Key Words

• active optics

• adaptive optics

• angular resolution

• baseline

• Cassegrain focus

• charge-coupled device (CCD)

• chromatic aberration

• coma

• coudé focus

• diffraction

• diffraction grating

• eyepiece lens

• false color

• focal length

• focal plane

• focal point

• focus (of a lens or mirror)

• grating

• imaging

• interferometry

• light-gathering power

• light pollution