René Paul Salathé
École Polytechnique Fédérale de Lausanne
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Featured researches published by René Paul Salathé.
Journal of Lightwave Technology | 1989
H.H. Gilgen; R.P. Novak; René Paul Salathé; W. Hodel; P. Beaud
The development of optical reflectometers with a spatial resolution in the submillimeter range is reviewed. Optical time-domain reflectometers (OTDRs) and optical low-coherence reflectometers (OLCRs) for nondestructive diagnostics of waveguide devices are discussed. Techniques, system performances, and experimental results are discussed for OTDRs and for OLCRs. Fields of applications for these techniques are indicated, and some preliminary conclusions are presented. A dynamic range of approximately 100 dB and a spatial resolution in the range of 10-60 mu m were achieved with both types of reflectometers. Nondestructive diagnostics on waveguide components and integrated optics circuits are feasible at these performance levels. >
Journal of Lightwave Technology | 1999
Alessandro Iocco; Hans Georg Limberger; René Paul Salathé; L.A. Everall; Karen E. Chisholm; J.A.R. Williams; Ian Bennion
A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems.
Optics Express | 2002
Andrew M. Kowalevicz; Tony H. Ko; Ingmar Hartl; James G. Fujimoto; Markus Pollnau; René Paul Salathé
A superluminescent Ti:Al2O(3) crystal is demonstrated as a light source for ultrahigh resolution optical coherence tomography (OCT). Single spatial mode, fiber coupled output powers of ~40 microW can be generated with 138 nm bandwidth using a 5 W frequency doubled, diode pumped laser, pumping a thin Ti:Al2O(3) crystal. Ultrahigh resolution OCT imaging is demonstrated with 2.2 microm axial resolution in air, or 1.7 microm in tissue, with >86 dB sensitivity. This light source provides a simple and robust alternative to femtosecond lasers for ultrahigh resolution OCT imaging.
IEEE Photonics Technology Letters | 1993
P. Lambelet; P.Y. Fonjallaz; Hans Georg Limberger; René Paul Salathé; C. Zimmer; H.H. Gilgen
Optical low-coherence reflectometry is used for the first time to investigate distributed-feedback structures within a single-mode fiber. This nondestructive method allows the location, the length, and the coupling coefficient of the grating to be determined precisely.<<ETX>>
IEEE Photonics Technology Letters | 1998
Hans Georg Limberger; Nguyen Hong Ky; Daniele M. Costantini; René Paul Salathé; Claude Muller; Glen R. Fox
An electrically tunable reflection filter based on a platinum-coated single-mode optical fiber that contains an intracore Bragg grating has been demonstrated. The device shows a dc tuning range of 2.15 nm with a corresponding electrical power of 0.54 W. Wavelength modulation (WM) has been observed at frequencies lower than 100 Hz. The wavelength shift depends linearly on the electrical input power. A maximum efficiency of 4.1 nm/W is obtained for dc tuning.
Lasers in Surgery and Medicine | 1996
Klaus Rink; Guy P. Delacretaz; René Paul Salathé; Alfred Senn; Dorota Nocera; Marc Germond; Pierre De Grandi; Stanislav Fakan
A non‐touch laser‐induced microdrilling procedure is studied on mouse zona pellucida (ZP).
Optics Express | 2002
Markus Laubscher; Mathieu Ducros; Boris Karamata; Theo Lasser; René Paul Salathé
Most current optical coherence tomography systems provide two-dimensional cross-sectional or en face images. Successive adjacent images have to be acquired to reconstruct three-dimensional objects, which can be time consuming. Here we demonstrate three-dimensional optical coherence tomography (3D OCT) at video rate. A 58 by 58 smart-pixel detector array was employed. A sample volume of 210x210x80 m3 (corresponding to 58x58x58 voxels) was imaged at 25 Hz. The longitudinal and transverse resolutions are 3 m and 9 m respectively. The sensitivity of the system was 76 dB. Video rate 3D OCT is illustrated by movies of a strand of hair undergoing fast thermal damage.
Smart Materials and Structures | 2003
Federico Bosia; Philippe Giaccari; J. Botsis; Mauro Facchini; Hans Georg Limberger; René Paul Salathé
In this paper, the behaviour of fibre Bragg grating sensors subjected to transversal as well as axial strains is characterized, both in the case of low-birefringent and polarization-maintaining single-mode optical fibres. Two configurations are considered. Firstly, diametrical compression is studied and the results compared to those previously obtained in the literature. Secondly, the sensors are embedded in an epoxy specimen and their response monitored when the latter is subjected to biaxial loading. In both cases, the experimental results are compared to those obtained by means of finite-element simulations and an appropriate analytical description of the opto-mechanical response of polarization-maintaining fibres.
Journal of Refractive Surgery | 1998
Matthias Böhnke; Philippe Chavanne; Ronald Gianotti; René Paul Salathé
PURPOSE We developed an instrument that permits non-contact, continuous, high speed and high precision monitoring of corneal thickness and tested the stability and reproducibility of measurements made over extended time periods and under various conditions of low surface reflectivity encountered during protracted exposure of the unmoistened corneal surface to ambient air. METHODS The optical pachymeter (basic component of a broad-band, all-fiber Michelson interferometer) was used to monitor changes in the central corneal thickness of enucleated porcine eyes. Measurements were performed on three groups of eight eyes, each with different surface characteristics: intact epithelium, mechanically abraded epithelium, and 90 microm excimer laser keratectomy. Corneal thickness was monitored continuously with values recorded every 2 to 3 minutes for periods up to 1 hour in the absence of surface rinsing. RESULTS The thicknesses of all unmoistened corneas could be monitored with a precision of 1 microm (ascertained using a calibration glass plate and a living human cornea) over the entire observation period. Under ambient air conditions, deturgescence occurred in each case, and ranged from 1 to 5 microm/min. The rate of corneal thinning was fairly constant during the first 15 minutes of monitoring, but was nonlinear thereafter. Corneas with an intact epithelium had the lowest thinning rate with only 10% of the original thickness lost during the course of 1 hour. Deturgescence increased to 25% in corneas that had mechanical removal of the epithelium and to 28.5% in those that had an anterior excimer laser keratectomy, during a similar time-period. CONCLUSION With this new interferometric method, continuous, non-contact measurement of corneal thickness is possible to within a precision of 1 microm for periods up to 1 hour, even under the modified surface conditions after photoablative keratectomy. This device may be useful for on-line monitoring of ablation depths during such procedures.
Journal of Biomedical Optics | 1998
Rudolf Wa¨lti; Matthias Bo¨hnke; Ronald Gianotti; Pascal Bonvin; Julien J. Ballif; René Paul Salathé
An optical low-coherence reflectometer is used for rapid noncontact measurements of the human corneal thickness in vivo. Thickness measurements on ten volunteers show a standard deviation of 3.4 μm. The experiments reveal that the optical reflectometer benefits from a 2.5 fold enhancement of the measurement precision and a 2.8 fold reduction in measurement time compared to a standard clinical ultrasonic pachometer.