The only way for us to observe light directly, no matter what its spectrum might be, is when some of its photons intercept our detectors (such as our eyes). Such light might tell us about say the path of a beam of light passing through a fog, but even then the light that stimulates our retinas is not the beam, just samples that were deflected into our detectors.

We might sometimes be able to deduce the presence and path of light indirectly, for example, an intense beam might accelerate an object in space without any visible light reaching our eyes. Then, if the evidence were suitable we might say: "Ahah! There was a pulse of light there!"

As for "full spectrum light", that is a rather messy concept. It changes according to whether you mean visible light only, or include radio, infra-red, gamma rays etc, and also how much energy there might be in each fraction of the bandwidth.

If you see what I mean...

Jon