PURPOSE: To show what the inside of a laser looks like, and to show that the laser removes lots of spectral components from the light in the tube and only lets one wavelength out.
DESCRIPTION: The metal cover has been removed from a weak helium-neon laser, allowing the internal components to be seen, including the tube and the mirrors. Using a hand-held diffraction grating the light from in the tube can be seen to have a large number of spectral components. The light outside hits a white screen; looking at the spot with the grating shows that it is monochromatic, illustrating the lasing action.
SUGGESTIONS: This one is best for individual viewing by a few people at a time.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Laser with case removed mounted in clear plastic tube, white card, diffraction gratings.
SETUP TIME: None.
Go back to Lecture-Demonstration Home Page.