Newton's rings interference pattern
Collimating lens and filter
Newton's rings plates illuminated
Newton's rings plates
Equipment set up on an optical bench
This experiment is an investigation of the many wave-like properties of light. Sir Isaac Newton first reported on a ring-shaped interference pattern in 1675 and, despite some disagreements with other scientists about what the pattern signified about the nature of light, the phenomenon was ultimately coined “Newton’s Rings.”
Rays of light reflected or transmitted from different surfaces of a thin film interfere with one another when the outgoing rays overlap (see this page/applet on Neutron Reflectometry). A simple example of this is the coloured pattern on the surface of a soap bubble, but two glass plates (or one glass plate and a curved lens) with a thin gap between them produces the same effect.
In this experiment, you will use the interference pattern (pictured above)—the Newton’s Rings—produced to determine the radius of a planoconvex lens and the wavelength of the incident light.
Current students can find more information on Learn Ultra.