This paper describes the design and fabrication of a system for acquisition and image processing to control the removal of thorns nopal vegetable (Opuntia ficus indica) in an automated machine that uses pulses of a laser of Nd: YAG. The areolas, areas where thorns grow on the bark of the Nopal, are located applying segmentation algorithms to the images obtained by a CCD. Once the position of the areolas is known, coordinates are sent to a motors system that controls the laser to interact with all areolas and remove the thorns of the nopal. The electronic system comprises a video decoder, memory for image and software storage, and digital signal processor for system control. The firmware programmed tasks on acquisition, preprocessing, segmentation, recognition and interpretation of the areolas. This system achievement identifying areolas and generating table of coordinates of them, which will be send the motor galvo system that controls the laser for removal
An algorithm for the analysis of the double clad fiber design is presented. The algorithm developed in the MATLAB
computing language, is based on ray tracing method applied to three-dimensional graphics figures which are composed
of a set of plans. The algorithm can evaluate thousands of ray paths in sequence and its corresponding pump absorption
in each of the elements of the fiber according to the Lambert-Beer law. The beam path is evaluated in 3 dimensions
considering the losses by reflexion and refraction in the faces and within the fiber. Due to its flexibility, the algorithm
can be used to study the ray propagation in single mode or multimode fibers, bending effects in fibers, variable
geometries of the inner clad and the core, and could also be used to study tappers.
We report the fabrication of glass multilayer doped with semiconductor nanoparticles. The glass
matrix was fabricated by Plasma Enhanced Chemical Deposition (PECVD using tetramethoxysilane
(TMOS) as precursor. The RF power was supplied by a RF-150 TOKYO HI-Power operating at
13.56 MHz and coupled to the RF electrodes through a matching box. The nanoparticles were
grown by pulsed laser deposition (PLD) of a PbTe target using the second harmonic of a Q-Switched
Quantel Nd:YAG laser in high purity inert gas atmosphere.
The influence of gas and background pressure and in the nanoparticle size and size distribution is
studied. The morphological properties of the nanostructured material were studied by means of High
Resolution Transmission Electron Microscopy(HRTEM), grazing-incidence smallangleX-ray
An experimental measurement by using Laser Induced Breakdown Spectroscopy (LIBS) and Photoacoustic
Induced by Laser Ablation (PILA), in order to monitoring the microcraks formation inside the
glass induced by laser pulses is presented in this work. The laser was operated in both single pulse and
multi-pulse Q:Switched regime using a passive Cr:YAG crystal as switching element. The LIBS spectra
captured inside the glass avoid identifying the sample composition without influence of surrounding
atmosphere like occurs if the spectra are obtained on the surface. On the other hand, the PILA signal
permits to monitor the process and its dependence from the number and intensity of micro-pulses.
The potential of Nd:YAG pulsed laser to processing PVC sheets minimizing HCl gases emission is investigated. We
studied the gas emission when the PVC is cut by either CO2 or Nd:YAG pulsed laser by using FTIR Spectroscopy.
Optical microscopy of laser treated PVC samples was performed in order to demonstrate the carbonization. On the other
hand, LIBS spectroscopy for two different ranges of pulse duration was employed in order to investigate the plume
composition during the Nd:YAG pulsed laser ablation process. The experiments shows that Cl atoms are emitted during
the Nd:YAG pulsed laser ablation although the HCl gases are produced at low levels. In order to explain the sub-surface
irregularities detected for Nd:YAG laser irradiation, a one-dimensional model is developed to study the temperature
evolution inside the sample. We demonstrate that the ablation mechanisms prevail on thermally drive emission until 70
μm, afterwards the thermal expansion process is already observed.
A method is proposed for the design of fundamental mode high power resonators, with joined stability zones. A
parameter is created which gives the minimum length a laser resonator should have while having at the same time the
broadest stabilities zones. For multimode and large mode volume resonators, a configuration is introduced for
maximizing the laser overall efficiency due to the compensation of the astigmatism induced by the flash lamp pumping
heating. The later configuration proposes a dual-active medium resonator, with 90 degree rotation around the optical axis
between the astigmatic thermal lenses of the mediums. The reliability of this configuration is corroborated
experimentally using a Nd:YAG dual-active medium resonator. It is found that in the pumping power range where the
astigmatism compensation is possible, the overall efficiency is constant, even when increasing the excitation power with
the consequent increase of the thermal lens dioptric power.
Thin films of ZnO and GaN have been deposited by pulsed laser deposition in atmospheres of oxygen and nitrgoen respectively. A time-of-flight ion probe and optical spectroscopy were used to study the interaction of the ablation plasma with the background gas. The deposition rate was measured using in situ optical reflectivity, and the thin film quality was assessed using x-ray diffraction and photoluminescence. By correlating the plasma measurements and the thin film characterization it was possible to identify the plasma regime required for the deposition of good quality films.