PURPOSE: To show white light interference.
DESCRIPTION: Spatially coherent white light emerges from a slit, strikes the two halves of the biprism, and is recombined on the ground glass screen. The screen pattern, viewed with a minicam in the macro-zoom lens mode, is the same as two-slit white light interference: a white center flanked by colored fringes, with blue destructive interference closest to the center causing the complementary color to be seen, etc. A red filter can be inserted into the system to see more fringes.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Bright point light source, slit, Fresnel biprism, ground glass screen and minicam with color monitor.
SETUP TIME: 15 min.
Go back to Lecture-Demonstration Home Page.