Vision in bright light condition is greatly improved: natural colours, clear and clean vision even in the distance and less eye fatigue. Therefore, the use of polarized lenses allows to filter radiations selectively, without damaging any detail of the image. In the presence of bright light, in fact, they act as a “Venetian blind” which blocks unwanted rays, while in the absence of glare they behave exactly like traditional lenses.
|VISION WITHOUT POLARIZED LENS||VISION WITH POLARIZED LENS|
STANAG 2920 and STANAG 4296 are standards for the evaluation of ballistic resistance in all member countries of NATO. The compliance with STANAG 4296 standard guarantees the ballistic resistance defined by STANAG 2920 standard, determining the ballistic resistance against bullets having a caliber of 3.6 mm (0,14″) and a weight of 325 mg, fired at a speed of 215 m/s, or 774 km/h (with the possibility of reaching even higher speeds as reported by the test report). STANAG 2920 allows to specify a speed V50 that represents the speed at which a bullet could perforate the eyepiece with a 50% probability. In addition, glasses complying with STANAG 4296 standard must also meet a number of requirements, such as:
- impact resistance according to the conditions defined by STANAG 2920 standard;
- criteria about their use: the glasses must be as light and comfortable as possible, have a maximum fogging reduction (through ventilation and/or an appropriate coating) and have a good resistance to scratches in case of prolonged use;
- optical quality: glasses must provide a visual field of at least 160° and must not distort vision;
- additional features: the glasses must have a gloss level as low as possible and must be compatible with the use of other protective elements.