Electronic Power Regulation
SureFire's LED illumination tools contain a rugged, sealed electronic power regulator that supervises the operation of the LED (with the exception of the A2 Aviator, in which the xenon lamp is regulated). This circuitry assesses battery output, monitors system performance, and controls power supplied to the LED. Power regulation provides a more consistent light output for the usable life of the batteries. Although any LED may continue to produce negligible light output for up to several hundred hours, the amount of useful light produced is of a shorter duration. Power regulation circuitry reduces the amount of negligible output and increases the overall duration of useful light output.
Beam Character and Reflector Design
Alkaline battery flashlight on left shows beam with dark spots and rings. SureFire E2e on right produces a smooth, pre-focused beam. Both lights are shown using new lamps and fresh batteries. Beam character determines an illumination tool's suitability for tactical use. It includes light distribution, or the way the beam's light is apportioned from the center outward, and irregularities, such as dark spots, hot spots, and rings. Irregularities are caused by imprecise reflectors, improperly surfaced reflectors, filament support leg shadows, or "adjustable focusing" that only re-arranges the beam's defects.
Many illumination tools exhibit inferior beam character. When directed at night on people, objects, or surfaces, they can produce a view that is confusing, misleading, or even alarming. For example, dark or bright spots in a moving beam can be mistaken for moving objects; bright rings tend to seize our attention. Hard-edged beams, like those of theatrical spotlights, can lack the surrounding light necessary for peripheral vision. Closeup photo shows beam-smoothing micro-texture on a SureFire reflector. This latter effect worsens under stress, when the brain concentrates on central images. A further problem occurs when a hard-edged beam causes people and objects to appear suddenly out of the dark, provoking an instinctive startle response that can trigger a weapon.
SureFire reflectors are designed to produce optimum beam character. Made from CNC-machined aluminum instead of stamped metal or molded plastic, they exhibit superior strength, heat transfer capabilities, and geometric exactness, the latter permitting precise placement of lamp filaments inside the reflector — within .005" of optimum.
Additionally, SureFire reflector surfaces are covered with tiny ripples that reflect light at slightly different angles, smoothing out beam irregularities and producing a bright central area surrounded by a gradually diminishing corona. This sort of beam is perfect for tactical applications because it clearly illuminates the main object of interest while providing enough light for the observer's peripheral vision.
Tempered Pyrex® Windows With Anti-Reflective Coatings
On illumination tools, the transparent covering that protects the reflector and lamp from debris and water is called the window (not "lens"). SureFire WeaponLight windows — and those of most SureFire flashlight models — are made of tempered, coated Pyrex glass, as explained below.
Pyrex — Pyrex glass is essentially ordinary glass with boron added, which gives it two desirable properties: it melts at a higher temperature and has a much smaller coefficient of expansion. In illumination tools, the latter quality helps resist cracking when one part of the window is heated more than another, as when an illumination tool is turned on, or when it is suddenly cooled, as when splashed with water.
Tempering — After performing any cutting, shaping, and drilling required to achieve its final shape, a piece of glass is tempered by heating it above the annealing point (about 1,100°F) and then quickly cooling it with forced air. The resulting surface compression stresses give the piece several times the structural strength of common slow-cooled, or annealed, glass.
Anti-reflective Coating — The windows of SureFire illumination tools have a thin coating of material that reduces reflection losses at the glass surface, which increases the net lumen output of the WeaponLight or flashlight.
