Fluorescence measurement is a technique used to detect and quantify the fluorescence emitted by a substance when it is exposed to light. This process occurs when a molecule absorbs photons and then re-emits them at a longer wavelength. Common applications include studying biological samples, such as proteins and cells, and analyzing environmental samples. In a typical fluorescence measurement setup, a light source, often a laser or LED, illuminates the sample. The emitted light is then collected and analyzed using a spectrometer or a photodetector. This method is highly sensitive and can provide valuable information about the concentration and properties of the fluorescent molecules present.