In the field of thermal radiation measurements, blackbody cavities are commonly used as reference standards for the calibration of heat flux meters. Applying the energy balance equation to the closed system including the cavity and the sensor, it is possible to predict the heat flux density absorbed by the heat flux meter. Calibration procedures developed at Laboratoire National de Métrologie et d'Essais (LNE) in recent years have allowed us to propose practical solutions for heat flux meters working below 100 kW · m −2 . The best relative uncertainties (k = 2) over the range of (10-100) kW · m −2 vary from 1.7 % to 3 %. During previous studies, three major facilities were constructed, each one with the objective to respond to different technical problems considering the measuring principle of these heat flux sensors. Following this approach, the sensitivity of these meters to radiation, the sensitivity to radiation and convection, and also the influence of the size of the source or of the positioning of the sensor (horizontally, vertically, etc.) have been investigated. As an outcome of this recent experience, a new vacuum blackbody cavity has been set up. As well as the possibility to calibrate at very low irradiance, there are also some substantive improvements in heating, thermal performance, and calibration methodology. After a summary of the state of the art of calibration methods and their limits, the article presents the preliminary results of the characterization obtained with this new facility for which the objective is to reduce the uncertainties by at least a factor of two for heat flux densities lower than 20 kW · m −2 .

Abstract. The ENV03 Solar UV project is aimed at improving the traceability of solar UV spectral irradiance measurement. This is achieved by developing new characterization methods and devices (stray light improved array spectroradiometer, Fourier Transform Spectrometer). The workpackages of the project are presented. We describe the output of two tasks in which the LNE is involved: the realization of a software for evaluating the measurement uncertainty using Monte Carlo technique, and the development of a reduced stray light array spectroradiometer fitted with band-pass filters to measure the UV spectral irradiance with an uncertainty <2%.

Résumé. Le projet européen PhotoClass a pour but de définir une nouvelle métrique pour l'évaluation de la performance des modules photovoltaïques (PV). Cette performance sera basée sur la production d'énergie annuelle en fonction des conditions d'ensoleillement du lieu géographique d'installation du champ PV et non plus sur la puissance crête. Cela implique une caractérisation des propriétés opto-électriques des dispositifs PV, des sources d'ensoleillement naturel et artificiel et des instruments associés. Dans ce projet le LNE travaille sur la linéarité et la dépendance en température de la réponse des dispositifs PV. Il évalue les performances d'un simulateur solaire incorporant des LED. Il caractérise un spectroradiomètre à matrice de détecteur couvrant le domaine spectral 350 nm-2000 nm utilisé pour mesurer l'éclairement solaire produit par les simulateurs à impulsion et développe une procédure d'étalonnage spécifique de ce type de spectroradiomètre pour cette application.

LNE-Cnam has changed its traceability chain for measuring the spectral irradiance of a light source. This facility allows calibration of spectral irradiance of a standard lamp based on a comparison with a High Temperature BlackBody (HTBB). The reference spectral irradiance is determined by measuring the temperature of the HTBB with a filter radiometer calibrated against our radiant flux reference. This traceability scheme differs from the one used in our former setup, which was mainly based on the International Temperature Scale, ITS-90. Both principles are used in National Measurement Institutes. Our facility uses well known methods [1] adapted to our best capabilities as well as a particular development in optical arrangement and filter radiometer calibration. Thanks to this new measurement setup, our spectral irradiance reference is now traceable to radiometric reference, that is our cryogenic radiometer [2]. We have extended our measurement capability to cover the spectral range from 250 nm to 2500 nm. We have simplified the process by reducing the number of benches (3 in 1) and the number of operations, and we have designed a compact measuring setup through the use of a rotating integrative sphere. This allows us to reduce by at least a factor two our measurement uncertainties over almost the entire spectral range. With this new measurement facility, France participates in the ongoing CCPR k1.a key comparison. This is a key comparison of the Consultative Committee of Photometry and Radiometry for Spectral irradiance from 250 nm to 2500 nm of tungsten halogen lamps. This communication shows the method used, and its validation.