interference phenomenon is common to all types of waves, acoustic, electromagnetic and others.Therefore, if the light has a wave properties, the superposition of the two light beams can not only lead to increased, but also to weaken the light or, in other words, a light interference.This means that the combined effect of the two light beams can give rise to dark, or figuratively speaking, light plus light can give dark.Experience confirms this conclusion.
Get a set of coherent light waves is possible, if a beam of light emanating from a source in any way to split into two beams, and then both the beam to bring together, with the light beams are different ways;This creates a path difference and imposing beams interfere.
There are different ways to implement these conditions.
In one experiment, a French physicist Fresnel point source light beam is split into two beams by means of two mirrors set to each other at an angle close to 180 °.
light rays coming from the source S to the screen AA.Direct rays do not fall on the screen, because they delay the partition QC.
the screen coming from the source S, light waves which run along two paths of different lengths so late in relation to each other.The waves that are reflected from the mirrors S and I and II, the two systems are coherent waves SB₁OC₁C₁ and SB₂OC₂C₂, as if coming from a source S₁ and S₂, that are false images S in the mirrors I and II.
OS₁S₂ in space, alternating light and dark bands.
describe the experience Fresnel monitoring the phenomenon of interference of light as the principle is simple, but it is technically difficult to implement.
splitting the light beam into two beams, followed by stacking occurs when illuminated by light rays of thin films.It is easy to observe the interference of light in thin films of soap bubbles.Received on a wire frame soap film and illuminating it with red light from the source, using a converging lens of our project the film onto the screen.On the screen the image of the film initially seems evenly illuminated.But as thinning of film due to flow of water (in the first row, and then in other parts of it), there are alternate red and dark horizontal stripes.A further refinement of the film observed pattern is changing on the ground dark bands appear red and vice versa.Similar patterns would be observed under a light soap film in any homogeneous light.The same pattern could be observed when illuminated films of other substances, such as oil slicks on the water surface.
What phenomena occur on a soap film illuminated by the homogeneous light?Parallel rays of light falling on the film.Reflected from the top and bottom of its borders and at the same time acquiring the path difference, there is an interference of light rays when applied at each other.If they collect the lens, the screen will get a series of bands of light, which is divided by dark intervals.When illuminated with white light interference film picture is colorful.This is a consequence of the complexity of white light, which is composed of different wavelengths forming the interference of the highs and lows of light at different places.
presence of alternating light and dark bands of monochromatic light and continuous spectra in the case of white light indicates its wave properties.
most widely used light interference found in the coated optics.What is it?
Light which is incident on the lens is partially reflected back;the proportion of the reflected light is typically a few percent.Lenses advanced optical technology are the lens system.As a result, reflections on the surface of each lens is a significant attenuation of the light.To reduce this effect, each lens surface on the interference coating is applied as a thin film.
coating thickness is selected so that the reflected waves are shifted by half a wavelength, and interfering, cancel each other.There will be no reflection losses, and all the light energy passes through the lens.The image will be more vivid - optics "enlightened."
