PURPOSE: To demonstrate diffraction of laser light around small spheres.
DESCRIPTION: Breathe on a glass plate and sprinkle the plate lightly with lycopodium powder to create diffraction sources for the laser light. Laser light shining around the tiny spheres of lycopodium powder is diffracted, creating a series of rings around the main spot on a distant screen. The average diameter of lycopodium powder spheres is about 4 microns.
Actually, this is a GLORY, not a HALO; a halo is a refraction/dispersion phenomenon while a glory is a diffraction phenomenon.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Laser with 8X collimator and glass plate with layer of lycopodium powder on laser cart.
SETUP TIME: 5 min.
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