Recently, integral (also known as lightfield or plenoptic) imaging concept has been applied successfully to microscopy. The main advantage of lightfield microscopy when compared with conventional 3D imaging techniques is that it offers the possibility of capturing the 3D information of the sample after a single shot. However, integral microscopy is now facing many challenges, like improving the resolution and depth of field of the reconstructed specimens or the development and optimization of specially-adapted reconstruction algorithms. This contribution is devoted to review a new paradigm in lightfield microscopy, namely, the Fourier-domain integral microscope (FiMic), that improves the capabilities of the technique, and to present recent advances and applications of this new architecture.
Fourier integral microscopy (FiMic), also referred to as Fourier light field microscopy (FLFM) in the literature, was recently proposed as an alternative to conventional light field microscopy (LFM). FiMic is designed to overcome the non-uniform lateral resolution limitation specific to LFM. By inserting a micro-lens array at the aperture stop of the microscope objective, the Fourier integral microscope directly captures in a single-shot a series of orthographic views of the scene from different viewpoints. We propose an algorithm for the deconvolution of FiMic data by combining the well known Maximum Likelihood Expectation (MLEM) method with total variation (TV) regularization to cope with noise amplification in conventional Richardson-Lucy deconvolution.
In the past few years the integral-imaging, or lightfield, concept has been applied successfully to microscopy. More specifically, in the case of fluorescent samples integral, or lightfield, microscopy offers the advantage of capturing the 3D information in a single shot. Due to its potential utility integral microscopy is now facing many challenges, like improving the resolution and depth of field, the development and optimization of specially-adapted reconstruction algorithms, or the search of applications in which lightfield microscopy is superior to existing techniques. This contribution is devoted to review the recent advances of integral microscopy and enunciate the right questions about the progress of the technique.
A new branch of research, dedicated to lightfield, has recently seen an important growth in the microscopist community and it is called integral or lightfield microscopy. One recent implementation of a lightfield microscope is the Fourier integral Microscope (FiMic). In this setup a microlens array (MLA) is placed at the Fourier plane of the objective lens, therefore, the sensor behind each microlens is capturing the spatial information of a different perspective of the sample. The spatio-angular information captured can used to reconstruct the 3D volume. A very wide field of research among microscopists is for objects that have an extremely low contrast or that are completely transparent. In order to obtain a 3D reconstruction of a transparent sample our work has been focused on the combination of the FiMic with a dark-field illumination. In this way a 3D reconstruction of phase objects is achieved.
Lately, Integral-Imaging systems have shown very promising capabilities of capturing the 3D structure of micro- scopic and macroscopic scenes. The aim of this work is to provide an optimal design for 3D-integral microscopy with extended depth of field and enhanced lateral resolution. By placing an array of microlenses at the aperture stop of the objective, this setup provides a set of orthographic views of the 3D sample. Adopting well known integral imaging reconstruction algorithms it can be shown that the depth of field as well as spatial resolution are improved with respect to conventional integral microscopy imaging. Our claims are supported on theoretical basis and experimental images of a resolution test target, and biological samples.
Integral Imaging is well known for its capability of recording both the spatial and the angular information of threedimensional (3D) scenes. Based on such an idea, the plenoptic concept has been developed in the past two decades, and therefore a new camera has been designed with the capacity of capturing the spatial-angular information with a single sensor and after a single shot. However, the classical plenoptic design presents two drawbacks, one is the oblique recording made by external microlenses. Other is loss of information due to diffraction effects. In this contribution report a change in the paradigm and propose the combination of telecentric architecture and Fourier-plane recording. This new capture geometry permits substantial improvements in resolution, depth of field and computation time