Vibration remote sensor based on speckles tracking, which uses an optical-inertial accelerometer, and method for correcting the vibrational noise of such a sensor

A correction method of vibrational noise of a vibration remote sensor based on speckles tracking, the method comprising:

• providing a vibration remote sensor based on speckles tracking, comprising the following components integral to a horizontal plane:
• a laser configured to emit a coherent light signal along an axis incident on a distant surface;
• receiving optics of a light signal returning from said distant surface along an optical axis;
• a measuring sensor of said light signal returning from said distant surface along said optical axis;
• an electronic processing unit of data detected by said measuring sensor configured to calculate a speckle pattern correlation;
• wherein:
• a first accelerometer is positioned between the receiving optics and the measuring sensor, the first accelerometer comprising:
• a linear element having torsion constant kθ, which is stretched, parallel to the optical axis, between two ends of a frame;
• a mechanical arm transversely fixed to said linear element;
• a first inertial metallic mass placed at one end of said mechanical arm opposite to said linear element;
• a magnet integral with said frame and positioned in front of said first inertial metallic mass at an adjustable distance dmm therefrom;
• a first optical reference integral with the first inertial metallic mass;
• a light source configured to illuminate said first optical reference;
• and
• a sensor for optical detection of a movement, normal to the optical axis, of said first optical reference integral with the first inertial metallic mass;
• said first accelerometer is positioned so that the first inertial metallic mass is free to oscillate at least along a first direction (yc), which is perpendicular to said horizontal plane;
• said light source is different from said laser;
• and
• said measuring sensor is additionally configured to detect successive images of the first optical reference, which is integral to the first inertial metallic mass, to measure its displacements along the first direction (yc);
• calculating a correlation centroid Cys of a speckle pattern and a correlation centroid Cyi(fy) of a displacement pattern of said first optical reference along said first direction (yc), wherein fy is a frequency of a signal detected by said first accelerometer;
• and
• calculating the corrected correlation centroid of the speckle pattern along said first direction (yc) as Cy=Cys−Cyi(fy).