All spectroscopic measurements are made through the use of a detector, which converts photons into a measurable signal. Spectroscopy is the study of how light interacts with matter, and a necessity for these studies is the ability to detect light. Broadly speaking, an. UV/UV-VIS detectors are most frequently used to measure components showing an absorption spectrum in the ultraviolet or visible region. From this information, we can often deduce a great deal of additional insight, including: Molecular identities –.