Simulation-Based Considerations on the Rayleigh Criterion in Super-Resolution Techniques Based on Speckle Interferometry

Abstract

This study sought to explain the physical phenomenon that eludes the constraints of the Rayleigh criterion in the microstructure observation method using speckle interferometry, for which super-resolution has been experimentally proven; the study was conducted using computer simulations. Separating the light from two light sources in close proximity, which exceeded the Rayleigh criterion under incoherent light, was believed to be impossible. The simulation results, however, showed that when coherent light is used, the separation of two close points is not necessarily impossible if the light phases between the two points are different. Furthermore, the resolution of microstructure observation techniques based on speckle interferometry was discussed. A new interpretation of the Rayleigh criterion in super-resolution techniques based on speckle interferometry was reported.

Role of Phase Information Propagation in the Realisation of Super-Resolution Based on Speckle Interferometry

“…Furthermore, the use of plane waves as the reference light of the speckle interferometer enables deformation measurements to be performed using only two speckle patterns before and after deformation. This has been demonstrated in previous reports [17,[21][22][23].…”

“…To avoid these problems, in the current study, I used an electromagnetic field simulation software (COMSOL Multiphysics) to investigate the physical phenomena in which the observation of microstructures beyond the diffraction limit was achieved using a new super-resolution technology based on speckle interferometry techniques [21][22][23]. A computer simulation model used in a previous report [23], shown in Figure 3a, was used as the optical system model in this study.…”

“…Employing the optical system used for the experiment shown in Figure 2, an experiment was performed by analysing the light reflected from a glass reflective diffraction grating as a measurement sample [17]. Because this study investigated the physical interpretation of the properties of the phase distribution of light from microstructures beyond the diffraction limit in super-resolution speckle interferometry techniques, the measurement object was used as a simplified model compared with the treatment in previous reports [23]. Specifically, the shape was set as a simple sample modelled by supplying a group of spherical-wave point sources with a phase distribution depending on the shape given to the reflected light from each point on the measurement object.…”

“…In the simulation model shown in Figure 3a, the mesh size was set by considering the load on the computer memory, as in a previous report [23]. In other words, 1/12 of the wavelength was set as the mesh size as a condition under which the influence of the mesh size did not extend to the calculation results as far as possible.…”

“…PLMs can be used to remove the effect of reflected waves from the walls and improve the accuracy of the analysis when performing calculations in a limited computational domain. In creating the simulation model, as in a previous report [23], the computational domain was defined with the minimum possible memory (memory capacity of 2 TB) to minimise the load on memory capacity.…”