Optics studies light, its propagation, and instruments for forming images and measuring optical spectra.
The central question is how light carries information from a source to an observer. A useful description must explain both where the light goes and how its distribution changes. In geometrical optics, light rays locate paths and images; in physical optics, an electromagnetic wave has a wave amplitude and a wave phase, so overlapping contributions can produce wave interference and diffraction. These descriptions address different levels of detail within the same subject. [ref].
An image is especially interesting because a single object point emits light in many directions. An optical lens redirects part of that spreading bundle toward a corresponding image point; repeating this construction over the object preserves spatial information. Simply gathering more light is insufficient: light rays from distinct object points must arrive at distinct locations. This is why an optical camera needs both an optical lens and a correctly positioned receiving surface. The thin lens example below makes that correspondence quantitative. [ref].
Optics is the branch of physics that focuses on the study of light and its interactions with matter. It encompasses the behavior of light in various mediums, including reflection, refraction, diffraction, and polarization. There are two main branches of optics: 1. **Geometric Optics**: This branch deals with the approximation of light as rays. It studies how light travels in straight lines, how it interacts with lenses and mirrors, and how images are formed by optical systems.
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