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Optical aberration refers to a set of defects that degrade the quality of images produced by optical instruments. These defects emerge due to subtle imperfections in lenses and mirrors, as perfect focusing of all incoming light rays at different angles is inherently challenging. Additionally, lenses introduce further complexities as they refract different parts of the light spectrum by varying amounts.
There are several types of optical aberrations:
- Chromatic Aberration: This results in the appearance of colored fringes around the image. It occurs because light of different wavelengths is brought to different focal points by a lens.
- Spherical Aberration: In this case, the image appears blurred due to varying focal lengths in different parts of a spherical lens or mirror.
- Astigmatism: This aberration causes the image to appear elliptical or cross-shaped, stemming from irregularities in the curvature of the lens.
- Coma: Images exhibit progressive elongation towards the edge of the field of view. Coma arises when light passing directly through a lens is focused differently than light entering the lens from an angle.
Advanced computer programs are now employed to design lenses that minimize these aberrations. Chromatic aberration, spherical aberration, astigmatism, and coma are among the primary defects considered in the design of optical systems. By employing sophisticated computational techniques, optical engineers aim to optimize lens design and reduce aberrations for improved image quality.