Apparatus and method using amplification cells for ring laser gyroscope cavity length control

Claim 2

A cavity length control system for a ring laser that includes a frame having a cavity therein for guiding a pair of counter propagating light beams and a cavity length control mirror mounted to the frame, comprising: means for extracting a portion of each of the counter propagating light beams from the cavity; means for splitting the light beams extracted from the cavity into a first source beam and a second source beam; first gain means for amplifying the first source beam, the first gain means including a first isotope of a gas having a first gain profile that includes a natural resonance frequency of the first isotope; second gain means for amplifying the second source beam, the second gain means including a second isotope of the gas having a second gain profile that includes a natural resonance frequency of the second isotope; and means for applying to the cavity length control mirror a control signal indicative of the detuning of the frequency of the first and second source beams from a central frequency determined from superimposing the first and second gain profiles to move the cavity length control mirror to produce a cavity length that permits light of a selected frequency to resonate in the cavity and also to stabilize the cavity length.

Claim 3

The cavity length control system of claim 1 wherein the first gain means comprises: means for passing the first source beam through a first chamber containing the first gas; and means for applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 4

The cavity length control system of claim 2 wherein the first gas comprises Ne 20 .

Claim 5

The cavity length control system of claim 1 wherein the second gain means comprises: means for passing the second source beam through a second chamber containing the second gas ; and means for applying an energizing voltage to the second gas so that the second source beam stimulates the second gas to produce light that is coherent with the second source beam and produce an amplified second source beam.

Claim 6

The cavity length control system of claim 4 wherein the second gas comprises Ne 22 .

Claim 7

The cavity length control system of claim 4 wherein the first gain means comprises: means for passing the first source beam through a first chamber containing the first gas; and means for applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 8

The cavity length control system of claim 6, wherein the means for applying the control signal to the cavity length control mirror comprises: means for producing a first electrical signal indicative of the intensity of the amplified first source beam; and means for producing a second electrical signal indicative of the intensity of the amplified second source beam.

Claim 9

The cavity length control system of claim 7, further comprising: a first lock-in amplifier for amplifying the first electrical signal; and a second lock-in amplifier for amplifying the second electrical signal.

Claim 10

The cavity length control system of claim 8, further comprising: an oscillator for producing a reference signal having a specified reference frequency; means for chopping the energizing voltages applied to the first and second gain means at the specified reference frequency; and means for applying the specified reference frequency to the first and second lock-in amplifiers.

Claim 11

The cavity length control system of claim 9, further including: first normalizing means for producing a first normalized signal that is indicative of the ratio of the signal output from the first gain means and the source intensity; second normalizing means for producing a second normalized signal that is indicative of the ratio of the signal output from the second gain means and the source intensity; and means for processing the first and second normalized signals output to control the position of the cavity length control mirror.

Claim 12

The cavity length control system of claim 9, further comprising: a first cathode and second cathode mounted to the first and second gain means, respectively; a switching device connected between the oscillator and the first and second cathodes; means for applying the specified reference frequency to the switching device; and means for controlling the switching device to switch the first and second cathodes between open and ground at the specified reference frequency.

Claim 13

The cavity length control system of claim 9, further comprising: means for producing a dc voltage proportional to the difference in signals output from the first and second lock-in amplifiers; an actuator connected to the cavity length control mirror for controlling the position of the cavity length control mirror relative to the frame of the ring laser gyroscope; and means for connecting the dc voltage to the actuator.

Claim 14

A cavity length control method in a ring laser that includes a frame having a cavity therein for guiding a pair of counter propagating light beams and a cavity length control mirror mounted to the frame, comprising the steps of: extracting a portion of one of the light beams from the cavity; splitting the light beam extracted from the cavity into a first source beam and a second source beam; amplifying the first source beam with first gain means including a first isotope of a gas having a first gain profile that includes a natural resonance frequency of the first isotope; amplifying the second source beam with second gain means including a second isotope of the gas having a second gain profile that includes a natural resonance frequency of the second isotope; and applying to the cavity length control mirror a control signal indicative of the detuning of the frequency of the first and second source beams from a central frequency determined fromsuperimposing the first and second gain profiles to move the cavity length control mirror to produce a cavity length that permits light of a selected frequency to resonate in the cavity

Claim 15

A cavity length control method in a ring laser that includes a frame having a cavity therein for guiding a pair of counter propagating light beams and a cavity length control mirror mounted to the frame, comprising the steps of: extracting a portion of one of the light beams from the cavity; splitting the light beam extracted from the cavity into a first source beam and a second source beam; amplifying the first source beam with first gain means including a first isotope of a gas having a first gain profile that includes a natural resonance frequency of the first isotope; amplifying the second source beam with second gain means including a second isotope of the gas having a second gain profile that includes a natural resonance frequency of the second isotope; and applying to the cavity length control mirror a control signal indicative of the detuning of the frequency of the first and second source beams from a central frequency determined fromsuperimposing the first and second gain profiles to move the cavity length control mirror to produce a cavity length that permits light of a selected frequency to resonate in the cavity

Claim 16

The cavity length control method of claim 13, further comprising the steps of: passing the first source beam through a first chamber containing the first gas; and applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 17

The cavity length control method of claim 14, including the step of forming the first gas to comprise Ne 20 .

