>>2197407They're call scan lines. I made a 4px by 4px pattern (see image), went to Edit > Create Pattern. Then on a new layer in my document went to Edit > Fill and chose the scan line pattern. I inverted it so the scan lines were white, then set it to a blending mode that looked nice (usually Overlay), reduced opacity a bit, and then masked it.
Hope that helps! Let me know if you have more questions.