This is public disclosure of a security threat using portable lasers to surreptitiously trigger fire suppression sprinklers. I publicly disclose the problem and introduce a novel and non-obvious device to prevent false activation due to heating from laser and/or focused light and/or small projectiles of all types of fire suppression sprinkler heads. This disclosure provides details of a device to prevent false triggering both existing designs of sprinkler heads and integration into future designs of sprinkler heads.