Ride like an insect, see like a bee: The CP-vision advantage

Cyclists are insatiable in their optical polarisation needs, paying up to $4000 for the right sunglasses. Here at Xmas Epic, after grinding at the intersection of attitude without remorse, we are proud to present the CP (Circularly Polarised) MurtlesTM.


We believe that the circular polarisation day has come. Timeless, smart, retro: circularly polarised. As a bonus you will be able to see in 3D. The optical sophistication belies the fact that they can be freely obtained (for free) from the cinema at the next 3D movie you see.

We note that Oakley have upped the ante and added to the LivestrongTM JawboneTM ($330) and Pit BossTM ($900) lineup with the new carbon fibre C-SIXTM ($2200). We suspect that this is a direct reaction to the release of the CP MurtlesTM.


Let’s recap on the mode of action of the standard Murtles (or equivalent: JawboneTM etc) that use linear polarisation. With a vertically oriented polarisation film, they block glare from reflections which are predominantly horizontally polarised. With two standard Murtles, one can do the classic “crossed polarisers” experiment that blocks all light by orienting them at 90o to each other. Here the vertically polarised light that passed through the first Murtles is blocked by the second Murtles that are at a perpendicular orientation.
crossed: black
parallel: light

The CP Murtles are an altogether more complex and interesting beast. Each lens allows light of different circular polarisation to pass. In circularly polarised light the direction of polarisation makes a spiral that is either left or right handed. In 3D cinema, the movie is projected with right and left circularly polarised light in two different stereoscopic views that are seen by the left and right eyes when wearing CP Murtles.

A simple test of your CP Murtles. Look in the mirror closing one eye and then the other. The lens with your open eye will be black. The black lens alternates as you switch eyes. Light reflected in a mirror changes the sense of the circular polarisation, and is block as it tries to go back through the same lens. Below shows pictures of a mirror taken through one lens the Murtles then through the other and shows the superior CP quality of the CP Murtles. The lens you photograph through is always the one that appears dark:

Because each lens passes a different circular polarisation, and the direction also turns out to be important, there are many combinations of the crossed polarizers experiment to try. First lets define the direction:


Head – Head All dark, just like standard Murtles.


Head – Tail (or Tail-Head) All light (!)


Tail – Tail Two light, two dark (!!)

Anyone see that coming? This does make sense if you think about it (and spend some days reading up on optics). The CP Murtles have +/-45o quarter wave plates on outside of the lens, horizontal polarisers on inside.

Finally, for those of you who wish to wear your CP Murtles together with your standard Murtles, the order is important. CP Murtles over standard Murtles: everything black:

Standard Murtles over CP Murtles, just like wearing double-strength sunglasses:

Bees have polarisation sensitive vision in the UV. This “P-vision” allows them to know the direction of the sun without seeing it, even from a small patch of sky or on a cloudy day. If you look at the sky at 90o from the sun’s direction through standard Murtles, you will notice that that colour of the sky will change from light to dark as you rotate the Murtles. Thus you too can do a “figure 8 dance” to communicate with bees about the distance and direction to a food source.

The naked human eye has a very slight polarisation sensitivity (“Haldinger’s brush“). Cyclist eyes, however, are usually clothed with the standard Murtles making them very sensitive to light polarisation. This gives rise to funny patterns when looking through car windscreens. The light from LCD screens is also quite polarised. Holding your head are certain angles when using a laptop while wearing standard Murtles (as you do) and the screen is black. Same applies to cycle computers. The screen of the Velomann v1.23 (90o) or Pro-SX4 (45o) is black with my head tilted. But with the CP MurtlesTM, no problemo, these difficulties dissappear. CP MurtlesTM: Polarised sunglasses without the artifacts.

Meanwhile in breaking news, Oakley have sold their first C-SIX on Nov.12 2009 for US$4000. Silly Australian had to get in first. The web site gives a price less than half as much.

“Oakley: How does it feel to know that you are THE FIRST PERSON IN THE WORLD to own a pair of the C SIX sunglasses?
Robert Lang: It feels weird… I have never experienced this kind of feeling before. I feel different. Special. Excited.”

“Oakley Elite C SIX utilizes pure carbon fiber, a material thinner than human hair yet stronger than high tensile steel. This breakthrough innovation from the aerospace industry is blended with resins and assembled into structures more than 40 layers thick. Five-axis Computer Numeric Control machining carves and shapes the composite with a process that requires more than 24 hours of continuous tooling.”

There we have it: 24 hours of continuous tooling. It actually does make sense.


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