LIBS Spectrometer - Build 2
To test whether I am limited by spectral resolution on the first build, I obtained another spectrometer.
The HR2000 Spectrometer is currently calibrated for ~470 to ~670 nm wavelength range and has a 10 micron entry slit. The ~200 nm bandwidth falls nicely into the linear range of the installed #9 rating.
H9 Grating Curve:
Following the same analysis as in the previous Data Analysis section:
The FWHM with this is 200 nm/2048 pixels * 2.0 pixels ~= 0.2 nm
About a factor of 5 improvement !
The spectrometer uses a different connector than the S2000 spectrometer:
But the signals I used (5V, Gnd, Ext. Trigger) are all there.
To be able to use the same 15 pin cable I used previously I got a 15 pin breakout board. This makes the HR2000 a drop-in replacement for the S2000.
To make alignment of the sample with both the focal point of the laser and the acquisition optics, I first made an adapter that allows me to connect a red laser into a SMA fiber connector. This way I can see what area the spectrometer 'sees'
At the same time I used some organic putty to fix a flashlight behind the YAG laser. Now I got a white spot where the YAG focuses and a red spot where the spectrometer fiber is focused.
I can move the collection lens back to defocus it a little. This will then cause the system to collect less light in case the spectrometer gets overwhelmed.