OPN and Optica mourn the loss of Optica Fellow and Senior Member Kostadinka “Dida” Bizheva, who passed away on 8 September 2025 at the age of 55. Bizheva served as a professor in the department of physics and astronomy at the University of Waterloo, Canada, where she was deeply committed to teaching and mentoring students. Her research focused on developing innovative optical imaging technologies designed for clinical diagnostic purposes, as well as for monitoring drug therapies and surgical procedures. Notably, Bizheva’s research enabled ultrahigh-resolution imaging of biological tissue, which allowed for the observation of cellular structures and blood vessels. She was an active Optica volunteer, serving as a governance volunteer and an editor for Optica Publishing Group journals.