Claim 18

The cavity length control method of claim 13, further comprising the steps of: passing the second source beam through a second chamber containing the second gas; and applying an energizing voltage to the second gas so that the second source beam stimulates the second gas to produce light that is coherent with the second source beam and produce an amplified second source beam.

Claim 19

The cavity length control method of claim 16, including the step of forming the second gas to comprise Ne 22 .

Claim 20

The cavity length control method of claim 17, further comprising the steps of: passing the first source beam through a first chamber containing the first gas; and applying an energizing voltage to the first gas in the first chamber so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 21

The cavity length control method of claim 18 wherein the step of applying the control signal to the cavity length control mirror comprises the steps of: producing a first electrical signal indicative of the intensity of the amplified first source beam; and producing a second electrical signal indicative of the intensity of the amplified second source beam.

Claim 22

The cavity length control method of claim 19, further comprising the steps of: amplifying the first electrical signal with a first lock-in amplifier; and amplifying the second electrical signal with a second lock-in amplifier.

Claim 23

The cavity length control method of claim 20, further including the steps of: producing a first normalized signal that is indicative of the ratio of the signal output from the first gain means and the source intensity; producing a second normalized signal that is indicative of the ratio of the signal output from the second gain means and the source intensity; and processing the first and second normalized signals output to control the position of the cavity length control mirror.

Claim 24

The cavity length control method of claim 20, further comprising the steps of: producing a reference signal having a specified reference frequency with an oscillator; chopping the energizing voltages applied to the first and second gain means at the reference frequency; and applying reference frequency to the first and second lock-in amplifiers.

Claim 25

The cavity length control method of claim 20 wherein the step of chopping the energizing voltages applied to the first and second gain means at the reference frequency includes connecting: a first and second cathode to the first and second gain cell means, respectively; and a transistor between the oscillator and the first and second cathodes.

Claim 26

The cavity length control method of claim 21, further comprising the steps of: producing a dc voltage proportional to the difference in signals output from the first and second lock-in amplifiers; connecting an actuator to the cavity length control mirror for controlling the position of the cavity length control mirror relative to the frame of the ring laser gyroscope; and connecting the dc voltage to the actuator.

Claim 27

A ring laser gyroscope, comprising: a frame having a cavity therein for guiding a pair of counter propagating light beams reflective means for confining the counterpropagating light beams to a predetermined optical path in the cavity, the reflective means including at least one cavity length control mirror mounted to the frame; cavity length control means for controlling the length of the optical path in the cavity, the cavity length control means including: means for extracting a portion of at least one of the light beams from the cavity; means for splitting the light extracted from the cavity into a first source beam and a second source beam; first gain means for amplifying the first source beam, the first gain means including a first isotope of a gas having a first gain profile that includes a natural resonance frequency of the first isotope; second gain means for amplifying the second source beam, the second gain means including a second isotope of the gas having a second gain profile that includes a natural resonance frequency of the second isotope; and means producing a control signal indicative of the detuning of the frequency of the first and second source beams from a central frequency determined from superimposing the first and second gain profiles; and actuator means responsive to the control signal for adjusting the position of the cavity length control mirror to produce a cavity length that permits light of a selected frequency to resonate in the cavity and to stabilize the cavity length.

Claim 28

A ring laser gyroscope, comprising: a frame having a cavity therein for guiding a pair of counter propagating light beams reflective means for confining the counterpropagating light beams to a predetermined optical path in the cavity, the reflective means including at least one cavity length control mirror mounted to the frame; cavity length control means for controlling the length of the optical path in the cavity, the cavity length control means including: means for extracting a portion of at least one of the light beams from the cavity; means for splitting the light extracted from the cavity into a first source beam and a second source beam; first gain means for amplifying the first source beam, the first gain means including a first isotope of a gas having a first gain profile that includes a natural resonance frequency of the first isotope; second gain means for amplifying the second source beam, the second gain means including a second isotope of the gas having a second gain profile that includes a natural resonance frequency of the second isotope; and means producing a control signal indicative of the detuning of the frequency of the first and second source beams from a central frequency determined from superimposing the first and second gain profiles; and actuator means responsive to the control signal for adjusting the position of the cavity length control mirror to produce a cavity length that permits light of a selected frequency to resonate in the cavity and to stabilize the cavity length.

