In our daily life, information about objects mainly comes into our sight through the linear propagation of light. However, when light encounters an inhomogeneous medium such as fog, ground glass, or biological tissue during its propagation, the incident photons are scattered multiple times due to the inhomogeneity of the medium’s refractive index. This scattering causes the propagation direction of the outgoing photons to become random, which forms a random speckle field. As a result, the imaging depth and resolution are reduced. This scattering phenomenon makes it more difficult to extract useful information from images and limits the application of light in imaging, focusing, and communication. In this paper, we utilize wavefront shaping technology based on feedback optimization to suppress the effects caused by this optical scattering phenomenon.

First, wavefront shaping technology is used based on feedback optimization. Under the conditions where the wavelength of light is 6.328×10^-7 m, the distance between the SLM and the scattering medium is 200 mm, the distance between the scattering medium and the CCD is 100 mm, there are 128×128 phase modulation units, and 10000 iterations are performed, the wavefront of the incident light wave is phase-modulated using the Hippopotamus optimization (HO) algorithm. Combined with the single fast Fourier transform algorithm based on the Fresnel diffraction integral, MATLAB is used to simulate the single-point focusing of light through the scattering medium and to assess the focusing quality. Then, an image projection test is carried out to obtain the Pearson correlation coefficient of the corresponding image projection, thus verifying its effectiveness. Finally, the multi-point focusing ability is tested. In this process, compared with the genetic algorithm (GA) under random noise conditions of 1%, 5%, and 10%, it is further proved that the HO algorithm can control the scattered light field and resist noise.

In our study, the single-point focusing ability of HO is tested, and the final light intensity enhancement of the target area can reach more than 1200 (Fig. 4). The correlation of the image projection can then exceed 0.86, as measured by the Pearson correlation coefficient (Fig. 5). Compared with GA under random noise conditions of 1%, 5%, and 10%, the results show that HO has better anti-noise ability than GA (Fig. 6). Finally, by testing the multi-point focusing ability, we observe that the background speckle of HO is less (Fig. 7), and at the same time, the line chart in (Fig. 8) shows that the average light intensity enhancement and relative standard deviation of HO are better than those of GA.

We present an HO algorithm that can be used for wavefront phase modulation, which enables precise regulation of the speckle field by modulating the front phase of the incident light wave. The abilities of single-point focusing, multi-point focusing, and image projection under the same conditions are explored and compared with GA under varying levels of noise interference. The results show that, compared with GA, HO exhibits better control performance and anti-noise ability under the same conditions. Especially in multi-point focusing and image projection, HO can produce a more uniform focus map and clearer image transmission. The research results provide new insights for the practical application of wavefront shaping technology based on iterative optimization.