Instrument for measuring sizes and quantity of particles in fluid medium

An instrument for measuring the size and quantity of particles in a fluid medium, comprising a dark chamber;

• a light source accommodated within said chamber;
• means for shaping a light beam emitted by said light source received in said chamber;
• means for introducing the fluid medium into said chamber so that it crosses the light beam shaped from the light source;
• an element simulating a calibrated particle mounted within said chamber;
• a light-sensitive device installed in said chamber to convert the light scattered by particles contained in the flow of the fluid medium which crosses the shaped light beam emitted by said light source, and also a part of the light beam, directed from said element to electric pulses;
• said element for simulating a calibrated particle being adapted to periodic change, in the course of measurements, the brightness of the light received by said light-sensitive device;
• means for varying the brightness of the part of light received by said light-sensitive device;
• a converter circuit for converting output electric pulses of said light-sensitive device to d.c. voltage, the input of said circuit being connected to the output of said light-sensitive device;
• a divider having an input connected to the output of said light-sensitive device;
• threshold devices having their signal inputs connected to the outputs of said divider which serves to distribute the electric pulses received from light-sensitive device according to the size of particles to said threshold devices;
• the output of said converter circuit being connected to reference inputs of said threshold devices whose trigger levels depend on the d.c. voltage at the output of said converter circuit;
• means for counting and displaying the quantity of pulses corresponding to the number of particles in the flow being studied, separately for each size group.