When dealing with technologies such as LED flashlights, optical physics, and metallurgy, the technical jargon can sometimes be a bit overwhelming. We have created this abbreviated glossary to help explain some of the common terms associated with tactical LED flashlights and related gear.
6061-T6 Aluminum - a precipitation hardening aluminum allow, containing magnesium and silicon as its major alloying elements. It has good mechanical properties and exhibits good weldability. It is one of the most common alloys of aluminum for general purpose use. It is commonly available in pre-tempered grades such as 6061-O (solutionized), 6061-T6 (solutionized and artificially aged), 6061-T651 (solutionized, stress-relieved, stretched, and artificially aged).
Crenellated - a series of rounded projections (or the notches between them) formed by curves along an edge. On the Elzetta ZFL-M60, this may be used for a striking tool, or to set the light bezel down while in the ON position so that the light/heat may escape between the scallops.
Hard Anodized - involves immersing aluminum in a bath of sulfuric acid, called an electrolyte, and running a low-voltage electric current through the acid solution. The result of normal anodizing is a thin coating of aluminum oxide (rust) on the surface of the original aluminum sheet. If the acid solution is cooled to the freezing point of water and the amount of electric current increased substantially, however, the process is called hard anodizing. Hard anodizing produces a much thicker coating of aluminum oxide, penetrating holes and fissures in the surface to create a more uniform appearance than regular anodized aluminum. Aluminum sheets processed by hard anodizing may have a dark brown or black surface, but other colors can be created. Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001") are known as Type II in North America, as named by MIL-A-8625, while coatings thicker than 25 μm (0.001") are known as Type III, hardcoat, hard anodizing, or engineered anodizing.
LED (Light-Emitting Diode) - a semiconductor light source. The LED is based on the semiconductor diode. When a diode is forward biased (switched on), electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is usually small in area (less than 1 mm2), and integrated optical components are used to shape its radiation pattern and assist in reflection. LED's present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability. However, they are relatively expensive and require more precise current and heat management than traditional light sources. Current LED products for general lighting are more expensive to buy than fluorescent lamp sources of comparable output.
Lumen - the SI (International System of Units) unit of luminous flux, a measure of the power of light perceived by the human eye. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light. The lumen is defined in relation to the candela by 1 lm = 1 cd X sr. That is, a light source that uniformly radiates one candela in all directions radiates a total of 4 p lumens. If the source were partially covered by an ideal absorbing hemisphere, that system would radiate half as much luminous flux -- only 2 p lumens. The luminous intensity would still be one candella in those directions that are not obscured.
Mil-Spec - A United States Defense Standard, often called a military standard, "MIL-STD", "MIL-SPEC", or (informally) "MilSpecs", is used to help achieve standardization objectives by the U.S. Department of Defense.
Polymer - a large molecule (macromolecule) composed of repeating structural units typically connected by covalent chemical bonds.
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