Poisson's Bright Spot

Optics > Diffraction

DCS# 6C20.10

POISSON'S BRIGHT SPOT

APPARATUS

diverging lens, f = -11 cm	202-21-E5
diverging lens, f = -20 cm	202-21-E5
ball bearing on microscope slide	202-21-E5
3 lens holders	113-01-C6
ring stands and clamps	202-01
laser	202-21-B6
large ground glass screen	202-21-D4
video camera	202-09-C4

DESCRIPTION

The diffraction pattern produced by a ball in the path of a laser beam is projected on a screen.

Patterns from a straight edge, circular apertures, and other objects can also be shown with this set up.

The CMOS camera and a laptop can also be used to display the image.

NOTES

Use macro setting on video camera. Turn AGC off and stop down aperture by pulling out auto/manual iris knob and turning it.

Circular obstacle was made by supergluing a ball bearing to a microscope slide.