Abstract Accumulating dust on Charge-Coupled Device/Complementary Metal-oxide-Semiconductor (CCD/CMOS) sensors can cause problems in detecting defects on observed object in some industrial production. This paper describes Differential Digital Holography (DDH) and observed effect of cancelling the negative impact of dust on optical sensor. The laboratory setup for recording digital holograms is described and shown graphically later in paper. Differential digital holography method is presented step by step. Furthermore, negative effect of accumulating dust on CCD/CMOS sensor and cancelling effect due to DDH method is explained. DDH method comprises of both hardware and software parts. Digital hologram recording process takes place on hardware and all image, i.e., digital hologram, while processing is performed by intensive calculations on processor. Experiments were conducted and graphical results are shown.

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[31] Zhang W., Wang M., Zheng M., and Wu J., An Effective Approach to Removing Zero-Order Term Overlap and Controlling image Distortion in Digital off-Axis Holography, Optics Communications, vol. 356, pp. 589-594, 2015. Kre imir Nenadi obtained his BScE degree in electronics and automation engineering in 2000 from University of J.J. Strossmayer, Faculty of Electrical Engineering in Osijek, Croatia. He recieved his PhD degree at University of J.J. Strossmayer, Faculty of Electrical Engineering in Osijek in 2009. He is presently working as Assistant Professor in the Department of Software Engineering at Faculty of Electrical Engineering in Osijek and as Cisco CCNA instructor at local Cisco Academy of Network Technologies. He is having a total of 15 years of teaching experience in various programming courses. His research interests include digital holography, image processing, risk assessment in ICT systems, security in ICT systems, data clustering, C and Java programming, Android application development, web programming technologies and efficient laser beam treatment of different kind of seeds. He has published 10 papers in International and National Journals, about 20 papers in International Conferences and National Conferences. Tomislav Galba obtained his BScE degree in computer science in 2010 from University of J.J. Strossmayer, Faculty of Electrical Engineering in Osijek, Croatia. He is presently working as Junior Research Assistant in the Department of Software Engineering at Faculty of Electrical Engineering in Osijek. He is having a total of 5 years of teaching experience in various programming courses. His research interests include efficient algorithms and data structures, ontologies and transformation of ontologies in other data forms, C and Java programming, optimization algorithms. He has published 2 papers in International and National Journals and about 5 papers in International Conferences and National Conferences. Irena Gali obtained her BSc degree as a teacher of mathematics and computer science in 1999 from University of J.J. Strossmayer, Faculty of Education, Osijek, Croatia. She received her Master of Science degree at University of Saarland, Max Planck Institute, Saarbr cken, Germany. She received her PhD degree at University of J.J. Strossmayer, Faculty of Electrical Engineering in Osijek in 2011. She is presently working as Assistant Professor in the Department of Software Engineering at Faculty of Electrical Engineering in Osijek. She is having a total of 16 years of teaching experience in various courses. Her research interests include projective metric geometry, partial differential equations, discrete and numerical mathematics, signals and systems, algorithms and data structures, digital image and video processing, computer graphics, programming in C, graphics pipeline BMRT and OpenGL. She has published 6 papers in International and National Journals, about 16 papers in International Conferences and National Conferences.