# Is it possible to reproduce Double-slit experiment by myself at home?

I want to reproduce this experiment by myself. What I need for this. What parameters of slits and laser/another light source it needs? Is it possible to make DIY-detector?

• The detector could be a whole separate question, especially if you are thinking of building a photomultiplier or something. Honestly, a successful experiment will show itself qualitatively upon visual inspection. If you want a more quantitative analysis, perhaps taking a RAW picture and looking at pixel values will suffice.
– user10851
Commented Feb 15, 2013 at 19:24
• You might be interested in quantum eraser experiment, that can also be reproduced at home, youtube.com/watch?v=R-6St1rDbzo Commented Feb 16, 2013 at 18:18
• duplicate or near-duplicate of physics.stackexchange.com/q/38440
– user4552
Commented May 22, 2013 at 4:42
– Noah
Commented Sep 23, 2013 at 0:12

It's actually quite easy to perform the experiment in the comfort of your own home. The simplest setup I have seen (as depicted in this, and other youtube videos) is to use a laser pointer and pencil lead, but you can certainly be more systematic and cut slits in some opaque material as well.

I would encourage you to experiment to answer the question of how far apart the slits need to be etc., but some basic math behind this is as follows: If the slits are a distance $d$ apart, if the light has wavelength $\lambda$, and if the distance between the slits and the screen is $L$, then the spacing $\Delta y$ between successive fringes on the wall will approximately be $$\Delta y \approx \frac{\lambda L}{d}$$ So let's say the laser is red so that $\lambda\approx 700 \mathrm{nm}$, the slits are $1\,\mathrm{mm}$ apart, and the screen is $1.5\,\mathrm m$ away from the slits, then we have $$\Delta y \approx \frac{(700\,\mathrm{nm})(1.5\,\mathrm{m})}{1\,\mathrm{mm}} = 1.05\,\mathrm{mm}$$ So you can actually try this and see if your results agree! (I might actually try this myself come to think of it; thanks for the question!)

Cheers!

• You can also use human hairs to produce at least single-slit diffraction patterns. Two hairs/graphite leads can in principle also do it, through Babinet's principle. Commented Feb 15, 2013 at 17:07
• What's about detector near one slit? Commented Feb 15, 2013 at 18:06
• I would add from my own experience that cutting slits in an opaque material often produces slits that are not entirely negligible in width (compared to $d$), so there may be a broad single-slit pattern modulating the double-slit pattern that is sought.
– user10851
Commented Feb 15, 2013 at 19:21
• What's about depth of slits? Does it have sense? Commented Feb 16, 2013 at 14:07

Absolutely, though the result does depend somewhat upon your definition of "at home".

Simply seeing the interference pattern is as simple as a laser pointer and a few narrow apertures (see the other answer(s))

People have successfully even done single-photon interference at home!

Laser pointer, nit comb, bit of cardboard from a cereal box to control the number of slits. Works perfectly!