2011 Philips UHP 400W

The first super-high-pressure mercury short-arc (UHP) lamp was introduced by Philips in 1994, and operated at a vapor pressure in excess of 150 bar for the production of white light. The source's extremely short arc (1 mm) results in a brightness that exceeds 1 Gcd/cm², which is ideal for the precise projection of light. The lamp was thus applied to video projection applications, and were made with an integral parabolic dichroic mirror whose purpose is to precisely collect the light emitted by the burner and partially correct its light color.

The first UHP lamps had a power rating of 120 W only due to limitations in lamp design and in thermal management. Over the years, the burner and its electrodes were improved and more powerful lamps were developed and released on the market. This trend was driven by the need for more intense light sources in larger video projectors in order to project larger and brighter images. This eventually led to lamps made with more efficient elliptical mirrors and with high-wattage burners, such as in the present 400 W model. Limitations in materials properties eventually capped the maximum power rating near 500 W.

The burner in this 400 W UHP lamp generates about 24 klm, i.e., the same amount of light as from a standard fluorescent-corrected HID mercury lamp of same wattage. The main difference is that here the source of light is 2.63 million times smaller in volume! This is the reason for is extremely high intrinsic brightness, which makes it so useful and efficient in projection lighting applications. The lamp's elliptical mirror collects and focus ~80 % of the emitted light (i.e., about 19 klm) on a tiny spot in front of the lamp.