Tifosi UV-Reactive Sunglasses Characterization

Intrigued by the claims of Tifosi's UV-reactive glasses, I sought to empirically validate their performance. Through rigorous photometric analysis, I aimed to discern whether these glasses truly enhanced visibility in varying light conditions, particularly for mountain biking enthusiasts traversing fluctuating terrains. These glasses are photochromic UV-reactive, meaning when you wear them inside and then go outside, they will change from nearly transparent orange to dark orange amber after ultraviolet light exposure.

First, we take a radiometric spectrum measurement of the unfiltered natural sunlight from the sky using a tripod-mounted OceanOptics spectrometer. It wasn't cloudy, so our spectrometer was pointed at the blue of the sky off 5-10 degrees or so from direct sunlight.
(Don't look at the sun even with your digital sensors!)

Next, we quickly mount the Tifosi lens in front of the opening of our spectrometer to cover all intake of light, making sure it is all filtered light. We then collect a new radiometric spectrum measurement.

From research at MIT, we can know what the sensitivity of the human eye is, essentially how well we can see each wavelength of light. It is a normal function centered around 550nm, and is normalized to a value of 1. We multiply eye sensitivity with the radiometric measurement to get the resultant photometric spectrum of unfiltered natural sunlight.

Now we do the same sensitivity multiplication to get the photometric spectrum of natural light as seen through the filter of the Tifosi lens. While the units themselves are arbitrary, they are consistent between trials as a qualitative value. Therefore we see the glasses reduce intensity by roughly 76%! Fairly substantial.

Finally, we compare the radiometric spectrums of the filtered and unfiltered light in order to determine what was absorbed in the lenses rather than continuing to the eye. This is simple through subtracting the filtered light from the unfiltered light. What we see is the glasses significantly reduce wavelengths on the blue end, which is strange given how the human eye is insensitive to blue light. It might also have to do with the way our brains can detect low levels of photons, and removing them frees up more processing power for object identification while moving at higher speeds. Tifosi orange->amber glasses have helped me with my mountain bike riding.

Measurements conducted with OceanInsight Ocean Optics Spectrometers, https://www.oceaninsight.com/products/spectrometers/

Do you need help with the technical instrumentation for characterization of your systems? Let me know!

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