Compressed Sensing with off-axis frequency-shifting holography

This work reveals an experimental microscopy acquisition scheme successfully combining Compressed Sensing (CS) and digital holography in off-axis and frequency-shifting conditions. CS is a recent data acquisition theory involving signal reconstruction from randomly undersampled measurements, exploiting the fact that most images present some compact structure and redundancy. We propose a genuine CS-based imaging scheme for sparse gradient images, acquiring a diffraction map of the optical field with holographic microscopy and recovering the signal from as little as 7% of random measurements. We report experimental results demonstrating how CS can lead to an elegant and effective way to reconstruct images, opening the door for new microscopy applications.Comment: vol 35, pp 871-87

Heterodyne detection of multiply scattered monochromatic light with a multipixel detector

International audienceA new technique is presented for measuring the spectral broadening of light that has been multiply scattered from scatterers in motion. In our method the scattered light is detected by a heterodyne receiver that uses a CCD as a multipixel detector. We obtain the frequency spectrum of the scattered light by sweeping the heterodyne local oscillator frequency. Our detection scheme combines a high optical etendue (product of the surface by the detection solid angle) with an optimal detection of the scattered photons (shot noise). Using this technique, we measure, in vivo, the frequency spectrum of the light scattered through the breast of a female volunteer

Effect of the Photon's Brownian Doppler Shift on the Weak-Localization Coherent-Backscattering Cone

We report the first observation of the dependence of the coherent-backscattering (CBS) enhanced cone with the frequency of the backscattered photon. The experiment is performed on a diffusing liquid suspension and the Doppler broadening of light is induced by the Brownian motion of the scatterers. Heterodyne detection on a CCD camera is used to measure the complex field (i.e., the hologram) of the light that is backscattered at a given frequency. The analysis of the holograms yield the frequency and the propagation direction of the backscattered photons. We observe that the angular CBS cone becomes more narrow in the tail of the Brownian spectrum. The experimental results are in good agreement with a simple theoretical model

Surface Texturization of Breast Implants Impacts Extracellular Matrix and Inflammatory Gene Expression in Asymptomatic Capsules:

Background: Texturing processes have been designed to improve biocompatibility and mechanical anchoring of breast implants. However, a high degree of texturing has been associated with severe abnormalities. In this study, the authors aimed to determine whether implant surface topography could also affect physiology of asymptomatic capsules. Methods: The authors collected topographic measurements from 17 different breast implant devices by interferometry and radiographic microtomography. Morphologic structures were analyzed statistically to obtain a robust breast implant surface classification. The authors obtained three topographic categories of textured implants (i.e., “peak and valleys,” “open cavities,” and “semiopened cavities”) based on the cross-sectional aspects. The authors simultaneously collected 31 Baker grade I capsules, sorted them according to the new classification, established their molecular profile, and examined the tissue organization. Results: Each of the categories showed distinct expression patterns of genes associated with the extracellular matrix (Timp and Mmp members) and inflammatory response (Saa1, Tnsf11, and Il8), despite originating from healthy capsules. In addition, slight variations were observed in the organization of capsular tissues at the histologic level. Conclusions: The authors combined a novel surface implant classification system and gene profiling analysis to show that implant surface topography is a bioactive cue that can trigger gene expression changes in surrounding tissue, even in Baker grade I capsules. The authors’ new classification system avoids confusion regarding the word “texture,” and could be transposed to implant ranges of every manufacturer. This new classification could prove useful in studies on potential links between specific texturizations and the incidence of certain breast-implant associated complications

MOUVEMENTS DE VIBRATIONS ETUDIES PAR HOLOGRAPHIE HETERODYNE

International audienceEn jouant avec l'amplitude, la phase et la fréquence des deux bras référence et signal, l'holographie hétérodyne est bien adaptée à l'analyse des vibrations. Les bandes latérales de vibrations peuvent être visualiées et des mesures stroboscopiques, sensibles à la phase mécanique peuvent être faites

Original treatment of constitutional painful callosities by surgical excision, collagen/elastin matrix (MatriDerm (R)) and split thickness skin graft secured by negative wound therapy

National audienceConstitutional painful callosities is an unusual pathology, integrated in the frame of "palmoplantar keratodermia" (PPK). Lesions are located at areas of support of the sole. These lesions are painful and disable the normal walking. Treatments are suspensive and painkillers. We report our experience of a single surgical treatment: surgical excision, split thickness skin graft applied on a dermal substitute and secured by negative wound therapy. A 28-year-old patient, affected by this disease, has a desire of pregnancy but her treatment is highly teratogen. A year post-op, wounds were healed. The walk was possible with a relief of the pain, without any ulcerations. The surgical treatment by excision and graft or flaps was previously reported for PPK. The use of dermal substitute was never described for this indication. Dermal substitute compensate the thickness of the soft tissue defect and give an accurate quality of elasticity in this localisation. The negative wound therapy enhances the quality and shortens the length of graft taking, and the adhesion of the dermal substitute on his bed. (C) 2009 Elsevier Masson SAS. All rights reserved

Off-axis compressed holographic microscopy in low-light conditions

International audienceThis Letter reports a demonstration of off-axis compressed holography in low-light level imaging conditions. An acquisition protocol relying on a single exposure of a randomly undersampled diffraction map of the optical field, recorded in the high heterodyne gain regime, is proposed. The image acquisition scheme is based on compressed sensing, a theory establishing that near-exact recovery of an unknown sparse signal is possible from a small number of nonstructured measurements. Image reconstruction is further enhanced by introducing an off-axis spatial support constraint to the image estimation algorithm. We report accurate experimental recovering of holographic images of a resolution target in low-light conditions with a frame exposure of 5 μs, scaling down measurements to 9% of random pixels within the array detector

High speed optical holography of retinal blood flow

International audienceWe performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms

Évaluation de la mobilité de l’épaule et de la qualité de vie après reconstruction du creux axillaire par lambeau perforant, dans le cadre de la maladie de Verneuil

International audienceBackground.-Hidradenitis suppurativa is a very debilitating disease, treated by antibiotics and excision. The reconstruction is usually done by secondary wound healing and/or split-thichness skin graft. The aim of this study was to evaluate the reconstruction of the axilla with local perforator flaps as a single stage surgical treatment. Methods.-This was a monocentric retrospective study conducted between November 2013 and June 2015. We included the patients with a severe axillary localization of the disease. Between 6 months and 1 year postoperatively, we noted length of complete healing, complications, patients satisfaction score about the surgery, DASH functional score, maximum abduction angle of the arm, and recurrence of the disease. Results.-Thirteen patients were included, for a total of seventeen affected axillae. We performed seven thoracodorsal artery perforator flaps, seven lateral intercostal artery perfo-rator flaps and three serratus anterior artery perforator flaps. The mean duration of follow-up was 279.1 AE 84.1 days (180-365). The average complete healing time was 20.5 AE 13.5 days (10-60). Six axillae were compounded (35%). The average recurrence rate of HS was 0%. The average Annales de chirurgie plastique esthétique (2019) 64, 68-7