Is My Calculation for Film Thickness Using Interference Method Accurate?

In summary, the conversation was about measuring film thickness by interference method and the equation used for it: d= (y1*y2)/(2*(n1y2-n2y1)). The person tried to calculate the flow using this equation but encountered some errors. After making some approximations and adjustments, they were able to find the correct equation: d=(y2*y1)/(4*n*(y2-y1)). They wondered what went wrong with the original equation and sought clarification on the terms used.
  • #1
tan-X1
3
0
After I read many articles about measuring film thickness by interference method.

I tried to calculate flow that papers but I can't

the equation is

d= (y1*y2)/(2*(n1y2-n2y1))

for an easy I approximate n1 =n2

so

d= (y1*y2)/(2*n(y2-y1))


y1 = 350 nm
y2 = 380 nm
n = 2.35

I want to find out "d"

it seems to be easy

but I always get d = 944 nm

unfortunately, it's wrong

d have to be 472

that means I forgot to divide 2 in this eq.

however, the eq use to be right.

I don't know what's wrong in my calculation.
 
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  • #2
Ahh, I am wondering

I track this eq from original eq

2nd=my1

2nd=(m+1/2)y2

I am able to get

d=(y2*y1)/(4*n*(y2-y1))

from this eq. I can get the right answer

so, what's wrong in this eq.

d= (y1*y2)/(2*n(y2-y1))

?
 
  • #3
Please do NOT post the same question in more than one forum.
 
  • #4
tan-X1 said:
the equation is

d= (y1*y2)/(2*(n1y2-n2y1))

for an easy I approximate n1 =n2

so

d= (y1*y2)/(2*n(y2-y1))
Why don't you explain what this equation represents and define the terms? What are n1 and n2? y1 and y2?
 
  • #5
Sorry mate.

Now, I've already known.

Thank you.
 

1. What is thin films interference?

Thin films interference is a phenomenon that occurs when light is reflected off of two surfaces of a thin film, causing constructive and destructive interference patterns. This results in a change in the color of the reflected light.

2. How does thin films interference occur?

Thin films interference occurs when light waves reflect off of two surfaces of a thin film, such as a soap bubble or a layer of oil on water. The light waves travel different distances and can either interfere constructively or destructively, resulting in different colors being reflected.

3. What factors affect thin films interference?

The thickness of the thin film, the wavelength of the incident light, and the refractive index of the materials involved are all factors that affect thin films interference. The angle of incidence and the type of light (polarized or unpolarized) can also play a role.

4. What is the difference between thin films interference and Newton's rings?

Thin films interference and Newton's rings are both examples of interference patterns, but they occur in different types of thin films. Newton's rings occur between a convex lens and a flat surface, while thin films interference occurs between two flat surfaces.

5. How is thin films interference used in real-life applications?

Thin films interference is used in many everyday products, such as anti-reflective coatings on glasses and camera lenses, as well as in the production of thin film solar cells. It is also used in scientific research to study the properties of materials and to create precise measurements for coatings and films.

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