Remote full-axis deformation sensing using multi-zeros optical beam: Interference of two multi-zeros beam

In previous paper, we described a novel deformation sensing technology using two conjugate multi-zeros optical beams for structure health monitoring. The multi-zeros beam has a phase term called the Gouy phase shift which is changing in proportion to the propagation distance, the initial beam waist size, and the order of the LG beam. We consider the effect of this phase term on the multi-zeros optical beam, and obtain a result that the +1st and −1st diffraction beams will rotate in opposite direction while preserving the profile of the multi-zeros optical beam. In this paper, rotation angle of multi-zeros beam in free space and transformation of it by lens are formulated quantitatively. Some results of numerical simulation are shown.