The optical radiation commonly called “light” is made up of waves that oscillate in all directions of the threedimensional space, that is to say vertically, horizontally and along all the angles between these dimensions. When this light meets a reflective surface (water, ice, snow, sand, street surface) it undergoes a process called polarization, that is, it begins to move in a two-dimensional range (vertical and horizontal).
The vertical light brings a lot of useful information to the human eye, enabling colour vision and the perception of contrasts. The horizontal light (polarized light), on the contrary, creates optical noise, disturbing vision and generating the so-called reverberation or glare.
Polarized lenses aim at erasing just those annoying reflections that cause glare. They are, in fact, lenses with a “vertical structure” they absorb the horizontal light rays, responsible for glare, letting only the vertical rays pass, which are “useful” and rich of information.
Vision in bright light condition is greatly improved: natural colours, clear and clean vision even in the distance and less eye strain. 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.
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Initially developed by NASA to protect the windows of spacecrafts from cosmic rays, REVO treatment used by COFRA is a multilayer coating conveniently studied and devised, obtained using innovative coating materials and a particular coating ion technology. The advantages of REVO treatment are the following:
Excellent water-repellent treatment performed on the surface of the lenses through a vacuum process that creates a thin and transparent film. The unique formula used during this process provides exceptional water repellency, making the lenses suitable for all those activities where there is high humidity, such as fishing. It can be applied to simple lenses or on the outer layer of any mirrored or REVO lens.
Innovative treatment able to combine both water and oil repellence. This treatment acts as an invisible protective film that can protects the surface of the lens. It can be applied to simple lenses or on the outer layer of any mirrored or REVO lens. This treatment provides the lenses with many advantages: water and oil repellence; resistance to stains and fingerprints; easy cleaning; abrasion resistance caused by particles or dust.
STANAG 2920 and STANAG 4296 are standards for the evaluation of ballistic resistance in all member countries of NATO. Unlike the compliance with the European Norm EN 166 which determines the impact resistance of a steel ball with a diameter of 6 mm and a mass of 0,86 g hitting the eyepieces at a speed of 45 m/s, 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 does not define a minimum protection threshold in the same way as EN 166, but it 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.