PURPOSE: To demonstrate single slit diffraction.
DESCRIPTION: 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 diffraction.
REFERENCES: (PIRA 6C10.15) See Demonstration Reference File for further information and source.
EQUIPMENT: Laser cart with beam collimator, variable single slit, 5cm focal length projection lens, and 5cm focal length simple lens.
SETUP TIME: 10 min..
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