Diffraction Gratings

Diffraction Grating A diffraction grating is a device used for wave analysis, consisting of a large number of equally spaced parallel slits.

Diffraction Grating vs. Double Slit Similar to the double slit except: Grating has more slits  increased light passing through  brighter interference pattern The maximas are sharper and narrower in grating Grating produces a greater resolution (more detail)

Double Slit vs. Diffraction grating

Types of Diffraction Grating Transmission Grating The light passes through the slits Reflection Light is reflected by the spacing

Monochromatic vs. White Light Source

White Light and Grating If the light striking the grating is not monochromatic but a mixture of wavelengths, each wavelength produces a pattern of bright maxima at different locations on the viewing screen

Spectroscope The instrument that performs this analysis is called a spectroscope.

Application: Spectral Analysis Can be used to determine the atomic makeup of distant objects as different atoms give off different spectrums of light which can be analyzed

DVD’s and CD’s The tracks of a CD or DVD act as a reflection diffraction grating, producing a separation of the colors of white light. The nominal track separation on a CD is 1.6 micrometers, corresponding to about 625 tracks per millimeter. For red light of wavelength 600 nm, this would give a first order diffraction maximum at about 22°.