Handheld laser induced breakdown spectroscopy device

• US 9,506,869 B2
• Filed: 10/14/2014
• Issued: 11/29/2016
• Est. Priority Date: 10/16/2013
• Status: Active Grant

• Current Assignee: TSI Incorporated
• Original Assignee: TSI Incorporated
• Inventors: Quant, Frederick, Farmer, Kenneth R., Tan, Phillip V., Stipe, Christopher B., Buckley, Steven G., Stockinger, Erik, Jensen, Daniel
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Amara, Mohamed K
• Application Number:
  US14/514,294
• Publication Number:
  US 20150103334A1
• Time in Patent Office: 777 Days
• Field of Search: 356/51, 356/326, 356/328, 356/402, 356/73
• US Class Current: 1/1
• CPC Class Codes: G01J 2003/1861 Transmission gratings
• CPC Class Codes: G01J 3/0221 the fibers defining an entry slit
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• 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 2201/0221 Portable; cableless; compact; hand-held
• CPC Class Codes: G01N 2201/0697 Pulsed lasers

Abstract

A novel device, method and systems disclosed managing the thermal challenges of LIBS laser components and a spectrometer in a handheld structure as well the use of simplified light signal collection which includes a bare fiber optic to collect the emitted light in close proximity to (or in contact with) the test material. In one example embodiment of the handheld LIBS device, a burst pulse frequency is 4 kHz is used resulting in a time between pulses of about 250 μs which is a factor of 10 above that of other devices in the prior art. In a related embodiment, an active Q-switched laser module is used along with a compact spectrometer module using a transmission grating to improve LIBS measurement while substantially reducing the size of the handheld analyzer.

Claims

1. An apparatus for performing laser-induced breakdown spectroscopy, comprising:

a housing configured as a handheld apparatus having an exit for electromagnetic radiation generated from within the housing;

an intracavity, active Q-switched OPO Nd;

YAG diode pumped solid state laser module that operates at an eye-safe wavelength of about 1574 nanometers and provides instantaneous laser emissions upon actuation, with a controller system operatively coupled thereto disposed and within the housing, the intracavity laser module including a reflective mirror and an output coupler mirror that form a first resonant cavity and form a second resonant cavity within the first resonant cavity for directing a laser beam through the exit with an energy level per pulse from about 4 millijoules (mJ) to about 10 millijoules (mJ), wherein the laser module operates at a power mode of about 30 watts or less, and wherein the active Q-switched Nd;

YAG OPO diode pumped solid state laser module and the laser beam operate with a numerical aperture as low as about 0.0555;

a fiber optic member disposed substantially in the housing for transferring light collected at a distal end of the fiber member without a collection lens or reflective mirror from a plasma induced of a sample material by the laser beam, the fiber optic member distal end being disposed adjacent the exit;

a spectrometer module disposed substantially in the housing for receiving light from a proximal end of the fiber optic member, the spectrometer module producing a spectral distribution corresponding to the sample material from the received light, wherein the controller system provides timing and control between the laser pulse and a spectrometer shutter of the spectrometer module; and

a sampling point interface member with a proximal opening disposed over the housing exit, the laser beam adapted to be projected through the proximal opening and through a distal opening of the interface member, the fiber optic member being disposed adjacent to the interface member distal opening, wherein the sampling point interface is configured in the shape of a cone member, the cone member having an opening opposite an exit opening disposed over the housing exit, wherein an end of the cone member includes a housing-to-sample material interaction section disposed about the housing exit, the interaction section having an area of less than about 2 cm^2.

2. The apparatus according to claim 1, wherein the spectrometer module includes a first spectrometer configured to operate in an ultraviolet wavelength range and a second spectrometer configured to operate in a visible wavelength range.

3. The apparatus according to claim 2, wherein the first and second spectrometer include a transmission grating.

4. The apparatus according to claim 1, further comprising a power source disposed within said housing and configured to deliver electric power to at least said laser module and said spectrometer module.

5. The apparatus according to claim 1, further comprising a display configured to display information and to receive commands from a user.

6. The apparatus according to claim 1, further comprising a sighting member configured to assist a user in directing the laser beam, wherein the sighting member is selected from the group consisting of a heat sink member disposed above the laser module and a targeting LED member adapted to project light at a target on the sampled material.

7. The apparatus according to claim 1, further comprising at least one proximity sensor near the housing exit, the proximity sensor configured to sense location of sampled material.

8. The apparatus according to claim 1, further comprising a haptic feedback module for providing feedback that a sample analysis is at an acceptable precision level.

9. The apparatus according to claim 1, wherein the spectrometer module includes a timing aperture or shutter configurable to delay for a predetermined time the collection of light after an initial plasma is formed.

10. The apparatus according to claim 1, wherein the OPO diode pumped laser module provides about 5 samples per minute, with about 60 pulses to about 100 pulses per sample, and less than about 3 seconds to about 12 seconds between samples.