EP0250070A1
Expired / Lapsed
EP
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Optical analysis method and apparatus having programmable rapid random wavelength access
Assignee: SPX Flow Technology Germany GmbH
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Filing: 1987-04-16
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Granted: —
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Expires: 2007-04-16
Abstract
Abstract The optical reflectance or transmittance concentration analyzer includes an acousto-optical tunable filter (AOTF) with a pair of crossed polarizers (3, 5) to select one of the tuned monochromatic light beams that pass from a light source (1) through the AOTF. The AOTF is tuned by a computer controlled digital-to-analog converter (12) through a tunable sweep oscillator (11). To obtain rapid wavelength change along with electronic chopping or wavelength modulation, the digital-to-analog converter output is added to the output of a high speed signal generator (18). The modulated light is conducted directly or through a fiber optic cable to the location of the optical measurement and impinges upon the sample where it is reflected or transmitted. The emerging light is collected onto detector(s) (10). The measurement time interval can be distributed among the required wavelengths or wavelength pairs according to an unequal scheme to decrease the error of the result in a calibration equation. The apparatus is particularly adaptable for use as an on-line concentration monitor in industrial process control because of tis stability, efficiency and ability to perform quick analyses.
Inventors
- 👤 Gabor J. Kemeny
- 👤 David L. Wetzel
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 06:59
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/85; G01J; G01J3/00; G01J3/12; G01J3/1256; G01N21/17; G01N21/47; G01N21/4738; G01J1/00; G01J1/42; G01J2001/4242; G01J4/00; G01N2021/1738; G01N2021/1742; G01N21/474; G01N2021/4742; G01N21/25; G01N21/31; G01N21/35; G01N21/3563; G01N21/4785; G01N2201/00; G01N2201/06; G01N2201/065; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
16 words
An apparatus for providing rapid random wavelength access for optical analysis of a sample comprising, ,
Claim 2
Independent Claim
16 words
An apparatus for providing rapid random wavelength access for optical analysis of a sample comprising, ,
Claim 3
Dependent Claim
109 words
(a) a light source, (b) an acousto-optic tunable filter positioned to accept light from the light source to provide emerging tuned output beams, (c) means to select a predetermined number of tuned beams from the acousto-optic tunable filter, (d) means to direct said predetermined number of selected tuned output beams onto the sample to be analyzed, (e) means to collect radiation that is reflected back or transmitted through said sample, (f) means for detecting and amplifying the reflected or transmitted radiation, (g) electronic tunable oscillator means connected to said acousto-optical tunable filter, and (h) electronic means providing timing and logic for wavelength selection via said electronic tunable oscillator means.
Claim 4
Dependent Claim
109 words
(a) a light source, (b) an acousto-optic tunable filter positioned to accept light from the light source to provide emerging tuned output beams, (c) means to select a predetermined number of tuned beams from the acousto-optic tunable filter, (d) means to direct said predetermined number of selected tuned output beams onto the sample to be analyzed, (e) means to collect radiation that is reflected back or transmitted through said sample, (f) means for detecting and amplifying the reflected or transmitted radiation, (g) electronic tunable oscillator means connected to said acousto-optical tunable filter, and (h) electronic means providing timing and logic for wavelength selection via said electronic tunable oscillator means.
Claim 5
Dependent Claim
27 words
The apparatus of claim 1 further comprising optical focusing means and a fiber optic connection between said predetermined number of selected tuned output beams and said sample.
Claim 6
Dependent Claim
18 words
The apparatus of claim 2 further comprising a fiber optic coupling between said sample and said detection means.
Claim 7
Dependent Claim
18 words
The apparatus of claim 1 wherein said electronic tunable oscillator is controlled by a computer controlled digital-to-analog converter.
Claim 8
Dependent Claim
18 words
The apparatus of claim 4 further comprising square or sine-wave generator means and phase sensitive (lock-in) amplifier means.
Claim 9
Dependent Claim
60 words
The apparatus of claim 5 wherein the electronic tunable oscillator means has an oscillator output and the computer controlled digital-to-analog converter has a digital-to-analog converter output and the output of said square or sine-wave generator means is coupled into the electronic tunable oscillator means such that the oscillator output is added to the control signal output of the digital-to-analog converter.output.
Claim 10
Dependent Claim
29 words
The apparatus of claim 1 wherein the detection means is formed from at least one material selected from the group consisting of germanium, lead sulfide, lead selenide or silicon.
Claim 11
Dependent Claim
30 words
The apparatus of claim 1 wherein the detecting means communicates with a prefilter and said detecting means furnishes a detector signal to said prefilter before said detector signal is amplified.
Claim 12
Dependent Claim
16 words
The apparatus of claim 1 further comprising means to collimate light emerging from said light source.
Claim 13
Dependent Claim
23 words
The apparatus of claim 9 further comprising a first polarizing means positioned to select at least one polarization direction from said collimated light.
Claim 14
Dependent Claim
21 words
The apparatus of claim 10 further comprising a second polarizing means positioned to select one of the emerging tuned output beams.
Claim 15
Independent Claim
70 words
A method of optical concentration and analysis of a sample wherein monochromatic light of different wavelength is selected in rapid succession with an acousto-optic tunable filter, the successive wavelengths of monochromatic light are guided onto the sample, the reflected or transmitted light intensity is measured and the concentration of the sample is determined by substituting the intensities at different wavelengths or intensity differences at various wavelengths into a calibration equation.
Claim 16
Independent Claim
70 words
A method of optical concentration and analysis of a sample wherein monochromatic light of different wavelength is selected in rapid succession with an acousto-optic tunable filter, the successive wavelengths of monochromatic light are guided onto the sample, the reflected or transmitted light intensity is measured and the concentration of the sample is determined by substituting the intensities at different wavelengths or intensity differences at various wavelengths into a calibration equation.
Claim 17
Dependent Claim
23 words
The method of claim 12 wherein the wavelength modulation is such that each wavelength or wavelength pair is selected for different time intervals.
References Cited (Backward Citations)
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