Active Illumination (AI) describes a rapidly evolving range of optical techniques with an increasing impact on scientific enquiry and experimentation. All AI techniques target optical radiation at user-defined region(s) of the specimen and use optical imaging to observe, and often to measure, the impact of the “perturbation”. AI has developed over the last two decades alongside the revolution of fluorescent proteins in biology (ref 7, 8), the instrumental and technological developments of confocal laser scanning microscopy (CLSM), solid state light sources (lasers and LEDs), fast galvo and optical MEMS technology, and of course the ubiquitous personal computer. We include among these techniques:
- Photoactivation and switching
- Constrained or adaptive illumination
- FRAP
- Ablation, cutting and marking
- Uncaging of caged compounds
- Optogenetics e.g. channelrhodopsin2