Patent EP0703445A2 successfully refreshed from Google Patents.
EP0703445A2
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Method and apparatus for measuring concentration of absorptive constituent in scattering medium
Assignee: Hamamatsu Photonics KK
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Filing: 1995-09-22
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Granted: —
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Expires: 2015-09-22
Abstract
Abstract A method for measuring a concentration of an absorptive constituent in a scattering medium comprises the steps of emitting two or more kinds of light having predetermined wavelengths; making said light incident at a light incidence position into said scattering medium; detecting said light at one or more photodetection points to acquire one or more photodetection signals; detecting light quantities and average flight pathlengths for said respective kinds of light based on said signals; and obtaining a concentration of said absorptive constituent by arithmetic processing using said light quantities and average flight pathlengths based on a predetermined relationship. The method permits absolute-value measurement of the concentration of the absorptive constituent inside the scattering medium having various exterior shapes.
Inventors
- 👤 Yutaka C/O Hamamatsu Photonics K.K. Tsuchiya
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 18:46
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1455; A61B5/14551; A61B5/14553; G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; A61B2562/00; A61B2562/02; A61B2562/0233; A61B2562/0242
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
200 words
A method for measuring a concentration of an absorptive constituent in a scattering medium, comprising: (a) a step of emitting two or more kinds of light having predetermined wavelengths, at which scattering coefficients are equal or regarded as equal, toward a scattering medium which is a measured object; (b) a step of making said light incident at a light incidence position into said scattering medium and letting said light propagate through said scattering medium; (c) a step of detecting said light having propagated through said scattering medium, at one or more photodetection points different from said light incidence position, thereby acquiring one or more photodetection signals; (d) a step of detecting light quantities and average flight pathlengths at said one or more photodetection points for said respective kinds of light having said wavelengths, based on said one or more photodetection signals; and (e) a step of obtaining a concentration of said absorptive constituent by arithmetic processing using said light quantities and said average flight pathlengths, based on a predetermined relationship among said light quantities, said average flight pathlengths, and a difference between absorption coefficients per unit concentration of said absorptive constituent, for said respective kinds of light having said wavelengths.
Claim 2
Dependent Claim
25 words
The method according to Claim 1, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of pulsed light.
Claim 3
Dependent Claim
68 words
The method according to Claim 1, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of sinusoidally modulated light having a predetermined modulation frequency component, wherein said light quantities are calculated from amplitudes of said predetermined modulation frequency component included in said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined modulation frequency component.
Claim 4
Dependent Claim
67 words
The method according to Claim 1, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of sinusoidally modulated light having a predetermined modulation frequency component, wherein said light quantities are calculated from dc components of said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined modulation frequency component included in said photodetection signals.
Claim 5
Dependent Claim
88 words
The method according to Claim 1, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of modulated light having a predetermined repetitive modulation frequency component, wherein said light quantities are calculated from amplitudes of said predetermined repetitive modulation frequency component or a frequency component of an integral multiple thereof included in said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined repetitive modulation frequency component or the frequency component of the integral multiple thereof.
Claim 6
Dependent Claim
77 words
The method according to Claim 1, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of modulated light having a predetermined repetitive modulation frequency component, wherein said light quantities are calculated from dc components of said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined repetitive modulation frequency component or a frequency component of an integral multiple thereof included in said photodetection signals.
Claim 7
Dependent Claim
72 words
The method according to Claim 1, wherein said predetermined relationship among said light quantities, said average flight pathlengths, and said difference between the absorption coefficients per unit concentration of said absorptive constituent, for said respective kinds of light having said wavelengths, is a relationship derived from that a partial differentiation of a natural logarithm of a light quantity detected with respect to an absorption coefficient is equal to an average flight pathlength.
Claim 8
Dependent Claim
181 words
The method according to Claim 1, wherein said step (e) comprises obtaining the concentration of the absorptive constituent in said scattering medium by arithmetic processing using said light quantities and said average flight pathlengths, based on a relationship expressed by the following formula: V = (∈₂ - ∈₁)⁻¹ × [p<L₁(λ₁)> + (1 - p)<L₁(λ₂)>]⁻¹ × ln[I₁(λ₁)/I₁(λ₂)] where V: the concentration of the absorptive constituent, ∈₁: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₁, ∈₂: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₂, <L₁(λ₁)>: the average flight pathlength for the light of the wavelength λ₁ at a photodetection point r₁, <L₁(λ₂)>: the average flight pathlength for the light of the wavelength λ₂ at the photodetection point r₁, I₁(λ₁): the quantity of detected light for the light of the wavelength λ₁ at the photodetection point r₁, I₁(λ₂): the quantity of detected light for the light of the wavelength λ₂ at the photodetection point r₁, and p: a predetermined value satisfying 0 ≦ p ≦ 1.
