Answer:
the minimum thickness of the coating is 128.25 nm
Explanation:
The computation of the minimum thickness of the coating is shown below:
In the case of non-reflective coatings, for determining the minimum film thickness needed we need to apply the following formula
Thickness = t = Wavelength ÷ 4n
where
n represent index of refraction of the coating material.
t = 631 ÷ (4 × 1.23)
= 128.25 nm
Hence, the minimum thickness of the coating is 128.25 nm