Atomic interferometric accelerometer with enhanced vibrational stability

Patent metadata

Field	Value
Publication number	US-2017307652-A1
Application number	US-201615138035-A
Country	US
Kind code	A1
Filing date	Apr 25, 2016
Priority date	Apr 25, 2016
Publication date	Oct 26, 2017
Grant date	—

Abstract

An atomic interferometric accelerometer comprises a laser that emits a pulsed beam at a first frequency, an electro-optic modulator that receives the beam, and a vacuum cell in communication with the electro-optic modulator. The electro-optic modulator outputs a first optical signal corresponding to the beam at the first frequency and a second optical signal having a second frequency different from the first frequency. The vacuum cell has a chamber for laser cooled atoms. The vacuum cell receives the optical signals such that they propagate in a direction that passes through the atoms. A piezo mirror retro-reflects the optical signals back through the vacuum cell in a counter-propagating direction. The piezo mirror is driven with substantially constant velocity during a beam pulse, thereby imparting a Doppler shift to the retro-reflected optical signals to create two non-symmetric counter-propagating lightwave pairs. One of the lightwave pairs supports interferometry while the other is non-resonant.

First claim

What is claimed is:

1 . An atomic interferometric accelerometer, comprising:
a laser device configured to emit a pulsed laser beam at a first frequency; an electro-optic modulator in optical communication with the laser device and configured to receive the pulsed laser beam at the first frequency, the electro-optic modulator configured to output a first optical signal corresponding to the pulsed laser beam at the first frequency and a second optical signal having a second frequency different from the first frequency; a vacuum cell in optical communication with the electro-optic modulator, the vacuum cell comprising a plurality of optically transparent sides that enclose a vacuum chamber in which laser cooled atoms reside, the vacuum cell configured to receive the first and second optical signals such that the first and second optical signals propagate in a direction that passes through the laser cooled atoms; and a piezo mirror structure in optical communication with the vacuum cell and configured to retro-reflect the first and second optical signals back through the laser cooled atoms in a counter-propagating direction; wherein the piezo mirror structure is driven with substantially constant velocity during each individual laser beam pulse, thereby imparting a Doppler shift to the retro-reflected first and second optical signals to create two non-symmetric counter-propagating lightwave pairs, wherein one of the lightwave pairs supports interferometry while the other of the lightwave pairs is non-resonant.

2 . The atomic interferometric accelerometer of claim 1 , wherein the laser device comprises a laser diode.

3 . The atomic interferometric accelerometer of claim 1 , further comprising a first collimator located in a first optical path between the laser device and the electro-optic modulator, wherein the pulsed laser beam is passed through the first collimator prior to being received by the electro-optic modulator.

4 . The atomic interferometric accelerometer of claim 3 , further comprising a second collimator located in a second optical path between the electro-optic modulator and the vacuum cell, wherein the first and second optical signals pass through the second collimator prior to being received by the vacuum cell.

5 . The atomic interferometric accelerometer of claim 4 , wherein the first and second collimators each comprise a single lens collimator or a multi-lens collimator.

6 . The atomic interferometric accelerometer of claim 1 , wherein the laser cooled atoms comprise alkali atoms selected from the group consisting of rubidium, and cesium.

7 . The atomic interferometric accelerometer of claim 1 , wherein the piezo mirror structure is located outside of the vacuum cell on an opposite side from the second collimator.

8 . The atomic interferometric accelerometer of claim 1 , wherein the piezo mirror structure comprises:
a piezoelectric element; a mirror element coupled to the piezoelectric element; and a quarter-waveplate coupled to the mirror element.

9 . The atomic interferometric accelerometer of claim 8 , further comprising a piezo controller operatively coupled to the piezoelectric element, the piezo controller imparting a sawtooth displacement at a first velocity to the piezoelectric element.

10 . The atomic interferometric accelerometer of claim 9 , further comprising a photodetector configured to receive a portion of the retro-reflected first and second optical signals and detect a beat note.

11 . The atomic interferometric accelerometer of claim 10 , wherein a retro-reflected frequency is beat with an incident frequency so that the beat note encodes information about the velocity of the piezoelectric element.

12 . The atomic interferometric accelerometer of claim 11 , wherein the beat note detected by the photodetector is used to track the velocity of the piezoelectric element.

13 . The atomic interferometric accelerometer of claim 10 , wherein the beat note produces an error signal that is sent in a feedback loop from the photodetector to the piezo controller to stabilize the velocity of the piezoelectric element.

14 . The atomic interferometric accelerometer of claim 10 , wherein the beat note is combined with a reference RF signal to produce an error signal that is sent in a feedback loop from the photodetector to the piezo controller to stabilize the velocity of the piezoelectric element.

15 . The atomic interferometric accelerometer of claim 10 , further comprising a set of beam splitters or Faraday isolators, which direct the emitted pulsed laser beam and the retro-reflected first and second optical signals to the photodetector.

16 . An atomic interferometric accelerometer, comprising:
a laser device configured to emit a pulsed laser beam at a first frequency; an electro-optic modulator in optical communication with the laser device and configured to receive the pulsed laser beam at the first frequency, the electro-optic modulator configured to output a first optical signal corresponding to the pulsed laser beam at the first frequency and a second optical signal have a second frequency different from the first frequency; a vacuum cell in optical communication with the electro-optic modulator, the vacuum cell comprising a plurality of optically transparent sides that enclose a vacuum chamber in which laser cooled atoms reside, the vacuum cell configured to receive the first and second optical signals such that the first and second optical signals propagate in a direction that passes through the laser cooled atoms; a piezo mirror structure in optical communication with the vacuum cell and configured to retro-reflect the first and second optical signals back through the laser cooled atoms in a counter-propagating direction; a piezo controller operatively coupled to the piezo mirror structure, the piezo controller imparting a periodic displacement at a first velocity to the piezo mirror structure; and a photodetector configured to receive a portion of the retro-reflected first and second optical signals and detect a beat note; wherein the beat note produces an error signal that is sent in a feedback loop from the photodetector to the piezo controller to stabilize the velocity of the piezo mirror structure; wherein the piezo mirror structure is driven with substantially constant velocity during each individual laser beam pulse, thereby imparting a Doppler shift to the retro-reflected first and second optical signals to create two non-symmetric counter-propagating lightwave pairs, wherein one of the lightwave pairs supports interferometry while the other of the lightwave pairs is non-resonant.

17 . The atomic interferometric accelerometer of claim 16 , wherein the laser device comprises a distributed Bragg reflector laser.

18 . The atomic interferometric accelerometer of claim 16 , wherein the piezo mirror structure comprises:
a piezoelectric element; a mirror element coupled to the piezoelectric element; and a quarter-waveplate coupled to the mirror element.

19 . The atomic interferometric accelerometer of claim 18 , wherein the piezo mirror structure is located outside of the vacuum cell on an opposite side from the electro-optic modulator.

20 . The atomic interferometric accelerometer of claim 18 , further comprising a set of beam splitters or Faraday isolators, which direct the emitted pulsed laser beam and the retro-reflected first and second optical signals to the photodetector.

Assignees

• Honeywell Int Inc

Inventors

• Compton Robert

Classifications

• G01P15/093 Primary

  by photoelectric pick-up · CPC title

• G01P15/0802 Primary

  Details · CPC title

• G01V7/00 Primary

  Measuring gravitational fields or waves; Gravimetric prospecting or detecting · CPC title

• G01V7/02

  Details · CPC title

• G01N21/64

  Fluorescence; Phosphorescence · CPC title