There are 3 ways to identify whether anti-blue light lenses have the function of anti-blue light:
(1) Spectrophotometer test method. This is a laboratory method, the equipment is expensive, bulky and not easy to carry, but the data is accurate, sufficient and quantitative. General retail stores are unlikely to use this method, but there is an alternative method, that is, the use of Shenyang Shangshan Medical Equipment Co., Ltd. produced the "portable blue light meter", can measure ultraviolet and blue light transmittance, this method is a multi-point wavelength-weighted average of the test, can test the integrated blue light value, but there is no sub-wavelength test value.
(2) Testing with an anti-blue light pen on the market. This method is low cost, easy to test, and can be used for terminal display, but there are three problems: First, the blue light emitted by the blue light pen on the market is basically around 405nm wavelength, with a bandwidth of about 10nm. It is blue-violet light. Relatively speaking, this wavelength light source or find some. If you want to 430nm as the center wavelength of the blue light source, you need a relatively special filter, the pen price will go up. Second, a single wavelength test is not sufficient for us. Third, we should also focus on the specific transmittance of each wavelength point, rather than a qualitative data. All in all, using the blue light pen method is a last resort and an optional reference.
(3) Utilizing corporate self-affirmation. At this point, we have to believe in the power of the brand, and believe that most lens manufacturers will not falsify the quality and efficacy of their products. For consumers, we can also use the same idea, for example, we say to the customer: "This brand is an international (domestic) famous brand, we have been selling for a long time, the user reputation is very good, you can rest assured; this is the product test report provided by the brand name, which is issued by the national authority, there will be no problem."
On the 2nd question, the answer is already obvious, the reason why different manufacturers provide different results of the blue light pen to test the same lens, is because each blue light pen has a different spectral range, only is 435 ± 20 nanometer blue light pen to test the efficacy of the anti-blue light lenses.