The Collimator Bulb used in the Proteus Lamb Sub-Assembly. The Proteus XR/a Automatic Collimator uses a special collimator light bulb. When the collimator lamp burns out, it must be replaced with a replacement bulb in the Proteus XR/a renewal parts section. The collimator used a halogen type of light bulb, it is also known as a tungsten halogen, quartz-halogen or quartz iodine lamp. It is an incandescent lamp consisting of a tungsten filament sealed into a compact transparent envelope that is filled with a mixture of an inert gas and a small amount of a halogen such as iodine or bromine. The Proteus XR/a collimator lamp is designed to operate at 24VAC for 150 hours continuous, other type replacement bulbs will burn out much quicker, as they are only designed for 50 hours continuous use at 24VAC. The bulb change is feasible without the realignment of the superposition of light field to X-ray field and is possible without qualified service personnel intervention. This selection process allows the bulb to be replaced by the end user with no alignment required for X-ray to light field.