Method and apparatus for depth profile analysis by laser induced plasma spectros copy
First Claim
1. A method of spectrochemical depth-profile analysis of heterogeneous material, comprising:
- a) directing a first burst of ablation laser pulses in a first beam at a sample to form an ablation crater with a bottom and wall;
b) directing a second single pulse or burst of laser pulses in a second beam having a smaller width than said first beam at the bottom of said crater so as to create a plasma that emits radiation representative of a component in the sample without significant contribution from the wall of the ablation crater, c) measuring the intensity of radiation from said plasma;
d) determining the concentration of said selected component in said material from the intensity of said radiation; and
e) evaluating the depth at which said plasma is created.
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Abstract
In a method of spectrochemical depth-profile analysis of heterogeneous materials, a first burst of ablation laser pulses in a first beam is directed at a sample to form an ablation crater. A second single pulse or burst of laser pulses in a second beam having a smaller width than said first beam is then directed at the bottom of the crater so as to create a plasma that emits radiation representative of a component in the sample without a significant contribution from the walls of the ablation crater. The intensity of radiation from the plasma is measured and the concentration of the selected component is determined from the intensity of the radiation. The depth at which the measurement is taken is then evaluated and the above steps repeated to determined the evolution of concentration of said selected component as a function of depth.
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Citations
32 Claims
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1. A method of spectrochemical depth-profile analysis of heterogeneous material, comprising:
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a) directing a first burst of ablation laser pulses in a first beam at a sample to form an ablation crater with a bottom and wall;
b) directing a second single pulse or burst of laser pulses in a second beam having a smaller width than said first beam at the bottom of said crater so as to create a plasma that emits radiation representative of a component in the sample without significant contribution from the wall of the ablation crater, c) measuring the intensity of radiation from said plasma;
d) determining the concentration of said selected component in said material from the intensity of said radiation; and
e) evaluating the depth at which said plasma is created. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for laser-based spectrochemical depth-profile analysis of a heterogeneous material, comprising:
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an energy source for generating pulses of energy in the form of a first beam of predetermined width incident on a sample to cause ablation thereof and thereby form a crater with a bottom and a wall;
an energy source for generating a single pulse or burst of pulses in a second beam of laser light, said second beam having a width less than said first beam and being directed at the bottom of said crater so as to form a plasma emitting radiation representative of a selected component present in said material without significant contribution from the wall of the crater;
a detector for measuring the intensity of radiation of said selected component at different depths of crater; and
a depth profile evaluator for determining the depth of the crater for each radiation intensity measurement. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification