The APOS 2015 continues a series of conferences that are intended to provide a central forum for an update and review of technical information covering a wide range of optical sensing fields from fundamental researches to systems and applications. The conference is open to researchers and professionals from not only Asia-Pacific Rim area but also all regions of the world. Plenary Speakers include: Limin Tong (Zhejiang University, China), 'Ultrasensitive Microfiber Optical Sensors: Challenges and Opportunities (Tentative)' Taewon Lim (Hyundai-Kia Motors, Korea), 'The Future of Sensor Technologies in Advanced Driver Assistance Systems' Min Gu (Swinburne University of Technology, Australia), 'Superresolution Fluorescence Endo-microscopy with Engineered Fibres'