Surface sensing probe and methods of use

A method for determining a translation of at least two locations on an object having a surface, the method comprising:

• a source of coherent radiation comprising at least two coherent radiation emissions, each of the at least two coherent radiation emissions having a beam centerline, a beam direction, and a beam waist;
• each of the at least two coherent radiation emissions creating an illumination state and a speckle pattern;
• each of the at least two coherent radiation emissions illuminating a neighborhood of a unique location on the object;
• sensing a first speckle pattern for each of the at least two coherent radiation emissions;
• sensing a second speckle pattern for each of the at least two coherent radiation emissions;
• determining a translation of each of the unique locations on the object in at least two dimensions from the first speckle pattern and the second speckle pattern for each of the at least two coherent radiation emissions wherein two of the at least two dimensions lie substantially in a plane of the surface of the object;
• wherein the at least two coherent radiation emissions each define an illumination beam waist;
• wherein the step of determining a translation of each of the unique locations on the object in at least two dimensions from the first speckle pattern and the second speckle pattern for each of the at least two coherent radiation emissions depends on a position of each of the illumination beam waists with respect to the surface of the object;
• wherein the position of each of the illumination beam waists with respect to the surface of the object defines a scaling factor for converting from a speckle shift to a surface translation for each of the coherent radiation emissions;
• and
• wherein a sign of each scaling factor depends on whether each of the illumination beam waists are in front of the surface or behind the surface.

A surface sensing apparatus to determine a translation of a location on an object having a surface, the surface sensing apparatus comprising:

• at least one laser source producing at least one beam of coherent radiation having a centerline, a beam direction, and a beam waist;
• the at least one beam of coherent radiation configured to illuminate a neighborhood of the location on the object;
• a sensor configured to detect a first speckle pattern corresponding to a first surface state and a second speckle pattern corresponding to a second surface state;
• at least one processor in communication with at least one memory element including instructions that when executed cause the processer to calculate a translation of the location on the object in at least two dimensions from the first speckle pattern and the second speckle pattern wherein two of the at least two dimensions lie substantially in a plane of the surface of the object;
• wherein each of the at least one beam of coherent radiation defines an illumination beam waist;
• wherein the instructions that when executed cause the at least one processer to calculate a translation of the location on the object in at least two dimensions from the first speckle pattern and the second speckle pattern depend on a position of the illumination beam waist with respect to the surface of the object;
• wherein the instructions that when executed cause the at least one processer to calculate a translation of the location on the object in at least two dimensions from the first speckle pattern and the second speckle pattern further depend on a scaling factor for converting from a speckle shift to a surface translation;
• and
• wherein a sign of the scaling factor depends on whether the illumination beam waist is in front of the surface or behind the surface.

A surface sensing apparatus to determine a translation of a location on an object having a surface the surface sensing apparatus comprising:

• at least one laser source configured to produce at least one beam of coherent radiation having a centerline, a beam direction, and a beam waist;
• the at least one beam of coherent radiation configured to illuminate a neighborhood of the location on the object;
• a sensor configured to detect a first speckle pattern corresponding to a first surface state and a second speckle pattern corresponding to a second surface state;
• at least one processor in communication with at least one memory element including instructions that when executed cause the processer to calculate a translation of the location on the object in at least two dimensions from the first speckle pattern and the second speckle pattern wherein two of the at least two dimensions lie substantially in a plane of the surface of the object;
• wherein the at least one beam of coherent radiation comprises at least two beams of coherent radiation wherein the at least two beams of coherent radiation are each configured to illuminate the neighborhood of a unique location on the object;
• wherein the sensor being further configured to detect a first speckle pattern and a second speckle pattern for each unique location on the object;
• and
• wherein the processor further configured to execute the instructions to calculate a translation of each unique location on the object;
• wherein each of the at least one beam of coherent radiation defines an illumination beam waist;
• wherein the instructions executed by the processor to calculate the translation of each unique location on the object depend on a position of each of the illumination beam waists with respect to the surface of the object;
• wherein the instructions executed by the processor to calculate the translation of each unique location on the object depend on a position of each of the illumination beam waists with respect to the surface of the object;
• wherein the instructions executed by the processor to calculate the translation of each unique location on the object apply a scaling factor for converting from a speckle shift to a surface translation for each beam of coherent radiation emission;
• and
• wherein a sign of each of the scaling factors depends on whether each of the illumination beam waists are in front of the surface or behind the surface.