In this paper we used Fresnel diffraction in order to study the effects of hydrofluoric acid concentration and temperature on glass etching rate. The technique is very simple and accurate, and nanoscale change of the glass thickness can be detected and measured during etching. Using measured etching rates we have fabricated several glass phase steps. The fabricated phase steps were characterized by Fresnel diffractometry and optical interferometry. Using this method one can fabricate and characterize low-cost phase shifters of appropriate accuracy in less than 1 h. (C) 2018 Optical Society of America
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