US3719822A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of generating a signal with a frequency between 1011 and 1015 hz with extreme frequency stability
Assignee: Massachusetts Institute of Technology
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Filing: 1971-03-29
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Granted: 1973-03-06
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Expires: 1991-03-29
Abstract
Abstract The output signal of a laser at a frequency Vf is mixed in a metal point contact diode with the output of a klystron having a variable frequency Vm. Because of the diode''s non-linearities, the current flowing through the diode will contain and reradiate sideband components at frequencies Vs Vf + OR - Vm. Simultaneously, the diode is subjected to a reference signal with a fixed frequency having a harmonic which falls at a frequency close to one of the sideband frequencies Vs. A beat note is produced which fluctuates in frequency due to the instability of the laser frequency Vf. The beat note frequency is compared with a stable source and an error signal corresponding to the fluctuations is obtained which in turn is used to adjust Vm to compensate for the instability in Vf, whereby the frequency Vs is stabilized to a degree equal to that of the reference source. Additionally, the frequency of the sideband is determined to the same degree of precision. This information is extremely important and useful in making frequency measurements in the infrared region where it is difficult to produce a beat note by standard techniques of mixing a high harmonic of a known microwave signal with an unknown high frequency due to the low power of such a high harmonic. Here, harmonics of the components of stabilized laser sideband are used as intermediate step frequencies to bridge the gap between the microwave and visible regions.
Inventors
- 👤 A Javan
- 👤 L Hocker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:10
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/13; H01S3/139; H01S3/1394; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/099
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
145 words
A method of generating a stabilized sideband laser frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + OR - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source.
Claim 2
Independent Claim
145 words
A method of generating a stabilized sideband laser frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + OR - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source.
Claim 3
Independent Claim
145 words
A method of generating a stabilized sideband laser frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source.
Claim 4
Independent Claim
145 words
A method of generating a stabilized sideband laser frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source.
Claim 5
Dependent Claim
63 words
A method of generating a signal with a frequency in the far infrared and infrared range as recited in claim 1 wherein said laser frequency Vf is mixed with radiation from a microwave source having an adjustable frequency Vm and wherein said error signal is fed back to said microwave source, whereby A stabilized sideband Vs Vf + or - Vm is produced.
Claim 6
Dependent Claim
51 words
A method of generating a signal with a frequency in the far infrared and infrared range as recited in claim 1 wherein said laser frequency Vf is mixed with radiation from a radio source having an adjustable frequency Vm and wherein said error signal is fed back to said radio source.
Claim 7
Dependent Claim
60 words
A method of generating a signal with a frequency in the far infrared and infrared range as recited in claim 1 further comprising: a. focusing the energy of the sideband frequency Vs into a parallel beam, b. directing said beam into a discharge tube exhibiting gain at the sideband frequency, c. amplifying said sideband frequency Vs in said discharge tube.
Claim 8
Dependent Claim
65 words
A method of generating a signal with a frequency in the far infrared and infrared range as recited in claim 1 further comprising: a. focusing the energy of the sideband frequency Vs into a parallel beam, b. directing said beam into a regenerative amplifier, said amplifier being on the threshold of oscillation but not quite oscillating, c. amplifying said sideband frequency in said regenerative amplifier.
Claim 9
Independent Claim
281 words
A method of generating a signal with a frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source, e. mixing an unstabilized laser frequency Vy with radiation from a source having an adjustable frequency Vx, thereby producing sideband frequencies Vz nVy + or - qVx, n and q being integers, f. mixing the sideband frequency Vz with a harmonic of Vm and an actual harmonic of Vf whose sum falls close to Vz, thereby producing a beat note, g. comparing the frequency of the beat note with the frequency of a second stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the second stable source, h. feeding back the error signal to the source to adjust Vx such that the frequency of the beat note and the second stable source are locked, whereby Vz remains constant to the same degree of stability as Vs.
Claim 10
Independent Claim
281 words
A method of generating a signal with a frequency in the far infrared and infrared range comprising: a. mixing a laser frequency Vf with radiation from a source having an adjustable frequency Vm thereby producing sideband frequencies Vs nVf + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a reference signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note, c. comparing the frequency of the beat note with the frequency of a stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the beat note and standard are locked, whereby Vs remains constant to the same degree of stability as the reference source, e. mixing an unstabilized laser frequency Vy with radiation from a source having an adjustable frequency Vx, thereby producing sideband frequencies Vz nVy + or - qVx, n and q being integers, f. mixing the sideband frequency Vz with a harmonic of Vm and an actual harmonic of Vf whose sum falls close to Vz, thereby producing a beat note, g. comparing the frequency of the beat note with the frequency of a second stable source, and obtaining an error signal responsive to the difference between the frequency of the beat note and the second stable source, h. feeding back the error signal to the source to adjust Vx such that the frequency of the beat note and the second stable source are locked, whereby Vz remains constant to the same degree of stability as Vs.
Claim 11
Independent Claim
196 words
A method of generating a signal with a frequency in the far infrared and infrared range comprising: a. subjecting the metal cat whisker of a first non-linear point contact diode with laser radiation of frequency Vf and with radiation from a microwave source having an adjustable output frequency Vm, said cat whisker having a diameter of the order of the wavelength corresponding to Vf, whereby a current is induced in and reradiated by the diode with sideband frequencies Vs nVf + or - qVm, n and q being integers, b. simultaneously subjecting the cat whisker to an extremely stable microwave signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note across the diode, c. comparing the frequency of the beat note with the frequency of a stable Source and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the microwave source to adjust Vm to phase lock the frequency of the beat note to the frequency of the stable source, whereby Vs remains constant to the same degree of stability as the microwave signal.
