. Generally, a low-pressure Sodium lamp requires a warm up period of about ten minutes before it reaches substantially full light output, and has to cool down before restart.