What we claim is:
1. An MnZn ferrite production process comprising a maximum temperature holding step for firing and a cooling step in a nitrogen atmosphere, wherein:
a nitrogen atmosphere changeover temperature T in said cooling step is below 1,1500 C. and equal to or higher than 1,0000 C., and a cooling rate V1 conforms to a condition defined by the following formula (1):
T(V11,450)1.5(1)
where T is the nitrogen atmosphere changeover temperature in C and V1 is the cooling rate in C.hour from T down to 900 C.
2. An MnZn ferrite production process comprising a maximum temperature holding step for firing and a cooling step in a nitrogen atmosphere, wherein:
a nitrogen atmosphere changeover temperature T in said cooling step is below 1,000 C. and equal to or higher than 900 C., and a cooling rate V1 conforms to a condition defined by the following formula (2):
T(V1450)0.5(2)
where T is the nitrogen atmosphere changeover temperature in C and V1 is the cooling rate in C.hour from T down to 900 C.
3. The MnZn ferrite production process according to claim 1, wherein said cooling rate V1 from said nitrogen atmosphere changeover temperature T down to 900 C. is 800 C.hour or less.
4. The MnZn ferrite production process according to claim 1, wherein a cooling rate V2 from 900 C. down to 600 C. is 200 to 800 C.hour.
5. The MnZn ferrite production process according to claim 1, wherein a maximum temperature in said maximum temperature holding step is 1,250 to 1,350 C. while a maximum temperature holding time is 2 to 7 hours.
6. The MnZn ferrite production process according to claim 1, wherein:
said MnZn ferrite comprises as main components 52 to 55 mol % of iron oxide as calculated on an Fe2O3 basis and 7 to 12 mol % of zinc oxide as calculated on a ZnO basis with the balance being manganese oxide, and contains as subordinate components 60 to 140 ppm of silicon oxide as calculated on an SiO2 basis, 350 to 700 ppm of calcium oxide as calculated on a CaO basis and 100 to 350 ppm of niobium oxide as calculated on an Nb2O5 basis.
7. The MnZn ferrite production process according to claim 6, wherein zirconium oxide is contained as an additional subordinate component in an amount of 50 to 350 ppm as calculated on a ZrO2 basis with respect to said main components.
8. The MnZn ferrite production process according to claim 6, wherein nickel oxide is contained as a further subordinate component in an amount of 0 to 4,500 ppm, exclusive of 0, as calculated on an NiO basis with respect to said main components.
9. The MnZn ferrite production process according to claim 6, wherein a phosphorus content is 30 ppm or less as calculated on a P basis with respect to said main components.
10. The MnZn ferrite obtained by the processes recited in claim 1, wherein a power loss of 280 kWm3 or less is achieved at an applied AC magnetic field of 100 kHz and 200 mT, as measured at a temperature of 100 C.
11. A ferrite core for power supplies, made up of the MnZn ferrite of claim 10.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for removing undesired artifacts in Fourier domain optical coherence tomography (FDOCT) systems using continuous phase modulation, comprising:
introducing a variable phase delay between a reference arm and a sample arm of an FDOCT interferometer using continuous phase modulation;
generating two or more spectral interferograms having different phase delay integration times; and
combining the spectral interferograms using signal processing to remove the undesired artifacts.
2. The method of claim 1, wherein FDOCT comprises Spectral domain optical coherence tomography (SDOCT).
3. The method of claim 2, wherein the undesired artifacts comprise DC, autocorrelation andor complex conjugate artifacts.
4. The method of claim 2, wherein introducing the variable phase delay comprises including the variable phase delay in the reference arm or the sample arm of the interferometer.
5. The method of claim 2, wherein introducing the variable phase delay comprises introducing the variable phase delay using a piezoelectric transducer associated with a mirror.
6. The method of claim 2, wherein introducing the variable phase delay comprises introducing the variable phase delay using an electro-optic, acousto-optic or photoelastic modulator in the reference arm or the sample arm of the FDOCT interferometer.
