The Michelson Interferometer
At the current moment I'm reading a book entitled "Teaching Relativity to your Dog". Great read by the way. Recommended (although I must admit that I do not understand everything that they talk about).
What they did do however, was to address the Michelson interferomemeter which explains wave interference in light very well, thus the name INTERFER(E)ometer.
Below is the diagram of the interferometer. It does look intimidating at first, but of course everything becomes simpler after explanation.
So a light source (ignore the "Coherent" bit) like a ray box is used to shoot a ray of light at a half silvered mirror. This mirror is used to split the light into two separate beams. Them being split, the energy carried by the light beam (amplitude) is halved. Needless to say, the light intensity will be less. Halved to be exact.
The two light beams then meet up at the same half silvered mirror after being reflected by a mirror set at an angle so as to intersect the other split ray of light at another point at the mirror. These two beams then interact with each other (this is obviously where the interference happens) and meet at the detector, where the light intensity is measured.
Here comes the fun bit: Depending on the distance travelled by the two waves, there might be no light detected at all, or the same intensity of light detected as the intensity of light emitted from the source. This is all due to interference.
Let's just look at the interference point in the half-silvered mirror: There are two waves of light interfering with each other. Depending on the distance travelled by the light, the peak of the first wave may collide with the wave of the second wave and become bigger, to the point that it is the same as the first (there is no additional energy detected after all). Of course, this only happens when the waves are in phase with each other. After reading the book, it has came upon me that the name of this process where the peak interacts with the peak is called constructive interference. As a result, you get an addition process.
Of course, the opposite would be called destructive interference, when the trough of the first wave collides with the peak of the second wave. When this happens, we say that the two waves are in antiphase with one another. As referred to by the word "destructive", the waves are destroyed, and there is no light detected on the detector at all.
Isn't it amazing? Light cancelled itself out. This is why we see wave interference patterns during the double slit experiment. Refer to my old post for explanations on that.
Cheers,
Matthew Tan
What they did do however, was to address the Michelson interferomemeter which explains wave interference in light very well, thus the name INTERFER(E)ometer.
Below is the diagram of the interferometer. It does look intimidating at first, but of course everything becomes simpler after explanation.
So a light source (ignore the "Coherent" bit) like a ray box is used to shoot a ray of light at a half silvered mirror. This mirror is used to split the light into two separate beams. Them being split, the energy carried by the light beam (amplitude) is halved. Needless to say, the light intensity will be less. Halved to be exact.
The two light beams then meet up at the same half silvered mirror after being reflected by a mirror set at an angle so as to intersect the other split ray of light at another point at the mirror. These two beams then interact with each other (this is obviously where the interference happens) and meet at the detector, where the light intensity is measured.
Here comes the fun bit: Depending on the distance travelled by the two waves, there might be no light detected at all, or the same intensity of light detected as the intensity of light emitted from the source. This is all due to interference.
Let's just look at the interference point in the half-silvered mirror: There are two waves of light interfering with each other. Depending on the distance travelled by the light, the peak of the first wave may collide with the wave of the second wave and become bigger, to the point that it is the same as the first (there is no additional energy detected after all). Of course, this only happens when the waves are in phase with each other. After reading the book, it has came upon me that the name of this process where the peak interacts with the peak is called constructive interference. As a result, you get an addition process.
Of course, the opposite would be called destructive interference, when the trough of the first wave collides with the peak of the second wave. When this happens, we say that the two waves are in antiphase with one another. As referred to by the word "destructive", the waves are destroyed, and there is no light detected on the detector at all.
Isn't it amazing? Light cancelled itself out. This is why we see wave interference patterns during the double slit experiment. Refer to my old post for explanations on that.
Cheers,
Matthew Tan
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