BH-485-CHA Digital Chlorophyll A Sensor The BOQU digital online chlorophyll sensor uses the characteristic that chlorophyll A has absorption peaks and emission peaks in the spectrum. It emits monochromatic light of a specific wavelength and irradiates water. The chlorophyll A in water absorbs the energy of the monochromatic light and releases a monochromatic light of another wavelength Color light, the intensity of light emitted by chlorophyll A is proportional to the content of chlorophyll A in water.