IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0923111
(2001-08-06)
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발명자
/ 주소 |
- Bottrell, Donald G.
- Capser, Todd M.
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출원인 / 주소 |
- R&D Limited Liability Partnership, LLP
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대리인 / 주소 |
Luedeka, Neely & Graham, P.C.
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인용정보 |
피인용 횟수 :
3 인용 특허 :
11 |
초록
▼
An optical communication device includes a first photon source emitting a first beam modulated with information. The first beam intersects a thin metal film and engenders a first surface plasmon wave thereon. Part of the first beam reflects from the metal film to form a reflected beam. A polarizatio
An optical communication device includes a first photon source emitting a first beam modulated with information. The first beam intersects a thin metal film and engenders a first surface plasmon wave thereon. Part of the first beam reflects from the metal film to form a reflected beam. A polarization structure rotates the polarization of the reflected beam. A reflecting structure reflects the reflected beam to form a second beam propagating back toward the film, which beam passes through the polarization structure again. On the metal film, the second beam engenders a second surface plasmon wave. Interaction between the first and second surface plasmon waves creates a surface plasmon standing wave. A second source provides a third beam intersecting the first and second beams at the metal film. Interaction between the third beam and the surface plasmon standing wave modulates the third beam as it passes through the metal film.
대표청구항
▼
An optical communication device includes a first photon source emitting a first beam modulated with information. The first beam intersects a thin metal film and engenders a first surface plasmon wave thereon. Part of the first beam reflects from the metal film to form a reflected beam. A polarizatio
An optical communication device includes a first photon source emitting a first beam modulated with information. The first beam intersects a thin metal film and engenders a first surface plasmon wave thereon. Part of the first beam reflects from the metal film to form a reflected beam. A polarization structure rotates the polarization of the reflected beam. A reflecting structure reflects the reflected beam to form a second beam propagating back toward the film, which beam passes through the polarization structure again. On the metal film, the second beam engenders a second surface plasmon wave. Interaction between the first and second surface plasmon waves creates a surface plasmon standing wave. A second source provides a third beam intersecting the first and second beams at the metal film. Interaction between the third beam and the surface plasmon standing wave modulates the third beam as it passes through the metal film. said measurement object pulse, and obtains the input time of measurement object pulse based on a correlation value between said pulse train and said pseudo-random noise code, and measures the approximate measurement object time representing a duration from the measurement start time to the input time of measurement object pulse, and said fine measuring means measures a time difference between a change point of said first reference clock and a change point of at least one pulse signal of said pulse train as said correction time of said approximate measurement object time. 5. The time measuring apparatus in accordance with claim 4, wherein said fine measuring means successively measures each time difference between a change point of said first reference clock and a change point of each pulse signal of said pulse train, and obtains an average value of thus measured time differences as said correction time. 6. The time measuring apparatus in accordance with claim 5, wherein said fine measuring means measures said time difference for each pulse signal of said pulse train based on a change point of said first reference clock closest to the change point of said pulse signal. 7. The time measuring apparatus in accordance with claim 6, wherein said fine measuring means comprises timer means for successively measuring a duration from a common reference time to a change point of each pulse signal of said pulse train and a duration from the common reference time to a change point of said first reference clock, and said fine measuring means calculates a time difference between neighboring change points of said pulse signal and said first reference clock based on measurement result by said timer means. 8. The time measuring apparatus in accordance with claim 5, wherein said fine measuring means judges a distribution of change points of respective pulse signals of said pulse train in one period of said first reference clock and identifies unnecessary pulse signals with reference to said distribution, and excludes time differences calculated based on unnecessary pulse signals from calculation of said average value. 9. The time measuring apparatus in accordance with claim 8, wherein said fine measuring means counts the number of change points of respective pulse signals belonging to each of time-divisional areas constituting one period of said first reference clock, and identifies said unnecessary pulse signals which belong to an area having a small count number. 10. The time measuring apparatus in accordance with claim 9, wherein said fine measuring means comprises counting means for counting the number of change points of respective pulse signals belonging to each of four time-divisional areas constituting one period of said first reference clock, said fine measuring means calculates a difference Δ12 representing a difference between a count value of 1stMIN area and a count value of 2ndMIN area as well as a difference Δ23 representing a difference between a count value of 2ndMIN area and a count value of 3rdMIN area based on count result of said counting means, wherein 1stMIN area has a smallest count value, 2ndMIN area has a next smallest count value, and 3rdMIN area has a third smallest count value, said fine measuring means identifies the unnecessary pulses whose change points belong to said 1stMIN area when the difference Δ12 is larger than the difference Δ23, or identifies the unnecessary pulses whose change points belong to said 1stMIN area and said 2ndMIN area when the difference Δ12 is smaller than the difference Δ23, or identifies the unnecessary pulses whose change points belong to said 1stMIN area, said 2ndMIN area, and 3rdMIN area when the difference Δ12 is equal to the difference Δ23. 