Different colored filters select the spectral regions of interest. Narrowband ("monochromatic") sensors are equipped with filters that restrict the spectral response to a narrow region, typically 10 nm FWHM (Figure 2). An example of a broadband radiance detector is the natural fluorescence detector (abbreviated LuChl) patented by Biospherical Instruments and used in Natural Fluorometers. To collect as many fluoresced photons as possible, an LuChl detector approximates the emission spectrum of chlorophyll.