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US 4,905,169 AGranted
Method and apparatus for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsTudor N. Buican, John C. Martin
Life of this patent
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Abstract
An apparatus and method simultaneously measures a plurality of spectral wavelengths present in electromagnetic radiation. A modulatable birefringent optical element is employed to divide a polarized light beam into two components, thereby producing a phase difference in two resulting light beams such that the two beams can be made to interfere with one another when recombined, the interference pattern providing the wavelength information required for the analysis of the incident light. The interferometer thus created performs in a similar manner to a Michelson interferometer, but with no moving parts, and with a resolution dependent on the degree of phase shift introduced by the modulator.
Claims36
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in fluorescence, the apparatus comprising in combination:
- a. a first polarizer for receiving the fluorescence having an electric field disposed in an arbitrary direction and for defining a first direction for the electric field of the fluorescence transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized light from said first polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized light is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the fluorescence;
- c. a second polarizer for receiving the two first light waves emerging from said birefringent means and resolving their electric fields along a second direction, so that two second light waves emerge plane polarized and with the same direction of polarization;
- d. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths is achieved;
- e. first detector means for receiving the two second light waves emerging from said second polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- f. means for receiving the electrical signal from said first detector means and for separating the signal into its spectral components.
4 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in polarized fluorescence, the apparatus comprising in combination:
- a. modulatable birefringent means for receiving substantially polarized fluorescence having an electric field disposed in a particular direction, said birefringent means having first and second optical axes along which the electric field of the fluorescence is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the fluorescence;
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation from a source thereof, the apparatus comprising in combination:
- a. a first polarizer for receiving electromagnetic radiation having an electric field disposed in an arbitrary direction, and for defining a first direction for the electric field of the electromagnetic radiation transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized electromagnetic radiation from said first polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized electromagnetic radiation is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the electromagnetic radiation;
- c. a second polarizer for receiving the two first light waves emerging from said birefringent means and resolving their electric fields along a second direction, so that two second light waves emerge plane polarized and with the same direction of polarization;
- d. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths results during the time period of occurrence of the electromagnetic radiation;
- e. first detector means for receiving the two second light waves emerging from said second polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- f. means for receiving the electrical signal from said first detector means and for separating the signal into its spectral components.
4 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in polarized electromagnetic radiation from a source thereof, the apparatus comprising in combination:
- a. modulatable birefringent means for receiving the polarized electromagnetic radiation, having an electric field disposed in a particular direction, said birefringent means having first and second optical axes along which the electric field of the polarized electromagnetic radiation is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the electromagnetic radiation;
- b. a polarizer for receiving the two first light waves emerging from said birefringent means and resolving their electric fields along a second direction, so that two second light waves emerge plane polarized and with the same direction of polarization;
- c. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths results during the time period of occurrence of the electromagnetic radiation;
- d. detector means for receiving the two second light waves emerging from said polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- e. means for receiving the electrical signal from said detector means and for separating the signal into its spectral components.
3 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in fluorescence, the apparatus comprising in combination:
- a. a beam-splitting polarizer for receiving the fluorescence having an electric field disposed in an arbitrary direction and for defining an initial direction for the electric field of the fluorescence transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized light from said polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized light is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the fluorescence;
- c. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths is achieved;
- d. reflecting means for reflecting the two first phase-shifted light waves emerging from said birefringent means back therethrough along the path of first entry thereof and in the opposite direction, so that the phase shift therebetween is increased, said polarizer receiving the two doubly phase-shifted light waves, each having an electric field, and resolving the electric fields thereof along the initial electric field direction, so that two second phase-shifted light waves emerge plane polarized with the same direction of polarization and travel at an angle to the fluorescence incident on said polarizer;
- e. detector means for receiving the two second light waves emerging from said polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- f. means for receiving the electrical signal from said detector means and for separating the signal into its spectral components.
4 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation from a source thereof, the apparatus comprising in combination:
- a. a beam-splitting polarizer for receiving electromagnetic radiation having an electric field disposed in an arbitrary direction and for defining an initial direction for the electric field of the electromagnetic radiation transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized light from said polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized light is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the fluorescent light;
- c. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths results during the time period of occurrence of the electromagnetic radiation;
- d. reflecting means for reflecting the two first phase-shifted light waves emerging from said birefringent means back therethrough along the path of first entry thereof and in the opposite direction, so that the phase shift therebetween is increased, said polarizer receiving the two doubly phase-shifted light waves, each having an electric field, and resolving the electric fields thereof along the initial electric field direction, so that two second phase-shifted light waves emerge plane polarized with the same direction of polarization and travel at an angle to the electromagnetic radiation incident on said polarizer;
- e. detector means for receiving the two second light waves emerging from said polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- f. means for receiving the electrical signal from said detector means and for separating the signal into its spectral components.
