paraxial image

Paraxial imagery, also known as first-order imagery, is a concept in geometrical optics that simplifies lens behavior by considering only rays close to the optical axis. This approximation assumes that the angles involved are very small, allowing for simpler mathematical treatment. In this model, all paraxial rays originating from a single object point converge at a single image point. This simplification is crucial for understanding how lenses form images, especially in the context of the thin lens approximation, where the lens thickness is negligible compared to its surface curvature. The paraxial approximation is fundamental to the Gauss theory of lenses, which uses principal and focal points to describe image formation.12345