Search

Line‐field confocal optical coherence tomography (LC‐OCT) is a new noninvasive technique for a real‐time, vertical, and horizontal imaging of the skin at cellular resolution. A 47‐year‐old female presented with a 6‐month history of an asymptomatic yellowish papule. LC‐OCT evaluation was able to show the diagnostic microscopic features of xanthogranuloma and showed an excellent correlation with vertical and horizontal histopathological sections by revealing enlarged dermal papillae containing multiple, bright roundish giant cells, corresponding to foamy histiocytes, and giant cells characterized by a dark center surrounded by a highly hyper‐refractile peripheral ring, corresponding to Touton cells. LC‐OCT may represent a valid, noninvasive alternative to histopathological examination in clinically atypical cases of xanthogranuloma.

This paper reports on the latest advances in line-field confocal optical coherence tomography (LC-OCT), a recently invented imaging technology that now allows the generation of either horizontal (x × y) section images at an adjustable depth or vertical (x × z) section images at an adjustable lateral position, as well as three-dimensional images. For both two-dimensional imaging modes, images are acquired in real-time, with real-time control of the depth and lateral positions. Three-dimensional (x × y × z) images are acquired from a stack of horizontal section images. The device is in the form of a portable probe. The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes. Using a supercontinuum laser as a broadband light source and a high numerical microscope objective, an isotropic spatial resolution of ∼1 µm is achieved. The field of view of the three-dimensional images is 1.2 mm × 0.5 mm × 0.5 mm (x × y × z). Images of skin tissues are presented to demonstrate the potential of the technology in dermatology. [Image: see text]

Background Non-invasive diagnostic techniques in dermatology gained increasing popularity in the last decade. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) are meanwhile established in research and clinical routine. While OCT is mainly indicated for detecting non-melanoma skin cancer, RCM has proven its usefulness additionally in distinguishing melanocytic lesions. Line-field confocal optical coherence tomography (LC-OCT) is an emerging tool combining the principles of both above-mentioned methods. Methods Healthy skin at different body sites and exemplary skin lesions (basal cell carcinoma, malignant melanoma, actinic keratosis) were examined using dermoscopy, RCM, OCT and LC-OCT. Standard features for RCM and OCT and comparable features for LC-OCT were analysed. Results LC-OCT has a lower penetration depth but superior resolution compared to OCT. In comparison with RCM, which provides only horizontal sections, LC-OCT creates both vertical and horizontal images in real time and has nearly the same cellular resolution. Discussion Our preliminary experiences suggest that LC-OCT combines the advantages of RCM and OCT, with optimal resolution and penetration depth to diagnose all types of skin cancer. Larger systematic studies are needed to further characterize the field of use of this device and its sensitivity and specificity compared to histology.

In this work, we present an ultra-fast line-field optical coherence elastography system (LF-OCE) with an 11.5 MHz equivalent A-line rate. The system was composed of a line-field spectral domain optical coherence tomography system based on a supercontinuum light source, Michelson-type interferometer, and a high-speed 2D spectrometer. The system performed ultra-fast imaging of elastic waves in tissue-mimicking phantoms of various elasticities. The results corroborated well with mechanical testing. Following validation, LF-OCE measurements were made in in situ and in in vivo rabbit corneas under various conditions. The results show the capability of the system to rapidly image elastic waves in tissues.

Epidermal three-dimensional (3D) topography/quantification has not been completely characterized yet. The recently developed line-field confocal optical coherence tomography (LC-OCT) provides real-time, high-resolution, in-vivo 3D imaging of the skin. This pilot study aimed at quantifying epidermal metrics (epidermal thicknesses, dermal-epidermal junction [DEJ] undulation and keratinocyte number/shape/size) using 3D LC-OCT. For each study participant (8 female, skin-type-II, younger/older volunteers), seven body sites were imaged with LC-OCT. Epidermal metrics were calculated by segmentations and measurements assisted by artificial intelligence (AI) when appropriate. Thicknesses of epidermis/SC, DEJ undulation and keratinocyte nuclei volume varied across body sites. Evidence of keratinocyte maturation was observed in vivo: keratinocyte nuclei being small/spherical near the DEJ and flatter/elliptical near the skin surface. Skin microanatomy can be quantified by combining LC-OCT and AI. This technology could be highly relevant to understand aging processes and conditions linked to epidermal disorders. Future clinical/research applications are to be expected in this scenario.

