Air lens for optical aquarium

description

The "air lens" consists of two thin glass bowls, connected to each other bowl-to-bowl, the peripheral rims are sealed, and the air lens is immersed in water.
Unlike the glass lens in the air, it is an air lens found in water. Although it is biconvex, you will notice that it is a diffuse lens; Peek at me a small object through it while it is submerged in water, and you will notice a simulated, smaller, straight and close image, similar to that obtained by a diffuse glass lens in the air.