We have used Full Field OCT (FFOCT) in its static (morphology contrast) and dynamic (metabolic contrast) modes mostly for tissue diagnosis. Last year we introduced a new way of optical sectioning 3D structures. For this purpose, we use Full Field Optical Transmission Tomography (FFOTT) a Gouy phase shift interference approach that takes place close to the focus of a microscope objective. We will show striking differences between FFOCT and FFOTT associated to the scattering anisotropy of tissue structures. Moreover, we will pay a particular attention to the requirements of FFOTT in term of spatial coherence and to the speckle appearance for both techniques.
Last year we introduced a new Full Field Optical Transmission Tomography (FFOTT) technique that we applied to CELL studies. This interferometric technique is based on the use of the Gouy phase shift that takes place close to a microscope objective focus. We will now show results obtained in biological tissues using both a static mode (morphology) and dynamic one (metabolic contrast). In particular we have been able with our 400 $ microscope to section in tissues. We will discuss the importance of the spatial coherence of the illumination and compare the results with those obtained with Full Field OCT.
This work focuses on making a novel ophthalmic Optical transmission tomography (OTT) device at the lowest possible cost and size. OTT prototype demonstrates images from all the layers in anterior human eye, while also benefiting from the cost-efficient design solutions: common-path architecture, mass-market CMOS cameras, latest USB data transfer standards, Arduino electronic control, etc. Notably, we show that the large degree of noise degradation (due to the use of low-cost optics/cameras) can be corrected with denoised neural networks. Moreover, the model trained on one type of camera (global shutter) can be used to improve signal in another camera (rolling shutter).
Our past contribution was to introduce a Gouy phase Full Field Optical Transmission technique applied to detect and characterise nanoparticles such as virus, vesicles and nano plastics in terms of size and refractive index. More recently we have adapted this interferometric approach to achieve optical tomography in cells and tissues. We will show improvements in sensitivity and resolution obtained with 20 nm virus as well as with biological tissues using both a static mode (morphology) and dynamic one (metabolic contrast). We discuss the importance of the illumination spatial coherence and compare the results with those obtained with Full Field OCT.
In this conference proceeding we illustrate an early concept of a new anterior eye imaging method—optical transmission tomography (OTT). Thanks to the 20× larger viewing area, OTT can enhance the precision of corneal cell/nerve density biomarkers compared to clinical specular and confocal microscopies. This holds promise for improving the selection of candidates for refractive surgery and for reducing the incidence rates of post-surgical dry eye, endothelial decompensation as well as other common complications.
At Langevin Institute, ESPCI Paris, we have developed a label-free approach to detect and track viruses in aquatic solutions using an interferometric microscopy approach working in transmission. By improving the experimental setup design, we have increased the sensitivity to detect viruses as small as 20nm in diameter, AAV viruses, which are of paramount importance for gene therapy. Furthermore, based on the variation of the interferometric signal along the axial position, we introduce a new way to perform single-shot volumetric imaging which enables high-precision 3D tracking.
We have recently (BOE July 2022) proposed an interferometric approach called full-field transmission tomography (FFOTT) based on the use of the Gouy phase shift that manifests at the focus of microscope objectives. Forward scattering of cellular structures larger than 100 nm being much greater than backscattering (used in OCT) performances constraints of the imaging system are strongly relaxed and setups using cheap microscopes and a smartphones become possible. Note that good quality 100X, NA+1.25 objectives are available for less than $100.
We show cells and tissues images through their morphological or metabolic contrasts modified by a chemical or biological environments.
Interferometric microscopy techniques have been recently developed to detect small particles at the nanoscale without the need for specific labeling. Here, we introduce a highly sensitive, label-free approach on a common path interferometric set-up working on a transmission that amplifies weak scattering signals coming from small particles. Using single-particle tracking analysis, we can track and differentiate viruses and other biotic particles in aquatic environment.
Furthermore, we have developed a fast assay based on antibody recognition of targeted virus in solution. We associate changes in diffusion and in the interferometric signal of the detected particles with the immune reaction between antibodies and surface proteins of the virus.
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