[en] A novel multichannel scanning interferometer designed for tomographically inferring contours of electron density in magnetically confined plasmas is described. The scanning element is a multi-sectored blazed rotating grating. The diffracted beam emerges at a different angle from each sector giving rise to a fan array of discrete beams for each rotation of the grating. Signals from the probing chords are multiplexed in time enabling the use of a single detecting element for the extraction of many channels of line integrated density information. An air turbine driven grating wheel assembly has been fabricated and initial tests performed. The proposed interferometer is to be installed on the H-1 helical axis stellarator currently under construction at the Australian National University. 16 refs., 12 figs