7. The method of claim 2, wherein continuous phase modulation comprises linear continuous phase modulation.
8. The method of claim 7, wherein linear continuous phase modulation comprises:
shifting a phase in the reference arm or the sample arm linearly over a round trip delay of 2\u03c6=2\u03c0 radians;
integrating a spectral interferometric signal over three out of four evenly spaced sequential continuous phase shifts of 2\u03c6=\u03c02 radians to provide a complex spectral interferogram; and
inverse transforming the complex interferogram to provide an A-scan free the undesired artifacts.
9. The method of claim 8, wherein integrating further comprises integrating over more than three sequential continuous phase shifts.
10. The method of claim 8, wherein integrating further comprises integrating over less than three sequential continuous phase shifts.
11. The method of claim 2, wherein continuous phase modulation comprises
sinusoidal continuous phase modulation.
12. The method of claim 11, wherein sinusoidal continuous phase modulation comprises:
shifting a phase in one of the reference arm or the sample arm sinusoidally in a repetitive manner;
integrating a spectral interferometric signal over four evenly spaced sequential quarter periods of the sinusoidal continuous phase modulation to provide a complex spectral interferogram; and
inverse transforming the complex spectral interferogram to provide an A-scan free of undesired artifacts.
13. The method of claim 12, wherein integrating further comprises integrating over more than four quarter periods.
14. The method of claim 12, wherein integrating further comprises integrating over less than four quarter periods.
15. A Fourier domain optical coherence tomography (FDOCT) interferometer comprising a variable phase modulator configured to introduce a variable phase delay between a reference arm and a sample arm of the FDOCT interferometer using continuous phase modulation, wherein the FDOCT interferometer comprises a Spectral domain optical coherence tomography (SDOCT) interferometer, the SDOCT interferometer being further configured to:
introduce a variable phase delay between a reference arm and a sample arm of the SDOCT interferometer using linear continuous phase modulation,
shift a phase in the reference arm or the sample arm linearly over a round trip delay of 2\u03c6=2\u03c0 radians;
integrate a spectral interferometric signal out of four evenly spaced sequential continuous phase shifts of 2\u03c6=\u03c02 radians to provide a complex spectral interferogram; and
inverse transform the complex interferogram to provide an A-scan free the undesired artifacts.
16. The SDOCT interferometer of claim 15, wherein the variable phase modulator is positioned in one of the reference arm or the sample arm.
17. The SDOCT interferometer of claim 15, wherein the variable phase modulator comprises a switchable phasepolarization modulator.
18. The SDOCT interferometer of claim 15, wherein the variable phase modulator comprises a piezoelectric transducer associated with a mirror.
19. The SDOCT interferometer of claim 15, wherein the variable phase modulator comprises an electro-optic, acousto-optic or photoelastic modulator.
20. The SDOCT interferometer of claim 15, wherein the variable phase modulator comprises:
a phase modulator; and
a driver coupled to the phase modulator and configured to provide signal and power to the phase modulator.
21. The SDOCT interferometer of claim 20, wherein the driver includes:
a function generator coupled to the phase modulator;
a switching amplifier coupled to the function generator; and
a power supply coupled to the switching amplifier.
22. The SDOCT interferometer of claim 21, wherein the function generator is configured to provide:
a tunable sine wave frequency having a range from about 1.0 Hz to about 1.0 MHz and a resolution of at least about 0.004 Hz;
a Continuous phase variation from about 0.0 to about 360 degrees and a degree resolution of at least about 0.09; andor
a peak to peak voltage amplitude of from about 0.0 to about 20.0 V and a resolution of at least about 20.0 mV.
23. The SDOCT interferometer of claim 21, wherein the function generator is configured to use a direct digital synthesis (DDS) integrated circuit.
24. The SDOCT interferometer of claim 21, wherein the power supply comprises a Class D switching amplifier, a small value resistor in series with the phase modulator andor a low pass filter.
