Holographic diffraction gratings to measure micromovements

Holographic diffraction gratings can measure micro movements, with a system that detects each period of the moving grating. One of the important features of this device is the grating period, which determines the measurement accuracy. The period can be on the order of fractions of micron, with high reproducibility and with an error of a quarter of period. One of the qualities of this system is its robustness; the measures are invariant to noise induced by device movements and environment thermal changes.