Visible Laser

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.
 

Equipment

Laser with case removed mounted in clear plastic tube, white card, diffraction gratings.

 

Suggestions

This one is best for individual viewing by a few people at a time.◙
 

Images

l1-32

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.
 

References

N. R. Isenor, Mechanical Model of a Q-Switched Laser, AJP 37, 1159-1160 (1969). ◙H. Weichel, W. A. Danne, and L. S. Pedrotti, Laser Safety in the laboratory, AJP 42, 1006-1013 (1974). ◙R. C. Nicklin, Laser vs Light Bulb Power Comparison, AJP 43, 111 (1975). ◙D. G. H. Andrews and D. R. Tilley, A computer model of laser action in the teaching of computational physics, AJP 59, 536-541◙(1991). ◙Michael E. Knotts, Apparatus for Teaching Physics: Making Laser Beams Visible, TPT 31, 402-403 (1993).