An active tracking system includes an imager configured to image the temperature of a biological tissue and a heating laser configured to heat regions of the biological tissue. The imager locates high-temperature regions of the biological tissue and the heating laser is controlled to point toward target regions of the biological tissue based on the located high-temperature regions. The active tracking system can be used to control a heating laser to continuously heat a target region of a biological tissue even when the target region moves relative to the heating laser. The active tracking system could allow one or more target regions of a biological tissue to be ‘tagged’ with heat by the heating laser and to be tracked even when the one or more target regions move relative to the heating laser. Devices and methods for operating such active tracking systems are also provided.