| SM ISO690:2012|
ANDRIEŞ, Ion; ARNĂUT, Vsevolod. Software tools for data measurements from interferograms. In: Materials Science and Condensed Matter Physics. Editia a 8-a, 12-16 septembrie 2016, Chişinău. Chişinău: Institutul de Fizică Aplicată, 2016, p. 257. ISBN 978-9975-9787-1-2.
|Materials Science and Condensed Matter Physics
Editia a 8-a, 2016
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
8-th Edition, Chişinău, Moldova, 12-16 septembrie 2016
The imaging interferometry analyzing methods are based on software processing of interferograms obtained by equipped with a CCD digital camera optical interferometry setups, and possess unique potential capabilities in domain of precise measurements. So, when measuring linear sizes in microscopic areas they allow receiving digital information with the precision comparable with the length of light wave, or higher at computer hologram processing. There is a wide variety of technologies and applications developed in this rapidly growing area. However, the high potentialities of imaging interferometry methods are not yet utilized in a full measure, so that to achieve the limiting (theoretical possible) values of measurements precision computer processing technologies are necessary. Modern digital CCD or CMOS cameras embedded in optical circuits to record interferograms present big matrices of physical sensors. They have high sensitivity and power of spatial resolution and provide the opportunity of measuring simultaneously a range of points across the image of a given sample. The strict mathematical modeling and software tools used in this case result in a more precise and detailed characterization of the specimen. In this paper, we present the development of two software tools designed for interferograms processing and analysis with the purpose of retrieval the high precision quantitative information. The first tool implements the phase measurements performed by conventional microinterferometer MII-4 equipped with a digital camera. This tool is intended for measurements of thickness and optical parameters of thin functional films commonly used in photonics. Reliable measurements of opaque film thickness with thickness much smaller than the wavelength of light (up to 20-30 nm) are possible by this equipment. Software tool possesses the following functional possibilities: measurement of opaque film thickness with thickness much smaller than the wavelength of light (up to 20-30 nm); measurement of opaque film thickness with thickness of several wavelengths; measurement of transparent film thickness for a given refractive index; measurement of refractive index of transparent films at a certain thickness obtained by other measurement methods; statistical processing of the measurement results and their storage in a database. In contrast to conventional layer thickness measuring devices such as profilometers or scanning force microscopes (AFM), this technique provides the full view field of analyzing specimens, is more rapid, noncontact, and does not require complicated specimen preparation. Thanks to these advantages, the modernized MII-4 interference microscope has great potential as a combined analysis system (optical microscope and layer thickness measurement device), particularly in thinfilms engineering. Moreover, the cheap USB web camera with more than 1 mln pixels is a good alternative to CCD camera connected to frame grabber. The second tool is intended for measurements by processing the complex interferograms that represent the objects images overlaid with a reference interference pattern. Method is based on computer processing of the objects’ images with a superimposed measuring interference raster with known pattern period. Pattern period acts as a scale division value and thus, determines the accuracy of measurements. By means of a computer processing of image the measurement accuracy can be determined by the number of pixels in a raster period. This allows to get the best possible for this measurement setup accuracy of linear sizes measurements.