How are wavelengths typically measured?

Wavelengths are typically measured in nanometers because this unit is appropriate for the scale of visible light and other forms of electromagnetic radiation. One nanometer equals one billionth of a meter, making it ideal for accurate measurements of wavelengths in the ultraviolet, visible, and near-infrared regions of the spectrum, which range from about 400 to 700 nanometers.

Using nanometers allows for precise distinctions among different colors of light and their applications in various fields, including lasers and optics. The other units mentioned, such as micrometers, millimeters, and centimeters, are larger measurements and generally not used for wavelengths in the ranges most relevant to lasers and light. For example, micrometers are more suitable for measurements that pertain to infrared wavelengths, while millimeters and centimeters would be more appropriate for objects rather than light wavelengths.