**Geometrical Optics**
======================

.. _small_angle_def:

**Small-angle approximation**

Approximation that is valid when the size of a spherical mirror is significantly smaller
than the mirror's radius; in this approximation, spherical aberration is negligible and
the mirror has a well-defined focal point.

.. py:currentmodule:: symplyphysics.optics.geometrical_optics

**Contents:**

.. toctree::
    :maxdepth: 4

    optics.geometrical_optics.invariants
    optics.geometrical_optics.lenses
    optics.geometrical_optics.mirrors
    optics.geometrical_optics.prisms
    optics.geometrical_optics.refraction
    optics.geometrical_optics.telescopes