Light-based spectroscopy with improved signal-to-noise ratio

• US 10,172,523 B2
• Filed: 06/22/2018
• Issued: 01/08/2019
• Est. Priority Date: 12/31/2012
• Status: Expired due to Fees

• Current Assignee: Omni Medsci, Inc.
• Original Assignee: Omni Medsci, Inc.
• Inventors: Islam, Mohammed N.
• Primary Examiner(s): Rahman, Md M
• Application Number:
  US16/015,737
• Publication Number:
  US 20180296097A1
• Time in Patent Office: 200 Days
• Field of Search: 356300
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 2576/02 specially adapted for a particular organ or body part
• CPC Class Codes: A61B 5/0013 Medical image data A61B1/00011, A61B6/56, A61B8/56 take precedence
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/4547 Evaluating teeth
• CPC Class Codes: A61B 5/6801 specially adapted to be attached to or worn on the body surface
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: G01J 2003/104 Monochromatic plural sources
• CPC Class Codes: G01J 2003/1208 Prism and grating
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/0218 : using optical fibers
• CPC Class Codes: G01J 3/108 : for measurement in the infrared range
• CPC Class Codes: G01J 3/14 : using refracting elements, e.g. prisms G01J3/18, G01J3/26 take precedence prisms per se G02B5/04
• CPC Class Codes: G01J 3/1838 : Holographic gratings
• CPC Class Codes: G01J 3/28 : Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/2823 : Imaging spectrometer
• CPC Class Codes: G01J 3/42 : Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01J 3/453 : by correlation of the amplitudes
• CPC Class Codes: G01M 3/38 : by using light G01M3/02 takes precedence
• CPC Class Codes: G01N 2021/3595 : using FTIR
• CPC Class Codes: G01N 2021/399 : Diode laser
• CPC Class Codes: G01N 21/35 : using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/3563 : for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/359 : using near infrared light
• CPC Class Codes: G01N 21/39 : using tunable lasers
• CPC Class Codes: G01N 21/85 : Investigating moving fluids or granular solids
• CPC Class Codes: G01N 21/88 : Investigating the presence of flaws or contamination
• CPC Class Codes: G01N 21/9508 : Capsules; Tablets
• CPC Class Codes: G01N 2201/0221 : Portable; cableless; compact; hand-held
• CPC Class Codes: G01N 2201/061 : Sources
• CPC Class Codes: G01N 2201/06113 : Coherent sources; lasers
• CPC Class Codes: G01N 2201/062 : LED's
• CPC Class Codes: G01N 2201/08 : Optical fibres; light guides
• CPC Class Codes: G01N 2201/12 : Circuits of general importance; Signal processing
• CPC Class Codes: G01N 2201/129 : Using chemometrical methods
• CPC Class Codes: G01N 33/02 : Food
• CPC Class Codes: G01N 33/025 : Fruits or vegetables
• CPC Class Codes: G01N 33/15 : Medicinal preparations ; Physical properties thereof, e.g. dissolubility drug screening with animal cells G01N33/5008
• CPC Class Codes: G01N 33/442 : Resins, plastics
• CPC Class Codes: G01N 33/49 : Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G16H 40/67 : for remote operation
• CPC Class Codes: G16Z 99/00 : Subject matter not provided for in other main groups of this subclass
• CPC Class Codes: H01S 3/0092 : Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/06758 : Tandem amplifiers
• CPC Class Codes: H01S 3/302 : in an optical fibre
• CPC Class Codes: Y02A 90/10 : Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A measurement system includes a light source having semiconductor sources, a multiplexer, and one or more fused silica fibers configured to form an output optical beam having one or more optical wavelengths modulated at a modulation frequency. A light beam set-up includes a monochromator forming a filtered optical beam. A measurement apparatus delivers the filtered optical beam to a sample. A receiver receives a spectroscopy output beam generated from the sample by the filtered optical beam. The receiver is configured to use a lock-in technique that detects the modulation frequency, and to generate first and second signals responsive to light received while the light source is off and on, respectively. The measurement system improves a signal-to-noise ratio of the spectroscopy output beam by differencing the first and second signals. The receiver processes the spectroscopy output beam using chemometrics or multivariate analysis to permit identification of materials within the sample.

