Reflection refers to the process by which light bounces off a surface. In optics, when light hits a reflective surface like a mirror, it changes direction based on the angle at which it strikes the surface (the angle of incidence) and the angle at which it reflects (the angle of reflection). This principle is governed by the law of reflection, which states that the angle of incidence equals the angle of reflection.
In the context of telescopes, reflection is crucial for gathering and focusing light. There are two main types of telescopes based on this principle:
- Reflecting Telescopes: These use mirrors to gather and focus light. A large concave mirror (main mirror) collects light from distant objects and focuses it to a single point. A smaller secondary mirror can direct the light to an eyepiece or camera. The advantage of using mirrors, as opposed to lenses, is that mirrors can be made much larger without the risk of chromatic aberration (distortion of colors). Additionally, mirrors are easier to support since they can be supported from behind, unlike lenses, which need to be supported at their edges.
- Refracting Telescopes: These rely on lenses to focus light. While they don’t directly use reflection for focusing, the principle of light reflection is still present in terms of the optical elements being designed to minimize distortions.