Incoherent optical processor for x-ray transaxial tomography

A single-channel incoherent optical processor that reconstructs an object from its 1-D x-ray projections has been developed. The projection data are recorded directly on x-ray film, which, after development, is used as the input transparency for the processor. The same computing algorithms used by commercial computed tomography units are optically implemented to reconstruct the object from these projections. The totally analog processor employs time-modulated OTF synthesis to achieve the necessary bipolar filtering operations. This technique involves a time-varying pupil plane mask in conjunction with synchronous demodulation of the detector output to obtain the desired response. Results are presented that are similar in quality to reconstructions produced by commercial scanners. The advantage of this system is that it should offer equivalent performance at a reduced cost.