The instructions tell you to shine the blue light pen onto the lens of the glasses, with a white background behind. The blue light pen test usually comes with cheap blue light glasses imported from China. You can’t tell to what extent they filter blue light, though. If you notice a blue reflection on the surface of the lens, it means that your blue light glasses are reflecting blue light. To do this test, tilt your glasses to an artificial light source. This is a very rough test but can give you an idea if your glasses are doing some work or are completely fake. Use a reflection test to tell if glasses are blue light (for daytime glasses) If you’ve already bought a pair, then contact the seller and ask them to provide the report as proof.Ģ. Read the transmittance spectrum report yourself, before you buy any pair of blue light glasses. How to read a transmittance spectrum report: If the seller doesn’t own a spectrophotometer, it means that don’t even know which wavelengths their glasses are targeting and you definitely should not buy from them! That’s why it’s the job of the seller to display the spectrophotometer results on their website. They can cost between $1000 to $10,000 and it doesn’t make sense to buy a machine which costs more than your glasses themselves! Lab-grade spectrophotometers are pretty expensive. The resulting graph (called a transmittance spectrum report) reveals to the smallest nanometer which wavelengths are being filtered, and at which intensity. Using a spectrophotometer is the most accurate way to tell if glasses are blue light. South Georgia & South Sandwich Islands (GBP £)
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