Optics: measuring and testing – By shade or color
Reexamination Certificate
2001-02-02
2003-09-30
St. Cyr, Daniel (Department: 2876)
Optics: measuring and testing
By shade or color
C356S410000
Reexamination Certificate
active
06628394
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to colorimeters and other instruments which use a light beam and a photodetector. More particularly, this invention relates to the use of optical gaskets or seals in colorimeters or other instruments.
BACKGROUND OF THE INVENTION
Colorimeters utilize a light beam, a sample cell or chamber (usually glass), and a photodetector. The light beam is normally passed through a liquid sample (contained in the cell or chamber) and one or more color filters before reaching the detector. A glass window may also be positioned in the light beam on each side of the sample cell.
When the liquid sample in the sample cell is cool and there is sufficient humidity in the ambient air, moisture will condense on the surface of the sample cell. Such condensation in the path of the light beam will interfere with the passage of light through the cell and thereby interfere with the accuracy of the testing.
There has not heretofore been provided an optical gasket system having the features and advantages provided by the system of the present invention.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided an optical gasket system for a colorimeter or other instrument which utilizes a light beam and a sample cell or chamber for a liquid to be tested. In a preferred embodiment, the system of the invention comprises the placement of an optically clear and pliable gasket or seal in contact with the surface(s) of the sample cell or chamber which is in the path of the light beam. The presence of the gasket or seal in intimate contact with the surface of the sample cell or chamber prevents moisture from condensing on such surface and thereby avoids the problem of condensation interfering with the passage of the light beam through the cell.
Although the gasket system of the invention is especially useful in conjunction with a colorimeter, it also has utility in other types of instruments which utilize a light beam and a sample cell or chamber (e.g. turbidimeter, reflectometer, particle counter, etc.).
Other features and advantages of the optical gasket system of this invention will be apparent from the following detailed description and the accompanying drawings.
REFERENCES:
patent: 3062963 (1962-11-01), Douty
patent: 3435209 (1969-03-01), Keahl
patent: 4193694 (1980-03-01), Smith
patent: 4324758 (1982-04-01), Eisentraut et al.
patent: 5078493 (1992-01-01), Evens et al.
patent: 5872361 (1999-02-01), Paoli et al.
patent: 5969812 (1999-10-01), Carver
patent: 5991048 (1999-11-01), Karlson et al.
Cyr Daniel St.
Edmundson Dean P.
Hach Company
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