Before you go ahead, I want to take this time to wish you all a Merry Christmas. If the downward spiraling economy has taken a toll on your finances and your kids are wondering where this year's gifts are, tell them Father Santa had swine flu and is in bed rest. :)
The following video from Giro's headquarters explains how they design sunglasses. What you'll see is a bunch of guys brainstorming design patterns. Then some of them produce said designs on CAD, later rapid-prototyping them on 3D printers to test the initial look and wear of the frame.
The Futures Channel has an interesting 10 min segment on the making of sunglasses. Again, Giro is the eye wear brand featured and the presentation goes a little into the behind the scenes manufacturing and testing at Giro's optics partner, Zeiss. The latter creates the lenses for Giro. The video can be seen by clicking on the image below.
You'll see in the above video that sports eye wear start their life as little pellets of polycarbonate (Abbe # = 31), which are then combined with specialized dyes to tint them which are then melted to ensure uniformity of color. The pellets are applied into an injection molding machine at high temperature and pressure and what results is the familiar look of an eye-shield.
Eight different types of washing later, the lenses get reflective and anti-scratch coatings. Optical coatings in lenses are almost always made of magnesium fluoride (MgF2). Sabrina Malnati, the manager of R&D at Zeiss Vision Sun lens Department, reviews their resolution, prismatic, impact and abrasion test protocols and the international standards that govern them.
What interested me most in the video is how the tints are created for these lenses using soluble organic dyes and metal oxide pigments. Tints are associated with enhancing optical attributes of lenses such as clarity, contrast and sharp vision. Designing towards an optimum tint is a subtle process. The highest quality lenses are optically accurate and do not distort shapes and lines or give the wearer discomfort.
What upset me is that Futures Channel calls the video the "Science of Sunglasses" but little is said about the optical science behind such eye wear.
So here are a few good resources I have collected if you want to learn more about the exciting field of lens optics from a technical standpoint.
1. The Science Of Color In Non-Technical Terms
2. Biology Of Color Vision
3. The Math and Physics Of Lens Design
4. How Sunglasses Are Made : Madehow.com
5. The Science Of Lens Treatments : Tints & Coatings
6. How Optical Lenses Are Created In A Lab : Video
Testing of sunglasses are really important not only because these things protect your eyes against harmful sunlight but also against impacts that could tear a hole in your eye if needed. I couldn't help attaching this explanatory video from Oakley's lab because the speaker, Bryan Shelton, seems to really knows what he's talking about. Enjoy.