Analog detection device in a sub-micron linear encoder based on a fibre-optic interferometer with a 333 coupler

This study demonstrates a high-resolution linear incremental encoder for high-precision feedback control loop. This novel encoder uses a fibre-optic interferometer with a 3 × 3 coupler and a signal comparator circuit to generate quadrate encoding output signals for the displacement measurement of the moving object. The encoder should be able to achieve a resolution of 95.5 nm and a measurement accuracy of ±0.38 μm.