– Chromatic aberration Figure 6-7
• The refraction of light by a lens depends on its wavelength.
• Differentwavelengthsarebroughtto focus at different focal points.
• Only one wavelength will be in focus and a colored halo will result.
• Combining layers of glass can resolve this.
– Spherical Aberration Figure 6-13
• Asphericalmirrordoesnotbringlightto a common focus at the same point (a curved focal plane). This results in a fuzzy image.
• Parabolic mirrors solve this problem but at the cost of field of view.
• If the mirror does not have a common focal length at all points the light is not brought to focus at a common focal plane (e.g. Hubble Space Telescope).