A glass lens is coated on one side with a thin film of magnesium fluoride (MgF_(2))to reduce reflection from the lens surface (Fig. 2.26). The Index of refraction of MgF_(2) is 1.38, that of the glass is 1.50. What is the least coating thickness that eliminates (via interference) the reflections at the middle of the visible specturm (lambda = 550nm)? Assume that the light is approxmately perpendicular to the lens surface.

A glass lens is coated on one side with a thin film of magnesium fluor

1.	A glass lens is coated on one side with a thin film of magnesium fluoride (MgF_(2))to reduce reflection from the lens surface (Fig. 2.26). The Index of refraction of MgF_(2) is 1.38, that of the glass is 1.50. What is the least coating thickness that eliminates (via interference) the reflections at the middle of the visible specturm (lambda = 550nm)? Assume that the light is approxmately perpendicular to the lens surface.
Answer» 112.4nm 78.2 nm 99.64 nm 225 nm Solution :C For destructive interference, `2n_(1)t_(MIN)=lambda/2` `:. t_(min)=550/(4xx1.38)=99.64nm.`

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