A Wavelength Multiplexed Optical Shaft Encoder

A wavelength multiplexed optical shaft encoder using a single optical fibre as the transmission medium between the transducer and the read-out unit is described. A ten bit system has been constructed, giving 0.1% resolution over 360 of arc. It is believed that this is the largest number of channels to date to be wavelength multiplexed into a single fibre waveguide.