Different Types Of Light Sources

Light can be generated through various sources with each source and its product having relative merits and demerits. Today, there are three types of sources that are commercially available. In ascending order of their merits, the three types of sources are, Halogen light source, Metal Halide light source and Xenon light source. All three sources employ different methods of light production. Halogen light source emits light on heating of filament, Metal Halide light source produces light when arc discharge ignites gaseous salt whereas Xenon light source produces light when the arc discharge ignites the gas. Though this difference in the technology of light production is immaterial to selling the instrument, it is essential for a sales person to know of the different technologies available so that, if the need arises, the sales person can discuss the issue with the concerned surgeon. All the different types of light sources come with a knob to vary the brightness of bulb.

Apart from the technology they use, these light sources also differ in their features. Halogen light has a temperature of 3200deg K giving it a yellowish cast, Metal halide light has a temperature of 5600deg K rendering it a blue-white cast whereas the Xenon light has a temperature in the range of 5800 to 6000deg K making it pure white in colour. This obviously translates in better colour visualisation which means ease in surgery. Xenon light source also remains bright over its entire life of minimum 500 hrs whereas Metal Halide and Halogen light sources gradually lose their brightness over their life of 250Hrs. approximately. This means that after 500 hrs, Xenon light source can stop anytime; even in the midst of a procedure causing loss of picture. To avoid this, the hospital staff has to be advised to keep one replacement bulb always in the operation theatre. There is no warm-up/cool-down time in Xenon light source whereas Metal Halide light source suffers for 30sec for warm-up and 5min for cool-down. Finally, Xenon light source is the most expensive of the lot followed by Metal Halide and then by Halogen light source.