Swarm-based algorithm for phase unwrapping

Abstract

A novel algorithm for phase unwrapping based on swarm intelligence is proposed. The algorithm was designed based on three main goals: maximum coverage of reliable information, focused effort for better efficiency, and reliable unwrapping. Experiments were performed, and a new agent was designed to follow a simple set of five rules in order to collectively achieve these goals. These rules consist of random walking for unwrapping and searching, ambiguity evaluation by comparing unwrapped regions, and a replication behavior responsible for the good distribution of agents throughout the image. The results were comparable with the results from established methods. The swarm-based algorithm was able to suppress ambiguities better than the flood-fill algorithm without relying on lengthy processing times. In addition, future developments such as parallel processing and better-quality evaluation present great potential for the proposed method.

Hilbert transform for modulation of interference fringes of liquid substances

“…However, the instruments and methodology reported so far require high stability and are also limited by the experimental set-up [3][4], this problem has been solved with the use of interferometers that provide the stability and measurement range that is not achieved with conventional refractometers and holographic techniques, among them the Jamin, Mach Zehnder and Michelson interferometers [4,[10][11]. Despite the reliability that interferometers provide to the measurement, the problem of a later demodulation of the fringe pattern obtained arises, this pattern shows the changes before and after the deformation to later obtain the optical phase, commonly, by means of techniques based on Fourier Transform [12], Wavelet [13][14][15][16][17][18] and Hilbert [19][20][21][22][23], the problem increases if the interferograms obtained have a circular configuration, their carrier frequency is very low, and they also present several reflections caused by the arrangement of the instruments and the analysed material, requiring more computational work and the implementation of new spectral and temporal analysis techniques [24][25][26][27][28][29][30][31][32].…”