System for optical fiber strain measure

An industrial machine, comprising:

• an axle;
• and
• a laser source configured to generate an output radiation;
• a strainable optical fiber having a first and a second facet, wherein the first facet is coupled to the laser source for receiving at least part of the output radiation and for transmitting therefrom a guided radiation over the optical fiber towards the second facet;
• means for calculating a measure of a strain of at least part of the optical fiber, wherein:
• the at least part of the optical fiber includes a first section and a second section, wherein the second section is movable by the strain of the at least part of the optical fiber according to a linear displacement of the second section with respect to the first section along the at least part of the optical fiber, the at least part of the optical fiber being attached to the axle;
• the second facet is configured to receive the guided radiation and to reflect therefrom a corresponding reflected radiation towards the first facet;
• the laser source is a self-mixing type which is configured to receive at least part of the reflected radiation guided from the second facet to the first facet and to mix the output radiation with the received radiation;
• and
• the calculating means are for calculating the measure of the strain of the at least part of the optical fiber through the linear displacement of the second section measured by the self-mixing effect in the laser source.

A measurement method, comprising:

• generating an output radiation using a self-mixing laser source;
• receiving at least part of the output radiation in a first facet of a strainable optical fiber having a first section and a second section;
• transmitting a guided radiation of the output radiation to a second facet of the optical fiber;
• straining at least part of the optical fiber according to a linear displacement of the second section with respect to the first section along the at least part of the optical fiber;
• receiving the guided radiation at the second facet and to reflecting a corresponding reflected radiation towards the first facet;
• receiving at least part of the reflected radiation at the laser source and mixing the output radiation with the received radiation;
• and
• calculating a measure of the strain of the at least part of the optical fiber through the linear displacement of the second section measured by the self-mixing effect in the laser source.