Nonreflective Film: Solving the Ref. Index Problem

In summary, the conversation discussed the idea of sandwiching a coating between lens surfaces in order to achieve minimum thickness and the difficulties encountered with the refractive index. It was also mentioned that there are two conditions for destructive interference at the front and back surfaces, with different equations due to potential phase differences. It was suggested to rederive the equations instead of looking them up. The conversation also mentioned the four rays that emerge from the lens and the need for destructive interference to occur.
  • #1
Andy1011
1
0
Homework Statement
A glass lens of index 1.5630 is to be nonreflecting on both surfaces. What should be the refractive index and thickness of the coating for a light of 5500 A to produce 0 reflactance?
Relevant Equations
2nd = m lambda
2nd = (2m+1)lambda/2
I thought of sandwiching the coating between lens sufaces and then applied the condition of minimum which gave a thickness of lambda/2*ref. Index and I got totally stuck at the ref. Index.
 
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  • #2
There are two conditions of destructive interference, one at the front surface and one at the back surface. The equaitons describing the conditions are not necessarily the same because of the phase difference that may or may not be there upon reflection. I would rederive them for myself instead of looking them up. There are four rays emerging from the lens that have to interfere destructively

Front surface
Path 1 air⇒coating; Path 2: coating⇒glass
Back surface
Path 1 coating⇒glass; Path 2: glass⇒air
 

FAQ: Nonreflective Film: Solving the Ref. Index Problem

What is nonreflective film and how does it solve the refractive index problem?

Nonreflective film is a type of thin film coating that is designed to reduce the amount of light reflected off of a surface. It works by altering the refractive index of the surface, which is the measure of how light bends as it passes through a material. By reducing the refractive index, nonreflective film reduces the amount of light that is reflected, resulting in a clearer and more transparent surface.

How does nonreflective film differ from other types of film coatings?

Nonreflective film differs from other film coatings in its focus on reducing the amount of light reflected off of a surface. Other types of film coatings may be designed for purposes such as protection, insulation, or decoration. Nonreflective film, on the other hand, is specifically engineered to solve the refractive index problem and improve the clarity of a surface.

What are the practical applications of nonreflective film?

Nonreflective film has a wide range of practical applications, including in optics, photography, and electronics. It is commonly used on camera lenses, eyeglasses, and computer and phone screens to reduce glare and improve visibility. It can also be used on solar panels to increase their efficiency by reducing light reflection.

How is nonreflective film applied to a surface?

Nonreflective film is typically applied using a process called physical vapor deposition (PVD). This involves heating a material, such as silicon dioxide, in a vacuum chamber until it vaporizes and then allowing it to condense onto the surface. The thickness of the film can be controlled to achieve the desired reduction in light reflection.

What are the limitations of nonreflective film?

While nonreflective film is an effective solution for reducing light reflection, it does have some limitations. It may not completely eliminate all reflections, especially at certain angles of light. Additionally, nonreflective film may be prone to scratches and other damage, which can reduce its effectiveness over time. It is important to carefully consider the specific application and environment before using nonreflective film.

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