Optical pH sensor
First Claim
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1. A method to sense pH of a fluid, said method comprising the steps of:
- supplying an optical source through an input fiber;
passing said optical source at a range of predetermined input angles to a sensor head having a transparent window in contact with a fluid, wherein said window has a high refractive index, and wherein a side of said window in contact with said fluid is coated with a thin protein layer to prevent fouling of said window due to accumulation of fat, oil and/or grease within said fluid on said window;
forming a reflective boundary between said fluid and said side of said window in contact with said fluid,collecting optical power reflected from said reflective boundary between said window and said fluid by a plurality of output fibers in said sensor head, wherein said output fibers are positioned with respect to said input fiber so as to collect optical power reflected from said reflective boundary at predetermined output angles; and
detecting a fouling of said sensor head based on reflected optical power collected by said output fibers;
if no fouling of said sensor head is detected, converting said reflected optical power collected by said output fibers to pH of said fluid.
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Abstract
A method to sense pH of a fluid and an optical pH sensor. The method includes the steps of supplying at least a portion of an optical source through an input fiber. The optical source is passed through a sensor head having a sapphire window to a fluid. Optical power reflected from the fluid is collected in a plurality of output fibers in the sensor head. The reflected optical power in the output fibers in the sensor head is thereafter converted to an electrical signal which is used to determine the pH of the fluid.
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Citations
16 Claims
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1. A method to sense pH of a fluid, said method comprising the steps of:
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supplying an optical source through an input fiber; passing said optical source at a range of predetermined input angles to a sensor head having a transparent window in contact with a fluid, wherein said window has a high refractive index, and wherein a side of said window in contact with said fluid is coated with a thin protein layer to prevent fouling of said window due to accumulation of fat, oil and/or grease within said fluid on said window; forming a reflective boundary between said fluid and said side of said window in contact with said fluid, collecting optical power reflected from said reflective boundary between said window and said fluid by a plurality of output fibers in said sensor head, wherein said output fibers are positioned with respect to said input fiber so as to collect optical power reflected from said reflective boundary at predetermined output angles; and detecting a fouling of said sensor head based on reflected optical power collected by said output fibers; if no fouling of said sensor head is detected, converting said reflected optical power collected by said output fibers to pH of said fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 14, 15)
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10. An optical pH sensor which comprises:
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an input fiber supplied with an optical source; a sensor head in communication with said optical source; a transparent window in said sensor head to permit passage of said optical source from said input fiber at a plurality of predetermined range of angles to a fluid to be tested, and said window constructed of a material having a high refractive index; a thin protein layer coating an external surface of said window between said window and said fluid to be tested, and said thin protein layer constructed to prevent fouling of said window due to accumulation of fat, oil and/or grease within said fluid on said window; a plurality of output fibers in said sensor head for collecting optical power reflected from a reflective boundary between said window and said fluid, said output fibers constructed in said sensor head with respect to said input fiber to collect optical power reflected from said reflective boundary at predetermined output angles, and said input fiber of said sensor head centrally located surrounded by said plurality of said output fibers; a receiver unit for converting optical output power to electrical voltage in order to determine pH of said fluid; and a sensor fouling detection and servicing unit for determining fouling of said sensor head due to accumulation of fat, oil and/or grease within said fluid on said window of said sensor head and/or deterioration of said thin protein layer. - View Dependent Claims (11, 12, 13, 16)
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Specification