I took this with my Nikon DSLR about a month ago. Today I was going through the photos and was just about to delete this otherwise unremarkable picture when I noticed a large artifact over the image of my wife's iPhone. It looks like a reflection. Is it coming from the camera, sensor, lens? What do you think?

enter image description here


1 Answer 1


Looks like a pattern created by the 2D diffraction grating. In the case of a smartphone screen, the individual pixels form the rectangular array, exactly like how the typical 2D grating is built. The effect can be more or less visible depending on the specific screen technology and pixel density.

from Plymouth Grating Laboratory: 2D diffraction pattern

  • \$\begingroup\$ Would it be visible to the naked eye, or is it an interaction of the grating on the phone's screen with the grid of the sensor of the camera that took the photo? \$\endgroup\$
    – Michael C
    Feb 1, 2019 at 14:13
  • \$\begingroup\$ Very cool. Interesting what conditions made it visible. \$\endgroup\$
    – Blago
    Feb 1, 2019 at 14:14
  • \$\begingroup\$ I tried several, mostly older screens and the full pattern was only visible in iPhone 6. some screens only showed 1D diffraction (a line of rainbow points) and in the others there was only a glare and nothing more. \$\endgroup\$
    – szulat
    Feb 1, 2019 at 17:20
  • \$\begingroup\$ @MichaelC yes, it is visible to the naked eye! \$\endgroup\$
    – szulat
    Feb 2, 2019 at 0:27

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