Surefire is a well-regarded tactical technology company that manufactures reliable LED flashlights. These are used by people whose lives can depend on flashlights such as the military, the police, the emergency servies, adventurers as well as those who work at night.
What is an LED?
LED (Light Emitting Diode) is a superior technology producing stronger and more consistent light than that produced by previous technologies. LEDs emit light when activated by a voltage applied across two leads attached to a semiconductor light source. A semiconductor crystal is ‘doped’ with impurities to increase what are called p- and n-type regions which form p-n junctions, the diodes that produce light when required. P-type regions are those that contain free holes created when a source of energy excites electrons to move to a higher energy shell than their normal one so vacating their previous position. This creates a positive charge as the normal balance between positively charged protons and negatively charged electrons has been upset by the removal of the electron. This positive charge can move from one part of the crystal to another through areas of electron holes. N-type regions, by contrast, contain many free electrons and therefore a negative charge. The crucial part of what happens in the LED occurs when voltage is applied to an LED and electron holes recombine with electrons releasing energy in the form of light.
Why choose Surefire LED flashlights?
The bodies of some Surefire LED flashlights are made from a strong, lightweight, aluminium alloy used in the aerospace industry. This material is highly resistant to potential damage from accidents. Other Surefire LED flashlights are made from the Nitrolon polymer which is lighter than aluminium and easy to handle during cold weather. The LED flashlights from this company use integrated sphere photometers that measure not candlepower (how much light falls on a bright spot) but lumens (the total amount of light produced). Surefire LED flashlights emit blue light of near UV wavelength that strikes a phosphor layer which absorbs this light and re-emits it as white light (a combination of most of the visible spectrum). Most flashlights have a power regulator that finely controls the LED. They also have a flexible beam configuration where light can be used in anything between a spotlight and a searchlight form. They use powerful, disposable 123A lithium batteries which function well over a large temperature range.