4 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in fluorescence, the apparatus comprising in combination:
- a. a first polarizer for receiving the fluorescence having an electric field disposed in an arbitrary direction, and for defining a first direction for the electric field of the fluorescence transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized light from said first polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized light is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the fluorescent light;
- c. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths is achieved;
- d. first reflecting means for reflecting the two first phase-shifted light waves emerging from said birefringent means back therethrough, so that the phase shift between the two light waves is increased;
- e. second reflecting means for receiving the two doubly phase-shifted first light waves emerging from said modulatable birefringent means and reflecting the two doubly phase-shifted first light waves back through said modulatable birefringent means, so that an additional phase shift is introduced between the two doubly phase-shifted first light waves;
- f. a second polarizer for receiving the two triply phase-shifted first light waves emerging from said birefringent means, each having an electric field, and resolving their electric fields along a second direction, so that two second light waves emerge plane polarized and with the same direction of polarization;
- g. detector means for receiving the light waves emerging from said second polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- h. means for receiving the electrical signal from said detector means and for separating the signal into its spectral components.
6 more elements
An apparatus for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation from a source thereof, the apparatus comprising in combination:
- a. a first polarizer for receiving the electromagnetic radiation having an electric field disposed in an arbitrary direction, and for defining a first direction for the electric field of the electromagnetic radiation transmitted therethrough;
- b. modulatable birefringent means for receiving the transmitted polarized light from said first polarizer, said birefringent means having first and second optical axes along which the electric field of the transmitted polarized light is resolved into two components, the light wave corresponding to each of the resolved electric field components traveling at a different velocity, so that two first light waves emerge from said birefringent means having different electric field directions and a shift in phase greater than one wavelength of the longest wavelength component of the electromagnetic radiation;
- c. means for modulating said birefringent means such that resolution suitable for measurement of the plurality of spectral wavelengths results during the time period of occurrence of the electromagnetic radiation;
- d. first reflecting means for reflecting the two phase-shifted first light waves emerging from said birefringent means back therethrough, so that the phase shift between the two light waves is increased;
- e. second reflecting means for receiving the two doubly phase-shifted first light waves emerging from said birefringent means and reflecting the two doubly phase-shifted light waves back through said birefringent means, so that an additional phase shift is introduced between the two doubly phase-shifted first light waves;
- f. a second polarizer for receiving the two triply phase-shifted first light waves emerging from said birefringent means, each having an electric field, and resolving their electric fields along a second direction, so that two second light waves emerge plane polarized and with the same direction of polarization;
- g. detector means for receiving the light waves emerging from said second polarizer and interacting therewith to produce an electrical signal characteristic of the interference pattern generated as a result of the interference of the two second light waves having different phase;
- and
- h. means for receiving the electrical signal from said detector means and for separating the signal into its spectral components.
6 more elements
A method for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation from a source thereof comprising the steps of:
- a. linearly polarizing the electromagnetic radiation having an electric field disposed in an arbitrary direction along a first direction;
- b. resolving the electric field of the linearly polarized electromagnetic radiation along two substantially orthogonal directions;
- c. introducing a phase shift of greater than one wavelength of the longest wavelength component of the electromagnetic radiation between light waves associated with each of the resolved electric fields;
- d. linearly polarizing the phase-shifted light waves along a second direction;
- e. detecting the interference pattern generated from the interaction of the linearly polarized, phase shifted light waves, thereby producing an electrical signal characteristic of the wavelength composition of the electromagnetic radiation;
- and
- f. analyzing the electrical signal to produce the wavelength pattern of the electromagnetic spectral radiation.
4 more elements
A method for simultaneously measuring a plurality of spectral wavelengths present in fluorescence, comprising the steps of:
- a. linearly polarizing the fluorescence having an electric field disposed in an arbitrary direction along a first direction;
- b. resolving the electric field of the linearly polarized fluorescence along two orthogonal directions;
- c. introducing a phase shift of greater than one wavelength of the longest wavelength component of the fluorescence between light waves associated with each of the resolved electric fields;
- d. linearly polarizing the phase-shifted light waves along a second direction;
- e. detecting the interference pattern generated from the interaction of the linearly polarized, phase shifted light waves, thereby producing an electrical signal characteristic of the wavelength composition of the fluorescence;
- and
- f. analyzing the electrical signal to produce the wavelength pattern of the fluorescence.
4 more elements
Dependencies are inferred from the claim text.