Raman sensor

• US 5,245,404 A
• Filed: 10/18/1990
• Issued: 09/14/1993
• Est. Priority Date: 10/18/1990
• Status: Expired due to Term

• Current Assignee: Physical Optics Corporation
• Original Assignee: Physical Optics Corporation
• Inventors: Kim, Richard C., Jannson, Tomasz P., Shirk, Kevin W., Moslehi, Behzad M. R.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US07/599,816
• Time in Patent Office: 1,062 Days
• Field of Search: 356/301, 356/328, 250/227.23, 385/37
• US Class Current: 356/301
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

A multiwavelength sensor for sensing light scattered from a scattering medium includes a light source, a uniform broadband reflection grating at the Littrow position, a fiber, and a detector. Light from the source is incident on the grating, which diffracts the light. The fiber has a first end into which the light diffracted from the grating is received and has a second end from which the light exits, the fiber being positioned so that the light is incident upon and scattered from the scattering medium. At least some of the light scattered from the medium is scattered back into the second end and out of the first end and incident upon the diffraction grating. Light out of the first end and diffracted from the grating is incident on the detector. The system is fully transparent so that light traveling toward the second end and light traveling back toward the first end are optically isolated and cross-talk is substantially nonexistent.

Claims

1. A Raman sensor for sensing incident light scattered from a scattering medium, said sensor comprising an incident light source, a uniform broadband reflection grating at the Littrow position, a detector, and a fiber having first and second ends, said light source, grating, detector, and fiber being positioned paraxially, said grating positioned to receive incident light from said light source, said fiber positioned to receive in said first end incident light diffracted from said grating and to direct said light so as to be incident on and to scatter from said scattering medium and back into said second end and out of said first end, said grating positioned to receive scattered light from said first end, said detector positioned to receive scattered light diffracted from said grating, said sensor being fully transparent so that said incident and said scattered light remain isolated from each other and cross-talk is substantially nonexistent.

2. A multiwavelength sensor for sensing incident light scattered from a scattering medium, said sensor comprising an incident light source, a uniform broadband reflection grating at the Littrow position, a detector, and a fiber having first and second ends, said light source, grating, detector, and fiber being positioned paraxially, said grating positioned to receive incident light from said light source, said fiber positioned to receive in said first end incident light diffracted rom said grating and to direct said light so as to be incident on and to scatter from aid scattering medium and back into said second end and out of said first end, said grating positioned to receive scattered light from said first end, said detector positioned to receive scattered light diffracted from said grating, said sensor being fully transparent so that said incident and said scattered light remain highly optically isolated from each other and cross-talk is substantially nonexistent.

3. A multiwavelength sensor for sensing light scattered from a scattering medium, said sensor comprising;

a. a slight source;

b. a uniform broadband reflection grating at the Littrow position and upon which light from the source is incident, said grating diffracting said light;

c. a fiber having a first end into which said light diffracted from said grating is received and having a second end rom which said light exits, said fiber being positioned so that said light is incident upon and scattered from said scattering medium, at least some of said light scattered from said medium being scattered back into said second end and out of said first end and incident upon said diffraction rating;

d. a detector upon which said light out of said first end and diffracted from said grating is incident;

said sensor being fully transparent so that light raveling toward the second end and light traveling back toward the first end are optically isolated and cross-talk is substantially nonexistent.

4. A multiwavelength sensor for sensing incident light scattered from a scattering medium, the sensor comprising:

a. a light source having wavelength λ

₀ ;

b. a uniform broadband reflection grating at the Littrow position and upon which light from said source is incident, said grating diffracting said light;

c. a fiber having one end into which said light diffracted from said grating is directed and positioned so that said light exiting an opposite end is incident upon and scattered from said scattering medium into wavelengths λ

₁ and λ

₂, said wavelengths λ

₁ and λ

₂ being scattered back into said opposite end and out of said one end and incident upon said diffraction grating, said wavelength λ

₁ being diffracted toward a first detector and wavelength λ

₂ being diffracted toward a second detector, said first and second detectors comparing wavelengths λ

₁ and λ

₂ ;

said sensor being fully transparent so that wavelength λ

₀ and wavelengths λ

₁ and λ

₂ are optically isolated and cross talk is substantially nonexistent.

5. A method of sensing light scattered from a scattering medium, said method comprising:

a. transmitting light from a light source;

b. diffracting said light via a uniform broadband reflection grating at the Littrow position and upon which said light is incident;

c. receiving light diffracted from said grating into a first end of a fiber, and transmitting said diffracted light out of a second end of said fiber, said fiber being positioned so that said diffracted light is incident upon and scattered from said scattering medium, at least some of said light scattered rom said medium being scattered back into said second end and transmitted out of said first end and incident upon said grating;

d. detecting said light transmitted out of said first end and scattered from said grating;

wherein light traveling toward the second end and light traveling back toward the first end are optically isolated and cross-talk is substantially nonexistent.