Scatter-plate microscope for lensless microscopy with diffraction limited resolution

Abstract

Scattering media have always been looked upon as an obstacle in imaging. Various methods, ranging from holography to phase compensation as well as to correlation techniques, have been proposed to cope with this obstacle. We, on the other hand, have a different understanding about the role of the diffusing media. In this paper we propose and demonstrate a ‘scatter-plate microscope’ that utilizes the diffusing property of the random medium for imaging micro structures with diffraction-limited resolution. The ubiquitous property of the speckle patterns permits to exploit the scattering medium as an ultra-thin lensless microscope objective with a variable focal length and a large working distance. The method provides a light, flexible and cost effective imaging device as an alternative to conventional microscope objectives. In principle, the technique is also applicable to lensless imaging in UV and X-ray microscopy. Experiments were performed with visible light to demonstrate the microscopic imaging of USAF resolution test target and a biological sample with varying numerical aperture (NA) and magnifications.

Extended depth-resolved imaging through a thin scattering medium with PSF manipulation

“…It is possible to separate or extract the speckle patterns of the objects placing beyond axial FOV and to realize a 3D Non-invasive single-shot imaging. Our method can also improve the imaging quality of lensless cameras 33 (using pseudo-random phase mask with convex bumps) and of lensless microscopy 34 (using a scatter-plate with a thin scattering layer) and adapt them to more complex diffusers. Solid-state samples with different strength of scattering (commercial standard scattering samples from 5 deg to 30 deg), strong forward biological scattering samples (1 mm chicken tissues) are tested with the proposed method.…”

Imaging through scattering media with the auxiliary of a known reference object

“…Similar to the work done by Singh et al . 27 , image reconstruction can be accomplished by calculating the cross-correlation between the camera image and the point spread function, except that our method does not require the operation in the time domain at the cost of introducing a reference point in space. By ensuring that the convolution terms are separated from the central autocorrelation, it is easy to directly window out the final reconstructed object from the speckle autocorrelation.…”

A compact single channel interferometer to study vortex beam propagation through scattering layers

“…In the first type, optical signal processing [6][7][8], correlation techniques [9][10][11][12][13] and phase retrieval algorithms [14,15] have been developed to decode a speckle signature and convert it into useful information. A second direction of research is to develop adaptive aberration correction methods to compensate for the disturbance introduced by the scattering medium [16,17].…”