Quadratic points of a surface in the projective 3-space are the points which can be exceptionally well approximated by a quadric. They are also singularities of a 3-web in the elliptic part and of a line field in the hyperbolic part of the surface. We show that generically the index of the 3-web at a quadratic point is ±1/3, while the index of the line field is ±1. Moreover, for an elliptic quadratic point whose cubic form is semi-homogeneous, we can use Loewner’s conjecture to show that the index is at most 1. From the above local results, we can conclude some global results: A generic compact elliptic surface has at least 6 quadratic points, a compact elliptic surface with semi-homogeneous cubic forms has at least 2 quadratic points and the number of quadratic points in a hyperbolic disc is odd. By studying the behavior of the cubic form in a neighborhood of the parabolic curve, we also obtain a relation between the indices of the quadratic points of a generic surface with non-empty elliptic and hyperbolic regions.

In this study, we developed a line-field Fourier domain optical coherence tomography (LF-FDOCT) system that performs lateral scanning using a two-dimension spatial light modulator and detects multiple channels of spectral domain OCT signal in parallel using a two-dimensional sensor. The LF-FDOCT system eliminates the need for mechanical scanning to acquire volumetric OCT data. It allows parallel acquisition of signal for B mode scan imaging through snapshot detection and offers unprecedented flexibility to select a fast scanning dimension. In this work, we describe the principle of LF-FDOCT imaging and present experimental results to demonstrate the effectiveness of this technology.

Recent OCT based investigations in humans and in experimental animals have shown that rods and cones outer segments elongate in response to light stimuli. In this manuscript we describe our efforts to implement phase-based “optoretinograms” (ORG) analysis framework to retinal images acquired with standard raster scanning FD-OCT system, that offers much lower phase stability compared to full field or line field OCT acquisition schemes. Our initial results, acquired in anesthetized mice in vivo, showcase successful extraction of phase-based ORG signal and its favorable comparison with intensity-based ORG signal extracted from the same data sets.

This paper reports the development of a new technique, free space line field spectral domain optical coherence reflectometry (LF-SD-OCR), which is able to produce tomographic like (quasi) images. Furthermore, the capabilities and cost benefits of the technique are demonstrated by constructing a handheld LF-SD-OCR device. For glossy paint systems and other suitable samples, the line field format produces quasi-tomographic (cross-sectional) imaging through the layers, with axial and lateral image resolutions of 1.3 µm and 40 µm respectively. From these, the clear coat thicknesses on the bonnet of cars were measured by graph search segmentation and maximum A-scan projection. In comparison with the widely used single point ultrasound and optical devices, our technique gives the user more confident interpretation of the results as it produces a cross-sectional image of the sample in a single-shot fashion without the need of any mechnical scanning. In addition, the produced device has higher resolution and lower cost (£1660 cost of the constructed one-off prototype as compared with over £10K for comparable universally capable ultrasonic devices), making the technique an economically viable alternative to ultrasound in the quality assurance of coating systems and other application areas such as plastic film manufacturing control.

This paper reports on line-field confocal optical coherence tomography (LC-OCT), a recently invented imaging technology now capable of generating either a horizontal (en face) section image at an adjustable depth, or a vertical section image (B-scan) at an adjustable lateral position. For both operating modes, images are acquired in real-time (10 frames/second), with real-time control of the depth and lateral positions. Using a supercontinuum laser as a broadband light source and a high numerical microscope objective, an isotropic spatial resolution of ∼ 1 μm is achieved. The imaging fields of view are 1.2×0.5 mm² (x×y, horizontal) and 1.2×0.5 mm² (x×z, vertical). LC-OCT has been used in dermatology for skin imaging.

