Rayleigh limit in inverse scattering imaging

[Amartansh]

I was reading that in inverse scattering approach, we divide the region of interest into discrete grids and size of each grid should be much smaller than the incident wavelength (usually smaller than one-tenth of wavelength).
By this logic, theoretically, I can use inverse electromagnetic scattering problem to image up to a resolution of λ/10 which is much better than the Rayleigh limit. Is this practically possible?? How technologies like MRI or ultrasound provide such high-resolution image with long wavelengths?

 

[Dale]

How technologies like MRI or ultrasound provide such high-resolution image with long wavelengths?

Ultrasound resolution is limited by wavelength. The speed of sound is about 1500 m/s and the frequency of diagnostic ultrasound is around 10 MHz, so the maximum resolution is about .15 mm.

MRI does indeed image much shorter than the wavelength. It encodes the spatial information into the frequency domain so you can use the Fourier transform to get spatial information. This makes it so you are not limited by the spatial wavelength of the radiation but by the sampling time.