Point Spread Function Engineering SRM

In conventional optical imaging systems, the image spot formed by a point light source after passing through the imaging system is called the point spread function (PSF) of the optical imaging system. Super-resolution imaging based on the modulation of the PSF is called PSF engineering for super-resolution imaging. Diffraction is a consequence of the wave characteristics of light. To break the diffraction limit, in 1994, the German scientist Stefan W. Hell first proposed the stimulated emission depletion (STED) technique, which can theoretically compress the effective PSF and circumvent the limitation of optical diffraction to achieve super-resolution imaging. Ground state depletion (GSD) microscopy is a second far-field super-resolution microscopy technique that was proposed by S. W. Hell and M. Kroug in 1995 and was experimentally demonstrated in 2007. Similar to STED, GSD is also a purely optical modulation method based on fluorescence on–off effects.