Publications de Rainer Leitgeb

Laser Doppler imaging for intraoperative human brain mapping

Marcel Leutenegger, Michaël Unser, Theo Lasser, Dimitri Nestor Alice Van De Ville, Rainer Leitgeb, Erica Martin-Williams

The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intrao ...

Elsevier2009

In vivo imaging of murine endocrine islets of Langerhans with extended-focus optical coherence microscopy

Theo Lasser, Martin Villiger, Michael Friedrich, Rainer Leitgeb, Anne Grapin-Botton, Joan Goulley

Aims/hypothesis Structural and functional imaging of the islets of Langerhans and the insulin-secreting beta cells represents a significant challenge and a long-lasting objective in diabetes research. In vivo microscopy offers a valuable insight into beta ...

Springer Verlag2009

Information Limits of Optical Coherence Imaging Through Scattering Media

Theo Lasser, Rainer Leitgeb

We develop an information-theoretic framework for the quantitative assessment of the maximum amount of information provided by optical coherence imaging through scattering media. We use our approach to investigate the fundamental dependence of the extracta ...

2009

See the Brain at Work—Intraoperative Laser Doppler Functional Brain Imaging

Marcel Leutenegger, Michaël Unser, Theo Lasser, Antonio Lopez, Dimitri Nestor Alice Van De Ville, Rainer Leitgeb, Erica Martin-Williams

During open brain surgery we acquire perfusion images non-invasively using laser Doppler imaging. The regions of brain activity show a distinct signal in response to stimulation providing intraoperative functional brain maps of remarkably strong contrast. ...

2009

Optical apparatus for dual beam heterodyne Fourier domain optical coherence tomography, has detector that synchronizes phase shift such that sample signal or sample interface moving at arbitrary velocity is detected by phase change

Adrian Bachmann, Theo Lasser, Roland Michaely, Martin Villiger, Rainer Leitgeb

NOVELTY - The apparatus has an optical unit for splitting a source field to produce and combine reference and biomedical sample light fields. An optical and electronic unit records a spectral interference pattern between combined light fields. A controlled ...

2008

Frequency encoded assessment of retinal physiology

Adrian Bachmann, Theo Lasser, Roland Michaely, Cédric Blatter, Rainer Leitgeb

We demonstrate in-vivo functional imaging of the human retina with Fourier domain optical coherence tomography employing frequency encoding of an excitation pattern. The principle is based on projecting a modulated rectangular pattern across the foveal reg ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2008

Theoretical analysis of complex-conjugate-ambiguity suppression in frequency-domain optical-coherence tomography

Michaël Unser, Roland Michaely, Rainer Leitgeb

New phase-shifting techniques have recently been proposed to suppress the complex-conjugate ambiguity in frequency-domain optical-coherence tomography. A phase shift is introduced, in an elegant fashion, by incorporating a small beam offset at the scanning ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Exact and Efficient Signal Reconstruction in Frequency-Domain Optical-Coherence Tomography

Michaël Unser, Rainer Leitgeb, Chandra Sekhar Seelamantula

We address the problem of tomogram reconstruction in frequency-domain optical-coherence tomography. We propose a new technique for suppressing the autocorrelation artifacts that are commonly encountered with the conventional Fourier-transform-based approac ...

OSA2008

Vectorial retinal blood flow and optical vessel vivisection for 3D angiography with high resolution resonant Doppler OCT

Adrian Bachmann, Theo Lasser, Roland Michaely, Martin Villiger, Cédric Blatter, Rainer Leitgeb

PURPOSE: To perform high speed and completely non-invasive 3D angiography at the optic nerve head region and to reconstruct vectorial 3D blood flow from optically segmented blood vessel structure as a pre-requisite for testing retinal function and physiolo ...

2007

Intensity based quantification of fast retinal blood flow in 3D via high resolution resonant Doppler spectral OCT

Adrian Bachmann, Theo Lasser, Roland Michaely, Martin Villiger, Cédric Blatter, Rainer Leitgeb

Resonant Doppler Fourier Domain Optical Coherence Tomography is a functional imaging modality for quantifying fast tissue flow. The method profits from the effect of interference fringe blurring in spectrometer-based FDOCT in the presence of sample motion. ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2007

Image formation in fluorescence coherence-gated imaging through scattering media

Theo Lasser, Rainer Leitgeb

Recently, we have experimentally demonstrated a new form of cross-sectional, coherence-gated fluorescence imaging referred to as SD-FCT (‘spectral-domain fluorescence coherence tomography’). Imaging in SD-FCT is accomplished by spectrally detecting self-in ...

