Obviously, it is possibly to spend much more time and money, to work with other
lasers or better interference filters. On this pathway you will definitely reach more
splendid results (cf. links to more sophisticated projects below).
The spectra shown here were recorded by help of the following means:
-- 540 nm long-pass interference filter (Ebay, producer unknown)
-- Laser cleaning filter (ca. 100 US $) placed in front of the laser pointer
-- Spectrometer from Science Surplus, 1800 lines diffraction grid, 50µm slit
-- Basic software "Spectrum Studio" V. 1.2, came with the spectrometer
-- Measurement times up to about one minute (sum of several runs)
-- Microscope objective: Nikon M Plan 10x/0.25 and sometimes 40x/0.65
Absolute wavenumber fit and wavenumber resolution are relatively low and some spectra
are showing strong noise. Nevertheless the spectra can serve as a basis for comparison
with internet sources, e.g. with the impressive "RRuff" Raman database (online).
When comparing the general appeal of your Raman spectrum with the internet Raman spectra
you should be able to find positives (clear fits) and exclusions (clear non-fits).
The main advantages of our DIY system are its very low price and the possibility
to use it in combination with an incident light microscope.
When using a 100x objective and the field diaphragm of the microscope in order
to confine the area under investigation you might reach an analysis spot size
as small as 30 Ám (as in the case of the Echiniscus tun).
Further potential applications are the identification of gems, in particular in order to
check for real diamonds, but also a check for poisonous lead white on your window frames
and the identification of synthetic resins.
But here is one serious drawback which must be mentioned: in many cases the green laser
might trigger some disturbing fluorescence which as a rule will overwhelm and spoil
your spectrum. So there will be many samples out there which cannot be analyzed.