Optical power meter using radiation pressure measurement

This paper describes a radiation pressure meter based on a diamagnetic spring. We take advantage of the diamagnetic property of pyrolytic carbon to make an elementary levitated system. It is equivalent to a torsional spring-mass-damper system consisting of a small pyrolytic carbon disc levitated above a permanent magnet array. There are several possible measurement modes. In this paper, only the angular response to an optical power single-step is described. An optical detection composed of a laser diode, a mirror and a position sensitive detector (PSD) allow measurement of the angular deflection proportional to the voltage delivered by the PSD. Once the parameters of the levitated system depending on its geometrical and physical characteristics have been determined regardless of any optical power, by applying a simple physical law, one can deduce the value of the optical power to be measured from the measurement of the first maximum of the output voltage amplitude

Demonstration of a Transportable Fabry–Pérot Refractometer by a Ring-Type Comparison of Dead-Weight Pressure Balances at Four European National Metrology Institutes

Fabry–Pérot-based refractometry has demonstrated the ability to assess gas pressure with high accuracy and has been prophesized to be able to realize the SI unit for pressure, the pascal, based on quantum calculations of the molar polarizabilities of gases. So far, the technology has mostly been limited to well-controlled laboratories. However, recently, an easy-to-use transportable refractometer has been constructed. Although its performance has previously been assessed under well-controlled laboratory conditions, to assess its ability to serve as an actually transportable system, a ring-type comparison addressing various well-characterized pressure balances in the 10–90 kPa range at several European national metrology institutes is presented in this work. It was found that the transportable refractometer is capable of being transported and swiftly set up to be operational with retained performance in a variety of environments. The system could also verify that the pressure balances used within the ring-type comparison agree with each other. These results constitute an important step toward broadening the application areas of FP-based refractometry technology and bringing it within reach of various types of stakeholders, not least within industry

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Caractérisation physico-chimique de surface des étalons de masse

Today the kilogram is the only remaining base units of the International System of Units (SI) still defined by a material artefact. Known as the international prototype of the kilogram, it is a cylinder made from the alloy 90% platinum, 10% iridium and its mass is defined to be exactly 1 kg. This prototype (as well as all other artefact mass standards) is, despite precautions, exposed to many contamination sources which lead to changes in its mass. The present definition is thus problematic for both the long-term stability and the universality of the unit of mass. For this reason, new lines of research are attempting to link the unit of mass to a fundamental constant of physics. These experiments could lead to a new definition. The French watt-balance project was launched in 2000 with the goal of linking the unit of mass to the Planck constant. A number of technical problems must be addressed. In particular, there will be severe constraints on the artefact mass standard used for the transfer. This artefact will be in the fringing field of a magnetic circuit delivering an induction of 1 T. Consequently, it must be made of a material not only having the smallest possible volumetric magnetic susceptibility (of the order of 10-5) but must also possess the other material properties that are indispensable to the best artefact mass standards (good hardness, high density, homogeneity,...). Certain alloys such as gold-platinum or certain other materials such as pure iridium might satisfy these criteria. In order to evaluate the performance characteristics of new materials, platinum-iridium was chosen as the reference alloy. To understand why the mass of an artefact may change with time, taking into account its surface characteristics as well as the conditions of its cleaning and storage, a number of experimental techniques must be used. These include: methods to determine surface roughness, spectroscopic methods to characterize surface contaminants and gravimetric tests of mass stability. Within the framework of these research tasks, we use techniques already available at the Institut National de Métrologie such as: a mirage-effect apparatus for studying adsorption of cleaning solvents, an optical roughness meter to study polishing techniques and a 100 g mass comparator for determining the mass stability after cleaning. In addition to these, a new device was developed to apply the technique of Thermo Desorption Mass Spectrometry to the study of physisorbed contaminants.Le kilogramme reste encore aujourd'hui la seule des sept unités de base du Système International (SI) définie par un étalon matériel appelé le prototype international du kilogramme. Ce prototype est un cylindre constitué d'un alliage de platine iridié (90%Pt-10%Ir) faisant par définition 1 kg exactement. Ce prototype ainsi que tout autre étalon de masse sont exposés à de nombreuses sources de contamination faisant évoluer leur masse malgré les précautions mises en oeuvre. Cette définition pose donc le problème de la pérennité et de l'universalité de l'unité de masse. C'est pourquoi de nouvelles pistes de recherche essayent de relier l'unité de masse à une constante physique fondamentale. Ces expériences pourraient conduire à une nouvelle définition. Ainsi, depuis 2000, le projet français de la balance du watt a été lancé afin de relier l'unité de masse à la constante de Planck. Parmi les options retenues pour réaliser le dispositif expérimental, le choix du matériau de la masse de transfert est particulièrement important puisque celle-ci sera très proche d'un circuit magnétique délivrant une induction de 1 T. Par conséquent, ce matériau doit non seulement avoir une susceptibilité magnétique volumique la plus faible possible (de l'ordre de 10-5) mais aussi présenter toutes les propriétés indispensables aux matériaux de la métrologie des masses (bonne dureté, forte masse volumique, alliage homogène,...). Certains alliages comme l'or-platine ou des matériaux comme l'iridium pourraient satisfaire ces critères. Afin de comparer les « performances »de ce nouveau matériau, le platine iridié a été choisi comme alliage de référence. Pour comprendre les mécanismes d'évolution de la masse en tenant compte de l'état de surface, du nettoyage et des conditions de conservation de ces étalons, il est indispensable de caractériser l'état de surface par des méthodes rugosimétriques, d'évaluer la stabilité par des méthodes de comparaisons de masse, et de caractériser les contaminants de surface par des méthodes spectrométriques. Dans le cadre de ces travaux de recherche, nous avons utilisé des techniques déjà présentes au sein de l'Institut National de Métrologie comme la technique de l'effet mirage pour l'étude de l'adsorption de solvants de nettoyage, un rugosimètre optique pour caractériser l'état de surface et le polissage, un comparateur de masse de 100 g pour étudier la stabilité après nettoyage mais aussi un nouveau dispositif de Spectrométrie de masse de Thermodésorption pour l'étude des molécules physisorbées