11. The time measuring apparatus in accordance with claim 10, wherein said fine measuring means invalidates all of calculated time differences and prohibits the calculation of said average value when said 3rdMIN area and MAX area are consecutive areas positioned before and after a change point of the reference clock used in the measurement of said time difference, wherein said MAX area has a largest count value. 12. The time measuring apparatus in accordance with claim 5, further comprising second reference clock generating means for generating a second reference clock having a phase difference of 180 degrees with respect to said first reference clock, wherein said fine measuring means comprises: first fine measuring means for obtaining a first correction time which is an average time difference between a change point of each pulse signal and a change point of said first reference clock; second fine measuring means for obtaining a second correction time which is an average time difference between a change point of each pulse signal and a change point of said second reference clock; and correction time selecting means for judging whether a distribution of change points of respective pulses is closer to the change point of said first reference clock or closer to the change point of said second reference clock, and selecting said first correction time when said distribution of change points of respective pulses is closer to the change point of said second reference clock or selecting said second correction time when said distribution of change points of respective pulses is closer to the change point of said first reference clock. 13. The time measuring apparatus in accordance with claim 12, wherein said coarse measuring means comprises: first coarse measuring means for inputting said pulse train in synchronism with said first reference clock and measuring said approximate measurement object time based on a correlation value between said pulse train and said pseudo-random noise code; second coarse measuring means for inputting said pulse train in synchronism with said second reference clock and measuring said approximate measurement object time based on a correlation value between said pulse train and said pseudo-random noise code; and measurement time selecting means for selecting the approximate measurement object time of said first coarse measuring means when said correction time selecting means of said fine measuring means selects said first correction time or selecting the approximate measurement object time of said second coarse measuring means when said correction time selecting means of said fine measuring means selects said second correction time. 14. The time measuring apparatus in accordance with claim 12, wherein said correction time selecting means is associated with counting means which counts the number of change points of respective pulse signals belonging to each of four time-divisional areas constituting one period of said first reference clock, said correction time selecting means compares the number of change points belonging to two consecutive areas positioned before and after the change point of said first reference clock with the number of change points belonging to two consecutive areas positioned before and after the change point of said second reference clock to identify one of said first and second reference clocks as having smaller change points, and selects the correction time measured based on the identified reference clock. 15. The time measuring apparatus in accordance with claim 14, wherein said counting means uses said first reference clock, a first auxiliary clock having a phase difference of 90 degrees with respect to said first reference clock, the second reference clock having a phase difference of 180 degrees with respect to said first reference clock, and a second auxiliary clock having a phase difference of 270 degrees with respect to said first reference clock, and said counting means identifies an area to which a change point of each pulse signal belongs based on a signal level of each clock at a change point of each pulse signal. 16. The time measuring apparatus in accordance with clai m 10, wherein said counting means uses said first reference clock, a first auxiliary clock having a phase difference of 90 degrees with respect to said first reference clock, the second reference clock having a phase difference of 180 degrees with respect to said first reference clock, and a second auxiliary clock having a phase difference of 270 degrees with respect to said first reference clock, and said counting means identifies an area to which a change point of each pulse signal belongs based on a signal level of each clock at a change point of each pulse signal. 17. A spectrum spread type distance measuring apparatus comprising: pulse train generating means for generating a pulse train corresponding to a pseudo-random noise code having a predetermined bit length in synchronism with a first reference clock; transmitting means for transmitting an electromagnetic wave modulated based on the pulse train generated by said pulse train generating means; receiving means for receiving a reflection wave reflected by a measurement object after said electromagnetic wave is transmitted from said transmitting means, and for restoring said pulse train; time measuring means for measuring a measurement object time based on the pulse train restored by said receiving means and said pseudo-random noise code, said measurement object time representing a duration from transmission of said electromagnetic wave to reception of said reflection wave; and means for detecting a distance from the distance measuring apparatus to said measurement object based on the measurement object time measured by said time measuring means, wherein said time measuring means comprises: coarse measuring