Ferran Laguarta

Sensofar Medical · Corporate

Stent quality control is a highly critical process. Cardiovascular stents have to be inspected 100% so as no defective stent is implanted in a human body. However, this visual control is currently performed manually and every stent could need tenths of minutes to be inspected. In this paper, a novel optical inspection system is presented. By the co...

Implantable medical devices, such as stents, have to be inspected 100% so no defective one is implanted into a human body. In this paper, a novel optical stent inspection system is presented. By the combination of a high numerical aperture microscope, a triple illumination system, a rotational stage, and a CMOS camera, unrolled sections of the oute...

Stent quality control is a critical process. A high numerical aperture stent inspection system has been developed, composed by a rotary stage, a CMOS camera and a triple illumination arrangement. Unrolled sections of the outer, inner and sidewalls surfaces are obtained with high resolution. With this system, coatings thickness are also measured, cy...

Stent quality control is a critical process. Coronary stents have to be inspected 100% so no defective stent is implanted into a human body. Skilled operators currently perform the quality process control visually, and every stent could need tens of minutes to be inspected. In this paper, a novel stent optical inspection system is presented. By the...

The device (100) comprises means (200) for rotatably hold-ing and positioning at least one stent-like object (400) and means (30E, 30B) for illuminating at least inner and outer surfaces (I, 0) thereof comprising at least wide field epi illumination means (30E) and diffuse back illumination means (30B) for simultaneously illuminating the stent-like...

In this paper we introduce a new optical technique for the measurement of aspheric and free-form optics and moulds. This technique, called confocal tracking, consists on tracking the focus on the sample while it is moved along the horizontal XY axes. Unlike all single-point based techniques, confocal tracking images the surface, which makes it poss...

Optical profiling techniques, mainly confocal and white light interferometry, have demonstrated to be suitable techniques for characterization of transparent thick films. Measurements are carried out by vertically scanning the upper and lower film interfaces. Thickness of the layer is determined from the two peaks in the confocal axial response or...

Traditional high-precision optical techniques, such as interferometry, are in ever-greater demand for noncontrolled environments. This is the case for the UPC-ZEBRA, a large-aperture interferometer that was built to measure vertical discontinuities (i.e., piston errors) in segmented mirrors. The large mechanical systems used to drive the interferom...

New material applications and novel manufacturing processes are driving a systematic rise in market demands concerning surface inspection methods and the performance of non-contact profilers. However, analysis of the specifications and application notes of commercial optical profilers shows that no single system is able to offer all the features a...

One of the most challenging applications of optical metrology is measuring the shape of the inner surfaces of nozzles such as those of fuel injectors, wiring dies and printheads. A current non-contact solution is confocal laser scanning microscopy (CLSM). However, the inner urfaces of the nozzles behave as though they were optically polished, which...

In segmented-mirror telescopes, wave-front discontinuities caused by segment misalignment are a major problem because they severely degrade optical performance. While angular misalignments are usually measured with deflectometric wave-front sensors (e.g., Shack-Hartmann sensors), a number of techniques have been proposed for the measurement of vert...

New material applications and novel manufacturing processes are driving a systematic rise in market demands concerning surface inspection methods and the performance of non-contact profilers. However, analysis of the specifications and application notes of commercial optical profilers shows that no single system is able to offer all the features a...

New material applications and novel manufacturing processes are driving a systematic rise in market demands concerning surface inspection methods and the performance of non-contact profilers. However, analysis of the specifications and application notes of commercial optical profilers shows that no single system is able to offer all the features a...

New material applications and novel manufacturing processes are driving a systematic rise in market demands concerning surface inspection methods and the performance of non-contact profilers. However, analysis of the specifications and application notes of commercial optical profilers shows that no single system is able to offer all the features a...

One of the applications, which is considered to be very difficult to carry out with most optical imaging profilers, is the shape and texture measurements of structured surfaces obtained from the superposition of various micro or sub-micrometric layers of dissimilar materials. Typical examples are the architectures of microelectronics samples made u...

Present trends in the design of ground-based telescopes point towards the use of segmented primary mirrors. A major problem in this type of mirror is the achievement of proper segment positioning, as they have to be aligned with an accuracy of the order of a fraction of a wavelength for near-diffraction-limit telescope performance in the infrared....

One of the new problems that has to be solved for segmented mirrors is related to periodic phasing, because for such mirrors to exhibit diffraction-limited performance the segments have to be positioned with an accuracy of a fraction of a wavelength. We describe the optical design of an instrument that measures the phasing errors (i.e., tip, tilt,...

The dynamic behaviour of a coherently pumped single-mode far-infrared ring laser with a homogeneously broadened three-level medium is analysed theoretically, considering detuning between amplifying transition and cavity frequencies. Phase diagrams as a function of cavity detuning and amplitude of the resonant pump field have been obtained, which sh...

Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their i...

One of the objectives of surface metrology is to obtain a better and faster assessment of the micro- or nanogeometry of component surfaces. In this way the innovative concept of the profiler is changing towards non-contact modular computer- controlled systems for measuring and analyzing shape and texture of a surface. In this paper we present a new...

Laser heating of glass samples is a simple and versatile method for obtaining polished surfaces of optical quality. Since laser beam intensity non-uniformity can translate into significant variations in the induced surface temperature, the success of the laser surface-polishing process strongly depends on obtaining uniform intensity profiles or fla...

An analysis is given of how nonuniformities in the laser beam intensity translate into variations on the induced temperature distribution on an irradiated sample. The study involves materials with different thermal conductivities. By use of a reshaped irradiating beam obtained with a multifaceted integrating mirror, a three-dimensional numerical ca...

