Nondestructive evaluation of solids by photothermal interferometry on nonreflective surfaces

Thermal expansion interferometry is a simple and very sensitive tool for nondestructive material analysis. In its basic form highly reflective surfaces are needed however. We developed a modified experimental set-up that can be used on any surface and found a theoretical description in good agreement with the results

Remote nondestructive material analysis by photothermal interferometry

Interferometry is used for the detection of thermal waves to study material properties. A symmetrical interferometer as thermal expansion detector was developed for photothermal nondestructive material analysis. After mixing a phase shifted reference signal electrically to the interferometer signal, phase and amplitude exchange phenomena have been observed

Photothermal interferometry for nondestructive subsurface defect detection

A symmetrical interferometer as thermal expansion detector was developed for photothermal nondestructive material analysis. Phase and amplitude exchange phenomena have been observed, when introducing an electronic reference phase shifter mixed to the interferometer signal. Experimental and theoretical results obtained with this system are presented

The role of human operators in safety perception of av deployment—insights from a large european survey

Autonomous vehicles are anticipated to play an important role on future mobility offering encouraging solutions to today’s transport problems. However, concerns of the public, which can affect the AVs’ uptake, are yet to be addressed. This study presents relevant findings of an online survey in eight European countries. First, 1639 responses were collected in Spring 2020 on people’s commute, preferred transport mode, willingness to use AVs and demographic details. Data was analyzed for the entire dataset and for vulnerable road users in particular. Results re-confirm the long-lasting discourse on the importance of safety on the acceptance of AVs. Spearman correlations show that age, gender, education level and number of household members have an impact on how people may be using or allowing their children to use the technology, e.g., with or without the presence of a human supervisor in the vehicle. Results on vulnerable road users show the same trend. The elderly would travel in AVs with the presence of a human supervisor. People with disabilities have the same proclivity, however their reactions were more conservative. Next to safety, reliability, affordability, cost, driving pleasure and household size may also impact the uptake of AVs and shall be considered when designing relevant policies

Two-wavelength double heterodyne interferometry using a matched grating technique

Two-wavelength double heterodyne interferometry is applied for topographic measurements on optically rough target surfaces. A two-wavelength He-Ne laser and a matched grating technique are used to improve system stability and to simplify heterodyne frequency generation

Dual wavelength heterodyne interferometry for rough surface measurements

For interferometric topography measurements of optically rough surfaces dual wavelength heterodyne Interferometry (DWHI) is a powerful tool. A DWHI system based on a two-wavelength HeNe laser and a matched grating technique is described. This set-up improves system stability and simple heterodyne frequency generation

Dual wavelength heterodyne interferometry using a matched grating set-up

Two-wavelength double heterodyne interferometry is applied for topographic measurements on rough target surfaces. A two-wavelength HeNe laser and a matched grating technique are used to improve system stability and to simplify heterodyne frequency generation. Results obtained with an experimental set-up will be presented. The results obtained show that a dual wavelength heterodyne interferometer is appropriate for high precision ranging. Progressing developments for large distances will be discussed

Modeling cross-national differences in automated vehicle acceptance

The technology that allows fully automated driving already exists and it may gradually enter the market over the forthcoming decades. Technology assimilation and automated vehicle acceptance in different countries is of high interest to many scholars, manufacturers, and policymakers worldwide. We model the mode choice between automated vehicles and conventional cars using a mixed multinomial logit heteroskedastic error component type model. Specifically, we capture preference heterogeneity assuming a continuous distribution across individuals. Different choice scenarios, based on respondents’ reported trip, were presented to respondents from six European countries: Cyprus, Hungary, Iceland, Montenegro, Slovenia, and the UK. We found that large reservations towards automated vehicles exist in all countries with 70% conventional private car choices, and 30% automated vehicles choices. We found that men, under the age of 60, with a high income who currently use private car, are more likely to be early adopters of automated vehicles. We found significant differences in automated vehicles acceptance in different countries. Individuals from Slovenia and Cyprus show higher automated vehicles acceptance while individuals from wealthier countries, UK, and Iceland, show more reservations towards them. Nontrading mode choice behaviors, value of travel time, and differences in model parameters among the different countries are discussed

Radiometric characterization of type-II InAs/GaSb superlattice (t2sl) midwave infrared photodetectors and focal plane arrays

In recent years, Type-II InAs/GaSb superlattice (T2SL) has emerged as a new material technology suitable for high performance infrared (IR) detectors operating from Near InfraRed (NIR, 2-3μm) to Very Long Wavelength InfraRed (LWIR, λ > 15μm) wavelength domains. To compare their performances with well-established IR technologies such as MCT, InSb or QWIP cooled detectors, specific electrical and radiometric characterizations are needed: dark current, spectral response, quantum efficiency, temporal and spatial noises, stability… In this paper, we first present quantum efficiency measurements performed on T2SL MWIR (3-5μm) photodiodes and on one focal plane array (320x256 pixels with 30μm pitch, realized in the scope of a french collaboration ). Different T2SL structures (InAs-rich versus GaSb-rich) with the same cutoff wavelength (λc= 5μm at 80K) were studied. Results are analysed in term of carrier diffusion length in order to define the optimum thickness and type of doping of the absorbing zone. We then focus on the stability over time of a commercial T2SL FPA (320x256 pixels with 30μm pitch), measuring the commonly used residual fixed pattern noise (RFPN) figure of merit. Results are excellent, with a very stable behaviour over more than 3 weeks, and less than 10 flickering pixels, possibly giving access to long-term stability of IR absolute calibration

LISA technology and instrumentation

This article reviews the present status of the technology and instrumentation for the joint ESA/NASA gravitational wave detector LISA. It briefly describes the measurement principle and the mission architecture including the resulting sensitivity before focussing on a description of the main payload items, such as the interferomtric measurement system, comprising the optical system with the optical bench and the telescope, the laser system, and the phase measurement system; and the disturbance reduction system with the inertial sensor, the charge control system, and the micropropulsion system. The article touches upon the requirements for the different subsystems that need to be fulfilled to obtain the overall sensitivity.Comment: 37 pages, 18 figures, submitted to CQ