lowdispersion

Low dispersion refers to the property of materials or optical systems to exhibit minimal variation of refractive index with wavelength. Dispersion arises because n varies with wavelength; in lenses this leads to chromatic aberration, while in fiber communications it causes pulse broadening. Materials with low dispersion have a high Abbe number, indicating small changes in refractive index across the visible spectrum (and near-infrared).

In optics, low-dispersion glass (often labeled LD or ED for extra-low dispersion) combines glasses with contrasting dispersion so that their combined dispersion cancels, yielding sharper images and less color fringing. Achromatic doublets and apochromatic lenses are classical outcomes of low-dispersion design; modern LD glasses are used in camera lenses, magnifiers, and corrective eyewear.

In fiber optics, dispersion refers to the spreading of optical pulses as they travel; low-dispersion fibers are engineered to minimize this effect at key communication wavelengths, notably around 1300 to 1550 nm. Techniques include choosing materials with near-zero dispersion at target wavelengths, using dispersion-shifted or dispersion-compensating fibers, and managing group velocity dispersion through fiber structure.

Common sources of low dispersion include certain mineral glasses (such as fluorite and some synthetic optical glasses), fused silica, and specialized polymer blends. The term is often used in marketing for lenses advertised as having low color fringing, or in fiber tech for components designed to preserve pulse shape.

Overall, low dispersion is a central criterion in precision optics and high-speed communications, balancing material properties, wavelength range, and design to reduce wavelength-dependent effects.