US3921099A
Expired / Lapsed
US
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Frequency stabilized laser
Assignee: Raytheon Co
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Filing: 1974-09-16
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Granted: 1975-11-18
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Expires: 1994-09-16
Abstract
Abstract Arrangements are disclosed for the frequency stabilization of a laser using an external gas cell providing an absorption resonance which is controllably tuned by means of the linear Stark effect. An error signal, which locks the laser to the desired oscillation frequency, is generated either by dither modulation of the Stark-effect cell voltage or by differential absorption in a pair of Stark-effect cells having their absorption resonances stagger tuned about the desired laser oscillation frequency. The disclosed arrangements are especially suited to stabilization of a waveguide CO2 laser operating on the P(20) 10.6 Mu laser transition. Advantages are the ability to stabilize the laser at any frequency within the laser tuning range and the elimination of undesired frequency modulation on the generated laser beam.
Inventors
- 👤 Richard L Abrams
- 👤 Thomas A Nussmeier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:30
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/13; H01S3/139; H01S3/1398
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
312 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; a Stark-effect cell disposed in the path of at least a portion of said laser beam and containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to said Stark-effect cell to adjust the center frequency of said absorption resonance to a value equal to said desired laser oscillation frequency; means for applying an alternating reference signal to said Stark-effect cell to vary the center frequency of said absorption resonance about said desired laser oscillation frequency at the frequency of said reference signal and thereby amplitude modulate the laser beam traversing said Stark-effect cell such that the amplitude of the fundamental modulation component is indicative of the magnitude of the frequency difference between the instantaneous oscillation frequency of said laser oscillator and the average center frequency of said absorption resonance, and the phase of said fundamental modulation component is indicative of the polarity of said frequency difference; means including microphone means disposed in said Stark-effect cell for sensing pressure changes in said gas resulting from changes in the amount of laser energy absorbed by said gas for producing an electrical signal corresponding to the amplitude modulation on said laser beam traversing said Stark-effect cell; means for producing from said reference signal and said electrical signal an error signal indicative of the magnitude and polarity of said frequency difference; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
Claim 2
Dependent Claim
312 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; a Stark-effect cell disposed in the path of at least a portion of said laser beam and containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to said Stark-effect cell to adjust the center frequency of said absorption resonance to a value equal to said desired laser oscillation frequency; means for applying an alternating reference signal to said Stark-effect cell to vary the center frequency of said absorption resonance about said desired laser oscillation frequency at the frequency of said reference signal and thereby amplitude modulate the laser beam traversing said Stark-effect cell such that the amplitude of the fundamental modulation component is indicative of the magnitude of the frequency difference between the instantaneous oscillation frequency of said laser oscillator and the average center frequency of said absorption resonance, and the phase of said fundamental modulation component is indicative of the polarity of said frequency difference; means including microphone means disposed in said Stark-effect cell for sensing pressure changes in said gas resulting from changes in the amount of laser energy absorbed by said gas for producing an electrical signal corresponding to the amplitude modulation on said laser beam traversing said Stark-effect cell; means for producing from said reference signal and said electrical signal an error signal indicative of the magnitude and polarity of said frequency difference; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
Claim 3
Dependent Claim
67 words
A frequency stabilized laser according to claim 1 and further including beam splitter means disposed in the path of said generated laser beam for dividing said generated laser beam into a first laser beam containing most of the energy in saId generated laser beam and a second laser beam directed into said Stark-effect cell and containing a small portion of the energy in said generated laser beam.
