I never paid much attention to polarized sunglasses until I moved to Hawaii. Polarization blocks glare. Polarization is what helps most when the sun is reflecting off the car in front of you, lighting up the clouds in front of you from behind, or reflecting off water or snow.
All Maui Jim sunglasses are polarized by default. If you need strong prescription sunglasses, Spy Optics is your best bet. My husband has a pair of prescription Spy Optics sunglasses these , and he loves them. Oakley prescription sunglasses only go up to a total power of -4 total power is the sum of sphere and cylinder on your glasses prescription.
Spy Optics prescription sunglasses go up to a total power of One last thing about sunglasses: wraparound matters. This should be my last sun protection-related post in the foreseeable future. The end! You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.
You are commenting using your Facebook account. However, those coatings are not nearly as effective in blocking UV radiation. On the other hand, window tinting in buildings and automobiles which is what we measured for our experiment is typically applied as a film or, as in the case of some automobiles, is added as a dye during the manufacturing process. With sunglasses, the focus is on the capacity of the lenses to absorb UV radiation, which can harm the eyes.
Also, window tinting in cars is regulated in different parts of the world, although the rules are less about UV protection than they are about the reduction in visible light transmission, which can reduce heat inside the vehicle but also decrease visibility at night. We used the same Ocean Optics spectrometer and accessories for both the eyewear and window tinting experiments:. Figure 1. Modular spectrometer components can be configured for various transmission setups.
This is just one of many possibilities. In both experiments, the integrating sphere was screwed in to one of the openings on the ACH holder. An optical fiber was then used to couple the integrating sphere to the spectrometer for the detection of light transmitted through the samples Figure 1. This helped to align the collimating lens with the integrating sphere. Light was delivered via the collimating lens through the sample and into the integrating sphere, which was coupled to the spectrometer.
The samples were placed in the path between the integrating sphere and the collimating lens, with the sample surface in contact with the port of the integrating sphere. Each sample was measured in three different locations with the average of the three samples shown in the graphs posted in this article.
An integrating sphere was used for the detection of transmission through the samples to ensure repeatable and accurate results with the curved surfaces of the eyewear and car windows. An integrating sphere is a good option if the reflectivity of the sample changes at different viewing angles. In fact, our measurements were very repeatable regardless of the curvature of the lenses. To evaluate a range of eyewear options, we tested six samples ranging from discount store sunglasses to luxury brand eyewear:.
The glasses were oriented with the outside of the eyewear lens touching the integrating sphere. We observed that the eyewear orientation, proximity to the integrating sphere, and measurement location had little or no effect on the consistency of the measurements. The ring stand held the ACH with the integrating sphere port pointing up to facilitate placement and measurement of the different shaped eyewear lenses.
A black cloth was used to prevent overhead lighting from entering the sphere. This was not unexpected as these glasses were not designed to block UV but to protect the wearer from chemical splashes, breaking glass or other projectiles. Usually they only filter a certain color at a certain location. Looking at clear plastics under stress through polarizing filter is often used to see where the plastic is stressed. For further fun, try using a digital watch with the sunglasses on.
Play around with the orientation of the watch. Tint is not a factor. Waterj2 is right about the stress. The stress can also be present in glass. When glass breaks, it tends to break where the stress is greatest. Safety glass used in cars and elsewhere is intentionally given this stress pattern so that it will shatter into small pieces when broken instead of long shards that could slice and stab.
I can say that to see the pattern, you must have polarized light going through the glass and then through a polarizing filter.
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