The surface metrology market today is moving towards non-contact modular computer-controlled systems for measuring and analysing contour and topography. In this paper a new optical profiler based on the concept of confocal microscopy is demonstrated. A visible laser beam is focused with a high numerical aperture optical system onto the smooth surfa...

The surface metrology market toady is moving towards non- contact modular computer-controlled system for measuring and analyzing roughness, contour and topography. In this paper we present a new optical instrument based on the concept of confocal microscopy. In this instrument, which is especially suitable for measurements on smooth surfaces, eithe...

The surface metrology market today is moving towards non- contact modular computer-controlled systems for measuring and analyzing roughness, contour and topography. Since most of these systems require a great accessibility to the surface to be measured they can not be used for the metrology of surfaces with intricate geometries, difficult access an...

A new integration method suited for spatially coherent high-power laser beams is demonstrated. The integrator system is based on a mirror with two facets, one of which can vibrate under the action of a piezoelectric translator. After reflection in the faceted mirror, the beam intensity distribution is modified to obtain greater uniformity. However,...

In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. We have designed and tested a very simple beam...

The development of new optical glass polishing methods that improve the production efficiency of standard components is of key interest for the optical industry. Laser polishing is a very attractive method since it requires no mechanical abrasives or surface-adapted polishing tools. Moreover, it can be applied to surfaces of very complicated topogr...

The smoothing of laser beam intensity spatial distributions is a practical need for the development of a majority of laser surface treatment applications. However, the current use of homogenizing waveguides such as kaleidoscopes is not generally a satisfactory solution because of their relatively high associated laser energy loss.

It is shown that optical surfaces traditionally ground in conventional glasses with high coefficients of thermal expansion may be polished by irradiation with a space- and time-controlled uniform CO(2) laser beam. Comparisons of a theoretical simulation model of the laser-driven heating process with the experimental results allow us to determine th...

The dynamic behavior of a coherently pumped ring laser with a homogeneously broadened four-level medium is analyzed theoretically, considering linearly polarized pump and generated laser beams. The laser is shown to be much more stable when these polarizations are parallel than when they are orthogonal. In the latter case the instability pump thres...

Coherently pumped lasers (CPL) operating in the far-infrared spectral region shown a wealth of instabilities1, including a behavior remarkably similar2,3 with the predictions of the paradigmatic Lorenz-Haken model of a single-mode homogeneously broadened laser4,5. The qualitative agreement; between theory and experiments2,3 was rather surprising, f...

We analyze the influence of light polari­zation on the dynamics of coherently pumped lasers using a single-mode ring laser model which considers a homogeneously broadened four-level medium. As typical in FIR laser experiments, we consider linearly polarized pump and generated laser beams. Phase diagrams as a function of cavity detuning and amplitud...

The dynamic behavior of the phase of the generated field in a Doppler-broadened optically-pumped far-infrared laser is theoretically investigated for the first time. The phase undergoes sudden jumps of approximately π radians, which allow to establish the actual symmetry of the main attractor in the phase space, explaining the heteroclynic characte...

We report the theoretical interpretation of Lorenz-like behavior recently observed for the first time in a laser by Weiss and Brock [Phys. Rev. Lett. 57 (1986) 2804]. By means of a three-level laser model it is shown that in an optically-pumped far-infrared laser, coherent pumping effects are partially smeared out by Doppler broadening and as a res...

On étudie le comportement dynamique d'un laser en anneau, unidirectionnel, sonomode et pompé optiquement, dont le milieu actif est composé par des atomes à trois niveaux affectés par élargissement Doppler. La formulation est basée sur un ensemble de 9N+1 équations réelles du type Maxwell-Bloch pour des ondes planes et approximation du champ moyen (...

This paper investigates the behavior of a coherently pumped single-mode unidirectional ring laser with a homogeneously broadened three-level active medium in which the pumping and lasing transitions share a common upper level. Special attention is given to the effect of the coherent optical pumping on the dynamic behavior of a laser, i.e., on three...

Recently Weiss and Brock observed Lorenz-type chaos in the 81.5μm emission from an optically-pumped ¹⁴ NH 3 laser ¹ . The theoretical interpretation of the experimental results is an open question, however. In fact, the Lorenz-Haken model refers to incoherently pumped lasers with homogeneously-broadened two-level active media ² . Models based on (a...

The unstable emission of an optically pumped FIR gas laser is theoretically analysed through numerical resolution of the associated Maxwell-Bloch equations. The instability domain in the main control parameters space is determined and an example of chaotic behaviour is examined.

A new type of forward-backward asymmetry is reported for the 119-micron emission from a linear-cavity CH3OH laser, near-resonantly pumped by a continuous-wave CO2 laser. The observed asymmetry is related to a strong traveling-wave pump field and also saturating standing-wave-generated fields, a situation typical for most optically pumped linear-cav...

A theoretical study is made of the gain for a linear-cavity (Fabry-Perot) FIR laser pumped by a traveling-wave infrared beam. Arbitrary field intensities and pressure and Doppler broadenings are considered. The simultaneous presence inside the laser cavity of the forward and backward generated waves produces strong competition and coupling effects...

In an inhomogeneously Doppler broadened three-level system, the gain lineshapes of a strong standing-wave generated field are analyzed when a fixed frequency traveling-wave pumps a transition sharing the upper level with the lasing transition. Population pulsations and nonlinear coherent effects are included in the numerical solution. The physical...