Such uses of the term should be avoided, but in certain contexts they are nevertheless very common. Sometimes, what is actually meant is for example an optical power, an irradiance or a radiant intensity – these are examples of very different quantities which should not be confused. In other cases, intensities are meant to be quantitative measures, but used in quite inaccurate ways. Such non-quantitative statements rarely create a risk of misunderstanding.

An actual numerical value is not specified in such cases. For example, such a statement could be “high intensity laser beams are used for laser material processing” – just like “the sun is very bright today”. The term intensity is often used in a non-quantitative way. Non-quantitative and Inaccurate Meanings of Intensity

Certainly, for quantitative reference it is important to clearly indicate which meaning of intensity is used. However, we must deal with literature using the term in different ways, as explained in the following sections. One may recommend using optical intensity only in a non-quantitative way and only use well-defined radiometric quantities like radiant intensity and irradiance for quantitative references. The term optical intensity (or just intensity) is quite common in optical physics and technology, but it is somewhat problematic, since it is used with substantially different meanings.

Intensity of light equation beam width