Claims

1. A measurement system comprising:

a light source configured to generate an output optical beam, comprising;

a plurality of semiconductor sources configured to generate an input optical beam;

a multiplexer configured to receive at least a portion of the input optical beam and to form an intermediate optical beam;

one or more fibers configured to receive at least a portion of the intermediate optical beam and to form the output optical beam;

wherein at least a portion of the one or more fibers comprises a fused silica fiber;

wherein the output optical beam comprises one or more optical wavelengths; and

wherein the output optical beam is modulated at a modulation frequency;

a light beam set-up comprising a monochromator configured to receive at least a portion of the output optical beam and to form a filtered optical beam;

a measurement apparatus configured to receive a received portion of the filtered optical beam and to deliver a delivered portion of the filtered optical beam to a sample; and

a receiver configured to receive at least a portion of a spectroscopy output beam from the sample that is generated by the delivered portion of the filtered optical beam, wherein the receiver is further configured to use a lock-in technique that detects the modulation frequency, and wherein the receiver is further configured to;

generate a first signal in response to light received while the light source is off; and

generate a second signal in response to light received while the light source is on;

wherein the measurement system is configured to improve a signal-to-noise ratio of the spectroscopy output beam by differencing the first signal and the second signal; and

wherein the receiver is further configured to process the at least a portion of the spectroscopy output beam to generate an output signal, wherein the receiver processing includes at least in part using chemometrics or multivariate analysis to permit identification of materials within the sample; and

wherein the output signal is based at least in part on a chemical composition of the sample.

2. The system of claim 1, wherein at least a portion of the one or more optical wavelengths is between 700 nanometers and 2500 nanometers, and wherein the light source comprises a super-continuum light source.

3. The system of claim 1, wherein the sample comprises plastics or food industry goods, and the measurement system is configured to be used for on-line process control.

4. The system of claim 1, wherein the light source is pulsed, and the receiver is further configured to perform time-gated detection and to be synchronized with one or more pulses from the light source.

5. A measurement system comprising:

a light source configured to generate an output optical beam, comprising;

a plurality of semiconductor sources configured to generate an input optical beam;

a multiplexer configured to receive at least a portion of the input optical beam and to form an intermediate optical beam;

one or more fibers configured to receive at least a portion of the intermediate optical beam and to form the output optical beam;

wherein at least a portion of the one or more fibers comprises a fused silica fiber;

wherein the output optical beam comprises one or more optical wavelengths; and

wherein the output optical beam is modulated at a modulation frequency;

a light beam set-up configured to receive at least a portion of the output optical beam and to form a filtered optical beam;

a measurement apparatus configured to receive a received portion of the filtered optical beam and to deliver a delivered portion of the filtered optical beam to a sample; and

a receiver configured to receive at least a portion of a spectroscopy output beam generated from the sample by the delivered portion of the filtered optical beam, wherein the receiver is further configured to use a lock-in technique that detects the modulation frequency, and wherein the receiver is further configured to;

generate a first signal in response to light received while the light source is off; and

generate a second signal in response to light received while the light source is on;

wherein the measurement system is configured to improve a signal-to-noise ratio of the spectroscopy output beam by differencing the first signal and the second signal;

wherein the receiver is further configured to process the at least a portion of the spectroscopy output beam to generate an output signal, wherein the receiver processing includes at least in part using chemometrics or multivariate analysis to permit identification of materials within the sample; and

wherein the light source and the receiver are remote from the sample.

6. The system of claim 5, wherein the light source comprises a super-continuum light source.

7. The system of claim 5, wherein the measurement system is configured to be used for on-line process control, and the measurement system is configured to perform non-destructive quality control or constitutive analysis.