means for measuring an approximate measurement object time based on said first reference clock, said approximate measurement object time representing a duration from a measurement start time to an input time of measurement object pulse; and fine measuring means, cooperating with said coarse measuring means and using a reference time of predetermined periods shorter than those of said first reference clock, for measuring a time difference between a change point of said first reference clock and the input time of measurement object pulse as a correction time of said approximate measurement object time, wherein coarse measuring means inputs said pulse train generated in accordance with the pseudo-random noise code in synchronism with the first reference clock, said pulse train serving as said measurement object pulse, and obtains the input time of measurement object pulse based on a correlation value between said pulse train and said pseudo-random noise code, and measures the approximate measurement object time representing a duration from the measurement start time to the input time of measurement object pulse, said fine measuring means measures a time difference between a change point of said first reference clock and a change point of at least one pulse signal of said pulse train as said correction time of said approximate measurement object time, and a precise measurement object time is obtained based on said approximate measurement object time measured by said coarse measuring means and said correction time measured by said fine measuring means. 18. The spectrum spread type distance measuring apparatus in accordance with claim 17, wherein said pulse train generating means generates surplus pulse signals for a predetermined time until an output of said receiving means is stabilized after said receiving means starts receiving said reflection wave, and then generates the pulse train corresponding to the pseudo-random noise code having a predetermined bit length in synchronism with a reference clock, and said time measuring means starts time measurement after said predetermined time has elapsed after said transmitting means starts transmission of said electromagnetic wave based on the pulse signal generated by said pulse train generating means. 19. A time measuring method, comprising the steps of: generating a first reference clock at predetermined periods; measuring an approximate measurement object time based on said first reference clock, said approximate measurement object time representing a duration from a measurement start time to an input time of measurement object pulse, measuring a time difference between a change point of said first reference clock and the input time of measurement object pulse as a correction time of said approximate measurement object time by using a reference time of predetermined periods shorter than those of said first reference clock, and obtaining a precise measurement object time based on said approximate measurement object time and said correction time. 20. The time measuring method in accordance with claim 19, wherein said step of measuring said time difference is performed based on a change point of said first reference clock closest to the input time of measurement object pulse. 21. The time measuring method in accordance with claim 19, wherein said reference time used in said step of measuring said time difference is a gate delay time of a gate circuit. 22. The time measuring method in accordance with claim 19, wherein said step of measuring said approximate measurement object time is performed by using a spectrum spread type measuring device which inputs a pulse train generated in accordance with a pseudo-random noise code in synchronism with said first reference clock, said pulse train serving as said measurement object pulse, and obtains the input time of measurement object pulse based on a correlation value between said pulse train and said pseudo-random noise code, and said step of measuring said time difference is performed to obtain a time difference between a change point of said first reference clock and a change point of at least one pulse signal of said pulse train as said correction time of said approximate measurement object time. 23. The time measuring method in accordance with claim 22, wherein the step of measuring said time difference is performed to successively measure each time difference between a change point of said first reference clock and a change point of each pulse signal of said pulse train, and then obtain an average value of thus measured time differences as said correction time. 24. The time measuring method in accordance with claim 23, wherein the step of measuring said time difference is performed to measure said time difference for each pulse signal of said pulse train based on a change point of said first reference clock closest to the change point of said pulse signal. 25. The time measuring method in accordance with claim 24, wherein said step of measuring said time difference comprises the steps of: successively measuring a duration from a common reference time to a change point of each pulse signal of said pulse train and a duration from the common reference time to a change point of said first reference clock; and calculating a time difference between neighboring change points of said pulse signal and said first reference clock based on measurement result. 26. The time measuring method in accordance with claim 23, wherein said step of measuring said time difference comprises the steps of: judging a distribution of change points of respective pulse signals of said pulse train in one period of said first reference clock; identifying unnecessary pulse signals with reference to said distribution; and excluding time differences calculated based on unnecessary pulse signals from calculation of said average value. 27. The time measuring method in accordance with claim 26, wherein said step of measuring said time difference comprises the steps of: counting the number of change points of respective pulse signals belonging to each of time-divisional areas constituting one period of said first reference clock; and identifying said unnecessary pulse signals which be
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