Pyrolytic carbon: applications of its diamagnetism in metrology

This paper presents some current or potential applications in metrology based on the diamagnetism of pyrolytic carbon (PyC). The magnetic repulsion force acting between a piece of PyC subjected to a magnetic flux can be used as magnetic spring either to control the position of the sensitive sensor element or to detect changes of a physical quantity to be measured. The first part of this paper provides examples briefly described of devices based on the diamagnetism of PyC for measuring mechanical quantities. There are two main configurations for magnetic levitation: one, used for measuring acceleration or inclination for instance, is based on the levitation of a PyC tile above a magnet or set of magnets; In the other, used to measure forces caused for example by contact or buoyancy, it is the permanent magnet that is levitated at a stable height above a fixed PyC tile. The second part describes current work at the Laboratoire Commun de Métrologie (LCM-LNE/CNAM) on the development of new laser power sensors using either diamagnetic force changes by photothermal excitation of electrons or diamagnetic torsion spring

New laser power sensor using diamagnetic levitation

International audienceThis paper presents a preliminary study of an elementary device consisting of a small plate made from pyrolytic carbon levitated above a magnet array which is sensitive to any irradiating laser power. This device might provide an interesting alternative to power meters based on thermal measurement techniques via the Stefan-Boltzmann law or the photon-electron interaction. We show that the photo-response of a pyrolytic carbon plate in terms of levitation height versus irradiation power in the range of 20 mW to 1 W is sufficiently linear, sensitive, and reproducible to be used as a laser power sensor. The elevation height change as a function of irradiance time appears to be a suitable measurement parameter for establishing a relation with the irradiating laser power. The influence of some quantities affecting the measurement results has been highlighted. The study demonstrates that such a device should prove useful for applications in metrology, industry, or emerging technologies

Pyrolytic Carbon: Applications of Diamagnetic Levitation in Metrology

International audienceThis paper presents some current or potential applications in metrology implementing the diamagnetic property of pyrolytic carbon (PyC). The magnetic repulsion force acting between a piece of PyC placed in a magnetic flux density can be used as magnetic spring either to control the position of the sensitive sensor part or to detect change of a physical quantity to be measured. Several examples of PyC-based sensors are presented

New optical power sensors using pyrolytic graphite

A new method for measurements of laser power, using pyrolytic carbon (PyC) levitation as torsional magnetic spring, to detect the moment of force provided by radiation pressure of laser beam is currently developed at the LCM LNE-Cnam. This new power-meter could measure laser power in the range from 300 mW to 100 W with an objective to reach a relative uncertainty of about 1%. Relative to a first experimental setup, the new configuration presented in this paper has been improved taking the main disturbing sources into account. The traceability to SI units of the measurement provided by this new power-meter is presented and discussed

Caractérisation physico-chimique de surface des étalons de masse

Le kilogramme reste encore aujourd'hui la seule unité de base du SI définie par un étalon matériel appelé le prototype international du kilogramme. Celui-ci est un cylindre constitué d'un alliage en platine iridié faisant par définition 1 kg. Ce prototype ainsi que tout autre étalon de masse sont exposés à de nombreuses sources de contamination faisant évoluer leur masse malgré de nombreuses précautions. Cette définition pose donc le problème de la pérennité et de l'universalité de l'unité de masse. C'est pourquoi de nouvelles pistes de recherche essayent de relier l'unité de masse à une constante physique fondamentale. Pour comprendre les mécanismes d'évolution de la masse en tenant compte de l'état de surface, du nettoyage et des conditions de conservation de ces étalons, il est indispensable de caractériser l'état de surface par des méthodes rugosimétriques, d'évaluer la stabilité par des méthodes gravimétriques et de caractériser les contaminants par des méthodes spectrométriques.Kilogram still remain the only unit of the International SI defined by an artefact called international prototype of kilogram. It is a cylinder constituted by 90% platinum and 10% iridium doing 1kg by definition. This prototype and mass standards are exposed to many contamination's sources being a mass evolution despite of precautions. This definition is not satisfactory for the durability and for the universality of the unit. New research's ways try to link unit of mass to a fundamental physical constant. To understand surface behavior and its effects on stability taking account of cleaning and conditions of conservation, it is essential to characterize surface quality by rugosimetric methods, to evaluate stability by gravimetric mthods, to characterize the contaminants of surface by spectrometric methods.PARIS-CNAM (751032301) / SudocSudocFranceF