Single Slit Diffraction - Fresnel And Fraunhofer


To demonstrate single slit diffraction.


Laser cart with beam collimator, variable single slit, 5cm focal length projection lens, and 5cm focal length simple◙lens.◙

Setup Time

10 min.




This system uses a collimator to produce a uniform laser beam which is then used to create either Fresnel or Fraunhofer diffraction from a single slit. ◙◙Align the laser and collimator system so that a uniform spot falls on the center of the screen. Insert the slit approximately 5 cm in front of the collimator (open several millimeters) and focus the slit onto the screen with the projection lens. Insert the 5cm lens at the narrowest part of the beam, and close the slit to see the Fresnel diffraction pattern. As the slit narrows the pattern changes from Fresnel diffraction to Fraunhofer diffrac


Allen L. Moen and David L. Vander Meulen, Fresnel Diffraction Using a He-Ne Gas Laser, AJP 38, 1095-1096 (1970). ◙R. Boyer and E. Fortin, Intensity Measurements in a Fresnel Diffraction Pattern, AJP 40, 74-76 (1972). ◙Partha P. Banerjee and Ting-Chung Poon, On a simple derivation of the Fresnel diffraction formula and a transfer function◙approach to wave propagation, AJP 58, 576-579 (1990). ◙T. W. Mayes and B. F. Melton, Fraunhofer diffraction of visible light by a narrow slit, AJP 62, 397-403 (1994). ◙Bruce Mechtly and Albert A. Bartlett, Graphical representations of Fraunhofer interference a