Turtlebot3 LIDAR NO TOPIC

[nfhe]

Hi,there.

I'm using Turtlebot3-Burger on Gazebo, with ROS-noetic on Ubuntu 20.04.I need to use laser data to estimate the distance to an obstacle . The problem is that When I run the program roslaunch_ turtlebot3_gazebo turtlebot3_stage_2.launch, the model in the gazebo interface is displayed normally, and the laser_visual can also be displayed normally in the interface. But I use rostopic list, I did not find the node:scan , I don`t find libgazebo_ros_laser.so in the upper left of gazebo .

My question is: is there any parameter I can modify in order to find the node scan? can you help me solve it? Thanks a lot.