This book includes original, peer-reviewed research papers from the 16th International Symposium on Measurement Technology and Intelligent Instruments (ISMTII 2025) and the 3rd International Conference of Optical Imaging and Measurement (ICOIM 2025), held in Wuhan, China on May 25&28, 2025. The topics covered include but are not limited to: Measurement and characterization for atomic-level manufacturing, micro and nanometrology, quantum sensing and instruments, metrology and instruments for integrated circuits, in-process and inline metrology, optical metrology and inspection, surface metrology, material characterization, machine learning and signal processing, intelligent instrument for automation, sensors and actuators, uncertainty, traceability and calibration, optical imaging, optical technology, application and precision measurement, optical measurement, photoelectric device, optoelectronics and communication, biomedical optics, and optical material. The papers showcased here share the latest findings on optical metrology, optical imaging, nanometrology, intelligent systems, and process control, making the book a valuable asset for researchers, engineers, and university students alike.