Well, it seems that you are quite curious about it. So, as a matter of fact, there are a lot of answers to this question because the precise inventor of sunglasses is unknown. However, according to a lot of documents, it is believed that sunglasses are invented by Chinese in the 15th century. However, the sunglasses of that time of course could not be equal to our sunglasses now. But it is still inspiring.
Well, first, you should know that early sunglasses are used for a special purpose and it wasn't to block the rays of the sun. According to some references, it wasn't until the 20th century that modern-type sunglasses came to be. In 1929, Sam Foster, founder of the Foster Grant company sold the first pair of Foster Grant sunglasses on the Boardwalk in Atlantic City, NJ. So we can say that Sam foster invented sunglasses at that time. And nowadays, sunglasses are wildly used in many places. And they have different types and different functions. And basically, they are polarized and have uv protection. So they can protect your eyes from sunlight and uv rays.
In ancient times, people have thought about the idea of finding something to cover on the eyes to decrease the amount of uv rays from the strong sun lights. It is not until 1929 that an entrepreneur named Sam Foster had put sunglasses into mass production in America. He was doing a roaring trade through his company called Foster Grant of Atlantic City. In 1936, Polaroid filters were invented which make the design of the glasses have the role of protecting against UV rays for the first time. It is a desirable item for health reasons as well as for reasons of fashion and comfort. It will be useful for many people, especially the soldiers who had to fight in the French summer. However, there have been few developments in sunglasses since then. The basic science and materials of the sunglasses almost remain the same for the last seventy years. Then, sunglasses become more and more popular among the customers.