Editing Digital light processing (section)

==== Xenon arc lamps ====
For [[xenon arc lamp]]s, a constant-current supply is used, which starts with a sufficiently high open-circuit voltage (between 5 and 20&nbsp;kV, depending on lamp) to cause an arc to strike between the electrodes, and once the arc is established, the voltage across the lamp drops to a given value (typically 20 to 50 volts<ref name="superior">{{cite web |title=Xenon Short Arc Lamps |url=https://www.sqpuv.com/PDFs/TechnicalSpecificationGuide.pdf |website=www.sqpuv.com |publisher=Superior Quartz Products |access-date=5 October 2021}}</ref>) while the current increases to a level required to maintain the arc at optimal brightness. As the lamp ages, its efficiency declines, due to electrode wear, resulting in a reduction in visible light and an increase in the amount of waste heat. The lamp's end of life is typically indicated by an LED on the unit or an onscreen text warning, necessitating replacement of the lamp unit.

Continued operation of the lamp past its rated lifespan may result in a further decrease in efficiency, the [[lightcast]] may become uneven, and the lamp may eventually become hot enough to the point that the power wires can melt off the lamp terminals. Eventually, the required start-up voltage will also rise to the point where ignition can no longer occur. Secondary protections such as a temperature monitor may shut down the projector, but a thermally over-stressed quartz arc tube can also crack or explode. Practically all lamp housings contain heat-resistant barriers (in addition to those on the lamp unit itself) to prevent the red-hot quartz fragments from leaving the area.