Question

What is the minimum thickness of coating which should be placed on a lens in order to minimize reflection of 566 nm light? The index of refraction of the coating material is 1.46 and the index of the glass is 1.71.

Answer 1

The thickness is
`t = 1.415 *10^(-7 ) \ m`

Step-by-step explanation:

From the question we are told that

The wavelength is
`\lambda = 566 \ nm = 566 *10^(-9) \ m`

The index of refraction of glass is
`n_g = 1.71`

The index of refraction of the coating is
`n= 1.46`

Generally the condition for destructive interference is

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

Here m is the order of the interference pattern and given from the question that we are considering minimizing reflection m = 0

t = thickness of the coating

substituting values

`2 t = (0 + (1)/(2) ) * ( 566 *10^(-9))/( 1.46 )`

=>
`t = 1.415 *10^(-7 ) \ m`