Particle concentration measuring method and device
AssigneeXerox Corporation
InventorsJoannes N. M. deJong, Gerald A. Domoto, John J. Ricciardelli, Gerhard H. Bay, Johann H. Metternich
Life of this patent
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Abstract
The method and apparatus for measuring the particle concentration in a fluid that is passed between a reciprocally movable window and a single photodetector. A collimated beam of light is directed through the window and fluid to the photodetector. The window is moved from a first predetermined location to a second predetermined location to vary the light beam path length, thus enabling at least two different photodetector output signals. The ratio of the two signals provides the data needed to determine the particle concentration in the fluid.
Claims5
Apparatus for measuring the particle concentration in a fluid comprising:
- a variable intensity collimated light source;
- means for transmitting a collimated light beam from the light source along a path and through a movable window, the movable window being reciprocally movable along said light beam path;
- a photodetector being spaced from and aligned with the movable window to receive the light beam transmitted from the movable window and to produce an output signal in response thereto;
- means for passing a fluid containing a concentration of particles therein between the movable window and the photodetector;
- means for moving the movable window from one predetermined position to a second predetermined position, so that the output signals from the photodetector are produced in accordance with the two predetermined positions, the two output signals being proportional to the distance of travel of the light beam through the fluid;
- means for controlling the intensity of the light source to maintain the sum of the two different output signals constant, so that the difference in the two output signals is a function of particle concentration;
- and
- circuit means for computing a difference over sum of the two output signals and determining the particle concentration of the fluid based on the difference over sum computation.
A method of measuring the particle concentration in a fluid comprising the steps of:
- transmitting a collimated beam of light from a variable intensity light source along a path and through a movable window;
- detecting the light beam with a photodetector spaced from the window and aligned with the light beam path, the photodetector producing an output signal in response to detection of a light beam, the output signals varying according to the distance between the movable window and the photodetector;
- reciprocally adjusting the location of the movable window from one predetermined position along the light beam path to a second predetermined position, so that two different output signals are produced;
- passing a fluid containing a concentration of particles therein between the movable window and the photodetector during the transmittal of light beams;
- controlling the intensity of the light source to maintain the sum of the two different output signals constant, so that the difference in the two output signals is a function of particle concentration;
- and
- computing a difference over sum of the two different output signals and determining the concentration of the particles in the fluid based on the difference over sum computation.
Dependencies are inferred from the claim text.