Dual-interrogated interferometer for fluid measurements

1 . A system comprising:

an interferometer that provides interfered light having interference fringes, wherein the interfered light comprises emitted light from the system interfered with received light by the system;

a high-rate sensor that detects the interfered light to create high-rate measurements;

a two-dimensional detector array that detects the interfered light to create two-dimensional detector array measurements; and

one or more processors that calculate fluid velocity in relation to the system, wherein the one or more processors are configured to:

identify a receive fringe for the two-dimensional detector array measurements;

identify a high-rate fringe for the high-rate measurements;

perform a statistical comparison of the receive fringe, wherein the statistical comparison identifies a portion of the receive fringe that most closely resembles the high-rate fringe;

identify a phase difference between the portion of the receive fringe and a transmit fringe associated with the emitted light from the system; and

calculate the fluid velocity associated with the phase difference.

2 . The system of claim 1 , wherein the two-dimensional detector array is a charge-coupled device.

3 . The system of claim 1 , wherein the high-rate sensor detects the interfered light at a smaller number of detectors compared to the two-dimensional detector array and has a lower dynamic range than the two-dimensional detector array.

4 . The system of claim 3 , wherein the high-rate sensor is a photomultiplier tube array.

5 . The system of claim 1 , wherein the one or more processors provide fluid velocity calculated from the high-rate measurements.

6 . The system of claim 1 , wherein the one or more processors provide fluid velocity calculated separately from both the high-rate measurements and the two-dimensional detector array measurements.

7 . A method comprising:

emitting light into an environment;

receiving reflected light from the environment;

interfering the light with the reflected light to provide interfered light;

detecting the interfered light at a high-rate sensor, the high-rate sensor providing high-rate measurements;

detecting the interfered light at a two-dimensional detector array, the two-dimensional detector array providing two-dimensional detector array measurements;

perform a statistical comparison of the two-dimensional detector array measurements to the high-rate measurements, wherein the statistical comparison identifies the portion of the two-dimensional detector array measurements that most closely resembles the high-rate fringe; and

calculating a phase shift of the reflected light based on the portion of the two-dimensional detector array measurements; and

calculate a fluid velocity associated with the phase shift.

8 . The method of claim 7 , wherein the two-dimensional detector array is a charge-coupled device.

9 . The method of claim 7 , wherein detecting the interfered light at the high-rate sensor comprises detecting the interfered light at a smaller number of detectors compared to the two-dimensional detector array and at a lower dynamic range than the two-dimensional detector array.

10 . The method of claim 7 , wherein the high-rate sensor is a photomultiplier tube array.

11 . The method of claim 7 , further comprising providing fluid velocity calculated from at least one of the high-rate measurements and the two-dimensional detector array measurements.

12 . A system comprising:

a laser source that generates light;

an emitter that emits the light into an environment of the system;

a receiver that receives reflected light, where the reflected light is the light reflected by particles in the environment;

an interferometer that produces interfered light by interfering the light with the reflected light to create interference fringes;

a coupler that couples the interfered light onto a first output path and a second output path;

a first sensor coupled to the first output path that provides a first set of measurements of the interfered light;

a second sensor coupled to the second output path that provides a second set of measurements of the interfered light, wherein the first sensor has a smaller number of detectors and a lower dynamic range than the second sensor; and

one or more processors that calculate fluid velocity in relation to the system wherein the one or more processors are configured to:

identify a receive fringe for the second set of measurements;

identify a high-rate fringe for the first set of measurements;

perform a statistical comparison of the receive fringe, wherein the statistical comparison identifies a portion of the receive fringe that most closely resembles the high-rate fringe;

identify a phase difference between the portion of the receive fringe and a transmit fringe associated with the emitted light from the system; and

calculate the fluid velocity associated with the phase difference.

13 . The system of claim 12 , wherein the first sensor is a photomultiplier tube array and the second sensor is a two-dimensional detector array.