Solar Eclipse Viewing: Are Your Glasses Safe?
For the upcoming eclipse on August 21, 2017 Guided Wave purchased some solar eclipse glasses on the Amazon website for a staff viewing party. Purchasing made sure that they had the ISO certification. A few days after the glasses were delivered we got an email from Amazon telling us that our glasses didn’t come from a vendor that was verified to conform to the ISO standards and that they were refunding our money.
We did some reading to try to understand the issues. According to the NASA website (eclipse.gsfc.nasa.gov/SEhelp/safety2.html): The solar radiation that reaches the surface of Earth ranges from ultraviolet (UV) radiation at wavelengths longer than 290 nm to radio waves in the meter range. The tissues in the eye transmit a substantial part of the radiation between 380 and 1400 nm to the light-sensitive retina at the back of the eye. While environmental exposure to UV radiation is known to contribute to the accelerated aging of the outer layers of the eye and the development of cataracts, the concern over improper viewing of the Sun during an eclipse is for the development of “eclipse blindness” or retinal burns.
Well, no one wants to purposely cook their retinas. So we wanted to check the glasses that we purchased. The American Astronomical Society (AAS) website had some advice on verifying eclipse glasses, saying “Unfortunately, you can’t check whether a filter meets the ISO standard yourself — doing so requires a specialized and expensive piece of laboratory equipment called a spectrophotometer that shines intense UV, visible, and IR light through the filter and measures how much gets through at each wavelength.”
Guided Wave manufactures both UV/Vis and Near Infrared (NIR) spectrophotometers that can measure fi lm transmission over the range of 200nm up to 2100nm.
This sounded like a perfect experiment to us! –
To find out IF our glasses were fake take a look at the experiment and results Solar Eclipse Glasses: are Your Glasses Safe? ►