Lasers can cause damage in biological tissues, both to the eye and to the skin, due to several mechanisms. Thermal damage, or burn, occurs when tissues are heated to the point where denaturation of proteins occurs. Another mechanism is photochemical damage, where light triggers chemical reactions in tissue.
March 9: Teams are allowed to begin negotiating with other teamsâ players who are set to become unrestricted free agents at the end of the league year. This is the first time the NFL is providing a window to negotiate with other teamsâ free agents prior to the start of free agency.
2017 NFL Free Agency. Free agency begins March 9, the start of the NFL's new league year, but signings are already happening. Transition tags can also be applied in this window, but the franchise tag is far more important -- and popular -- because it ensures the team a hefty return if a player ultimately departs. (Transition tags are cheaper, but offer only the opportunity to match an offer.)