Low-dispersion glass (LD glass) is a type of glass with reduced chromatic aberration, meaning the refractive index does not change as strongly with different wavelengths of light. In other words, the light passing through the glass has a smaller spread or dispersion between its constituent colors, resulting in a reduced "rainbow effect" at high-contrast edges. Wavelength dispersion in a certain material is characterized by its Abbe number; LD glass has a higher Abbe number than conventional types. Crown glass is an example of a relatively inexpensive low-dispersion glass.