What are concave mirrors used in telescopes?

In a reflecting telescope, instead of a convex objective lens, a concave mirror is used to collect parallel rays from the object and form an image at the focal point. Then the convex eyepiece lens is used to magnify this image for the viewer. Concave mirrors focus light at a focal point using reflection, not refraction. read more

ALL mirrors in telescopes are to collect/concentrate and focus the received light. A combination of concave and convex mirrors and lenses is used to collect a larger area of light and focus it onto a smaller, possibly brighter image surface. read more

Large telescopes traditionally have a concave mirror at one end. Similar to how a concave mirror works in a microscope, the concave mirror in the telescope collects light. Instead of shining the light up to a specimen, it shines the light from distant stars onto a flat mirror. read more

Today, two types of telescopes are widely used: refractor telescopes, which employ lenses, and reflector telescopes, which have mirrors. In a reflector telescope, light from the object of interest enters the far end of the telescope and strikes a concave mirror at the end closest to the viewer. read more