D=0.61λ/N*sin（ /2）
D: Độ phân giải
If you want to improve the resolution, you can by: 1. Reduce λ, such as using ultraviolet light as a light source; 2. Tăng N, such as in cedar oil; 3. Tăng the , that is, reduce the distance between the objective lens and the specimen as much as possible