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Ultra-high pressure mercury lamp

In projection, theatre and photographic lighting, as well as in many other industrial and commercial lighting applications, a high intensity beam is required. To make the optical arrangement of such equipment economical, the bulb must be small and bright. If the discharge tube of a high pressure mercury lamp is used as the basis, two important design methods can be adopted:

(1) Shorten the electrode spacing of the discharge tube while keeping the voltage constant. To prevent overheating of the discharge tube surface, the diameter of the glass shell should be increased and changed to a shape closer to a sphere. This lamp is called a short arc high pressure mercury lamp (ME).

(2) Increase the voltage gradient of the discharge. This produces a thin tube lamp, and due to the high surface temperature, ventilation or water cooling (MD type) must be used.

Short arc high pressure mercury lamps are mainly used in projection systems that do not require high color fidelity. There are lamps with a range of uses from 100 watts to more than 5000 watts, such as illuminators used for threading in textiles, detectors for float glass production, and some other optical equipment in copying and image projection systems.

Unlike short arc high pressure mercury lamps, water-cooled high pressure mercury lamps are high brightness thin tube light sources. Its discharge tube must be sealed in a double-layer glass shell, cooling water passes between the layers of the glass shell, and there is an electrical connection device between the double-layer glass shells. This lamp can be used for photolithography, contour projection and photochemical reactions. Its light intensity is high and the surrounding temperature is low because most of the heat has been taken away by water.

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