Claim 29

The ring laser gyroscope of claim 25 wherein the first gain means comprises: means for passing the first source beam through a first chamber containing the first gas; and means for applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 30

The ring laser gyroscope of claim 26 wherein the first gas comprises Ne 20 .

Claim 31

The ring laser gyroscope of claim 25 wherein the second gain means comprises: means for passing the second source beam through a second chamber containing the second gas ; and means for applying an energizing voltage to the second gas so that the second source beam stimulates the second gas to produce light that is coherent with the second source beam and produce an amplified second source beam.

Claim 32

The ring laser gyroscope of claim 28 wherein the second gas comprises Ne 22 .

Claim 33

The ring laser gyroscope of claim 28 wherein the first gain means comprises: means for passing the first source beam through a first chamber containing the first gas; and means for applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 34

The ring laser gyroscope of claim 30, wherein the means for applying the control signal to the cavity length control mirror comprises: means for producing a first electrical signal indicative of the intensity of the amplified first source beam; and means for producing a second electrical signal indicative of the intensity of the amplified second source beam.

Claim 35

The ring laser gyroscope of claim 31, further comprising: a first lock-in amplifier for amplifying the first electrical signal; and a second lock-in amplifier for amplifying the second electrical signal;

Claim 36

The ring laser gyroscope of claim 32, further comprising: an oscillator for producing a reference signal having a specified reference frequency; means for chopping the energizing voltages applied to the first and second gain means at the specified reference frequency; and means for applying the specified reference frequency to the first and second lock-in amplifiers.

Claim 37

The ring laser gyroscope of claim 33, further including: first normalizing means for producing a first normalized signal that is indicative of the ratio of the signal output from the first gain means and the source intensity; second normalizing means for producing a second normalized signal that is indicative of the ratio of the signal output from the second gain means and the source intensity; and means for processing the first and second normalized signals output to control the position of the cavity length control mirror.

Claim 38

The ring laser gyroscope of claim 34, further comprising: a first cathode and second cathode mounted to the first and second gain means, respectively; a switching device connected between the oscillator and the first and second cathodes; means for applying the specified reference frequency to the switching device; and means for controlling the switching device to switch the first and second cathodes between open and ground at the specified reference frequency.

Claim 39

The ring laser gyroscope of claim 32, further comprising: means for producing a dc voltage proportional to the difference in signals output from the first and second lock-in amplifiers; an actuator connected to the cavity length control mirror for controlling the position of the cavity length control mirror relative to the frame of the ring laser gyroscope; and means for connecting the dc voltage to the actuator.

Claim 42

The method of claim 37, further comprising the steps of: passing the first source beam through a first chamber containing the first gas; and applying an energizing voltage to the first gas so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 43

The method of claim 38, including the step of forming the first gas to comprise Ne 20 .

Claim 44

The method of claim 37, further comprising the steps of: passing the second source beam through a second chamber containing the second gas; and applying an energizing voltage to the second gas so that the second source beam stimulates the second gas to produce light that is coherent with the second source beam and produce an amplified second source beam.

Claim 45

The method of claim 40, including the step of forming the second gas to comprise Ne 22 .

Claim 46

The cavity length control method of claim 41, further comprising the steps of: passing the first source beam through a first chamber containing the first gas; and applying an energizing voltage to the first gas in the first chamber so that the first source beam stimulates the first gas to produce light that is coherent with the first source beam and produce an amplified first source beam.

Claim 47

The method of claim 42 wherein the step of applying the control signal to the cavity length control mirror comprises the steps of: producing a first electrical signal indicative of the intensity of the amplified first source beam; and producing a second electrical signal indicative of the intensity of the amplified second source beam.

Claim 48

The method of claim 43, further comprising the steps of: amplifying the first electrical signal with a first lock-in amplifier; and amplifying the second electrical signal with a second lock-in amplifier.

Claim 49

The method of claim 44, further including the steps of: producing a first normalized signal that is indicative of the ratio of the signal output from the first gain means and the source intensity; producing a second normalized signal that is indicative of the ratio of the signal output from the second gain means and the source intensity; and processing the first and second normalized signals output to control the position of the cavity length control mirror.

Claim 50

The method of claim 45, further comprising the steps of: producing a reference signal having a specified reference frequency with an oscillator; chopping the energizing voltages applied to the first and second gain means at the reference frequency; and applying reference frequency to the first and second lock-in amplifiers.

Claim 51

The method of claim 46 wherein the step of chopping the energizing voltages applied to the first and second gain means at the reference frequency includes connecting: a first and second cathode to the first and second gain cell means, respectively; and a transistor between the oscillator and the first and second cathodes.

Claim 52

The cavity length control method of claim 47, further comprising the steps of: producing a dc voltage proportional to the difference in signals output from the first and second lock-in amplifiers; connecting an actuator to the cavity length control mirror for controlling the position of the cavity length control mirror relative to the frame of the ring laser gyroscope; and connecting the dc voltage to the actuator.