文档介绍：Newton’s Rings
(Caution: the report still have some mistakes inevitably.)
Purpose of the experiment
Applying Newton’s rings to observe the phenomenon of equal thickness interference with reflected light and transmitted light respectively, then analyze the physical principles.
Get familiar with image processing and learn to use software concerned, such as Image J and Visio.
Analyze reasons for different patterns resulted from different light sources.
Apparatus
Sodium lamp (with a central wavelength of )
Other illuminant (purple, white and red leaser)
Newton’s rings
Imaging lens
Frosted glass screen
Camera (CCD)
Rulers used for calibration (smallest tick interval is )
Computer
Principles of the experiment
Background
Newton’s rings is named after Isaac Newton, who first studied them in 1717.
When viewed with monochromatic light, Newton's rings appear as a series of concentric, alternating bright and dark rings centered at the point of contact between the two surfaces. When viewed with white light, it forms a concentric-ring pattern of rainbow colors, because the different wavelengths of light interfere at different thicknesses of the air layer between the surfaces.
Principle of Newton’s rings
Newton’s ring posed of a segment of large-radius convex lens with its convex side to a glass plane (.(a)). The light source is usually
monochromatic light. Because of the gap between the plane lens and the convex lens, the reflected ray and the incident ray will have optical path difference. As a result the two rays will interfere with each other. The whole process is called equal thickness interference, which is one type of film interference.
When two beams interfere with each other, there will be a superposition of waves due to the characterization of light waves. If the optical path difference Δs is integral multiple of the wavelength λ, ., the superposition will cause the maximum amplitude and result in the brightest region of the