CHG-18 Online Chlorophyll Analyzer The chlorophyll sensor utilizes the characteristic that chlorophyll A has an absorption peak and an emission peak in the spectrum, and emits a specific wavelength of monochromatic light to illuminate into the water, and chlorophyll A in the water absorbs the energy of the monochromatic light, releasing a single wavelength single. The color of light, the intensity of chlorophyll A emission is proportional to the content of chlorophyll A in water.