BRAINCAKEReflecting Telescopes
A reflecting telescope uses a large concave mirror, instead of a lens, as its objective. The arrangement you need to know is the Cassegrain arrangement:
• a large concave parabolic primary mirror with a hole in its centre collects the light
• a small convex secondary mirror reflects the light back towards the primary
• the light passes through the hole in the primary and is focused just behind it, where an eyepiece (or camera) is placed
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Key terms in this lesson
- chromatic aberration
- A fault in an image formed by a lens in which different wavelengths of light are refracted by different amounts, producing coloured fringes and a blurred image.
- diffraction
- The spreading out of a wave as it passes through a gap or travels round an obstacle.
More in Astrophysics
- Refracting Telescopes
- Angular Magnification
- Chromatic and Spherical Aberration
- Resolving Power
- Radio Telescopes
- Charge-Coupled Devices
- Apparent Magnitude
- Parsecs and Light Years
All 24 lessons in Astrophysics · All AQA A-level Physics topics