Toward the reflectance measurement of micro components

Today, the controls by reflection of optical coatings are most of the time made with flat samples thanks to commercial spectrophotometers. However, components become smaller and more complex, curvature radius of lenses or mirrors are larger, so that measures are not so accurate and sometimes are not possible. Flat samples don’t represent anymore the real reflection ability of the component. So to perform this kind of measurements, special devices are needed. A new means developed by the French Atomic Energy Commission (CEA) is proposed to fill in this gap. This device has a accuracy of 0.06% on flat sample over the 400 nm to 950 nm wavelength range with a spot size of 100 mm. It can measure the reflectance of samples even if their shapes are spherical. We investigate stainless steel balls and optical micro components (mirrors and lens) thanks to the tiny size of the analyzing spot of our reflectometer. Herein we introduce our first results on small optical components and show the limiting factors of our device

Recent advances in laser diode cutting technology associated to desktop and industrial inkjet printing

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Is it possible to check microcomponent coatings?

International audienceOptical microcomponents are increasingly used in laser optical systems because of their many and novel industrial applications. These components are coated in order to enhance their optical performance, but optical characterizations are very difficult due to the shapes and small size. Thus, to perform this kind of measurement, special devices are needed. It is difficult to check component optical responses after manufacturing. Thus a new method, developed by the French Atomic Energy and Alternative Energies Commission, is proposed to fill this gap

Is it possible to check microcomponent coatings?

International audienceOptical microcomponents are increasingly used in laser optical systems because of their many and novel industrial applications. These components are coated in order to enhance their optical performance, but optical characterizations are very difficult due to the shapes and small size. Thus, to perform this kind of measurement, special devices are needed. It is difficult to check component optical responses after manufacturing. Thus a new method, developed by the French Atomic Energy and Alternative Energies Commission, is proposed to fill this gap

Scaling laws in laser-induced potassium dihydrogen phosphate crystal damage by nanosecond pulses at 3ω

International audienceA model for the description of laser-induced damage in bulk potassium dihydrogen phosphate (KDP) by nano-second laser pulses is addressed. It is based on the heating of nanometric plasma balls whose absorption efficiency is described through the Mie theory. The plasma optical indices are then evaluated within the Drude model framework. This modeling provides an evaluation of the scaling law exponent x linking the damage threshold laser pulse energy density F c to the pulse duration ␶ as F c = ␣␶ x , where ␣ is a constant. The inverse problem for which the knowledge of experimental data allows one to determine physical parameters of the model is considered. The results suggest that the critical plasma density is reached in a time much shorter than the pulse duration. Information about the nature of defects responsible for the damage initiation is also provided

Walking, cycling, and public transport for commuting and non-commuting travels across 5 European urban regions: Modal choice correlates and motivations

The objective of this study was to explore individual and contextual-level characteristics associated with active (walking and cycling) and public transport as main travel modes for both non-commuting and commuting purposes, in residents of five European urban regions. We also described participant-reported motivations for modal choice for each journey purpose. The study used multilevel models to investigate cross-sectional associations of individual (i.e. age, gender, educational level) and contextual (defined by a combination of residential neighbourhood characteristics in typologies) characteristics with the choice of active and public transport as outcome. Based on an online survey of 6037 residents of Ghent and suburbs (Belgium), Paris and inner suburbs (France), Budapest and suburbs (Hungary), the Randstad (including the cities of Amsterdam, Rotterdam, The Hague and Utrecht in the Netherlands) and Greater London (United Kingdom), we observed associations with both individual and contextual characteristics. Results of the multilevel modelling show that the probability of using active or public transport as main mode varies depending on both individual and contextual characteristics. At individual level, relations with gender, age, education, weight status and having at least one child varied according to main transport mode and/or purpose. For example, overweight participants reported lower level of cycling for commuting and non-commuting travels than normal-weight participants. In the context of non-commuting travels, participants with one or more child reported less public transport use and more walking (vs participants without children). Among contextual-level variables, urban characteristics of the residential neighbourhood defined by four clusters (according to food environment, recreational facilities and active mobility opportunities) were associated with public transport and walking but not with cycling. For active transport the most important reasons were “I like to travel (on foot or by bike)” and “I want to be physically active” for both travel purposes. “Public transport facilities nearby” was indicated as the most important reason for public transport (for both trip purposes) – the second was “Journey time”. Our findings highlight the importance of exploring a combination of multiple correlates at individual and contextual level according to journey purposes and suggest that the role of health-related individual characteristics such as weight status need further exploration

Quantitative estimation of crazing in sol-gel layers by automated optical microscopy analysis

International audienceThis paper describes how to quantify the scattering that appears in thin films deposited on a flat substrate. The defects appear during the deposition process and are hard to identify from classical optical microscopy pictures due to their small surface and contrast. A new way to probe the microroughness of optical components is described for heterogeneous or large samples (cm2) that requires a statistical analysis of each image over a full mapping of the sample. Due to possible optical misalignment or surface waviness, an automatic adjustment of the optical focus plane was implemented for each image during the surface mapping. In this way, we could measure the scattering using a microscope set-up. The results are linked to diffuse reflection and transmission losses (extinction coefficient k) and several different contributions from the total scattering are identified