#spherical selection

A Place, Three men, One Life

This article A Clean Well-lighted Placehas profound meaning in itself, and its author is a famous writer. When I first read this story, I only feel angry about this young waiter and pity for the old man. After our teacher analyzing it during the class, I have a better understanding about this story and I want to share my opinions with you. The story reveals a common phenomenon in our society,…

When you buy glasses, how to choose the lens ? (1)

  When refer to how to choose the lens. we will talk about the refractive index, coefficient of wear resistance, spherical selection, Abbe number, anti-fouling ability, brand selection, and functional choice.

    1.Refractive index

The refractive index of the lens is determined by the material of lens.

In the case of the same thickness of the center, the lens of the same degree and the same…