Hi, I'm trying to perform a double slit diffraction experiment without using a laser, but instead using a super-bright, white LED. This LED has been placed inside a sealed box with a small pinhole opening (~1/32 inch diameter). This however introduces the problem that the light is incoherent, and rather than seeing a diffraction pattern I see two slits of light projected across the room. I have tried distances ranging from 5 feet to well over 50 feet (the latter using a camera as an integrator to see any pattern that may be invisible to the naked eye). In all cases, I see only 2 slits, or two almost superimposed slits (like a wide single slit with a dark patch running down the center, not diffraction just two lines of light that are almost on top of each other). I thought about using a polarizer and a red filter to make the light as close to coherent as possible, but this did not help. The diffraction pattern appears when using a laser however, as expected. I am wondering what could be the problem. I've tried varying the wall-slits and slits-light distances, basically all possible combinations. I've tried using only a red filter (very good red filter, only allows a small bandwidth through), using only a polarizer (to make all the light oscillate in the same direction), both red filter and circular polarizer, but nothing has worked. I am concerned that perhaps the material my slits are in is too thick for the LED light, since its 1/8 inch thick, and most experiments are done on cardstock or a thin opaque film. Does anyone have any suggestions that may help create a diffraction pattern? Using a laser is not an option, as that defeats the entire purpose, and I know that it can be done using non-coherent light, as that is how Young and Fresnel did it.