Line-field confocal optical coherence tomography (LC-OCT) is an imaging technique based on time-domain OCT with line illumination and line detection. The focus is adjusted during the scan of the sample depth to image with high lateral resolution (~ 1 μm), similar to the axial resolution, at a central wavelength of ~ 800 nm. The LC-OCT prototypes reported so far were all based on a Linnik-type interferometer. We present in this paper a LC-OCT device based on a Mirau interferometer. This Mirau-based LC-OCT device has the advantage of being more compact and lighter. In vivo imaging of human skin with a resolution of 1.3 μm × 1.1 μm (lateral × axial) is demonstrated at 12 frames per second over a field of 0.9 mm × 0.4 mm (lateral × axial).

A line-field, spectral-domain optical coherence tomography (LF-SD-OCT) system was build for in-vivo, non-contact, cellular resolution imaging of biological tissue at 2.5 kHz frame rate. Test images acquired from healthy human subjects show that the LF-SD-OCT is able to image the cellular structure of semitransparent tissue such as the human cornea, as well as highly scattering tissue such as skin. This system may serve as a valuable diagnostic tool to ophthalmologists and dermatologists for diagnosis and monitoring the treatment of various corneal and skin diseases.

Line-field confocal optical coherence tomography (LC-OCT) is an imaging technique in which A-scans are acquired in parallel through line illumination with a broadband laser and line detection with a line-scan camera. B-scan imaging at high spatial resolution is achieved by dynamic focusing in a Linnik interferometer. This paper presents an LC-OCT device based on a custom-designed Mirau interferometer that offers similar spatial resolution and detection sensitivity. The device has the advantage of being more compact and lighter. In vivo imaging of human skin with a resolution of 1.3 µm × 1.1 µm (lateral × axial) is demonstrated over a field of 0.9 mm × 0.4 mm (lateral × axial) at 12 frames per second.

Line-field confocal optical coherence tomography (LC-OCT) is an imaging method based on dynamically-focused line-field time domain OCT to generate cellular resolution images of biological tissues, either in vertical sections (cross-sectional) or in horizontal sections (en face), with field of views of 1.2 × 0.5 mm2 (horizontal) and 1.2 × 0.4 mm2 (vertical). A handheld LC-OCT probe has recently been developed to facilitate the use of this imaging technique in dermatology for non invasive detection of skin cancers. We present here a video mosaicking method to reconstruct LC-OCT images with extended fields of view from a sequence of images obtained by a free displacement by the user of the LC-OCT probe on the skin surface. The lateral field of view is extended in both vertical and horizontal section images to ~ 5 mm, while maintaining an isotropic spatial resolution of ~ 1 μm. LC-OCT imaging with video-mosaicking is demonstrated for following the edges of large skin structure, as a proof-of-principle of in vivo tumor margin delineation, and for extending the lateral field of vertical section images, in order to approach the field of view of histology in this direction.

Vector fields and line fields, their counterparts without orientations on tangent lines, are familiar objects in the theory of dynamical systems. Among the techniques used in their study, the Morse–Smale decomposition of a (generic) field plays a fundamental role, relating the geometric structure of phase space to a combinatorial object consisting of critical points and separatrices. Such concepts led Forman to a satisfactory theory of discrete vector fields, in close analogy to the continuous case. In this paper, we introduce discrete line fields. Again, our definition is rich enough to provide the counterparts of the basic results in the theory of continuous line fields: an Euler–Poincare formula, a Morse–Smale decomposition and a topologically consistent cancellation of critical elements, which allows for topological simplification of the original discrete line field.

Line-field confocal optical coherence tomography (LC-OCT) is a recently introduced technique for ultrahigh-resolution vertical section (B-scan) imaging of human skin in vivo. This work presents a new implementation of the LC-OCT technique to obtain horizontal section images (C-scans) in addition to B-scans. C-scan imaging is achieved with this dual-mode LC-OCT system using a mirror galvanometer for lateral scanning along with a piezoelectric chip for modulation of the interferometric signal. A quasi-identical spatial resolution of ∼ 1 µm is measured for both B-scans and C-scans. The images are acquired in both modes at a rate of 10 frames per second. The horizontal field of view of the C-scans is 1.2 × 0.5 mm2, identical to the vertical field of view of the B-scans. The user can switch between the two modes by clicking a button. In vivo cellular-resolution imaging of human skin is demonstrated in both B-scan and C-scan modes, with the possibility to navigate within the skin tissues in real time.

