System for measuring the absorption of a laser emission by a sample
AssigneesCentre National De La Recherche Scientifique, Universite Paris-Saclay
InventorAlexandre Dazzi
Life of this patent
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Abstract
A system for measuring the absorption of a laser radiation by a sample is provided. The system comprises: •(i) a pulsed laser source, suitable for emitting pulses at a repetition frequency fl and arranged so as to illuminate the sample; •(ii) an AFM probe arranged so as to be able to be placed in contact with the region of the surface of the sample on one side, the AFM probe having a mechanical resonance mode at a frequency fm; and •(iii) a detector configured to measure the amplitude of the oscillations of the AFM probe resulting from the absorption of the laser radiation by the region of the surface of the sample, characterized in that it also comprises a translation system designed to displace the sample at a frequency fp.
Claims13
A system for measuring the absorption of a laser radiation by a sample with a nanometric or subnanometric spatial resolution comprising:
- (i) a pulsed laser source, suitable for emitting pulses at a tunable wavelength and at a repetition frequency fl and arranged so as to illuminate a portion of the sample so as to induce a thermal expansion of a region of the surface of the sample;
- (ii) an AFM probe comprising a beam bearing an AFM tip oriented in a so-called vertical direction and arranged so as to be able to be placed in contact with the region of the surface of the sample in which a thermal expansion is induced on one side and held mechanically on another side, the AFM probe having a mechanical resonance mode at a frequency fm;
- and
- (iii) a detector configured to measure the amplitude of the oscillations of the AFM probe resulting from the absorption of the laser radiation by the region of the surface of the sample,
- wherein the system further comprises a piezoelectric translation system designed to displace the sample in said vertical direction, the displacement being modulated at a frequency fp, and in that the detector is configured to measure the amplitude of a frequency component fm of the oscillations of the AFM probe, the frequency fp being chosen so as to generate oscillations of the AFM probe at the frequency fm by a mix of acoustic waves.
A method for measuring the absorption of a laser radiation by a sample with a nanometric or subnanometric spatial resolution, the method comprising the following steps:
- a. illuminating a region of the surface of the sample with a pulsed laser source designed to emit pulses at a tunable wavelength and at a repetition frequency fl;
- b. placing an AFM probe, comprising a beam having an AFM tip oriented in a so-called vertical direction on one side and held mechanically on another side, so as to be able to place the AFM tip in contact with the illuminated region of the surface of the sample on one side, the probe having a mechanical resonance mode at a frequency fm;
- c. displacing the surface of the sample in said vertical direction using a piezoelectric translation system supporting the sample, the displacement being modulated at a frequency fp chosen so as to generate oscillations of the AFM probe at the frequency fm by a mix of acoustic waves, and
- d. detecting and measuring the amplitude of the oscillations of the AFM probe resulting from the absorption of the laser radiation by the surface.
Dependencies are inferred from the claim text.