A multi-port imaging system is developed for simultaneous measurement of source and test regions in a linear plasma device. The system combines two viewing port images to an imaging sensor with the same working distance. The system is installed in the DT-ALPHA device [A. Okamoto, et al., Plasma Fusion Res. 7, 2401018 (2012)] for the proof of principle. Bandpass filtered images of a plasma column are taken. The electron density profile of a plasma column passing through orifices is obtained by the He I line intensity ratio method. The result demonstrates effectiveness of the system.