Spaltenfarbe

Spaltenfarbe is a term used in the context of optical instruments, particularly microscopes and telescopes, to describe a chromatic aberration. Specifically, it refers to the appearance of colored fringes or bands around the edges of objects when viewed through a lens system that is not perfectly corrected for dispersion. This phenomenon occurs because different wavelengths of light are refracted at slightly different angles by the lens material. When white light passes through a simple lens, it is split into its constituent colors, similar to a prism. This splitting can result in a red halo appearing on one side of an object and a blue or violet halo on the other.

The severity of spaltenfarbe depends on the design of the optical system and the quality of the lenses. More sophisticated lens designs, such as apochromatic objectives in microscopes or complex eyepiece designs in telescopes, incorporate multiple lens elements made from different types of glass to minimize or eliminate this aberration. These corrected systems aim to bring more wavelengths of light to a common focal point, thereby reducing the distracting colored fringes. While some residual spaltenfarbe might still be present in less advanced or lower-cost instruments, it is a key consideration for manufacturers striving for high-fidelity imaging. Observing spaltenfarbe can indicate a limitation in the optical correction of an instrument.