Claim 9
Dependent Claim
283 words
The method according to Claim 1, wherein said step (e) comprises obtaining the concentration of the absorptive constituent in said scattering medium by arithmetic processing using said light quantities and said average flight pathlengths, based on a relationship expressed by the following formula: V = (∈₂ - ∈₁)⁻¹ × [p<L₁(λ₁)> + (1 - p)<L₁(λ₂)> - q<L₂(λ₁)> - (1 - q)<L₂(λ₂)>]⁻¹ × ln{[I₁(λ₁)·I₂(λ₂)]/[I₁(λ₂)·I₂(λ₁)]} where V: the concentration of the absorptive constituent, ∈₁: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₁, ∈₂: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₂, <L₁(λ₁)>: the average flight pathlength at a photodetection point r₁ for the light of the wavelength λ₁, <L₁(λ₂)>: the average flight pathlength at the photodetection point r₁ for the light of the wavelength λ₂, <L₂(λ₁)>: the average flight pathlength at a photodetection point r₂ for the light of the wavelength λ₁, <L₂(λ₂)>: the average flight pathlength at the photodetection point r₂ for the light of the wavelength λ₂, I₁(λ₁): the quantity of detected light at the photodetection point r₁ for the light of an intensity B₁ and the wavelength λ₁, I₁(λ₂) the quantity of detected light at the photodetection point r₁ for the light of an intensity B₂ and the wavelength λ₂, λ₂(λ₁): the quantity of detected light at the photodetection point r₂ for the light of the intensity B₁ and the wavelength λ₁, I₂(λ₂): the quantity of detected light at the photodetection point r₂ for the light of the intensity B₂ and the wavelength λ₂, p: a predetermined value satisfying 0 ≦ p ≦ 1, and q: a predetermined value satisfying 0 ≦ q ≦ 1.
Claim 10
Independent Claim
204 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium, comprising: (a) a light source for emitting two or more kinds of light having predetermined wavelengths, at which scattering coefficients are equal or regarded as equal, toward a scattering medium which is a measured object; (b) light incidence means for making said light incident at a light incidence position into said scattering medium and making said light propagate through said scattering medium; (c) photodetection means for detecting said light having propagated through said scattering medium, at one or more photodetection points different from said light incidence position to acquire one or more photodetection signals; (d) parameter detecting means for detecting light quantities and average flight pathlengths at said one or more photodetection points for said respective kinds of light having said wavelengths, based on said one or more photodetection signals; and (e) arithmetic processing means for obtaining a concentration of said absorptive constituent by arithmetic processing using said light quantities and said average flight pathlengths, based on a predetermined relationship among said light quantities, said average flight pathlengths, and a difference between absorption coefficients per unit concentration of said absorptive constituent, for said respective kinds of light having said wavelengths.
Claim 11
Dependent Claim
25 words
The apparatus according to Claim 10, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of pulsed light.
Claim 12
Dependent Claim
68 words
The apparatus according to Claim 10, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of sinusoidally modulated light having a predetermined modulation frequency component, wherein said light quantities are calculated from amplitudes of said predetermined modulation frequency component included in said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined modulation frequency component.
Claim 13
Dependent Claim
67 words
The apparatus according to Claim 10, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of sinusoidally modulated light having a predetermined modulation frequency component, wherein said light quantities are calculated from dc components of said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined modulation frequency component included in said photodetection signals.
Claim 14
Dependent Claim
88 words
The apparatus according to Claim 10, wherein said two or more kinds of light having predetermined wavelengths are two or more Kinds of modulated light having a predetermined repetitive modulation frequency component, wherein said light quantities are calculated from amplitudes of said predetermined repetitive modulation frequency component or a frequency component of an integral multiple thereof included in said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined repetitive modulation frequency component or the frequency component of the integral multiple thereof.
