Geometrical Optics: Explaining Concepts with Fermat's Principle

In summary, Fermat's principle helps explain why we need forms of mirrors and lenses in order to create an image.
  • #1
isnainidiah
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How do you use Fermat's principle of least time to explain various concepts in geometrical optics?
 
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  • #2
isnainidiah said:
How do you use Fermat's principle of least time to explain various concepts in geometrical optics?
You can use Fermat's principle to derive the laws on which geometrical optics is based: The laws of reflection and refraction.
 
  • #3
For example, do a Google search for "law of refraction fermat principle" and you'll find many web pages and even a video which try to explain how the law of refraction can be derived from Fermat's principle. If you don't understand one of those derivations, post a link to it and ask questions about the specific things that you're stuck on.
 
  • #4
Okay thank you,,

So when we talk about optic geometry, we just explain the reflection and refraction, isn't it ??

then what if the answer to the question "how do you use Fermat's principle to explain the need for forms of mirrors and lenses"?
 
  • #5
isnainidiah said:
So when we talk about optic geometry, we just explain the reflection and refraction, isn't it ??
Yes. That is the basis of geometrical optics.

isnainidiah said:
then what if the answer to the question "how do you use Fermat's principle to explain the need for forms of mirrors and lenses"?
I don't quite understand the question. Use Fermat to derive the laws of optics, then use those laws to design mirrors and lenses to do what you would like (form images, for example).
 
  • #6
Yeah i mean, how we use fermat principle to explain the required shapes of lenses and mirrors ?
 
  • #7
isnainidiah said:
Yeah i mean, how we use fermat principle to explain the required shapes of lenses and mirrors ?
Usually, the need for designing certain shapes of the mirrors and lenses is for aberration correction purpose. Aberration comes in various forms, all of them have adverse effect on the formed image, so suppressing them by designing certain shapes and/or material of the mirrors and lenses is demanded.
 
  • #8
blue_leaf77 said:
Usually, the need for designing certain shapes of the mirrors and lenses is for aberration correction purpose. Aberration comes in various forms, all of them have adverse effect on the formed image, so suppressing them by designing certain shapes and/or material of the mirrors and lenses is demanded.
So, the design of mirror and lens just for certain purpose, is'n it?
Then, we derived the fermat principle that can we use to design the mirror and lens for certain purpose, is'n it
 
  • #9
isnainidiah said:
So, the design of mirror and lens just for certain purpose, is'n it?
Then, we derived the fermat principle that can we use to design the mirror and lens for certain purpose, is'n it
Are you asking about correcting for abberations? Or just asking about the basic shapes of lenses and mirrors?
 
  • #10
The (practical) purpose for which lenses or mirrors with certain shapes needs to be produced usually comes first, then one applies the theories either through Fermat's principle or merely ray tracing to analyse the optical elements.
 
  • #11
Doc Al said:
Are you asking about correcting for abberations? Or just asking about the basic shapes of lenses and mirrors?
I asking about basic shapes of lenses or mirror and also another shapes of lenses or mirror,
 
  • #12
blue_leaf77 said:
The (practical) purpose for which lenses or mirrors with certain shapes needs to be produced usually comes first, then one applies the theories either through Fermat's principle or merely ray tracing to analyse the optical elements.
So, we need the purpose first,
then we can use many theories to analyse it, isn't it ?
 
  • #13
isnainidiah said:
So, we need the purpose first,
then we can use many theories to analyse it, isn't it ?
It should be that way, you don't normally use your design software to design optics as a plaything as weird as you want (except for learning purpose). There must be a specific purpose for certain optics design.
 
  • #14
blue_leaf77 said:
It should be that way, you don't normally use your design software to design optics as a plaything as weird as you want (except for learning purpose). There must be a specific purpose for certain optics design.
Okay, thak your for the explanation
 

FAQ: Geometrical Optics: Explaining Concepts with Fermat's Principle

What is Fermat's Principle?

Fermat's Principle is the fundamental principle of geometrical optics, which states that light follows the path of least time between two points. This principle helps explain the behavior of light when passing through different mediums and encountering obstacles.

How is Fermat's Principle used in geometrical optics?

Fermat's Principle is used in geometrical optics to predict the path of light as it travels through different mediums and encounters different obstacles. It helps us understand how light bends and reflects, and allows us to make calculations and predictions about the behavior of light.

What is the difference between geometrical optics and other branches of optics?

Geometrical optics is a branch of optics that deals with the behavior of light in terms of rays and their paths. It simplifies the understanding of light by assuming that light travels in straight lines and does not consider the wave nature of light. Other branches of optics, such as physical and quantum optics, take into account the wave nature of light.

Can Fermat's Principle be applied to all types of light?

Fermat's Principle can be applied to all types of light, including visible light, infrared, ultraviolet, and even other forms of electromagnetic radiation such as radio waves and microwaves. As long as the light can be described as a wave, Fermat's Principle can be used to explain its behavior in geometrical optics.

How is Fermat's Principle related to the law of reflection and the law of refraction?

Fermat's Principle is closely related to the law of reflection and the law of refraction, as it helps to explain and derive these laws. The law of reflection states that the angle of incidence is equal to the angle of reflection, and Fermat's Principle can be used to show that this is the path of least time for light. Similarly, the law of refraction states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, and Fermat's Principle can be used to prove this relationship as well.

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