Green Laser Through Calcite

[pointer]

Has anybody noticed that if you shine a cheap green laser through rhombic calcite (Iceland Spar) you can see the red in the beam. Calcite is famous for splitting light into two but what is going on? Am I seeing an interpretation of the infrared? Or is it unrelated?
However shining a red laser, the beam is not visible in the calcite at all and with a purple laser the beam shows a faint red within the crystal. If anybody can tell me what is going on I would love to know.

 

[WizardG]

It's called fluorescence. There are impurities in your crystal which glow when excited. It's the same phenomenon that makes dayglo colors light up under a blacklight, the wavelengths involved here are just a bit different.

 

[pointer]

Yes I understand about fluorescence and inclusions but why does it make the red visible in the green beam and the red invisible in the red beam?

 

[farbe2]

Because the fluorescence is only excited by a specific wavelength.
Look a glow in the dark stuff, if you shine your 405nm pointer on that, you would get a glow. If you use your red one, you don't get any glow. (the glow in the dark stuff works differently, however the principle is the same)

The crystal will only convert certain wavelengths to the red light you see.
It could be that only the 808nm pump light of your greenie gets converted, or its only the 532nm light.
However shining 405 or 638nm in it will result in no glow at all because the wavelength is wrong.

 

[pointer]

Because the fluorescence is only excited by a specific wavelength.
Look a glow in the dark stuff, if you shine your 405nm pointer on that, you would get a glow. If you use your red one, you don't get any glow. (the glow in the dark stuff works differently, however the principle is the same)

The crystal will only convert certain wavelengths to the red light you see.
It could be that only the 808nm pump light of your greenie gets converted, or its only the 532nm light.
However shining 405 or 638nm in it will result in no glow at all because the wavelength is wrong.

Thank you for this.

 

[paul1598419]

About 60 years ago I collected rocks and minerals. I had some calcite which would spit light depending on its polarity. I bought some several years ago to have for experimental purposes. If you place the calcite over a line drawn on paper with the correct alignment you should be able to see two lines. If you haven't already tried this you are in for a surprise.