In most applications of optical computed tomography (OpCT), limited-view problems are often encountered, which can be solved to a certain extent with typical OpCT reconstructive algorithms. The concept of entropy first emerged in information theory has been introduced into OpCT algorithms, such as maximum entropy (ME) algorithms and cross entropy (CE) algorithms, which have demonstrated their superiority over traditional OpCT algorithms, yet have their own limitations. A fused entropy (FE) algorithm, which follows an optimized criterion combining self-adaptively ME with CE, is proposed and investigated by comparisons with ME, CE and some traditional OpCT algorithms. Reconstructed results of several physical models show this FE algorithm has a good convergence and can achieve better precision than other algorithms, which verifies the feasibility of FE as an approach of optimizing computation, not only for OpCT, but also for other image processing applications.

The real time acquisition of the optical radiation information of multi points in free space is a difficult problem for the optical fluid fields testing. Traditional data acquisition systems are based on multichannel charge coupled device (CCD), with which the optical radiation information from multi directions can be obtained. However these systems are hard to fit the requirement of parallel beam imaging, and hence bring great errors of inverse computations. A multichannel real time data acquisition system based on a digital signal processor (DSP) and a number of optical fiber bundles (OFBs) is proposed in this paper for fluid field reconstructions. Each OFB unit can acquire the optical radiation information that transmits into its entrance aperture via a sensor unit consisting of an optical fiber coupler and a phototransistor. The DSP acts as a main controller that switches on the exposure of all phototransistors synchronously based on the mechanism of electronic shutter. The synchronous sensed signals are locked by a peak hold circuit and then outputted to analog-to-digital converters (ADCs), and therefore the real time acquisition of the optical radiation information of multi points in free space can be realized, which offers the original parallel beam imaging data for the fluid field reconstructions.