Net curtain diffraction

 I fired the laser though the net curtain and got a pattern on a screen 4 metres away. At first I thought that it was just showing light shining through the holes because the beam is a couple of mm wide and covers several holes. But there does appear to be some kind of diffraction extending beyond the central blob.

I tried to apply the diffraction grating formula to the line that goes through 12 on the ruler. So the first fringe n=1 is roughly 5mm from the centre. Small angle approximation means sin(theta) = 5/4000. Slit separation through close inspection of the weave with a 10x magnifying glass shows gap to be 0.5mm. So wavelength = 0.0005 x 5/4000 = 625nm. That's almost perfect. But it seems at odds with some of the contributions here https://www.researchgate.net/post/How_to_explain_the_diffraction_pattern_through_a_net_curtain Maybe it is the use of a laser and not an LED.