FAQs
Frequently Asked Questions
What is a Nano-texture and How Does it Work?
A nano-texture is a collection of cone-like features that are fabricated into the surface of an optic like a lens or prism. An individual feature has height and width dimensions that are in the tens to a few hundred billionths of a meter, the nano-meter (nm) scale. These features are packed so tightly that their spacing is everywhere no more than 150-250nm. Now imagine a blue or red light wave travelling through such a surface where a wave front will first encounter the tips of the features and then gradually more and more of the feature before entering the bulk of the optic. Without any flat interface to bounce off, the blue and red waves just travel right through without reflection – anti-reflection (AR).
What are Motheye Structures, and is an RAR Nano-texture the Same Thing?
For night flying moths, having smooth reflective eyes is a sure way to get eaten by owls, so evolving stealthy non-reflecting eyes was critical to survival. But not just any non-flat surface would do – large features with a rough or matte appearance scatter too much light and make vision blurry. So nature evolved nano-meter scale, non-scattering but AR features packed in a regular honeycomb array on the eyes of moths, suitably referred to as “Motheye”. Such a graded AR function has also evolved for the “Glass-wing” Butterfly to allow its transparent wings to become invisible against the background foliage. Interestingly, the features on the wings of the Glasswing butterfly are distributed randomly thereby avoiding another pitfall – that of macro-scale organized scattering of light at high angles – known as diffraction – that occurs when even nano-meter scale features are arranged in a regular array. TelAztec’s Random Anti-Reflection, or RAR nano-texturing process creates such randomly distributed features that provide extreme AR function over a huge range of wavelengths, all while avoiding losses from scatter or diffraction.
How Low is the Reflection Loss from RAR Nano-textured Optics?
The graded refractive index function produced by nano-texturing reduces reflections to levels typically below 0.1% over a huge range of wavelengths. For laser applications, the reflection loss can be driven 10 times lower to the 0.01% level over a specific band such as the 266-365nm UV laser range, or the 1030-1080nm near infrared wavelength range of industrial laser optics, or the 1500-1600nm telecommunications optics wavelength band.
Does an RAR Nano-textured Surface Absorb Light?
The structures that make up the RAR nano-texture are created by removing material from a polished surface using a proprietary and patented dry plasma etch process. This fast and efficient subtractive manufacturing method results in the texture inheriting all of the optical, mechanical, and chemical durability of the bulk optic material. So for RAR nano-textured lenses, fiber end caps and windows made from low absorption fused silica glass, we say that there is “Zero-Added Surface Absorption” from the nano-texture.