LiBS analyzer sample presence detection system and method
A LIBS analyzer and method includes a laser configured to produce a plasma on a sample at a focal point on the sample and a spectrometer responsive to radiation emitted from the plasma and configured to produce an output spectrum. A detector is positioned to detect low intensity pre-firing radiation produced by the laser and reflected off the sample from the focal point. The intensity of the low intensity pre-firing radiation is compared to a predetermined minimum and the laser pump sequence is halted if the intensity of the low intensity pre-firing radiation is less than the predetermined minimum.
1. A LIBS analysis method comprising:
initiating a laser pump sequence to produce low intensity pre-firing radiation;
analyzing said low intensity pre-firing radiation to determine if a sample is present;
if the analysis reveals the sample is present, continuing the laser pump sequence; and
if the analysis reveals the sample is not present, halting the laser pump sequence.
2. The method of claim 1 in which the intensity of said low intensity pre-firing radiation is compared to a predetermined minimum.
3. The method of claim 1 in which a laser pump sequence includes, at least before the first full laser discharge pump duration, a short pump duration which produces said low intensity pre-firing radiation but not a high intensity laser discharge.
4. The method of claim 3 in which there is a short pump duration before each full laser discharge pump duration in the laser pump sequence.
5. A LIBS analysis method comprising:
firing a laser configured to produce a plasma on a sample at a focal point on the sample;
receiving radiation emitted from the plasma and producing a spectrum;
detecting low intensity pre-firing radiation produced by the laser and reflected off the sample;
comparing the intensity of said low intensity pre-firing radiation to a predetermined minimum and halting laser firing if the intensity of said low intensity pre-firing radiation is less than said predetermined minimum; and
continue firing the laser if the intensity of said low intensity pre-firing radiation is greater than said predetermined minimum.