I think these patterns are due to internal reflections in the foil. The light just bounces between the surfaces just as it does in a pane of glass...
A 532 nm DPSS laser should not produce other wavelengths.
I think these patterns are due to internal reflections in the foil. The light just bounces between the surfaces just as it does in a pane of glass, giving some lines in places they should not be.
A 532 nm DPSS laser should not produce other wavelengths. The doubling process is very selective when it comes to incoming wavelength, which is 1064 nm from the solid state.
If the emission was as broad as the pictures suggest it should actually be very easy to construct green lasers anywhere between 525 and 531 nm just by adjusting the reflective coating. Realistically something like that is not possible (try to find any such lasers for sale), and i think it must simply be an artefact of using this type of grating.
Benm, I can't agree. The furthest lines have a distinctively yellower color. And CaliKirk and I got identical results from using different gratings (flexible vs. solid.) A grating should not change the wavelength of anything -- it simply cannot have that property.
In addition, I observed the same effect with my 589, making it likely that this is due to coatings, and not the grating.
As the laser warms up and the wavelength decreases the light frequency is increasing.
But when it is super cold, it looks like the first order is 529.25, then as it warms up the first order transitions slowly up to ~527.
I'm pretty sure atomic transitions of Nd don't change with temperature. I welcome a correction if you can find a source. A green pointer is 532.09nm at all times. Any variation you're reading from this is variation in your instrumentation.
What do you mean the first order? Has it highest intensity? wavelength? Just the first spot on the left (right)?
The "first order" is used in connection to grating diffraction orders. (look for pictures "grating orders")
There could be variations in that number due to a multimode (longitudinal) operation.
I have watched it change over time as it heats up. Not a great deal, but it does change and if others are seeing this also, I doubt seriously that my USB2000 commercial spectrometer is the fault.
It decreased from 532.20 to 531.69, IIRC.