Most light sources use either a filament lamp (vacuum, halogen or xenon), a xenon lamp or a LED lamp. Historically, halogen bulbs were the gold standard for lighting in medical facilities and operation rooms. However, their short lifespan means inopportune and costly blackouts and the heat they generate poses a safety threat. LED light addresses these two issues with an exponentially longer lifespan and a bulb remaining cool to touch.
The basic requirements of medical lighting are:
A quartz encasement is found at its core, filled with halogen gas. A tungsten filament is affixed at the center of the encasement and it becomes illuminated when electricity is circulated through it. To produce light with a halogen bulb, heat must be generated. At the onset, the heat is low and the filament glows red. The more electricity is fed to the filament, the hotter it gets, the brighter the illumination and the whiter the light. With a whiter light, it is easier for the human eye to see the illuminated area. As more electricity is fed to the filament, more heat is generated (and wasted) and more energy is consumed. The halogen gas stops the blackening of the bulb and slows the thinning of the tungsten filament.
Simply a semi-conductor in the form of a diode (two conductive materials placed in contact with each other) housed in a glass or plastic translucent casing. When electricity is applied, the current can only flow in one direction and the atoms in the material getting the electrical current flow become charged with energy. This energy is released into the other conductive material in the form of electrons, thereby generating light. Only little heat is generated in the process.
Light source ratings
Colour rendering index (CRI).
Quantifies how faithful the colours are rendered by the light source in comparison with an ideal or natural light source. A high CRI is required in colour-critical applications.
Kelvin colour temperature scale.
The lower the number, the “warmer” the colour. A whiter colour is desirable for medical diagnosis.