Monitoring system and method for detecting flowing microscopic objects

A method for detecting microscopic objects located in a flowing fluid, comprising:

• supplying light emitted by at least one LED to a flowing fluid having microscopic objects suspended thereon;
• capturing a sequence of images of the flowing fluid by means of an image capture system comprising a plurality of pixels;
• processing said sequence of images and determining the presence of microscopic objects within said flowing fluid and the shape thereof,
• the method being characterized by:
• at said image capture system, capturing an image frame every Tframe seconds, Tframe being higher than or equal to TEXP, wherein TEXP is the exposure time of said pixels comprised in said image capture system;
• providing a strobe signal from said image capture system;
• for each frame, calculating a pulse amplitude setpoint and a pulse duration setpoint from the intensity of each frame by executing an algorithm that prioritizes rises in the pulse amplitude rather than rises in the pulse duration;
• at a pulse generator, receiving said pulse duration setpoint and generating from said pulse duration setpoint and from said strobe signal a pulsed signal having period Tframe and having pulses of duration TON, TON<<Tframe, said duration TON being obtained from said pulse duration setpoint and said strobe signal being used for synchronizing the pulses of duration TON with the time instant at which the pixels in the image capture system start to capture an image;
• calculating a reference voltage of duration TON from said pulse amplitude setpoint, said reference voltage being used for obtaining a polarization current of said at least one LED;
• providing a voltage enabling to provide a current Io′ to said at least one LED at pulses of duration TON, said voltage being provided by a an RC network comprising at least one capacitor and a resistor, wherein said at least one capacitor works as a pulse energy storage means and said resistor regulates the charging speed of the a pulse energy storage means, said RC network being configured for the at least one capacitor to become fully charged in a time duration Tframe−TON, wherein Tframe is the time period between two consecutive image frames captured by the image capture system.

A method for detecting microscopic objects located in a flowing fluid, comprising:

• supplying light emitted by at least one LED to a flowing fluid having microscopic objects suspended thereon;
• capturing a sequence of images of the flowing fluid by means of an image capture system comprising a plurality of pixels;
• processing said sequence of images and determining the presence of microscopic objects within said flowing fluid and the shape thereof,
• the method being characterized by:
• at said image capture system, capturing an image frame every Tframe seconds, Tframe being higher than or equal to TEXP, wherein TEXP is the exposure time of said pixels comprised in said image capture system;
• providing a strobe signal from said image capture system;
• for each frame, calculating a pulse amplitude setpoint and a pulse duration setpoint from the intensity of each frame by executing an algorithm that prioritizes rises in the pulse amplitude rather than rises in the pulse duration, said algorithm being done as follows:
• from current PAS, PDS and luminance generated with said PAS and PDS, checking whether the current luminance is within a design range LUMAMIN<current LUMA<LUMAMAX;
• if LUMAMIN<current LUMA<LUMAMAX, then no control is required;
• otherwise, it is checked whether the time duration of the deviation with respect to the established range is larger than a design hysteresis time and
• if the current luminance is out of the design range for a time duration shorter than the defined hysteresis time, then no control is required;
• otherwise, it is checked whether or not the current pulse amplitude setpoint PAS corresponds to a maximum value of intensity and,
• if not, then (912) the following calculation is performed:
• new_PAS=(Iframe−Iframe_setpoint)×Gain_PAS, the new_PAS value being used to update said potentiometer;
• if the current pulse amplitude setpoint PAS corresponds to a maximum value of intensity the pulse duration is adjusted as follows:
• new_PDS=(Iframe−Iframe_setpoint)×Gain_PDS, the value of new_PDS being used to update said potentiometer;
• at a pulse generator, receiving said pulse duration setpoint and generating from said pulse duration setpoint and from said strobe signal a pulsed signal having period Tframe and having pulses of duration TON, TON<<Tframe, said duration TON being obtained from said pulse duration setpoint and said strobe signal being used for synchronizing the pulses of duration TON with the time instant at which the pixels in the image capture system start to capture an image;
• calculating a reference voltage of duration TON from said pulse amplitude setpoint, said reference voltage being used for obtaining a polarization current of said at least one LED;
• providing a voltage enabling to provide a current Io′ to said at least one LED at pulses of duration TON, said voltage being provided by a an RC network comprising at least one capacitor and a resistor, wherein said at least one capacitor works as a pulse energy storage means and said resistor regulates the charging speed of the a pulse energy storage means, said RC network being configured for the at least one capacitor to become fully charged in a time duration Tframe−TON, wherein Tframe is the time period between two consecutive image frames captured by the image capture system.