EP0206433A2
Expired / Lapsed
EP
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Methods for measuring the light absorbance of a fluid medium
Assignee: Dow Chemical Co
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Filing: 1986-06-24
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Granted: —
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Expires: 2006-06-24
Abstract
Abstract The presence and concentration of a light absorbing constituent in a fluid medium is determined in-situ by immersing in such medium a probe having a prism at one end whose refractive index is greater than that of the medium and causing light including a wavelength absorbable by such constituent to traverse an optical path through the prism and undergo successive attenuated total reflections. At each reflection some of the light will be absorbed by the constituent. The intensity of light emerging from the prism is measured at one or more wavelengths, including one absorbable by such constituent. The concentration of the constituent is determined by comparison of the measured intensity with values obtained from like measurements performed on like mediums containing known concentrations of the constituent.
Inventors
- 👤 Richard D. Mclachlan
- 👤 Ray W. Chrisman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 03:52
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/55; G01N21/552; G01N21/25; G01N21/31; G01N21/33; G01N21/84; G01N21/85; G01N21/8507; G01N2201/00; G01N2201/08
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
A probe for determining the concentration of a light absorbing constituent in a fluid medium, said probe comprising a housing immersible in said medium and terminating at one end in a prism having a base and at least two adjacent, angularly displaced, externally exposed faces; at least one optical input fiber extending from adjacent said base outwardly of said housing for optical coupling to a source of light including a wavelength absorbable by said constituent; and at least one optical output fiber extending from adjacent said base outwardly of said housing for optical coupling to light intensity measuring apparatus, said one end of each of said input and output fibers being so positioned relative to one another and to said prism that light transmitted from said one end of said input fiber into said prism is totally internally reflected by said faces onto said one end of said output fiber.
Claim 2
Dependent Claim
150 words
A probe for determining the concentration of a light absorbing constituent in a fluid medium, said probe comprising a housing immersible in said medium and terminating at one end in a prism having a base and at least two adjacent, angularly displaced, externally exposed faces; at least one optical input fiber extending from adjacent said base outwardly of said housing for optical coupling to a source of light including a wavelength absorbable by said constituent; and at least one optical output fiber extending from adjacent said base outwardly of said housing for optical coupling to light intensity measuring apparatus, said one end of each of said input and output fibers being so positioned relative to one another and to said prism that light transmitted from said one end of said input fiber into said prism is totally internally reflected by said faces onto said one end of said output fiber.
Claim 3
Dependent Claim
24 words
The probe according to Claim l, wherein said one end of said input fiber is parallel to said one end of said output fiber.
Claim 4
Dependent Claim
36 words
. 3. The probe according to Claim 1, wherein said one end of said input fiber and said one end of said output fiber are arranged on lines which converge in the direction of said prism.
Claim 5
Independent Claim
152 words
An apparatus for determining the presence in a fluid medium of a light absorbing constituent, said apparatus comprising a probe having a housing; a transparent prism at one end of said housing having a base and at least to adjacent, angularly displaced external faces; a source of light including a wavelength absorbable by said constituent; at least one optical input fiber supported by said probe for transmitting light from said source to the base of said prism; at least one optical output fiber supported by said probe for transmitting light from said base externally of said housing; and means coupled to said output fiber for measuring the intensity of light transmitted thereby, said fibers and said faces of said prism being so arranged relative to one another that light transmitted to said base by said input fiber enters said prism and is totally internally reflected by said faces onto said output fiber.
Claim 6
Independent Claim
152 words
An apparatus for determining the presence in a fluid medium of a light absorbing constituent, said apparatus comprising a probe having a housing; a transparent prism at one end of said housing having a base and at least to adjacent, angularly displaced external faces; a source of light including a wavelength absorbable by said constituent; at least one optical input fiber supported by said probe for transmitting light from said source to the base of said prism; at least one optical output fiber supported by said probe for transmitting light from said base externally of said housing; and means coupled to said output fiber for measuring the intensity of light transmitted thereby, said fibers and said faces of said prism being so arranged relative to one another that light transmitted to said base by said input fiber enters said prism and is totally internally reflected by said faces onto said output fiber.
Claim 7
Dependent Claim
19 words
The apparatus according to Claim 4, wherein said housing is formed of material capable of immersion in said medium.
