# Michelson Interferometer Pattern

• ed2288
The concentric circles are a result of the interference pattern created by the overlapping of the two beams. The thickness of the fringes is due to the difference in path length between the two beams, which can be controlled by adjusting the mirrors. This creates a pattern of equal thickness fringes, or lines, which can be observed in a Michelson interferometer. In summary, the pattern of straight line fringes of equal thickness in a Michelson interferometer is created by the interference of two beams of light that are not perfectly aligned due to differences in path length.
ed2288

## Homework Statement

Explain how a pattern of straight line fringes of equal thickness can be observed in a michelson interferometer.

## Homework Equations

see diagram 1/3 of the way down page at http://www.holo.com/holo//book/book6&7.html

## The Attempt at a Solution

I really am stuck with this. From my understanding, light comes out of a laser and hits a beam splitter. One beam hits mirror 1, the other beam hits mirror 2 and they both bounce back to the splitter where they recombine, pass through the microscope objective and hit the screen. Now correct me if I'm wrong, but surely you will get total constructive interference if the path length difference due to the mirrors is one wavelength, and total destructive interference if its half a wavelength. I've read Hecht and looked online but I really can't seem to understand why you would even get concentric circle fringes!? Surely its got to be all dark or all light?

Thanks

Last edited by a moderator:
Laser light is not perfectly parallel. There is some small amount of beam spreading.

Ben Niehoff said:
Laser light is not perfectly parallel. There is some small amount of beam spreading.

That shouldn't matter, since both beams are spreading by the same amount.

It has more to do with the recombined beams not being in perfect alignment.

## 1. What is a Michelson Interferometer Pattern?

A Michelson Interferometer Pattern is a visual interference pattern that results from the interference of light waves in a Michelson Interferometer, a scientific instrument used to measure the wavelength of light and the index of refraction of materials. The pattern consists of alternating light and dark fringes, which can be used to make precise measurements.

## 2. How does a Michelson Interferometer create a pattern?

The Michelson Interferometer uses a beam splitter to divide a single light source into two beams, which then travel along two different paths and are recombined at a detector. This recombination results in an interference pattern due to the constructive and destructive interference of the two light waves.

## 3. What can the Michelson Interferometer Pattern be used for?

The Michelson Interferometer Pattern is commonly used in scientific research to measure the wavelength of light, determine the refractive index of materials, and study the properties of light. It is also used in practical applications such as in the development of optical instruments and for quality control in industries such as optics and semiconductor manufacturing.

## 4. How is the Michelson Interferometer Pattern analyzed?

The Michelson Interferometer Pattern is analyzed by measuring the distance between the fringes, which is related to the wavelength of light, and by counting the number of fringes, which can be used to determine the index of refraction of a material. The pattern can also be recorded and analyzed using computer software for more precise measurements.

## 5. What are the advantages of using a Michelson Interferometer Pattern?

The Michelson Interferometer Pattern offers several advantages, including high precision and accuracy in measurements, non-destructive testing, and the ability to measure a wide range of wavelengths. It is also a relatively simple and cost-effective instrument, making it a valuable tool in various fields of science and industry.

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