New developments for optical measurements in flames will be described. The lecture will demonstrate how these new approaches provide new insights on: 1. Triggering of thermoacoustic oscillations 2. Measuring simultaneously local flow velocity and air-fuel ratio (without any ‘seeding’) 3. Measuring soot generation and temporal evolution in flames of hydrogen blends At the end of the lecture, some fluid mechanics applications will be outlined, which will include boiling for nuclear technology, electrolysis for hydrogen production, droplet erosion of wind turbine blades, thermal energy storage and designing bubbly chocolate