How a scanning galvanometer works

Laser  galvanometer is a special motion device specially used in the field of  laser processing, it relies on two galvanometers to reflect the laser to  form the motion in XY plane. Laser galvanometer is different from  general motor, laser galvanometer has very small inertia, and in the  process of movement of the load is very small, there are only two small  reflective lenses X and Y, respectively, with different motor control  deflection, the system response is very fast.

Laser galvanometer movement two basic kinds of movement: one for jumping movement and one for marking movement. 

In  the process of jumping movement, the axis moves to the position to be  processed, and the laser is off, which does not affect the processing of  the trajectory, so it can move at a very high speed. During the marking  movement, the laser is turned on to process the trajectory, so the user  needs to set the appropriate speed of movement according to the actual  processing requirements.

The  galvanometer is an excellent vector scanning device. It is a special  oscillating motor (laser vibrator), the basic principle is to energize  the coil in the magnetic field to generate torque, but different from  the rotating motor, its rotor through the mechanical new spring or  electronic methods plus a reset torque, the size and the rotor deviation  from the equilibrium position of the angle is proportional to the  current and the rotor deflected to a certain angle, the electromagnetic  torque and the size of the restoring torque is equal, so it can not be  like a normal motor like rotation, can only be deflected, deflection  angle is proportional to the current. Therefore, it can not rotate like  an ordinary motor, but can only be deflected, and the deflection angle  is proportional to the current.

Basic structure of the galvanometer control system 

The  vibrating mirror system consists of the above parts to form a basic  system, in which the main components of the vibrating lens for the X / Y  two mirrors, respectively, to control the rotation of the X / Y lens of  the two motors, according to the actual needs of the human-machine  operating system can also be added, encoder and so on.

Basic requirements for controllers 

Because  the laser marking machine relies on the X / Y oscillator deflection of  the cooperation, the laser will be reflected to the table surface, for  accurate engraving. The control of the oscillator is controlled by the  controller open-loop control, so the requirements must be linear, that  is, the input signal with the deflection angle is a linear relationship  between. Because the vibration mirror is a fast precision machinery, so  it is required from one working state to another working state requires  the acceleration of the greater the better, so that the marking of empty  time is infinitely small.

Scanner  motion adopts buffer motion mode, that is, the user needs to transfer  motion and process data to the axis motion buffer, and then start the  buffer motion, the motion controller will sequentially and continuously  execute the motion data transferred by the user until all the motion  data are all motion completed. In the laser galvanometer motion control  system there is not only motion control, but also laser control. How to  effectively deal with the galvanometer motion and laser switch with is a  very important issue, only effective coordination of the laser and the  relationship between the motion, in order to move a precise trajectory.

Motion  Control: During the marking movement, the laser will move along the  given marking trajectory according to the set marking speed, and the  laser oscillator motion controller will automatically turn on the laser  during the execution of marking-related instructions. If the next  instruction is still a marking instruction, the laser will be turned on  until the last marking instruction is finished, or the instruction in  the buffer is finished, and the laser will be turned off automatically  if it encounters a jump instruction in the buffer in the middle of the  process, and the laser will not be turned on again until it encounters a  marking instruction. In order to ensure the correct marking trajectory  before starting the movement, it is necessary to adjust the coordinates  of the galvanometer and empty the buffer at the same time.

Laser  control: It mainly includes controlling the switching control of the  laser and the duration of the laser emission, controlling the on-off of  the laser by using the OP instruction, and controlling the laser energy  according to the different lasers, corresponding to the size of the  control energy through the analog and digital outputs, as well as the  duty cycle of the output port PWM.

Main applications 

It  is mainly used for laser marking, including laser cutting, stage  lighting control, laser perforation and so on. It is a non-contact,  non-polluting, non-abrasive new marking process with automated control  and greatly improved reliability. Laser marking is the use of high  energy density laser beam, with the laser beam on the surface of the  material regular movement, while controlling the laser beam on and off,  so that the surface of the target material physical or chemical changes,  the laser beam can be processed on the surface of the material to  create a designated pattern.

Compared  with the traditional marking process, laser marking has the following  advantages: fast marking speed, clear handwriting. Non-contact  processing, low pollution, no wear and tear. Easy to work, strong  anti-counterfeiting ability. High-speed automatic operation, low  production cost, reliable operation.