HMI SE

Overview

"HMI SE" stands for HMI Single Ended, meaning a single-ended HMI discharge lamp. The abbreviation does not describe a specific device, but rather the design of the light source: in a single-ended lamp, both electrical contacts are located at one end of the arc tube, while the double-ended variant (DE) has one contact at each end.

HMI (Hydrargyrum Medium-arc Iodide) is a daylight discharge lamp: the light is generated by an arc between two electrodes in a quartz envelope, exciting mercury vapor and metal halides. HMI lamps are therefore tuned to daylight and require a ballast and an ignitor for operation.

Design: Single Ended vs. Double Ended

The fundamental difference lies in the socket and the corresponding fixtures:

• Single Ended (SE): single-ended base (e.g., a G22 base for lower wattages). This design is commonly found in HMI PARs and compact fixtures.
• Double Ended (DE): contact at both ends of the lamp. This form is typical for classic HMI Fresnel fixtures from manufacturers like ARRI, Mole-Richardson, or LTM.

SE and DE lamps are not interchangeable; each fixture is designed for exactly one type of base and a specific socket.

Technical Data (Example 575 W SE)

As a concrete example, consider the common 575 W HMI SE lamp (Single Ended), which is used in 575 W HMI PARs and compact Fresnels (ARRI, Mole-Richardson), among others:

The color of fresh HMI lamps initially runs higher and drops towards the nominal value with operating hours; aged lamps shift in color and should be replaced promptly. Hot-restrike versions (often marked with "HR" in manufacturer codes) allow for reignition while hot.

On-Set Usage

HMI SE lamps are primarily used where a compact, single-ended design is required – for example, in HMI PARs for directed, hard daylight. When ordering and retrofitting on set, it is crucial to select the correct design (SE vs. DE), the appropriate base, and the correct wattage for the respective fixture, as an incorrect lamp simply won't fit or could damage the fixture. Key manufacturers include Osram (brand name "HMI") and Philips, whose single-ended variant is marketed as MSR (Medium Source Rare-earth).