Latest developments in the EMIR technique of infrared imaging electromagnetic fields
23 Mar 2001-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 4360, pp 48-59
TL;DR: In this article, a thermal optimisation of the sensor, taking into account the amplitude modulation frequency, is presented, which is applied to the analysis of the EM field, at 12 GHz, in the vicinity of the end of a waveguide.
Abstract: EMIR technique is now able to measure the polarisation ofEM fields, thanks to highly anisotropic photothermal films. Thefilms and the numencal model used to evaluate their e1ecuomagneuc behaviour are desciibed. Based on the use of a mode!,a thermal optimisation ofthe sensor, taking into account the amplitude modulation frequency, is presented. The technique is applied to the analysis of the EM field, at 12 GHz, in the vicinity of the end of a waveguide. Validation is achieved through comparison ofthe experimental results to theoiy.Keywords: infrared thermography, microwaves, photothermal effect 1. INTRODUCTIONONERA is developing and improving the EMIR (E1ecWoMaetic InfraRed) method allowing to visualise EM ElectroMagnetic) fields [1]. This method, mainly used for non desuctive evaluation of dielectiic or absorbing materials,antenna radiation pattern characterisation and mapping of the electric field arind objects or inside cavities, consists inmeasuring by means of an JR camera the temperature increase of a thin photothermal film, which is proportional to theintensity of the electric field component tangential to the film [2]. In order to avoid the distortion of the temperature fielddue to the natural convection, and to increase the spaual resolution, the amplitude of the EM field is modulated at a low
Citations
More filters
TL;DR: In this paper, a plane to plane iterative phase retrieval process has been developed and tested with respect to a large number of conflguration parameters such as to flnd an optimal conflgence on a wide frequency range (0.5{20GHz).
Abstract: The framework of our work is the application of a fast method to estimate the radiation pattern of an antenna from the measurement of the electric-fleld magnitude in the near-fleld region using infrared (IR) camera. IR acquisition techniques allows quasi- realtime measurements of the magnitude of the electrical fleld on planar surfaces in near-fleld conditions. However the antennas radiation patterns can only be estimated from near-fleld electrical magnitude and phase measurements. Consequently a classical plane to plane iterative phase retrieval process has been developed and tested with respect to a large number of conflguration parameters such as to flnd an optimal conflguration on a wide frequency range (0.5{20GHz). In order to achieve and validate such a study, some comparisons have been performed on data obtained either by numerical simulation or classical near-fleld technique based upon radio-frequency (RF) probe scanning on simple horn antennas. Among all the studied parameters we will focus onto the in∞uence of the dynamic range of the measurements on the reconstructed radiation patterns and on validations from experimental results.
6 citations
01 May 2017
TL;DR: In this article, a dual high-frequency generator was described and tested using the thermal imager, and the thermal track was processed in the “Therma CAM Resercher Professional 2.9”.
Abstract: The paper describes one of several possible uses dual high-frequency generator. This generator has been previously described by [1] and presented at several conferences. Here are described and tested measurement using the thermal imager. Generator irradiated suitable material. Material changes electromagnetic energy to heat. Thermal imager track is recorded. Thermal track is processed in the “Therma CAM Resercher Professional 2.9”.
Cites methods from "Latest developments in the EMIR tec..."
...More information for the specified method of measurement is available in the literature [2, 3, 4, 5, 6, 7, 8, 9, 10]...
[...]
References
More filters
TL;DR: A brief history of the various techniques used to obtain thermal images of electromagnetic fields is first presented in this article, where an analysis of the thermal problems involved is presented, and the solution to these problems is the key for the enhancement of the technique and for really quantitative work.
38 citations
TL;DR: In this paper, the authors present a system for quantifying electromagnetic fields using a lock-in infrared thermographic system, where the modulated amplitude of the temperature leads to the intensity of the electromagnetic field, and the purpose of such a system is to eliminate both radiato-convective and conductive effects which produce a blurring of the thermal image and hence degrade the accuracy of the measurement.
Abstract: Lock-in infrared thermographic systems developed since more than ten years allow the measurement of both amplitude and phase of periodic temperature fields. They have been essential ly used for mechanical testing, mainly for stress field analysis, and for NDE. The present system is applied to the quantitative characterization of electromagnetic fields. The modulated amplitude of the temperature leads to the intensity of the field. The purpose of such a system is to eliminate both radiato-convecti ve and conductive effects which produce a blurring of the thermal image and hence degrade the accuracy of the measurement. Experiments demonstrate the real enhancement of the technique when compared to classical steady state measurements. The interest of the thermal phase image is also presented.
4 citations
TL;DR: The amplitude and phase space distributions of EM (electromagnetic) fields (Xand Ku bands) are imaged and measured using microwaves interferometry revealed by photothermal films and lock-in infrared thermography as mentioned in this paper.
Abstract: The amplitude and phase space distributions of EM (electromagnetic) fields (Xand Ku bands) are imaged and measured using microwaves interferometry revealed by photothermal films and lock-in infrared thermography. Such EM fields imaging is a powerful tool for NDE (non Destructive Evaluation) of dielectric and radar absorbing materials.
3 citations