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NXT lenses

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NXT® lenses

In the past there were fragile lenses with excellent optical properties or tough lenses with poor optical properties.

NXT® has changed all that.

NXT® was formulated in the early 1990s for new generation attack helicopter windshields. The new material is bulletproof, lightweight and optically superior. After years of intensive research to optimise the technology, Bigatmo’s NXT® lenses are the next step in its evolution.

Next Generation optical properties

NXT® lenses are formed in glass molds with long, carefully controlled curing times, producing lenses with very low internal stresses. The result is a clear lens with advanced optical properties and virtually no chromatic aberration. It’s easy to see the difference with NXT®:

Polariscope images to comparing internal stresses between NXT® (left) and polycarbonate (right)

Polariscope images show internal stresses in lenses. NXT® (left) and polycarbonate (right)

Images comparing chromatic aberration between NXT® (left) and polycarbonate (right)®

Images comparing chromatic aberration between NXT® (left) and polycarbonate (right)

Low internal stresses are just one of the measures used to evaluate the optical quality of a lens: Bigatmo NXT® lenses also have a much higher abbe number than polycarbonate (improving the clarity of the lens) a refractive index that makes them ideal for both plano and RX applications, and a low surface reflection (reducing glare). Combined with the strength and toughness of NXT®, these elements result in a truly unbeatable lens.

Strength

NXT® has been described as clear armour. A sheet just 6mm thick will stop a .22 bullet. The video shows an NXT® block stopping a 9mm round dead in its tracks:

 

Bullet block

Bullet block

Our lenses are less than 2mm thick and certainly aren’t bullet proof. However, NXT® is by far the strongest lens material on the market. It passes ANSI’s High-Velocity Impact Test; a stringent test where 1/4-inch steel spheres are fired at the lens at a velocity of 150 feet-per-second.  If an NXT® lens is hit, the material returns to its original shape with virtually no residual distortion. In fact, it’s hard to see the impact point on NXT®:

Images comparing the effects of an impact test on NXT® (left) and polycarbonate (right)

Images comparing the effects of an impact test on NXT® (left) and polycarbonate (right)

NXT® also doesn’t suffer from stress cracking or hairline cracks – the quality of the lens won’t deteroriate, making it extremely durable and long lasting.

Lightweight

With a specific gravity of 1.11 (g/cm³) NXT® is just about the lightest lens material available. This makes our sunglasses so comfortable you’ll forget you’re wearing them. For comparison, the most common materials used for sun lenses are Polycarbonate (sg 1.22), CR39 (sg 1.32) and crown glass (sg 2.53).