Sunday, July 20, 2014

The Curious Case of The Self-Lensing Goggles

It was part of my job responsibilities (if not my job description) for a long time to figure out how to do things that were a little bit "out there" using what we had and no more, so let me be clear that a lot of what I say on ere and the conclusions I draw are not necessarily "new concepts" but simply new connections made between pre-existing concepts.

I don't like biking in the rain, but when you bicycle to work everyday, it's bound to happen more than once that it's bright and sunny when you ride to work, but then overcast and raining when it's time to head home. If I refused to ride in the rain, I might be stuck at work for a good long while (as I'm writing this, I've been off-shift for about five hours, and it's still coming down) or reduced to calling someone to pick me up (which somewhat defeats the purpose of biking instead of driving my own car).

I've been caught out in the rain before, and I've learned to pack appropriately. Towels, goggles, spare socks (for cold weather only), waterproof shoes I can wear without socks (for warm weather only), and of course my standard fare of lights for visibility in incliment weather.

Except my goggles don't have prescription lenses, and I do wear eyeglasses. While I'm quite comfortable staggering around my apartment without my glasses on, or walking to the library in the dead of winter, riding a bicycle at speeds of ten to fifteen miles an hour is a different matter.

At least, until the rain starts to build up a film on the goggles.

Everyone beyond fifth grade (and most people earlier than that) should know that light passing water is stretched, not unlike the "glass" of a magnifying-glass or eyeglasses. You see the effect most pronounced when looking though a glass of water, either to the hand on the other side or a straw in the middle, or when looking at objects in a swimming pool or bathtub. This effect actually appears everywhere water is present, in drops budding down a leaf or a window...

When my goggles grow a thick film of water, which happens when the rain is coming down at any rate heavier than a sprinkle, the lensing effect starts to kick in; while the effect (and the flowing water) isn't perfect, about a third of each side hits the sweet spot that matches my own prescriptions.

The sweet spot moves around because the thickness of the water is always changing, older water dripping off the bottom and newer water splattering on on top, but the ratio of blurriness to clarity seems to remain remarkably consistent. I'm not sure of the rating on my eyeglass's lenses, but I can't help but wonder if my own handicapped eyes happen to be in a "sweet spot" of their own.

Any optometrists out there in my audience care to weigh in?

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