Color correction in lens systems
Basically, this involves leveraging a long-known property of certain types of crystals. Even back in 1886, the optics pioneer from Jena, Professor Ernst Abbe, recognized that calcium fluoride crystals were uniquely suited for correcting colors in lenses and went on to develop the concept of apochromatic correction. Apochromatic corrected lens systems refract light in an entirely different manner and, thus, achieve very precise overlapping of the red, green and blue rays of light. The result is that no more chromatic aberrations occur. In the field of photography, the abbreviation APO is frequently used to refer to apochromatic lenses. Thus far, mainly higher quality, light-intensive telephoto lenses have been introduced as double lenses. But, now that HDTV technology has become popular, lenses for television cameras have become yet another market for calcium fluoride crystals.
”In color viewing systems, it really depends how cleverly highly refractive and low-refractive glasses are combined. Here, the objective is to retain the refraction that is needed to either increase or decrease the size of an object and, on the other hand, correct the color aberrations that occur. Here, calcium fluoride crystals, such as those produced in entirely new sizes and volumes by SCHOTT LITHOTEC in Jena, are well-suited, because they have a relatively low index of refraction and an extremely high Abbe Number, in comparison with optical glasses,” explains Peter Maushake, Product Manager of Optical Materials at SCHOTT LITHOTEC in Jena, Germany.
Calcium fluoride is known for being one of the hardest materials in the fluoride crystal family. The excellent processing possibilities that result from this are yet another reason why it is particularly well-suited for use in manufacturing a broad range of optical components.
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