Among all applications of geometric optics, the one that stands out most for its use in everyday life is the study of spherical lenses, either in sophisticated astronomical research equipment, or in ordinary digital cameras, whether in spectacle lenses or magnifying glasses.

We call **spherical lens ** the optical system consists of three homogeneous and transparent means, the boundaries between each pair being two spherical surfaces or a spherical surface and a flat surface, which we call lens faces.

For a simple study we will consider that the second medium is the lens itself, and that the first and third means are exactly the same, usually the air-immersed glass lens.

## Lens Types

Among the spherical lenses that are used, six of them are of major importance in the study of optics, namely:

### Biconvex Lens

It is convex on both sides and has a thinner periphery than the central region, its elements are:

### Flat Convex Lens

It is flat on one side and convex on the other, has a thinner periphery than the central region, its elements are:

### Concave Convex Lens

It has one concave and one convex face, has a thinner periphery than the central region. Its elements are: