The phenomenon of Newton's rings, named after Isaac Newton, is an interference pattern caused by the reflection of light between two surfaces - a spherical surface and an adjacent flat surface. When viewed with a monochromatic light it appears as a series of concentric, alternating light and dark rings centered at the point of contact between the two surfaces.
Using this apparatus, observation of equal thickness interference and calculation of surface curvature by measuring interference fringe separations of Newton Ring can be performed.