Claim 8
Dependent Claim
62 words
The apparatus according to Claim 4, wherein said light source emits light of at least two different wavelengths one of which is not absorbable by said constituent, and wherein said apparatus includes 'a second output fiber adjacent a first output fiber, and a second light intensity measuring means coupled to said second output fiber for measuring the intensity of light transmitted thereby.
Claim 9
Dependent Claim
27 words
The apparatus according to Claim 4 including a plurality of output fibers, and a corresponding plurality of light intensity measuring means coupled to the respective output fibers.
Claim 10
Independent Claim
169 words
A method for determining the concentration of at least one light absorbing constituent in a fluid medium, said method comprising: (a) immersing in said medium a probe having at one end thereof.a prism, said prism having a refractive index greater than that of said medium and having at least two angularly displaced, adjacent faces in contact with said medium; (b) transmitting light from a source to said prism, said light including at least one wavelength absorbable by said constituent and being transmitted into the prism at such an angle of incidence relative to said faces so as to be totally internally reflected within said prism and thence outwardly of said probe through its other end; (c) measuring the intensity of the light of said wavelength that emerges from said probe; and (d) comparing the intensity value thus obtained to corresponding values obtained by the application of steps (a), (b), and (c) to at least two calibration mediums like said fluid medium but containing different, known concentrations of said constituent.
Claim 11
Independent Claim
169 words
A method for determining the concentration of at least one light absorbing constituent in a fluid medium, said method comprising: (a) immersing in said medium a probe having at one end thereof.a prism, said prism having a refractive index greater than that of said medium and having at least two angularly displaced, adjacent faces in contact with said medium; (b) transmitting light from a source to said prism, said light including at least one wavelength absorbable by said constituent and being transmitted into the prism at such an angle of incidence relative to said faces so as to be totally internally reflected within said prism and thence outwardly of said probe through its other end; (c) measuring the intensity of the light of said wavelength that emerges from said probe; and (d) comparing the intensity value thus obtained to corresponding values obtained by the application of steps (a), (b), and (c) to at least two calibration mediums like said fluid medium but containing different, known concentrations of said constituent.
Claim 12
Dependent Claim
22 words
The method according to Claim 8, wherein the light transmitted into said prism enters and leaves said prism along spaced, parallel paths.
Claim 13
Dependent Claim
36 words
The method according to Claim 8., wherein the light transmitted to said prism and the light reflected from said prism enter and leave said prism along spaced paths that converge in a direction toward said prism.
Claim 14
Independent Claim
175 words
A method for determining the concentration of at least one light absorbing constituent in a fluid medium, said method comprising: (a) immersing in said medium a probe having at one end thereof a prism, said prism having a refractive index greater than that of said medium and having at least two angularly displaced, adjacent faces in contact with said medium; (b) transmitting light from a source to said prism, said light including at least one wavelength absorbable by said constituent and at least one other wavelength not absorbable by said constituent and being transmitted into said prism at such an angle of incidence so as to be totally internally reflected within said prism and thence outwardly of said probe through its other end; (c) measuring the intensity of the reflected light of each of said wavelengths to obtain a ratio therebetween; and (d) comparing the ratio thus obtained to corresponding ratios obtained by the application of steps (a), (b), and (c) to calibration mediums like said fluid medium but containing different, known concentrations of said-constituent.
Claim 15
Independent Claim
175 words
A method for determining the concentration of at least one light absorbing constituent in a fluid medium, said method comprising: (a) immersing in said medium a probe having at one end thereof a prism, said prism having a refractive index greater than that of said medium and having at least two angularly displaced, adjacent faces in contact with said medium; (b) transmitting light from a source to said prism, said light including at least one wavelength absorbable by said constituent and at least one other wavelength not absorbable by said constituent and being transmitted into said prism at such an angle of incidence so as to be totally internally reflected within said prism and thence outwardly of said probe through its other end; (c) measuring the intensity of the reflected light of each of said wavelengths to obtain a ratio therebetween; and (d) comparing the ratio thus obtained to corresponding ratios obtained by the application of steps (a), (b), and (c) to calibration mediums like said fluid medium but containing different, known concentrations of said-constituent.
Claim 16
Dependent Claim
35 words
The method according to Claim 11, wherein said fluid medium contains a plurality of different light absorbing constituents and wherein the light transmitted to said prism includes a frequency absorbable by each of said constituents.
References Cited (Backward Citations)
No citation records indexed.
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