Multilayer diffractive optical element material selection method based on transmission, total internal reflection, and thickness

peer reviewedThe polychromatic integral diffraction efficiency (PIDE) metric is generally used to select the most suitable materials for multilayer diffractive optical elements (MLDOEs). However, this method is based on the thin element approximation, which yields inaccurate results in the case of thick diffractive elements such as MLDOEs. We propose a new material selection approach, to the best of our knowledge, based on three metrics: transmission, total internal reflection, and the optical component’s total thickness. This approach, called “geometric optics material selection method” (GO-MSM), is tested in mid-wave and long-wave infrared bands. Finite-difference time-domain is used to study the optical performance (Strehl ratio) of the “optimal” MLDOE combinations obtained with the PIDE metric and the GO-MSM. Only the proposed method can provide MLDOE designs that perform. This study also shows that an MLDOE gap filled with a low index material (air) strongly degrades the image quality

Concept de la détection micromécanique sur base de la résonance de plasmons de surface

L'objectif de cette thèse est une étude théorique et expérimentale d’un concept original de détection.Le principe de détection, qui était développé dans le manuscrit, consiste à exploiter l’effet de résonance de plasmons de surface (SPR) pour contrôler un mouvement mécanique induit dans un transducteur primaire par un stimulus à détecter

Study of a possible X-ray sensor based on the Plasmon Surface Resonance for the next generation of instruments

peer reviewedWith the new generation of X-ray space observatories, such as IXO in preparation, we explore a new technology in order to improve the spectral resolution and the sensitivity of future instruments. We have studied the possibility to create a sensor based on the Surface Plasmon Resonance (SPR), already used in chemistry and biomedical applications, and have determined the preliminary constraints on its size, energy resolution and working temperature

A Simple Method for Thermal Characterization of Low-Melting Temperature Phase Change Materials (PCMs)

The successful implementation of a high-efficient latent heat storage system necessitates an appropriate experimental approach to investigate and quantify the variations of the Phase Change Material (PCM) thermal properties caused by its aging, as well as its potential demixing induced by cyclic freezing and melting. In this paper, we present a concept for the PCM characterization. The proposed method is relatively simple to be implemented. It consists of a cyclic cooling and melting of the PCM sample placed into a tube and monitoring its temperature evolution with a set of temperature sensors. In our work, the temperature evolution of the sample, as well as its sensitivity to the thermal parameters have been numerically investigated using the COMSOL Multiphysics® software

A Simple Method for Thermal Characterization of Low-Melting Temperature Phase Change Materials (PCMs)

The successful implementation of a high-efficient latent heat storage system necessitates an appropriate experimental approach to investigate and quantify the variations of the Phase Change Material (PCM) thermal properties caused by its aging, as well as its potential demixing induced by cyclic freezing and melting. In this paper, we present a concept for the PCM characterization. The proposed method is relatively simple to be implemented. It consists of a cyclic cooling and melting of the PCM sample placed into a tube and monitoring its temperature evolution with a set of temperature sensors. In our work, the temperature evolution of the sample, as well as its sensitivity to the thermal parameters have been numerically investigated using the COMSOL Multiphysics® software

Design optimization of large-size format edge-lit light guide units

In this paper, we present an original method of dot-pattern generation dedicated to design optimization of large-size format ELBUs (Edge-Lit Light Guide Unit), where the number of dots greatly exceeds the maximum allowable number of optical objects supported by most common ray-tracing software. In the proposed method, in order to simplify the computational problem, an original optical system is replaced by an equivalent one. Accordingly, the original dot pattern is splitted into multiple small sections. Then, these sections are replaced by equivalent cells with continuous diffusing film. After that, we adjust the TIS (Total Integrated Scatter) two-dimensional distribution over the grid of equivalent cells, using an iterative optimization procedure. Finally, the obtained optimal TIS distribution is converted into the dot size distribution by applying an appropriate conversion rule. An original semi-empirical equation dedicated to rectangular large-size LGPs (Light Guide Plate) is proposed for the initial guess of the TIS distribution. It allows significantly reducing the time needed to dot pattern optimization

Thickness optimization algorithm to improve multilayer diffractive optical elements performance

peer reviewedThe diffractive zone thicknesses of conventional diffractive optical elements (DOEs) are generally obtained using the thin element approximation (TEA). However, the TEA yields inaccurate results in the case of thick multilayer DOEs (MLDOEs). The extended scalar theory (EST) is an alternative thickness optimization method that depends on the diffractive order and the optimization wavelength. We developed an algorithm to research suitable EST input parameters. It combines ray-tracing and Fourier optics to provide a performance estimate for each EST parameter pair. The resulting “best” MLDOE designs for three different material combinations are analyzed using rigorous finite-difference time-domain. Compared to the TEA, the proposed algorithm can provide performing zone thicknesses

Integration of excimer laser micromachining in a biomedical sensor microfabrication process

In the frame of the Interreg IV project “MICROBIOMED”, the Centre Spatial de Liège (CSL) participated to the development of an original concept of plasmonic-related instrumentation platform dedicated to diagnostic biosensing tests out of the laboratory. The developed instrumental platform includes both disposable one-use microfluidic affinity biochip and compact optical readout device for biochip monitoring involving mobile Internet devices for data processing and communication. The biochip includes both microfluidic and optical coupling structures formed into a single plastic slab (see Fig. 1). The microfluidic path of the biochip operates in passive capillary pumping mode. The optical detection part involves Surface Plasmon Resonance phenomenon. An essential advantage of the developed biochip is that its implementation involves conventional hot embossing and thin film deposition process, perfectly suited for mass production of low-cost microfluidic biochip for biochemical applications. In this presentation we focus on the fabrication of the fluidic channels and capillary structures with a commercial excimer laser mask projection system working at 193 nm. Micro-pillars of 25μm width for the capillary pump as in Fig. 1 have been ablated in the PMMA master slab used for the replication chain of the biochip prototype. By simply changing the pattern on the motorized mask, micro-pillars from 10µm to 50 µm diameter have been also machined successfully in PMMA and even glass. The mask is made of a structured metallic thin layer deposited on a quartz substrate and prepared at CSL by direct writing laser technique. The excimer laser mask projection technique allows ablating several tens of µpillars per second in the field of view of the laser beam. The entire micro-pillars area of the biochip master is then performed by a simple step and repeat laser process. The topography and dimensions of the µstructures have been measured by SEM and interferometric optical profilometry. The dynamic hydrophilic behavior of a liquid drop on the micro-pillars structure has been monitored with the camera of a contact angle instrument.MICROBIOME