Reflector Telescope Works
A reflector, or reflecting telescope uses an arrangement of one or more curved mirrors to gather light and return it along an optical path to a point of focus. The most critical element of this type of telescope is the major light gathering source – the primary mirror. Light strikes the parabolic, reflective surface of the primary and returns to a point of focus called the focal plane. Because each spherical or parabolic shaped primary mirror is slightly different, the distance the light needs to travel to achieve focus is called the focal length. At its focus point, the image (in a simple reflector telescope) is collected on another mirror surface called the secondary. The secondary mirror is then aimed towards the viewer who uses a series of lenses called an eyepiece to magnify the image and send it to the eye.