Ultra-wide-range measurements of thin-film filter optical density over the visible and near-infrared spectrum

Significance Statement

The work described in this paper was also presented at the last SPIE Conference Advances in Optical Thin Films V (Jena, Germany, 7-10 September 2015) and selected for an invited talk (“Wide-range Multimodal Characterization of the Optical Properties of Complex Thin-film Filters”) to be done at the next OSA Conference Optical Interference Coatings (Tucson, Arizona, USA, 19-24 June 2016).

Since the publication of this paper, additional features were added to the set-up, like the ability to achieve reflection and scattering measurements (up to the detection background fixed by Rayleigh scattering limit in air) or the implementation of a self-adaptive mechanism for the tuning of the spectral resolution of the measurements in the range between 0.2 and 2 nm (article in preparation). 

About the author

Michel Lequime is Eméritus Professor at Centrale Marseille, a French engineer high school, and senior scientist at the optical thin-film group of Institut Fresnel. Currently, his research interests concern the development of in situ optical monitoring systems, the comprehensive characterization of optical surfaces through spatially and angularly resolved light scattering measurements and the theoretical study of optical properties of thin-film stacks including metamaterials layers. He is credited with twenty six patents and more than two hundred publications and presentations in the areas of non-linear optics, space optics, fiber optic sensors, scattering phenomena and optical interference coatings. He is a member of the OSA and SPIE, and has served as Secretary of the Board of the French Optical Society (SFO, 2009-13).


Journal Reference

Optics Express, Vol. 23, Issue 20, pp. 26863-26878 (2015).

Michel Lequime, Simona Liukaityte, Myriam Zerrad, Claude Amra

Institut Fresnel, CNRS, Aix-Marseille Univ. (France)


We present the improved structure and operating principle of a spectrophotometric mean that allows us for the recording of the transmittance of a thin-film filter over an ultra-wide range of optical densities (from 0 to 11) between 400 and 1000 nm. The operation of this apparatus is based on the combined use of a high power supercontinuum laser source, a tunable volume hologram filter, a standard monochromator and a scientific grade CCD camera. The experimentally recorded noise floor is in good accordance with the optical density values given by the theoretical approach. A demonstration of the sensitivity gain provided by this new set-up with respect to standard spectrophotometric means is performed via the characterization of various types of filters (band-pass, long-pass, short-pass, and notch).

© 2015 Optical Society of America

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