Beam configuration is produced by focusing and/or diffusing the light from an illumination tool’s emitter, and it includes (1) the angle of the cone of light emitted by a flashlight or WeaponLight, which can be narrow or wide; (2) light distribution within the light cone, which can be bright in the center and dimmer elsewhere, or the reverse, or extremely even throughout the cone. Light distribution also includes irregularities — hot spots, dark rings, or bright rings — caused by imprecise reflectors, improperly surfaced reflectors, or "adjustable focusing" that only re-arranges the beam's defects.
Inferior illumination tools produce beams with dark or bright spots, which in a moving beam can be mistaken for moving objects; or bright central “hot spots” that tend to seize your attention. Hard-edged beams, like those of theatrical spotlights, can lack the surrounding light necessary for peripheral vision. This latter effect worsens under stress, when the brain concentrates on central images, and when people and objects seem to appear suddenly out of the dark, provoking an instinctive startle response.
In contrast, the superior beam configuration in SureFire flashlights and WeaponLights results from light that is focused and diffused in a manner optimized for the illumination tool’s particular application, such as close-range use, or long-distance spotlight/searchlight use, or somewhere in between. Diffusion or “smoothing out” of the beam is achieved by means of adding either tiny irregularities or a series of regular shapes into the surface of the tool’s focusing element (more below) reflector or refractor. Both methods effectively randomize the light as it leaves the focusing element, thus blurring the edges of any central bright cone or other light/dark boundary produced by the tool’s focusing element.
A third method of diffusion is passing the light through a translucent window, such as those on our SureFire Beam Diffusers.
Focusing Reflectors and Refractors
Focusing is done by means of either a reflector that “bounces” the light off a shiny surface, or via a refractor, or lens, that “bends” the light as it passes through a clear substance such as glass or polymer. SureFire uses both methods, depending on the illumination tool’s application.
Reflectors— SureFire reflectors are made from CNC-machined aluminum instead of stamped metal or molded plastic. Our reflectors exhibit superior strength, heat-transfer capabilities, and geometric exactness, the latter permitting precise placement of emitters inside the reflector, typically within .005" of optimum. Additionally, SureFire reflector surfaces are textured 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 type 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.
TIR Lenses —SureFire Total Internal Reflection (TIR) lenses are primarily refracting elements, but as their name implies they also utilize reflection. Our TIR lenses are precision-molded from a clear, tough cyclo-olefin polymer that surrounds the LED emitter and gathers virtually all the light produced, then reflects and refracts it forward in a carefully designed beam pattern. Typically the pattern is a comparatively “tight” brighter central cone of light that provides good reach; this is surrounded by a cone containing the remainder of the emitted light, which provides illumination for your peripheral vision.
Tempered Windows With Anti-Reflective Coatings
The transparent covering that protects the reflector and emitter of an illumination tool from debris and water is called the window. SureFire WeaponLight windows and those on most SureFire flashlight models are made of tempered, coated Pyrex glass. Pyrex 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.
After performing any cutting, shaping, and drilling required to achieve its final shape, a piece of Pyrex 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. Additionally, 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.