8. The system of claim 5, wherein at least a portion of the one or more optical wavelengths is between 700 nanometers and 2500 nanometers.

9. The system of claim 5, wherein the light beam set-up further comprises a monochromator to at least in part contribute to forming the filtered optical beam.

10. The system of claim 5, wherein the light beam set-up is further configured to separate the filtered optical beam into a reference arm and a sample arm, wherein at least a portion of the sample arm forms the delivered portion of the filtered optical beam, and wherein the reference arm is configured to be coupled to the light source, wherein the reference and sample arms are further coupled to the receiver, and wherein the receiver is further configured to use the reference arm to at least partially cancel out effects from fluctuations in the light source.

11. The system of claim 5, wherein the light source is pulsed, and the receiver is further configured to perform time-gated detection and to be synchronized with one or more pulses from the light source.

12. The system of claim 5, wherein the sample comprises plastics or food industry goods, and wherein the sample further comprises hydro-carbons, nitrogen or oxygen.

13. A measurement system comprising:

a light source configured to generate an output optical beam, comprising;

a plurality of semiconductor sources configured to generate an input optical beam;

a multiplexer configured to receive at least a portion of the input optical beam and to form an intermediate optical beam;

one or more fibers configured to receive at least a portion of the intermediate optical beam and to form the output optical beam;

wherein at least a portion of the one or more fibers comprises a fused silica fiber;

wherein the output optical beam comprises one or more optical wavelengths; and

wherein the light source and output optical beam are pulsed;

a light beam set-up configured to receive at least a portion of the output optical beam and to form a filtered optical beam;

a measurement apparatus configured to receive a received portion of the filtered optical beam and to deliver a delivered portion of the filtered optical beam to a sample; and

a receiver configured to receive at least a portion of a spectroscopy output beam generated from the sample by the delivered portion of the filtered optical beam, wherein the receiver is further configured to perform time-gated detection and to be synchronized with one or more pulses from the light source;

wherein the receiver is further configured to process the at least a portion of the spectroscopy output beam to generate an output signal, wherein the receiver processing includes at least in part using chemometrics or multivariate analysis to permit identification of materials within the sample; and

wherein the output signal is based at least in part on a chemical composition of the sample, and wherein the light source and receiver are remote from the sample.

14. The system of claim 13, wherein the output optical beam is modulated at a modulation frequency, and wherein the receiver is configured to use a lock-in technique that detects the modulation frequency.

15. The system of claim 14, wherein the receiver is further configured to perform band filtering at the modulation frequency, and wherein the modulation frequency has a phase, and wherein the receiver is configured to lock onto the phase.

16. The system of claim 15, wherein the receiver is further configured to:

generate a first signal in response to light received while the light source is off; and

generate a second signal in response to light received while the light source is on;

wherein the measurement system is configured to improve a signal-to-noise ratio of the spectroscopy output beam by differencing the first signal and the second signal.

17. The system of claim 16, wherein the light beam set-up further comprises a monochromator to at least in part contribute to forming the filtered optical beam, wherein the light beam set-up is further configured to separate the filtered optical beam into a reference arm and a sample arm, wherein at least a portion of the sample arm forms the delivered portion of the filtered optical beam, and wherein the reference arm is configured to be coupled to the light source, wherein the reference and sample arms are further coupled to the receiver, and wherein the receiver is further configured to use the reference arm to at least partially cancel out effects from fluctuations in the light source.

18. The system of claim 17, wherein at least a portion of the one or more optical wavelengths is between 700 nanometers and 2500 nanometers.

19. The system of claim 18, wherein the measurement system is configured to be used for on-line process control, wherein the sample comprises plastics or food industry goods, and wherein the sample further comprises hydrocarbons, nitrogen or oxygen.

20. The system of claim 19, wherein the light source comprises a super-continuum light source.