Analytical method using laser-induced breakdown spectroscopy

• US 5,751,416 A
• Filed: 08/29/1996
• Issued: 05/12/1998
• Est. Priority Date: 08/29/1996
• Status: Expired due to Fees

• Current Assignee: Mississippi State University
• Original Assignee: Mississippi State University
• Inventors: Cook, Robert L., Zhang, Hansheng, Singh, Jagdish P., Yueh, Fang-Yu
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Ratliff, Reginald A.
• Application Number:
  US08/705,267
• Time in Patent Office: 621 Days
• Field of Search: 356/311, 356/300, 356/318, 356/38, 356/36, 356/417
• US Class Current: 356/311
• 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 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/30 Measuring the intensity of spectral lines directly on the spectrum itself G01J3/42, G01J3/44 take precedence
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma

Abstract

The invention relates to an analytical method using laser-induced breakdown spectroscopy.

Claims

1. A laser-induced breakdown spectroscopy apparatus comprising:

means for providing laser light;

a mirror harmonic separator;

a coated dichroic mirror;

a focusing lens system; and

a detector,

wherein laser light is directed via said mirror harmonic separator, said dichroic mirror and said focusing lens system onto a sample to be analyzed; and

an emission spectrum of said sample is directed via said focusing lens system through said dichroic mirror to said detector.

2. The apparatus of claim 1, wherein said detector is an intensified diode array detector or an intensified charge couple device detector.

3. The apparatus of claim 1, wherein said dichroic mirror transmits wavelengths in the range of 180-1,000 nm, but reflects wavelengths from 500-540 nm, and said laser light is produced from an Nd:

YAG laser.

4. The apparatus of claim 1, wherein said dichroic mirror is positioned at a 45°

angle relative to a line between said detector and said sample to be analyzed.

5. The apparatus of claim 1, further comprising a doubling crystal.

6. The apparatus of claim 1, wherein said means for providing laser light is a pulsed laser selected from the group consisting of a CO₂, excimer krypton fluoride, neodymium yttrium-aluminum garnet, ruby, titanium sapphire, aluminum gallium arsenide, indium gallium arsenide phosphide, aluminum indium gallium phosphide, and dye lasers.

7. The apparatus of claim 1, wherein said focussing lens has a focal length of 100-1,000 mm.

8. The apparatus of claim 1, wherein said means for providing laser light has a pulse power density of ≧

1 GW/cm².

9. The apparatus of claim 1, wherein said means for providing laser light is a pulsed laser operating at a frequency of 5-30 Hz.

10. The apparatus of claim 1, wherein said means for providing laser light is a pulsed laser sending a pulse of 5-15 n sec.

11. The apparatus of claim 1, further comprising a fiber optic link between said focusing lens system and said detector.

12. The apparatus of claim 11, wherein said fiber optic link is a fiber optic bundle having a core diameter of 0.05 to 0.2 mm.

13. A method for analyzing composition of molten glass by laser-induced breakdown spectroscopy, comprising analyzing a sample of molten glass using:

means for providing laser light, a mirror harmonic separator, a coated dichroic mirror, a focusing lens system, and a detector wherein laser light is directed via said mirror harmonic separator, said dichroic mirror and said focusing lens system onto a sample to be analyzed and including directing an emission spectrum of said sample via said focusing lens to said dichroic mirror to said detector.

14. An instrument for process control using:

means for providing laser light, a mirror harmonic separator, a coated dichroic mirror, a focusing lens system, and a detector wherein laser lightis directed via said mirror harmonic separator, said dichroic mirror and said focusing lens system onto a sample to be analyzed and including directing an emission spectrum of said sample via said focusing lens to said dichroic mirror to said detector.