Claim 4
Dependent Claim
271 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; beam splitter means disposed in the path of said generated laser beam for dividing at least a portion of said generated laser beam into first and second laser beams traversing different paths; first and second Stark-effect cells disposed in the respective paths of said first and second laser beams, each Stark-effect cell containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to each of said Stark-effect cells to generate respective electric fields in said first and second cells such that the center frequency of the absorption resonance for the gas in one of said cells in slightly below said desired laser oscillation frequency and the center frequency of the absorption resonance for the gas in the other of said cells is slightly above said desired laser oscillation frequency; means for producing first and second electrical signals indicative of the relative amount of laser energy absorbed in said first and second Stark-effect cells; means for producing from said first and second electrical signals an error signal indicative of the difference between said first and second electrical signals; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
Claim 5
Dependent Claim
271 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; beam splitter means disposed in the path of said generated laser beam for dividing at least a portion of said generated laser beam into first and second laser beams traversing different paths; first and second Stark-effect cells disposed in the respective paths of said first and second laser beams, each Stark-effect cell containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to each of said Stark-effect cells to generate respective electric fields in said first and second cells such that the center frequency of the absorption resonance for the gas in one of said cells in slightly below said desired laser oscillation frequency and the center frequency of the absorption resonance for the gas in the other of said cells is slightly above said desired laser oscillation frequency; means for producing first and second electrical signals indicative of the relative amount of laser energy absorbed in said first and second Stark-effect cells; means for producing from said first and second electrical signals an error signal indicative of the difference between said first and second electrical signals; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
Claim 6
Dependent Claim
26 words
A frequency stabilized laser according to claim 3 wherein the respective dc signals applied to said first and second Stark-effect cells are at different voltage levels.
Claim 7
Dependent Claim
66 words
A frequency stabilized laser according to claim 3 wherein each of said Stark-effect cells includes a pair of spaced electrically conductive plates disposed parallel to one another on opposite sides of the laser beam traversing said cell and between which said dc signal is applied, the spacing of the plates of said first cell being different from the spacing of the plates of said second cell.
Claim 8
Dependent Claim
300 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; beam splitter means disposed in the path of said generated laser beam for dividing at least a portion of said generated laser beam into first and second laser beams of substantially equal energy and traversing different paths; first and second Stark-effect cells disposed in the respective paths of said first and second laser beams, each Stark-effect cell containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to each of said Stark-effect cells to generate respective electric fields in said first and second cells such that the center frequency of the absorption resonance for the gas in one of said cells is slightly below said desired laser oscillation frequency and the center frequency of the absorption resonance for the gas in the other of said cells is slightly above said desired laser oscillation frequency; first and second photodetector means for producing from said first and second laser beams respective first and second electrical signals of an amplitude indicative of the amount of laser energy absorbed in said first and second Stark-effect cells, respectivelY; difference amplifier means for producing from said first and second electrical signals an error signal indicative of the magnitude and polarity of the difference in amplitude between said first and second electrical signals; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
Claim 9
Dependent Claim
300 words
A frequency stabilized laser comprising: a laser oscillator for generating a laser beam at a frequency within a predetermined range of frequencies including a desired laser oscillation frequency, said laser oscillator including tuning means for adjusting the oscillation frequency of said laser oscillator; beam splitter means disposed in the path of said generated laser beam for dividing at least a portion of said generated laser beam into first and second laser beams of substantially equal energy and traversing different paths; first and second Stark-effect cells disposed in the respective paths of said first and second laser beams, each Stark-effect cell containing a gas having an absorption resonance in the vicinity of said desired laser oscillation frequency; means for applying a dc signal to each of said Stark-effect cells to generate respective electric fields in said first and second cells such that the center frequency of the absorption resonance for the gas in one of said cells is slightly below said desired laser oscillation frequency and the center frequency of the absorption resonance for the gas in the other of said cells is slightly above said desired laser oscillation frequency; first and second photodetector means for producing from said first and second laser beams respective first and second electrical signals of an amplitude indicative of the amount of laser energy absorbed in said first and second Stark-effect cells, respectivelY; difference amplifier means for producing from said first and second electrical signals an error signal indicative of the magnitude and polarity of the difference in amplitude between said first and second electrical signals; and means for feeding said error signal back to said tuning means to control the oscillation frequency of said laser oscillator in accordance with said error signal to stabilize said generated laser beam at said desired laser oscillation frequency.
References Cited (Backward Citations)
US3622908A
Cited
US3842367A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |