Defogging lens design for infrared laser active imaging by orbital angular momentum meta-surface

Imaging in scattering media has been a big problem, as the ballistic light carrying object information is swamped by background noise, thus degrading the imaging quality. In addressing this issue, active illumination imaging technology has various advantages over passive imaging since it can introduce several controllable parameters, such as polarization, coded aperture, and so on. Here, we actively introduce orbital angular momentum into the scattering imaging, which can effectively enhance the mid/high frequency components of the object. Then, it is fused with the low-quality image obtained by traditional imaging, which can effectively enhance the visualization. Compared with the results of direct imaging, the signal-to-noise ratio is improved by up to 250%–300%, and the image contrast is improved by up to 300%–400%. This method may find applications in foggy environments for autonomous driving, lidar, and machine vision.