he-ne laser

This 5 milliwatt 405 nanometer (nm) violet light laser is a fun way to excite certain mineral specimens into fluorescence. Some minerals that will fluoresce under longwave ultraviolet light may actually fluoresce under visible violet light as well. Specimens like aragonite from Sicily, calcite from Challenger Cave, sodalite from Greenland, meionite from Canada, just to name a few, will fluoresce intensely when exposed to this laser light.

Neon

This experiment explores the polarization, spatial and temporal coherence of the output of a He-Ne laser, as well as the basic conditions for laser action. Charles Townes (Nobel Prize 1964) and Arthur L. Schawlow (UofT BSc 1941, UofT PhD 1949, Nobel Prize 1980) invented the laser in 1958.

Henemeaning

3rd year Arts and Sciences undergraduate and Varsity Blues volleyball player, Anastasia Danilova, working on an earlier version of the Helium-Neon Laser.

Hrs015b

One of the most interesting mineral specimens to respond to a 405nm laser is the sphalerite from the Horn Silver Mine in Utah. Not only will the sphalerite fluoresce brightly with a 405nm laser, the phosphorescence is so intense, that you can write your initials across the specimen using the laser, and watch your initials continue to phosphoresce in the dark!

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Important Note: Although this laser emits visible violet light, and not ultraviolet light, it is still dangerous to expose your eyes to this beam of light. This laser is NOT a toy, and should not be used by a child without adult supervision. Do NOT point this laser into the sky, or at any flying aircraft, as this may be against local law. Be careful not to expose your eyes to either the direct beam, or a reflected beam off a shiny surface.

Another very interesting mineral to fluoresce with a 405nm laser is the daylight fluorescing hyalite opal from Mexico. This opal actually fluoresces best under 420nm violet light, so the 405nm laser causes these opals to explode with fluorescent intensity. Below is a picture of this hyalite opal photographed fluorescing by daylight, and then fluorescing with the 405nm laser. As you can see from the photograph, at the point of impact of the laser, the photograph is way overexposed, as the hyalite opal fluoresced a very bright and intense green.