Optical-mechanical vibrating beam accelerometer

• US 9,983,225 B2
• Filed: 01/14/2016
• Issued: 05/29/2018
• Est. Priority Date: 06/29/2015
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Fertig, Chad, Savchenko, Arthur, Tin, Steven
• Primary Examiner(s): Raevis, Robert R
• Application Number:
  US14/996,116
• Publication Number:
  US 20160377647A1
• Time in Patent Office: 866 Days
• Field of Search: None
• CPC Class Codes: G01P 15/093 by photoelectric pick-up
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: H01S 5/0014 Measuring characteristics or properties thereof measuring techniques per se G01J, G01K, G01N, G01R
• CPC Class Codes: H01S 5/0085 for modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

Systems, devices, techniques, and methods are disclosed for an opto-mechanical vibrating beam accelerometer. In one example, a system is configured to couple a laser into optical resonance with opto-mechanically active (OMA) anchors suspending a proof mass; lock frequencies of the laser to optical resonances of the OMA anchors, resulting in a modulated laser coupled with the OMA anchors; demodulate a photocurrent that detects the modulated laser coupled with the OMA anchors to detect at least an amplitude or a phase of the modulated laser; lock a frequency of the modulated laser to dynamically track instantaneous resonance frequencies of mechanical modes of the OMA anchors through changes to the amplitude or phase of the modulated laser induced by coupling of the modulated laser to the OMA anchors; and measure an acceleration based on instantaneous resonance frequencies of the OMA anchors through changes to the amplitude or phase of the modulated laser.

Claims

1. A system configured to:

couple one or more lasers into optical resonance with one or more opto-mechanically active (OMA) anchors suspending a proof mass in an accelerometer;

lock frequencies of the one or more lasers to one or more optical resonances of the one or more opto-mechanically active anchors, resulting in a modulated laser coupled with the one or more opto-mechanically active anchors;

demodulate a photocurrent generated by a photodiode that detects the modulated laser coupled with the one or more opto-mechanically active anchors to detect at least one of an amplitude or a phase of the modulated laser;

lock a frequency of the modulated laser to dynamically track instantaneous resonance frequencies of one or more mechanical modes of the one or more opto-mechanically active anchors through changes to at least one of the amplitude or the phase of the modulated laser induced by the coupling of the modulated laser to the mechanical modes of the one or more opto-mechanically active anchors; and

measure an acceleration of the accelerometer based at least in part on the instantaneous resonance frequencies of the one or more mechanical modes of the one or more opto-mechanically active anchors, as dynamically tracked through the changes to the at least one of the amplitude or the phase of the modulated laser.

2. The system of claim 1, wherein the one or more opto-mechanically active anchors comprise one or more double-ended tuning fork structures.

3. The system of claim 2, wherein the one or more double-ended tuning fork structures each comprise:

two or more photonic crystal mechanical beams with a gap between the two or more photonic crystal mechanical beams.

4. The system of claim 1, wherein the system is further configured to calibrate a scale factor of the accelerometer.

5. The system of claim 4, wherein the system is further configured to:

apply a reaction force to the proof mass using a pushing laser, wherein being configured to calibrate the scale factor comprises being configured to detect a response of the accelerometer to the pushing laser.

6. The system of claim 1, wherein the system is further configured to calibrate a bias of the accelerometer.

7. The system of claim 6, wherein the system is further configured to:

couple a stiffening laser into the one or more opto-mechanically active anchors coupled to the proof mass, wherein calibrating the bias comprises detecting a response of the accelerometer to the stiffening laser.

8. A method comprising:

coupling one or more lasers into optical resonance with one or more opto-mechanically active (OMA) anchors suspending a proof mass in an accelerometer;

locking frequencies of the one or more lasers to one or more optical resonances of the one or more opto-mechanically active anchors, resulting in a modulated laser coupled with the one or more opto-mechanically active anchors;

demodulating a photocurrent generated by a photodiode that detects the modulated laser coupled with the one or more opto-mechanically active anchors to detect at least one of an amplitude or a phase of the modulated laser;

locking a frequency of the modulated laser to dynamically track instantaneous resonance frequencies of one or more mechanical modes of the one or more opto-mechanically active anchors through changes to at least one of the amplitude or the phase of the modulated laser induced by the coupling of the modulated laser to the mechanical modes of the one or more opto-mechanically active anchors; and

measuring an acceleration of the accelerometer based at least in part on the instantaneous resonance frequencies of the one or more mechanical modes of the one or more opto-mechanically active anchors, as dynamically tracked through the changes to the at least one of the amplitude or the phase of the modulated laser.

9. The method of claim 8, wherein coupling the one or more lasers into optical resonance with the one or more opto-mechanically active (OMA) anchors comprises coupling the one or more lasers into optical resonance with one or more double-ended tuning fork structures that each comprise two or more photonic crystal mechanical beams with a gap between the two or more photonic crystal mechanical beams.

10. The method of claim 8, further comprising calibrating a scale factor of the accelerometer.

11. The method of claim 10, further comprising:

passing a stiffening laser through a calibration opto-mechanical coupling structure; and

imposing a pushing laser on the proof mass,

wherein calibrating the scale factor comprises detecting a response of the accelerometer to the stiffening laser and the pushing laser.

12. The method of claim 8, further comprising calibrating a bias of the accelerometer.

13. The method of claim 12, further comprising coupling a stiffening laser into the one or more opto-mechanically active anchors coupled to the proof mass, wherein calibrating the bias comprises detecting a response of the accelerometer to the stiffening laser.

14. A device comprising:

means for coupling one or more lasers into optical resonance with one or more opto-mechanically active (OMA) anchors suspending a proof mass in an accelerometer;

means for locking frequencies of the one or more lasers to one or more optical resonances of the one or more opto-mechanically active anchors, resulting in a modulated laser coupled with the one or more opto-mechanically active anchors;

means for demodulating a photocurrent generated by a photodiode that detects the modulated laser coupled with the one or more opto-mechanically active anchors to detect at least one of an amplitude or a phase of the modulated laser;

means for locking a frequency of the modulated laser to dynamically track instantaneous resonance frequencies of one or more mechanical modes of the one or more opto-mechanically active anchors through changes to at least one of the amplitude or the phase of the modulated laser induced by the coupling of the modulated laser to the mechanical modes of the one or more opto-mechanically active anchors; and

means for measuring an acceleration of the accelerometer based at least in part on the instantaneous resonance frequencies of the one or more mechanical modes of the one or more opto-mechanically active anchors, as dynamically tracked through the changes to the at least one of the amplitude or the phase of the modulated laser.

15. The device of claim 14, wherein the one or more opto-mechanically active anchors comprise one or more double-ended tuning fork structures.

16. The device of claim 15, wherein the one or more double-ended tuning fork structures each comprise:

two or more photonic crystal mechanical beams with a gap between the two or more photonic crystal mechanical beams.

17. The device of claim 14, wherein the system is further configured to calibrate a scale factor of the accelerometer.

18. The device of claim 17, wherein the system further comprises:

means for apply a reaction force to the proof mass using a pushing laser, wherein being calibrating the scale factor comprises detecting a response of the accelerometer to the pushing laser.

19. The device of claim 14, further comprising means for calibrating a bias of the accelerometer.

20. The device of claim 19, further comprising:

means for coupling a stiffening laser into the one or more opto-mechanically active anchors coupled to the proof mass, wherein calibrating the bias comprises detecting a response of the accelerometer to the stiffening laser.