What does achromatic mean in the context of optics?

In the context of optics, the term "achromatic" refers specifically to lenses designed to minimize or eliminate chromatic aberration, which is the distortion that occurs when different wavelengths of light are refracted at different angles. This effect can lead to the appearance of color fringes around objects, similar to the way a prism disperses light into a spectrum of colors.

When a lens is described as achromatic, it means that it is engineered to refract light in such a way that this rainbow effect is significantly reduced, providing clearer and more accurate imaging. This is achieved through a combination of materials and configurations that allow for the correction of color distortion, making achromatic lenses particularly valuable in applications requiring high precision, such as microscopes and telescopes.

The other options do not accurately reflect the meaning of "achromatic" in optics. For instance, a lens that enhances color or only works in low light does not pertain to the elimination of color distortion. Similarly, colored lenses designed for sunlight do not align with the definition, as they actually involve the addition of color rather than the absence of it.