LiBS Analyzer Sample Presence Detection System and Method

• US 20170219429A1
• Filed: 04/11/2017
• Published: 08/03/2017
• Est. Priority Date: 02/26/2015
• Status: Active Grant

• Current Assignee: SciAps, Inc.
• Original Assignee: SciAps, Inc.
• Inventors: Day, David R., Sackett, Donald W.
• Granted Patent: US 9,970,815 B2
• Time in Patent Office: Days
• CPC Class Codes: G01J 3/027 Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/069 Supply of sources

Abstract

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.

Claims

1. A LIBS analysis method comprising:

initiating a laser pump sequence;

analyzing 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 analyzed radiation is low intensity pre-firing radiation emitted by the laser and analyzing radiation to determine if the sample is present includes detecting said low intensity pre-firing radiation and reflected by the sample.

3. The method of claim 2 in which the intensity of said low intensity pre-firing radiation is compared to a predetermined minimum.

4. The method of claim 2 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.

5. The method of claim 4 in which there is a short pump duration before each full laser discharge pump duration in the laser pump sequence.

6. The method of claim 1 in which analyzing radiation to determine if the sample is present includes analyzing the plasma using a spectrometer producing a spectrum.

7. The method of claim 6 in which analyzing includes measuring the maximum signal in a predetermined wavelength range of the spectrum.

8. The method of claim 7 in which if the maximum signal amplitude in a predetermined wavelength range of the spectrum is less than a predetermined amplitude then the laser pump sequence is halted.

9. The method of claim 8 in which the predetermined amplitude is 200 and the predetermined wavelength range is 200-400 nm.

10. The method of claim 6 further including analyzing the spectrometer produced spectrum to determine elements present in the sample by averaging spectrum results for each laser discharge.

11. The method of claim 10 in which any spectrum produced by any laser discharge subsequent to a determination that the sample not present is ignored.

12. 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