Laser Induced Breakdown Spectroscopy (LIBS) Apparatus with Dual CCD Spectrometer

• US 20160334335A1
• Filed: 05/11/2015
• Published: 11/17/2016
• Est. Priority Date: 05/11/2015
• Status: Active Grant

• Current Assignee: Metrohm Spectro Incorporated
• Original Assignee: BWT Property, Inc.
• Inventors: Zhou, Xin Jack, Wang, Sean Xiaolu, Li, Qun
• Granted Patent: US 9,766,182 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• 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

Abstract

This invention discloses a compact laser induced breakdown spectroscopy (LIBS) apparatus suitable for field operations. The LIBS apparatus comprises a Q-switched laser with laser pulse energy between several tens and several thousands of micro joules (μJ), which is significantly lower than that of traditional LIBS lasers. The spectrograph of the LIBS apparatus employs a dual CCD (charge coupled device) design, which maintains compact size and in the meantime offers large spectral coverage and high spectral resolution.

Claims

1. A laser induced breakdown spectroscopy (LIBS) apparatus for measuring the LIBS spectrum of a subject, the LIBS apparatus comprising:

a pulsed laser light source configured to produce a laser beam;

an optical focusing element configured to focus the laser beam onto a surface of the subject to produce a plasma emission; and

an optical spectrometer device configured to measure an optical spectrum of the plasma emission to obtain a LIBS spectrum;

wherein the optical spectrometer device comprises a diffract grating configured to diffract the plasma emission in at least two diffraction orders and at least two detector arrays configured to measure a spectral intensity of the diffracted plasma emission in the at least two diffraction orders.

2. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the pulsed laser light source has a repetition rate of greater than 100 Hz.

3. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the pulsed laser light source has a repetition rate of greater than 1000 Hz.

4. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the pulsed laser light source has a pulse width of less than 10 nanoseconds (ns).

5. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the pulsed laser light source has a pulse energy of 1-10000 micro joules (μ

J).

6. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the pulsed laser light source is a passively Q-switched diode pumped solid state (DPSS) laser.

7. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the at least two detector arrays are CCD (charge coupled device) arrays.

8. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, wherein the at least two diffraction orders are +1 and −

1 diffraction orders.

9. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 1, further comprising a vibration device configured to vibrate the optical focusing element to scan the laser beam over an area on the surface of the subject.

10. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 9, wherein the vibration device produces a 1-dimentional (1-D) vibration pattern.

11. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 9, wherein the vibration device produces a 2-dimentional (2-D) vibration pattern.

12. The laser induced breakdown spectroscopy (LIBS) apparatus of claim 9, wherein the vibration device produces a random vibration pattern.