Apparatus for measuring multi-wavelength transmittance using learned LED temperature compensation model

A submersible apparatus for measuring multiple wavelengths of light transmittance through a liquid, the submersible apparatus comprising:

• a plurality of light emitting diodes (LEDs) having different peak output wavelengths;
• a first light detector configured to detect an intensity of light;
• a structure surrounding the plurality of LEDs and the first light detector, wherein the structure allows the submersible apparatus to be submersed in the liquid, and wherein the structure is shaped to allow a volume of the liquid to reside between the plurality of LEDs and the first light detector such that an amount of light able to transmit through the liquid from the plurality of LEDs is detected by the first light detector;
• an optical unit configured to collect the light from the plurality of LEDs and direct the light through the liquid without a need for moving parts;
• a second light detector configured to measure an intensity of the plurality of LEDs, the second light detector positioned adjacent to the optical unit, wherein the optical unit is positioned between the plurality of LEDs and the second light detector;
• at least one first temperature sensor mounted adjacent the plurality of LEDs and at least one second temperature sensor mounted adjacent the first light detector configured to record a temperature of the plurality of LEDs and the first light detector during transmission measurements;
• and
• a microprocessor programmed to:
• a) activate a LED of the plurality of LEDs;
• b) while the LED is activated, read and store signals from the at least one first and second temperatures sensors and the first light detector as digital values;
• c) deactivate the LED;
• d) apply a predictive model of a performance of the LED and the first light detector over different temperature and temperature gradients to the digital values to generate a transmittance value for the LED that is temperature compensated and independent of effects of current temperatures of the LED and the first light detector and rates of change of the current temperatures;
• and
• e) repeat a-d for additional LEDs of the plurality of LEDs such that transmittance values generated for the LED and the additional LEDs represent different wavelengths of light.