25. The SDOCT interferometer of claim 21, wherein the power supply comprises a half-bridge switching amplifier.
26. The SDOCT interferometer of claim 15, further configured to integrate over more than three sequential continuous phase shifts.
27. The SDOCT interferometer of claim 15, further configured to integrate over less than three sequential continuous phase shifts.
28. A Fourier domain optical coherence tomography (FDOCT) interferometer comprising a variable phase modulator configured to introduce a variable phase delay between a reference arm and a sample arm of the FDOCT interferometer using continuous phase modulation, wherein the FDOCT interferometer comprises a Spectral domain optical coherence tomography (SDOCT) interferometer, the SDOCT interferometer being further configured to:
introduce a variable phase delay between a reference arm and a sample arm of the SDOCT interferometer using sinusoidal continuous phase modulation;
shift a phase in one of the reference arm or the sample arm sinusoidally in a repetitive manner;
integrate a spectral interferometric signal over four evenly spaced sequential quarter periods of the sinusoidal continuous phase modulation to provide a complex spectral interferogram; and
inverse transform the complex spectral interferogram to provide an A-scan free of undesired artifacts.
29. The SDOCT interferometer of claim 28, further configured to integrate over more than four quarter periods.
30. The SDOCT interferometer of claim 28, further configured to integrate over less than four quarter periods.
31. A computer program product removing undesired artifacts in Fourier domain optical coherence tomography (FDOCT) systems using continuous phase modulation, the computer program product comprising:
computer readable storage medium having computer readable program code embodied in the medium, the computer readable program code comprising:
computer readable program code configured to introduce a variable phase delay between a reference arm and a sample arm of an FDOCT interferometer using continuous phase modulation;
computer readable program code configured to generate two or more spectral interferograms having different phase delay integration times; and
computer readable program code configured to combine the spectral interferograms using signal processing to remove undesired artifacts.
32. The computer program product of claim 31, wherein FDOCT comprises Spectral domain optical coherence tomography (SDOCT).
33. The computer program product of claim 32, wherein the undesired artifacts comprise DC, autocorrelation andor complex conjugate artifacts.
34. The computer program product of claim 32, wherein continuous phase modulation comprises linear continuous phase modulation.
35. The computer program product of claim 34, further comprising:
computer readable program code configured to shift a phase in the reference arm or the sample arm linearly over a round trip delay of 2\u03c6=2\u03c0 radians;
computer readable program code configured to integrate a spectral interferometric signal over three out of four evenly spaced sequential continuous phase shifts of 2\u03c6=\u03c02 radians to provide a complex spectral interferogram; and
computer readable program code configured to inverse transform the complex interferogram to provide an A-scan free the undesired artifacts.
36. The computer program product of claim 35, wherein the computer readable program code configured to integrate further comprises computer readable program code configured to integrate over more than three sequential continuous phase shifts.
37. The computer program product of claim 35, wherein the computer readable program code configured to integrate further comprises computer readable program code configured to integrate over less than three sequential continuous phase shifts.
38. The computer program product of claim 32, wherein continuous phase modulation comprises sinusoidal continuous phase modulation.
39. The computer program product of claim 38, further comprising:
computer readable program code configured to shift a phase in one of the reference arm or the sample arm sinusoidally in a repetitive manner;
computer readable program code configured to integrate a spectral interferometric signal over four evenly spaced sequential quarter periods of the sinusoidal continuous phase modulation to provide a complex spectral interferogram; and
computer readable program code configured to inverse transform the complex spectral interferogram to provide an A-scan free of undesired artifacts.
40. The computer program product of claim 39, wherein the computer readable program code configured to integrate further comprises computer readable program code configured to integrate over more than four quarter periods.
41. The computer program product of claim 39, wherein the computer readable program code configured to integrate further comprises computer readable program code configured to integrate over less than four quarter periods.