Interference Pattern: Non-Laser Light Sources

In summary, the double slit experiment can be performed without a laser by using a narrow collimating gap and a coherent light source, such as an LED or even sunlight. The light does not have to be chromatic, but it does need to be coherent in order to see the interference pattern. A lens may be needed to see the pattern clearly, and it is best to perform the experiment in a dark room to avoid interference from other light sources.
  • #1
Quantumgravity
18
0
Is there any way to perform the double slit experiment and see the interference pattern without using a laser? If so, what type of light do you need?
 
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  • #2
As far as I understand it- the light need not be chromatic at all.
 
  • #3
christianjb said:
As far as I understand it- the light need not be chromatic at all.
What do you mean by chromatic?

As for how to do it.. collimate the light by letting it pass through a very narrow gap (say, between two razor blades). Then have it go through another such gap, or your double slit perhaps. You may need some kind of lens to appreciate the pattern. Works fine with a normal battery torch.. well.. actually it's a pain because you likely need a dark room to be able to see the small amount of light involved, and you need to block out the extra torchlight.. it's fiddly.
 
  • #4
Sorry- I meant coherent. It may have to be reasonably monochromatic in order to see interference.
 
  • #5
The interference will occur even if the light is not monochromatic, but of course all the patterns will overlap and mix and the overall pattern, whilst still there, will be more difficult to see.
 
  • #6
It does have to be coherent though, which is the reason for the collimation. :wink:
 
  • #7
cesiumfrog said:
As for how to do it.. collimate the light by letting it pass through a very narrow gap (say, between two razor blades). Then have it go through another such gap, or your double slit perhaps. You may need some kind of lens to appreciate the pattern. Works fine with a normal battery torch.. well.. actually it's a pain because you likely need a dark room to be able to see the small amount of light involved, and you need to block out the extra torchlight.. it's fiddly.

Right. We do it by using a semi-transparent "diffuser" screen as the final target, and looking at the back side, in the direction of the slits and the light source. If you turn out the room lights and block stray light from the source, you can easily get a dim but clearly visible interference pattern that's perhaps a centimeter wide. Our initial collimating slit is 0.1 mm wide, and we use a small high-intensity desk lamp as the light source, with a clear-glass bulb so the filament makes for a fairly small source already.
 
  • #8
Thanks for the input.
 
  • #9
actually any light that has been emitted by the same source is coherent, so you can get an interference pattern using sunlight and or a flashlight. however an led would be better as there would be fewer differences over the emitter surface.
 

1. What is an interference pattern?

An interference pattern is a visual phenomenon that occurs when two or more waves of light overlap and interfere with each other. This interference can result in a pattern of bright and dark bands, which can be observed in various experiments and demonstrations.

2. How is an interference pattern created?

An interference pattern is created when two or more waves of light meet at a specific point in space. These waves can come from different sources or be reflected or diffracted from a single source. When they overlap, the waves can either reinforce or cancel each other out, resulting in the observed pattern.

3. Can interference patterns only be created with laser light sources?

No, interference patterns can be created with any type of light source, including non-laser sources such as natural sunlight or incandescent bulbs. However, laser light sources are often used in experiments because they produce a coherent and concentrated beam of light, making it easier to observe and measure the interference pattern.

4. What factors can affect the interference pattern?

The interference pattern can be affected by various factors such as the wavelength and intensity of the light sources, the distance between the sources, and the medium through which the light waves are passing. Any changes in these factors can alter the interference pattern that is observed.

5. What are the practical applications of interference patterns?

Interference patterns have many practical applications in fields such as physics, astronomy, and engineering. They are used in experiments to study the properties of light and to measure small distances. They are also utilized in technologies such as holography, fiber optics, and interferometry.

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