Arranging opening time, back beam height, tension, opening Angle, drafting, reed-in reasonably were adopted in weaving process. These practice ensures no loop and enhance weaving efficiency.

Then you send laser light through a beam splitter to divide the beam between the two arms, and let the light bounce back and forth a few times before returning to the beam splitter.

If the two arms have identical lengths, then interference between the light beams returning to the beam splitter will direct all of the light back toward the laser.