2007

Vectorial reconstruction of retinal blood flow in three dimensions measured with high resolution resonant Doppler Fourier domain optical coherence tomography

Adrian Bachmann, Theo Lasser, Roland Michaely, Martin Villiger, Cédric Blatter, Rainer Leitgeb

Resonant Doppler Fourier domain optical coherence tomography (FDOCT) is a functional imaging tool for extracting tissue flow. The method is based on the effect of interference fringe blurring in spectrometer-based FDOCT, where the path difference between s ...

SPIE Society of Photo-optical Instrumentation Engineers2007

Field confinement with aberration correction for solid immersion lens based fluorescence correlation spectroscopy

Theo Lasser, Jelena Mitic, Ramachandra Rao, Rainer Leitgeb

The solid immersion lens (SIL) as a tool for increasing the field confinement as well as providing optimal performance by aberration compensation in a confocal fluorescence correlation spectroscopy (FCS) system is illustrated here. Using Zernike polynomial ...

2007

Resonant Doppler flow imaging and optical vivisection of retinal blood vessels

Adrian Bachmann, Theo Lasser, Martin Villiger, Cédric Blatter, Rainer Leitgeb

For Fourier domain optical coherence tomography any sample movement during camera integration causes blurring of interference fringes and as such reduction of sensitivity for flow detection. The proposed method overcomes this problem by phase-matching a re ...

2007

Non-iterative exact signal recovery in frequency domain optical coherence tomography

Michaël Unser, Thierry Blu, Rainer Leitgeb

We address the problem of exact signal recovery in frequency domain optical coherence tomography (FDOCT) systems. Our technique relies on the fact that, in a spectral interferometry setup, the intensity of the total signal reflected from the object is smal ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2007

Optical imaging apparatus for sample imaging method e.g. in-vivo measurement of full three-dimensional tissue volume has at least one detector that detects resulting spectral interference pattern at exit of interferometer

Adrian Bachmann, Theo Lasser, Lukas Steinmann, Martin Villiger, Rainer Leitgeb

The invention concerns an optical imaging apparatus comprising (o) a light source (1) , (p) sample holding means, (q) an interferometer, (r) reference means, (s) an objective (8) which is adapted to have its sample side focal plane crossing a sample held i ...

2007

Complex Ambiguity-Free Fourier Domain Optical Coherence Tomography through Transverse Scanning

Theo Lasser, Roland Michaely, Rainer Leitgeb

We introduce a simple and cheap method for phase-shifting Fourier domain optical coherence tomography (FDOCT) that does not need additional devices and can easily be implemented. A small beam offset at the fast beam-scanning mirror introduces a causal phas ...

OSA2007

Logarithmic Transformation Technique for Exact Signal Recovery in Frequency-Domain Optical-Coherence Tomography

Michaël Unser, Rainer Leitgeb

We address the problem of exact signal recovery in frequency-domain optical-coherence tomography (FDOCT). The standard technique for tomogram reconstruction is the inverse Fourier transform. However, the inverse Fourier transform is known to yield autocorr ...

SPIE2007

Dual-beam heterodyne Fourier domain optical coherence tomography

Adrian Bachmann, Theo Lasser, Roland Michaely, Rainer Leitgeb

We report on a novel method combining achromatic complex FDOCT signal reconstruction with a common path and dual beam configuration. The complex signal reconstruction allows resolving the complex ambiguity of the Fourier transform and to enhance the achiev ...

2007

Phase sensitive Fourier domain optical coherence tomography

Adrian Bachmann, Theo Lasser, Rainer Leitgeb

Optical Coherence Tomography (OCT) is an imaging technique with high axial resolution in the micro-meter-scale range combined with a high sensitivity allowing for example to probe weakly back-scattering structures beneath the surface of biological tissues ...

2006