Super-resolution imaging with modulation of point spread function

The spatial resolution of an imaging system using waves is limited by the spatial bandwidth of the point spread function (PSF) of the system, which is related to the wavelength. However, when the PSF is modulated either in amplitude or phase or in both, the resulting spatial bandwidth of the PSF is increased. In this study, the PSF-modulation method is used to obtain super-resolution imaging of objects and to distinguish wave sources that are closely located in space and are not normally separable due to diffraction limit. In imaging using waves, such as ultrasound, acoustics, optics, electromagnetics, radar, and sonar, the PSF can be modulated in their respective fields. For example, in ultrasound, shear wave in biological soft tissues has a low wave speed and thus has a small wavelength. A ring-shaped shear wave can be generated locally (remotely) deep in the tissue by the radiation force of a focused Bessel beam, X wave, or other limited-diffraction beam at their focuses [Lu, 2021 IEEE IUS, 2021 ASA POMA] to produce a sharp peak at the center of the ring (due to shear wave focusing with a small wavelength). This sharp peak of the shear wave modulates the center of a conventional focused beam transmitted after the shear wave ring is produced. The modulated focused beam is then used to scan through an object to obtain a super-resolution image after removing the contribution of the original beam. In this talk, the theory, computer simulation, and experiment results of the super-resolution method will be presented.