Claim 12
Independent Claim
196 words
A method of generating a signal with a frequency in the far infrared and infrared range comprising: a. subjecting the metal cat whisker of a first non-linear point contact diode with laser radiation of frequency Vf and with radiation from a microwave source having an adjustable output frequency Vm, said cat whisker having a diameter of the order of the wavelength corresponding to Vf, whereby a current is induced in and reradiated by the diode with sideband frequencies Vs nVf + or - qVm, n and q being integers, b. simultaneously subjecting the cat whisker to an extremely stable microwave signal having a harmonic whose frequency falls close to Vs, thereby producing a beat note across the diode, c. comparing the frequency of the beat note with the frequency of a stable Source and obtaining an error signal responsive to the difference between the frequency of the beat note and the stable source, d. feeding back the error signal to the microwave source to adjust Vm to phase lock the frequency of the beat note to the frequency of the stable source, whereby Vs remains constant to the same degree of stability as the microwave signal.
Claim 13
Dependent Claim
210 words
A method of generating a signal with a frequency in the far infrared and infrared range as recited in claim 7 further comprising: a. subjecting the metal cat whisker of a second non-linear point contact diode with laser radiation of frequency Vx and with radiation from a microwave source having an adjustable output frequency Vy, said cat whisker having a diameter of the order of the wavelength corresponding to Vx, whereby a current is induced in and reradiated by the diode with sideband frequencies Vz nVx + or - qVy, n and q being integers, b. simultaneously subjecting the cat whisker of said second diode to a harmonic of Vf and an equal harmonic of Vm whose sum falls close to Vz, thereby producing a beat note across said second diode, c. comparing the frequency of the beat note with the frequency of a second stable source and obtaining an error signal responsive to the difference between the frequency of the beat note and the second stable source, d. feeding back the error signal to the microwave source to adjust Vy to phase lock the frequency of the beat note to the frequency of the second stable source, whereby Vz remains constant to the same degree of stability as Vs.
Claim 14
Independent Claim
238 words
A method of measuring an unknown far infrared or infrared frequency to a high degree of accuracy comprising: a. mixing an unstabilized lower laser frequency VL with radiation from a microwave source having an adjustable frequency Vm, thereby producing sideband frequencies Vs nVL + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a microwave reference frequency VR having a harmonic whose frequency falls slightly lower than Vs, thereby producing a first beat note, c. comparing the first beat note frequency with the frequency of a stable source and obtaining an error signal responsive to the difference between the frequency of the first beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the first beat note and stable source are locked, whereby Vs remains constant to the same degree of stability as the reference source, said frequency Vs being equal to the harmonic of the microwave reference frequency, VR, plus the first beat note frequency, e. mixing the unknown frequency with a harmonic of VL and an equal harmonic of Vm whose sum falls slightly lower than the unknown frequency, whereby a second beat note frequency is produced and whereby said unknown frequency is determined as being equal to the sum of the harmonic of VL and the equal harmonic of Vm plus the second beat note frequency.
Claim 15
Independent Claim
238 words
A method of measuring an unknown far infrared or infrared frequency to a high degree of accuracy comprising: a. mixing an unstabilized lower laser frequency VL with radiation from a microwave source having an adjustable frequency Vm, thereby producing sideband frequencies Vs nVL + or - qVm, n and q being integers, b. mixing the sideband frequency Vs with a microwave reference frequency VR having a harmonic whose frequency falls slightly lower than Vs, thereby producing a first beat note, c. comparing the first beat note frequency with the frequency of a stable source and obtaining an error signal responsive to the difference between the frequency of the first beat note and the stable source, d. feeding back the error signal to the source to adjust Vm such that the frequency of the first beat note and stable source are locked, whereby Vs remains constant to the same degree of stability as the reference source, said frequency Vs being equal to the harmonic of the microwave reference frequency, VR, plus the first beat note frequency, e. mixing the unknown frequency with a harmonic of VL and an equal harmonic of Vm whose sum falls slightly lower than the unknown frequency, whereby a second beat note frequency is produced and whereby said unknown frequency is determined as being equal to the sum of the harmonic of VL and the equal harmonic of Vm plus the second beat note frequency.
Claim 16
Dependent Claim
46 words
A method of measuring an unknown far infrared or infrared frequency to a high degree of accuracy as recited in claim 9 wherein the harmonic of VR falls slightly higher than Vs, whereby Vs is equal to the harmonic of VR minus the beat note frequency.
Claim 17
Dependent Claim
65 words
A method of measuring an unknown far infrared or infrared frequency to a high degree of accuracy as recited in claim 9 wherein the mixing of the unknown frequency is with a harmonic of VL minus a harmonic of Vm, and said unknown frequency is determined as being equal to the harmonic of VL minus the harmonic of Vm plus the second beat note frequency.
Claim 18
Dependent Claim
63 words
A method of measuring an unknown far infrared or infrared frequency to a high degree of accuracy as recited in claim 9 wherein the sum of the harmonic of VL and Vm falls slightly higher than the unknown frequency, whereby the unknown frequency is determined as being equal to the harmonic of VL and harmonic of Vm minus said second beat note frequency.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |