Abstract

Abstract
Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in real time. This paper describes a non-destructive approach and all required signal processing steps to characterize the thin inner layers and also to improve the imaging speed and the signal to noise ratio. The algorithm was developed by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This GPU-accelerated white light interferometry technique non-destructively assesses the samples and has high imaging speed advantage, overcoming the bottlenecks in PET performs quality control.

Abstract
A spectral calibration technique, a data processing method and the importance of calibration and re-sampling methods for the spectral domain optical coherence tomography system were numerically studied, targeted to optical coherence tomography (OCT) signal processing implementation under graphics processing unit (GPU) architecture. Accurately, assigning the wavelength to each pixel of the detector is of paramount importance to obtain high quality images and increase signal to noise ratio (SNR). High quality imaging can be achieved by proper calibration methods, here performed by phase calibration and interpolation. SNR was assessed employing two approaches, single spectrum moving window averaging and consecutive spectra data averaging, to investigate the optimized method and factor for background noise reduction. It was demonstrated that the consecutive spectra averaging had better SNR performance. © 2012 The Author(s).

Abstract
High-precision dosimeters are needed in brachytherapy treatments to ensure safe operation and adequate working conditions, to assess the correspondence between treatment planning and dose delivery, as well as to monitor the radiation dose received by patients. In this paper we present the development of a multi-sensor dosimeter platform targeted for brachytherapy environments. The performance of different scintillating materials response is assessed. The emission bands of most common scintillator materials used in ionizing radiation detection are typically below 550 nm, thus they may be prone to stem effect response. To avoid this effect we propose the use of scintillators with longer wavelength emission. Samples of neodymium doped glasses are evaluated as new infrared radioluminescent scintillators for real-time dosimeters, namely lithium lead boron silver (LLB4Ag) and lithium bismuth boron silver (LBiB4Ag) glasses. Their response is compared with the response of organic scintillator BCF-60 with a 530nm response.

Abstract
The emergence of optical fiber tapers allowed for the development of new sensing heads to measure physical and external parameters. In the last five years, investigation became more intense with the rapid development of new types of fiber such as microstructured fiber. This chapter aims to present the latest work based on tapers: single tapers, interferometers based on tapers, tapers combined with other structures such as Bragg gratings or surface plasmon resonance. Finally, it also describes new taper geometries and tapers in microstructured fiber. © 2013 by Nova Science Publishers, Inc.

Abstract
Spatial solitons are robust localized nonlinear waves that are able to propagate without significant changes to their structure. Most of the proposal of the application of solitons uses them to transmit and process information in optical fibers and optical circuits. In the later the solitons can be guided through different paths by presetting some soliton characteristics (such as the phase), and even using some solitons to control the path of other pulses. In this paper, we use these properties of optical spatial solitons in a cubic nonlinear media to have lightons: phonon-like oscillations of a chain of solitonic light pulses. Conceptually, this work aims to explore the dual nature of solitons as a particle-like wave, by considering the displacement wave of solitons in a 1-dimensional chain.