Abstract: Methods and systems for determining characteristics of fluids are described. A method involves illuminating a portion of a fluid by emitting light having an emission spectrum spanning at least from an infrared band to an ultraviolet band, and producing an output signal by receiving the light upon being scattered by the fluid using an optical detector. A controller may select a target sub-band of the emission spectrum based on information associated with the fluid, and may further determine a characteristic of the fluid using at least a portion of the output signal associated with the target sub-band of the emission spectrum. Alternatively, or additionally, a controller may apply an operator to the output signal, and may further determine the characteristic of the first fluid by applying a machine learning model to a result of the operator as applied to the first output signal.