A photoactivation device for modulating the physiology of a target biological activity by directing a photoactivating beam of light having a predetermined set of photoactivating light parameters on a target surface, the device comprising:a photoactivating light source for emitting the photoactivating beam of light;a positioning means operatively coupled to the photoactivating light source for allowing selective positioning of the photoactivating light source relative to the target surface;a position evaluating means for evaluating the position of the photoactivating light source relative to the target surface.