In this study, the industrial inspection of optical thin film on touch screen panels was demonstrated using line field spectral domain optical coherence tomography. The conventional Fourier domain optical coherence tomography system requires a single scanner for two-dimensional cross-sectional images and two scanners for volumetric images. Our developed line field spectral domain optical coherence tomography has the advantage of needing only a single scanner for volumetric images, while two-dimensional cross-sectional images are obtained by the parallel acquisition of an illuminated line on a sample using an area camera. Further, the image acquisition speed was enhanced by implementing a high speed camera (340 frames per seconds) with improved quantum efficiency at near infrared region enabling two-fold frame rate. Cross-sectional and volumetric images were acquired to detect the internal sublayer defects in the optical thin films, which are difficult to observe using visual or machine vision-based inspection methods. The developed pseudo code for defect identification in optical thin films was well-utilized here for the defect inspection. The system characterization is demonstrated using United State Air Force (USAF) resolution target. The results indicate the possible application of the proposed system in touch screen panel inspection for the quality assurance of products at the consumer end.

We present a novel method for simultaneous measurement of the thickness and refractive index distribution of a transparent specimen by a line-field swept-source interferometer. In this study, by illuminating with the line-field beam instead of the point-focused beam, multiple interferences along the line-field distribution are measured simultaneously by using a combination of a novel swept source of 800-nm central region and a Si-based 1024-pixel charge-coupled device (CCD) detector. When the transparent specimen has an uneven thickness or nonuniform refractive index, the whole distribution of these two parameters can be also simultaneously measured over the illuminated region with a one-step comparison process. Using four types of transparent specimens, the thickness and refractive index distribution of each sample and a group sample paired with two specimens are accurately measured during the single wavelength scanning time of 27 ms by using the swept source with a 36-Hz sweeping rate and the CCD detector with a 36-kHz line rate.

The integrability of certain classes of dynamic systems is shown on the tangent bundles to twodimensional manifolds. In this case, the force fields have the so-called variable dissipation and generalize the previously considered fields.

There is a lack of information on optimal measurement configuration of hyperspectral imagers for on-line measurement of a wheat canopy. This paper aims at identifying this configuration using a passive sensor (400–750 nm). The individual and interaction effects of camera height and angle, sensor integration time and light source distance and height on the spectra's signal-to-noise ratio (SNR) were evaluated under laboratory scanning conditions, from which an optimal configuration was defined and tested under on-line field measurement conditions. The influences of soil total nitrogen (TN) and moisture content (MC) measured with an on-line visible and near infrared (vis-NIR) spectroscopy sensor on SNR were also studied. Analysis of variance and principal component analysis (PCA) were applied to understand the effects of the laboratory considered factors and to identify the most influencing components on SNR. Results showed that integration time and camera height and angle are highly influential factors affecting SNR. Among integration times of 10, 20 and 50 ms, the highest SNR was obtained with 1.2 m, 1.2 m and 10° values of light height, light distance and camera angle, respectively. The optimum integration time for on-line field measurement was 50 ms, obtained at an optimal camera height of 0.3 m. On-line measured soil TN and MC were found to have significant effects on the SNR with Kappa values of 0.56 and 0.75, respectively. In conclusion, an optimal configuration for a tractor mounted hyperspectral imager was established for the best quality of on-line spectra collected for wheat canopy.

International audience; We propose an approach to the problem of global reconstruction of an orientation field. The method is based on a geometric model called "bisector line fields", which maps a pair of vector fields to an orientation field, effectively generalizing the notion of doubling phase vector fields. Endowed with a well chosen energy minimization problem, we provide a polynomial interpolation of a target orientation field while bypassing the doubling phase step. The procedure is then illustrated with examples from fingerprint analysis.