With the development of technology, people have been finding more and more ways to use light. From everyday household uses to medical applications, light is becoming more and more integral to our lives.
With the growing importance of light, it is important to understand how it works. How does light function? What happens when you change certain parameters of light?
One of the most interesting aspects of light is its interference pattern. When two waves of light intersect, a pattern of brightness emerges. This pattern reveals some interesting facts about the waves themselves.
For instance, if two perpendicular waves intersect, then the resulting brightness will be uniform across the surface. If one wave is greater in amplitude than the other, then there will be a difference in brightness across the intersection. These are just two examples of what can be revealed by the interference pattern.
Higher resolution
In this case, instead of decreasing the wavelength of the light, we can increase the spacing between fringes. This is called fringe spacing or inter-fringe spacing.
If we increase the fringe spacing, then we are actually decreasing the resolution of the interferometer. Because there are more gaps in between where there is light and where there is darkness, it is harder to determine whether a particle passed through that particular gap or not.
It is easier to tell with more narrow fringes whether a particle passed through or not. With less narrow fringes, it is harder to tell—there may be more of them that look the same, making it difficult to determine which ones passed through and which ones did not.
There are many different ways that this experiment can be carried out, but all of them depend on one factor: whether or not the interferometer has higher or lower resolution.
Easier to see smaller objects
If the wavelength of the light is decreased, the spacing between the fringes will also get smaller. This means that it will become easier to see smaller objects, like very small particles or differences in surface texture.
This is due to the fact that the difference in wavelength between the peaks of the light and the valleys of the light becomes smaller.
If we imagine a very long rope with waves on it, then we can understand this concept more clearly. If we shorten the length of the rope, then we will also make it thinner. Thus, there will be less space between the waves.
We can use this idea to understand how diffraction works with optical devices like lenses and mirrors. If we use lenses and mirrors that are more dense, then they will produce more accurate images because they capture more detail in what is being reflected or transmitted through them.
Easier to distinguish colors
Scientists have also considered the other direction: What will happen to the spacing between colors if the wavelength of the light is increased?
The answer is that it would be easier to distinguish colors. This is because there would be more separation between colors, i.e. a greater difference in wavelength.
Imagine separating red, orange, yellow, green, blue, and purple into ten equally spaced bins. It would be much easier to sort the items into the correct bin if they were all different shades of red, orange, yellow, green, blue, or purple.
The same applies to fringes: it would be easier to detect them if they were more distinct. The fringe dots would be larger and farther apart, making it easier to tell whether or not a given glass has a wave pattern on it.
Slower waveforms
Let’s go back to the analogy of the train and the tracks. If we lower the speed of the train, it will take longer for it to pass between two markers.
The same is true for light. If we decrease the wavelength of the light, it will take longer for it to pass between two mirrors. However, since time is related to speed, it will also affect how long a time period this happens in.
If we decrease the speed of light to 1 m/s, a blue train passing between two markers would take one minute to do so. This is because it takes one minute for light to travel one meter.
This shows that although light travels faster than any other known physical entity, it can still be slowed down.
Greater depth of field
Decreasing the wavelength of the light will result in greater depth of field. This is due to the fact that the fringes will be closer together, making it harder for the camera to determine whether or not it is a pixel of the correct color or a fringe between pixels.
As mentioned before, when the light has a shorter wavelength, more photons (particles of light) are emitted per second. In order for the camera to receive enough light to correctly determine the pixels, it must keep the shutter open for a longer time.
Since the shutter will have to be open longer, more of the fringes will be captured, creating a greater depth of field. In other words, everything in front of and behind your intended subject will be more clearly visible.
Higher frame rate at given resolution
We have already discussed how the limit of spatial fringing is dependent on the wavelength of the light. If the wavelength is longer, then the fringe spacing can be longer as well.
If you were to use red light instead of violet/blue light, then the fringing would be much greater due to the longer wavelength. This is why ultraviolet lenses filter out red light and infrared lenses filter out blue/violet light—to reduce this fringing effect.
The number of frames per second (fps) that a camera can capture is dependent on many things, but one important one is battery life. High-frame rate cameras use more energy per shot due to having to operate internal systems at a faster rate.
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