Publications by authors named "Xavier Levecq"

We present a compact multi-modal and multi-scale retinal imaging instrument with an angiographic functional extension for clinical use. The system integrates scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT) and OCT angiography (OCTA) imaging modalities and provides multi-scale fields of view. For high resolution, and high lateral resolution in particular, cellular imaging correction of aberrations by adaptive optics (AO) is employed.

View Article and Find Full Text PDF

For more than 15 years, Imagine Optic have developed Extreme Ultra Violet (EUV) and X-ray Hartmann wavefront sensors for metrology and imaging applications. These sensors are compatible with a wide range of X-ray sources: from synchrotrons, Free Electron Lasers, laser-driven betatron and plasma-based EUV lasers to High Harmonic Generation. In this paper, we first describe the principle of a Hartmann sensor and give some key parameters to design a high-performance sensor.

View Article and Find Full Text PDF

High-quality in-depth imaging of three-dimensional samples remains a major challenge in modern microscopy. Selective plane illumination microscopy (SPIM) is a widely used technique that enables imaging of living tissues with subcellular resolution. However, scattering, absorption, and optical aberrations limit the depth at which useful imaging can be done.

View Article and Find Full Text PDF

We propose an adaptive optics light-sheet fluorescence microscope (AO-LSFM) for closed-loop aberrations' correction at the emission path, providing intrinsic instrumental simplicity and high accuracy when compared to previously reported schemes. The approach is based on direct wavefront sensing, i.e.

View Article and Find Full Text PDF

The wavefront quality of white-light supercontinuum is crucial for applications like waveform synthesis or imaging. It has been here generated by 1030 nm centered sub-picosecond pulses in YAG and characterized with a Shack-Hartmann wavefront sensor across different parts of the spectrum. It shows a good wavefront quality of λ/11 and little dependence on the wavelength of the supercontinuum.

View Article and Find Full Text PDF

Imaging of the human retina with high resolution is an essential step towards improved diagnosis and treatment control. In this paper, we introduce a compact, clinically user-friendly instrument based on swept source optical coherence tomography (SS-OCT). A key feature of the system is the realization of two different operation modes.

View Article and Find Full Text PDF

We present a new compact multi-modal imaging prototype that combines an adaptive optics (AO) fundus camera with AO-optical coherence tomography (OCT) in a single instrument. The prototype allows acquiring AO fundus images with a field of view of 4°x4° and with a frame rate of 10fps. The exposure time of a single image is 10 ms.

View Article and Find Full Text PDF

Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware.

View Article and Find Full Text PDF

We demonstrate that sample induced aberrations can be measured in a nonlinear microscope. This uses the fact that two-photon excited fluorescence naturally produces a localized point source inside the sample: the nonlinear guide-star (NL-GS). The wavefront emitted from the NL-GS can then be recorded using a Shack-Hartmann sensor.

View Article and Find Full Text PDF

The recent development of short-wavelength optics (X/EUV, synchrotrons) requires improved metrology techniques in terms of accuracy and curvature dynamic range. In this article a stitching Shack-Hartmann head dedicated to be mounted on translation stages for the characterization of X-ray mirrors is presented. The principle of the instrument is described and experimental results for an X-ray toroidal mirror are presented.

View Article and Find Full Text PDF

We present what we believe to be the first automatic alignment of a synchrotron beamline by the Hartmann technique. Experiments were performed, in the soft-x-ray range (E=3 keV, lambda=0.414 nm), by using a four-actuator Kirkpatrick-Baez (KB) active optic.

View Article and Find Full Text PDF

We report, for the first time to our knowledge, experimental demonstration of wave-front analysis via the Hartmann technique in the extreme ultraviolet range. The reference wave front needed to calibrate the sensor was generated by spatially filtering a focused undulator beam with 1.7- and 0.

View Article and Find Full Text PDF