Claim 15
Dependent Claim
77 words
The apparatus according to Claim 10, wherein said two or more kinds of light having predetermined wavelengths are two or more kinds of modulated light having a predetermined repetitive modulation frequency component, wherein said light quantities are calculated from dc components of said photodetection signals, and wherein said average flight pathlengths are calculated from phase delays of said predetermined repetitive modulation frequency component or a frequency component of an integral multiple thereof included in said photodetection signals.
Claim 16
Dependent Claim
72 words
The apparatus according to Claim 10, wherein said predetermined relationship among said light quantities, said average flight pathlengths, and said difference between the absorption coefficients per unit concentration of said absorptive constituent, for said respective kinds of light having said wavelengths, is a relationship derived from that a partial differentiation of a natural logarithm of a light quantity detected with respect to an absorption coefficient is equal to an average flight pathlength.
Claim 17
Dependent Claim
182 words
The apparatus according to Claim 10, wherein said arithmetic processing means (e) obtains the concentration of the absorptive constituent in said scattering medium by arithmetic processing using said light quantities and said average flight pathlengths, based on a relationship expressed by the following formula: V = (∈₂ - ∈₁)⁻¹ × [p<L₁(λ₁)> + (1 - p)<L₁(λ₂)>]⁻¹ × ln[I₁(λ₁)/I₁(λ₂)] where V: the concentration of the absorptive constituent, ∈₁: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₁, ∈₂: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₂, <L₁(λ₁)>: the average flight pathlength for the light of the wavelength λ₁ at a photodetection point r₁, <L₁(λ₂)>: the average flight pathlength for the light of the wavelength λ₂ at the photodetection point r₁, I₁(λ₁): the quantity of detected light for the light of the wavelength λ₁ at the photodetection point r₁, I₁(λ₂): the quantity of detected light for the light of the wavelength λ₂, at the photodetection point r₁, and p: a predetermined value satisfying 0 ≦ p ≦ 1.
Claim 18
Dependent Claim
284 words
The apparatus according to Claim 10, wherein said arithmetic processing means (e) obtains the concentration of the absorptive constituent in said scattering medium by arithmetic processing using said light quantities and said average flight pathlengths, based on a relationship expressed by the following formula: V = (∈₂ - ∈₁)⁻¹ × [p<L₁(λ₁)> + (1 - p<L₁(λ₂)> - q(L₂(λ₁)> - (1 - q)<L₂(λ₂)>]⁻¹ × ln{[I₁(λ₁)·I₂(λ₂)]/[I₁(λ₂)·I₂(λ₁)]} where V: the concentration of the absorptive constituent, ∈₁: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₁, ∈₂: the absorption coefficient per unit concentration of the absorptive constituent for the light of the wavelength λ₂, <L₁(λ₁)>: the average flight pathlength at a photodetection point r₁, for the light of the wavelength λ₁, (L₁(λ₂): the average flight pathlength at the photodetection point r₁ for the light of the wavelength λ₂, <L₂(λ₁)>: the average flight pathlength at a photodetection point r₂ for the light of the wavelength λ₁, <L₂(λ₂)>: the average flight pathlength at the photodetection point r₂ for the light of the wavelength λ₂, I₁(λ₁): the quantity of detected light at the photodetection point r₁ for the light of an intensity B₁ and the wavelength λ₁, I₁(λ₂): the quantity of detected light at the photodetection point r₁ for the light of an intensity B₂ and the wavelength λ₂, I₂(λ₁): the quantity of detected light at the photodetection point r₂ for the light of the intensity B₁ and the wavelength λ₁, I₂(λ₂): the quantity of detected light at the photodetection point r₂ for the light of the intensity B₂ and the wavelength λ₂, p: a predetermined value satisfying 0 ≦ p ≦ 1, and q: a predetermined value satisfying 0 ≦ q ≦ 1.
Claim 19
Dependent Claim
25 words
Use of the apparatus according to any one of claims 10 to 18 for measuring a concentration of an absorptive constituent in a scattering medium.
Claim 20
Independent Claim
51 words
A method and apparatus for measuring a characteristic of a light scattering medium, wherein a plurality of different kinds of light which will behave similarly in a selected scattering medium are directed toward the scattering medium and light from the scattering medium is analysed to determine the characteristic of the medium.
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