# Double slit details.

1. Mar 18, 2005

### RandallB

Anyone know where to find some well documented Double slit experiment results?

Thorough and complete detailed information on all parts:
Wavelength used, width of slits, separation of slits,
Distance from slits to detection screen or film.
Flat screen or detail on a curve in detection screen.
Complete detail on interference pattern produced:
That is Position and size of every pattern produced, i.e. detail of the widening separation between pattern nodes to as far out and as many nodes as possible.

2. Mar 18, 2005

### mathman

Try Google using "double slit". You will get a lot of hits on detailed descriptions.

3. Mar 19, 2005

### RandallB

Now there is an idea "google" should have though of that!

Sorry for the sarcasm, the point is, out of " about 631,000 " does anyone know of a reference that might actually include complete detail of the whole test and detailed results not just the detail of their descriptions and opinions.

4. Mar 19, 2005

sounds like you're trying to get out of doing a lab report. lol.

Regards,

5. Mar 19, 2005

### RandallB

Nope never been in a lab good enough for the info I'd like! I’m just amazed at the overwhelming amount of detailed explanation available on sites confirming how bright or informative they are, But with no real background supporting data from actual test layouts and real detailed test results to back it up with.

Be happy to produce my own but I don’t own a lab. Do you know any lab’s (University or other) willing to even talk to an outsider? Midwest would be nice but I’d go anywhere.

6. Mar 19, 2005

### Staff: Mentor

If you just want to verify the formula for the locations of the interference maxima, $n \lambda = 2d \sin \theta$, all you need is a laser that produces light of a known wavelength, and some slits of known width and spacing, that can be "covered" by the laser beam. Just let the beam fall on the slits, and let the interference pattern fall on a screen a suitable distance away to allow it to show as a string of spots. Measure the positions of the spots, and the distance from the slits to the screen, and apply a little trigonometry.

A cheap laser pointer will probably work, if you can find out the wavelength. In our undergraduate lab, we use helium-neon lasers, which have a well-known wavelength of 632.8 nm.

Suitable slits are not so easy to find, except from companies like Pasco Scientific that specialize in school and college lab equipment. Pasco's item# OS-9179 is a set of two 2x2-inch slides, one with four single slits of different widths, the other with four pairs of slits with different widths and spacings. The slits are cut in metal film and the widths and spacings are supposed to have a tolerance of 5 microns, which works out to 12.5% for a 0.04mm slit. The set costs $125. If you want to verify the formula for intensity as a function of angle, basically $I = I_0 \cos^2 (something)$, you'll need a photometer and a fiber-optic probe that you can move through small increments, and a fairly bright laser. With Pasco's stuff, you're looking at least$1000.

If you have a college or university physics department nearby, you might be able to talk one of the professors into showing you the equipment and letting you try it out during a slow period. This would probably be easier at a small school where things are run informally. Or you can find out when they're going to do that experiment in their general physics or intermediate optics course, and sit in on it.