Analyzer sample detection method and system
A spectrometer system and method including a laser source for directing a laser beam to a sample producing plasma radiation on the sample. At least one fiber of a fiber bundle is connected to an illumination source for directing light to the sample. A spectrometer subsystem receives plasma radiation from the sample via the detection fiber bundle. A camera receives light from the illumination source reflected off the sample for detecting the presence of the sample.
1. A handheld LIBS spectrometer comprising:
a housing;
an optic stage in the housing and moveable with respect to the housing and including a laser focusing lens;
a laser source mounted in the housing for directing a laser beam to a sample via the laser focusing lens for producing a plasma on the sample;
at least one spectrometer in the housing for analyzing plasma radiation;
an illumination source in the housing for directing light to the sample via the laser focusing lens;
a camera in the housing for imaging the sample; and
a controller subsystem responsive to images of the sample and controlling the illumination source, the laser source, and the camera and configured to:
energize the illumination source to direct light to the sample via the laser focusing lens,
control the camera to take a first image of the sample,
deenergize the illumination source,
control the camera to take a second image of the sample,
subtract one of the first and second images of the sample from the other of the first and second images of the sample to produce intensity data, and
disable the laser source if the intensity data falls below a predetermined threshold.
2. The system of claim 1 in which the controller subsystem is further responsive to the at least one spectrometer and configured to analyze plasma radiation spectrometer data to detect whether a sample is present and, if not, disable the laser source.
3. The system of claim 1 further including a first mirror between the laser source and the focusing lens, the first mirror including an aperture for the laser beam to pass therethrough.
4. The system of claim 3 further including a fiber bundle having a common end oriented to receive plasma radiation passing through said focusing lens and redirected to the fiber bundle common end by said first mirror.
5. The system of claim 4 in which one fiber of said fiber bundle is coupled to said at least one spectrometer.
6. The system of claim 4 in which one fiber of said fiber bundle is coupled to said illumination source.
7. The system of claim 1 in which the controller subsystem is configured to control energizing of the laser source and including computer instructions which:
initiate a laser pulse sequence in response to a fire command,
analyze the resulting spectrum from each laser pulse to determine if sample is present,
if the analyzed spectrum reveals a sample is present, continue pulsing the laser to test the sample; and
if the analyzed spectrum reveals a sample is not present, halt the laser pulse sequence.
8. The system of claim 7 in which analyzing the resulting spectrum for each laser pulse includes measuring the maximum signal in a predetermined wavelength range of the spectrum.
9. The system of claim 8 in which the controller subsystem computer instructions automatically halt the laser pulse sequence if the maximum signal amplitude in a predetermined wavelength range of the spectrum is less than a predetermined amplitude.
10. The system of claim 9 in which the predetermined amplitude is 200 and the predetermined wavelength range is 200-400 nm.
11. The system of claim 9 in which the controller subsystem computer instructions automatically continues the pulsing the laser source if the maximum signal amplitude in the predetermined wavelength range is greater than the predetermined amplitude.
12. A handheld LIBS spectrometer comprising:
a housing;
an optic stage in the housing and moveable with respect to the housing and including a laser focusing lens;
a laser source mounted in the housing for directing a laser beam to a sample via the laser focusing lens for producing plasma on the sample;
at least one spectrometer in the housing for analyzing plasma radiation;
an illumination source in the housing for directing light to the sample via the laser focusing lens;
a camera in the housing for imaging for imaging the sample; and
a controller subsystem configured to:
energize the illumination source to direct light to a sample via the laser focusing lens, and
analyze camera images to determine if a sample is present and in response to the analysis, if no sample is present, inhibit energizing the laser source.
13. The system of claim 12 in which the controller subsystem is configured to:
energize the illumination source to direct light to the sample via the laser focusing lens,
control the camera to take a first image of the sample,
deenergize the illumination source,
control the camera to take a second image of the sample,
subtract one of the first and second images of the sample from the other of the first and second images of the sample to produce intensity data, and
disable the laser source if the intensity data falls below a predetermined threshold.
14. A method of LIBS spectroscopy comprising:
directing light to a sample before spectroscopically analyzing the sample;
imaging the sample with a camera while light is directed to the sample;
imaging the sample when no light is directed to the sample;
subtracting the image of the sample when no light is directed to the sample from the image of the sample when light is directed to the sample to produce intensity data;
if the intensity data is below a predefined threshold, inhibiting laser firing; and
if the intensity data is above the predefined threshold, then directing a laser beam to the sample and analyzing plasma radiation created when the laser beam is incident on the sample.
15. The method of claim 14 further including, between laser pulses, directing light to the sample, imaging the sample while light is directed to the sample, imaging the sample when no light is directed to the sample, subtracting the image of the sample when no light is directed to the sample from the image of the sample when light is directed to the sample to produce intensity data, and if the intensity data is below a predefined threshold, inhibiting further laser firing.
16. The method of claim 14 in which directing a laser beam to the sample includes directing the laser beam through an aperture in a mirror and then through a laser focusing lens.
17. The method of claim 16 in which analyzing plasma radiation includes directing plasma radiation to a common end of a fiber bundle and then to a spectrometer via at least one fiber of the fiber bundle.
18. The method of claim 16 in which directing light to the sample includes directing light via a fiber of the fiber bundle to the mirror and then through the laser focusing lens.
19. The method of claim 14 further including:
initiating a laser pulse sequence in response to a fire command,
analyzing the resulting spectrum from each laser pulse to determine if a sample is present,
if the analyzed spectrum reveals a sample is present, continue pulsing the laser to test the sample for a test duration; and
if the analyzed spectrum reveals the sample is not present, halting the laser pulse sequence.
20. The method of claim 19 in which analyzing the resulting spectrum for each laser pulse includes measuring the maximum signal in a predetermined wavelength range of the spectrum.
21. The method of claim 20 including halting the laser pulse sequence if the maximum signal amplitude in a predetermined wavelength range of the spectrum is less than a predetermined amplitude.
22. The method of claim 21 in which the predetermined amplitude is 200 and the predetermined wavelength range is 200-400 nm.
23. The method of claim 21 including automatically continuing pulsing the laser source if the maximum signal amplitude in the predetermined wavelength range is greater than the predetermined amplitude.