This paper represents the configuration of optical tomography sensor by using infrared emitter and phototransistor. The projection geometry of the sensor is based on the combination of two orthogonal and two rectilinear projections arrays. A fixture is designed for holding all emitter–receiver pairs in parallel. Selection of phototransistor is explained so that the tomography sensor developed is free of noise cause by surrounding environment. This paper describes all points to be considered when design an optical tomography sensor.