Question

The non reflective coating on a camera lens with an index of refraction of 1.29 is designed to minimize the reflection of 636-nm light. If the lens glass has an index of refraction of 1.56, what is the minimum thickness of the coating that will accomplish this task

Answer 1

The minimum thickness is
`t = 1.0192 *10^(-7) \ m`

Step-by-step explanation:

From the question we are told that

The refractive index is
`n = 1.29`

The wavelength of the light is
`\lambda = 636 \ nm = 636 *10^(-9) \ m`

The refractive index of the glass lens is
`n_g = 1.56`

Generally the condition for destructive interference of a films is

`2t = [ m + (1)/(2) ] (\lambda)/(n)`

for minimum m = 0

`2t = [ 0 + (1)/(2) ] (\lambda)/(n)`

=>
`2t = [ 0 + (1)/(2) ] (636 *10^(-9))/(1.56)`

=>
`t = 1.0192 *10^(-7) \ m`