using linuxcnc for laser fiber marking

I think that the slowing in the corners is probably due to you having G64 Pn active still.

Do you still get this with G64 P0 ? (I would expect a corner rounding instead)

It works but it does not benefit me.
However at the beginning of the shape and the end of the shape, the increase and decrease of speed still happens.

I think your acceleration is still set _way_ too low

PCW wrote:

I think your acceleration is still set _way_ too low
 

you are right.
I set the acceleration to the maximum value and it was solved

But now there is another problem
When the cursor moves at high speed,The square location on the screen shifts
I think that's why I use velocity mode for pid , But I do not know how to solve it.
 

Sorry, can you describe the current problem in more detail?

Sure! 
in below I uploaded one zip file contains two videos , video 1 shows the gcode output in linuxcnc , and video 2 shows the actual output with galvo 


I used configuration provided by PCW in here