Bigatmo Sunglasses

In the past there were fragile lenses with good optical properties and tough lenses with mediocre ones. NXT® has changed all that.
There is no single measure used to define the optical properties of a material. Instead, a number of factors are considered, including the method of manufacture. NXT® lenses are formed in glass molds with long, carefully controlled, curing times which produces lenses with very low internal stresses. This combined with other technical measurements including refractive index, abbe number and the amount of surface reflection are all considered when determining the optical quality of a lens. Lenses made from NXT® are of an excellent optical quality.

Here is a comparison between NXT® and Polycarbonate. The lenses are scanned using a Polariscope which shows the internal stresses. The clarity of the NXT ® lens on the left dramatically illustrates its superior optical properties.



Here are some images comparing ‘chromatic aberration’ between NXT® and Polycarbonate. The clear one on the left is NXT®!

Sometimes being lightweight is a good thing. Wearing sunglasses should not be a burden; in fact our objective is to make them so comfortable that you forget you’re wearing them. Weight is obviously important, especially over time. NXT® has a specific gravity of 1.11 (g/cm³) which is just about the lightest lens material available. 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).

NXT® has been described as clear armour and the video clip link on this page is an excellent demonstration of its strength. It shows a ballistics test of a 9mm round impacting an NXT® block.

In fact; a 6mm sheet of NXT® will stop a .22 bullet (a 6mm polycarbonate sheet won‘t). We don‘t make safety specs – just excellent sunglasses. Our lenses are less than 2mm thick and they certainly aren‘t bullet proof, but NXT® is by far the strongest lens material on the market. Your eyes are a very precious asset and we believe there is no excuse for using anything else.



ANSI Z87.1 High-Velocity Impact Test: The American National Standards Institute (ANSI) has established the most stringent impact and projectile penetration standards for optical lenses. The standard specifies that high-impact lenses must pass ‘high-velocity’ testing where 1/4-inch steel pellets are ‘shot’ at the lens at a velocity of 150 feet-per-second. Lenses made from NXT® material pass the ANSI Z87.1 High-Velocity Impact Test and the FDA Drop Ball Test.*

The strength and durability of NXT® has other benefits – our lenses won‘t suffer from stress cracking and if a lens receives an impact the material will return to its original shape with the only damage being seen at the point of impact and virtually no residual distortion.

These photos show lenses after an impact test. It is hard to see the impact point on the NXT® lens.



*In the basic impact test, a 1-inch (2.54 cm) steel ball is dropped on the lens from 50-inches (127 cm).

Another feature of NXT® is its resistance to the common chemicals people use every day. These include household products such as bleach and nail polish remover or solvents like alcohol and acetone.

We do not produce safety specs and our sunglasses should not be treated as such, especially when handling chemicals. Never deliberately apply chemicals to Bigatmo lenses.