Study on Measurement Errors of Position Sensor with Two-Dimension Holographic Variable Line-Space Plane Gratings

In recent years, a new fiber optic position sensing technology with holographic variable line-space (VLS) plane grating is developed. The period of VLS plane grating is about less than 10 micron. The grooves of the holographic VLS plane grating are not straight in general. Due to the grooves bend of 2-D holographic VLS plane gratings, measurement errors of the position sensor are inevitable when the scanning direction of a position sensor isn't in the symmetry axis of a VLS plane grating. This work briefly describes the theoretical background to the position sensor concept and the geometry theory of holographic VLS gratings. We report a theoretical analysis of the measurement errors in two basic cases: translation deviation and rotation deviation. The proposed method has been applied to examples of computer simulation. The results obtained are quite noteworthy.