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1. (WO2008051478) BLANCHISSAGE OPTIQUE PAR DES IMPULSIONS DE FORTE PUISSANCE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS
What is claimed is:
1. A method comprising:
photobleaching a sample by applying a monochromatic illumination at a first intensity level to said sample for a first duration, wherein said first intensity level is
slightly lower than a photodamage threshold of said sample;
reducing intensity of said illumination from said first intensity level to a second
intensity level without changing wavelength of said illumination, wherein said second intensity level is substantially lower than said first intensity level; and applying said illumination at said second intensity level to said sample for a second
duration so as to measure an optical response of said sample.

2. The method of claim 1, wherein said optical response includes a Raman spectrum of the sample.

3. The method of claim 1, wherein said first and said second intensity levels are related by the following equation:
Pp = (1 + X) PA, wherein X > 0, and wherein "PP" refers to said first intensity level and
"PA" refers to said second intensity level.

4. The method of claim 1, further comprising:
computing a figure-of-merit (FOM) from said optical response;
repeating said photobleaching, said applying, and said computing steps until a most recently computed figure-of-merit is within a predetermined range of an immediately previously computed figure-of-merit; and
after said repeating is over, performing an optical spectroscopic measurement on said sample using said illumination only at said second intensity level.

5. The method of claim 4, wherein performing said optical spectroscopic measurement includes collecting a Raman spectrum of the sample.

6. The method of claim 4, wherein said FOM includes one or more of the following:
a first computation of total intensity of a first plurality of points on a fluorescence
spectrum obtained through measurement of said optical response;
a second computation of sum of square of intensities of a second plurality of points on said fluorescence spectrum;
a first detection of lack of saturation in said fluorescence spectrum; and
a second detection of presence of a CH peak in said fluorescence spectrum.

7. The method of claim 4, wherein said predetermined range is about 2% to 5% above an optical detector readout variation.

8. The method of claim 1, further comprising:
determining said second intensity level by:
applying said illumination to a non-photob leached location on the sample;
varying intensity levels of said illumination applied to said non-photobleached
location and detecting light emitted or scattered from said non- photobleached location at each varied intensity level using an optical
detector; and identifying a highest intensity level that fails to saturate said optical detector
during said varying as said second intensity level.

9. The method of claim 1, further comprising:
using a pre-determined value for said photodamage threshold.

10. The method of claim 9, further comprising:
storing said pre-determined value in an electronic memory prior to said
photobleaching.

1 1. The method of claim 1, further comprising:
determining a value for said photodamage threshold at run time prior to commencing said photobleaching.

12. The method of claim 1, wherein values of said first and said second durations are predetermined or determined at run time.

13. The method of claim 1, wherein said monochromatic illumination is a laser illumination.

14. A system comprising:
a sample; and
an excitation source configured to illuminate said sample using monochromatic light, wherein said excitation source is configured to provide the following:
a first illumination having a first intensity level and configured to be applied to said sample for a first duration so as to photobleach said sample,
wherein said first intensity level is slightly lower than a photodamage
threshold of said sample, and
a second illumination identical in wavelength to said first illumination and
having a second intensity level, wherein said second intensity level is substantially lower than said first intensity level, and
wherein said second illumination is configured to be applied to said sample
after said first illumination for a second duration so as to measure an
optical response of said sample.

15. The system of claim 14, wherein said excitation source includes one of the following: a software-controlled dual intensity CW laser; and
a combination of a fixed intensity CW laser and a neutral density filter.

16. The system of claim 14, wherein said first and said second illuminations are
configured to be applied to said sample along the same optical path.

17. The system of claim 14, wherein said first and said second illuminations are
configured to be applied to said sample along different optical paths.

18. The system of claim 14, further comprising:
a collection optics to collect photons scattered, reflected, or emitted from said sample when said sample is illuminated by said second illumination; and
a spectral analysis system coupled to said collection optics to receive a portion of said collected photons therefrom and to responsively measure a spectrum of said sample using said portion of said collected photons.

19. The system of claim 18, wherein said collection optics includes:
an optical filter for receiving photons emitted, scattered, or reflected from said sample and for generating filtered photons therefrom, wherein said filtered photons
include those of the photons received from the sample that have wavelengths other than the wavelength of said second illumination; and
a collection lens coupled to said optical filter for sending said filtered photons
received from the optical filter to the spectral analysis system.

20. The system of claim 18, wherein said spectral analysis system includes a dispersive spectrometer that comprises:
an entrance slit to receive said portion of said collected photons from said collection optics; and
a plurality of gratings to provide wavelength-specific dispersion of said portion of
said collected photons received at the entrance slit so as to measure said
spectrum of said sample.

21. The system of claim 18, further comprising:
a detector optically coupled to said spectral analysis system to receive an output
signal therefrom and to responsively provide optical data to generate a
wavelength-specific spectral image of said sample.

22. The system of claim 21, wherein the detector is one of the following: a charged
coupled device (CCD), and a complementary metal oxide semiconductor (CMOS) array.

23. The system of claim 14, further comprising:
an optical filter for receiving photons emitted, scattered, or reflected from said sample when said sample is illuminated by said second illumination and for
generating a first set of filtered photons therefrom, wherein said first set of
filtered photons includes those of the photons received from the sample that have wavelengths other than the wavelength of said second illumination;
a liquid crystal-based tunable filter to receive said first set of filtered photons from
said optical filter and to generate a second set of filtered photons therefrom, wherein said second set of filtered photons include only those photons from
said first set of filtered photons that have a wavelength to which said tunable filter is tuned;
a collection lens coupled to said tunable filter for sending said second set of filtered photons received from the tunable filter to a detector; and
said detector coupled to said collection lens to receive said second set of filtered
photons therefrom and to responsively provide optical data to generate a
wavelength-specific spectral image of said sample at the wavelength to which said tunable filter is tuned.

24. A system comprising:
means for applying a laser illumination to a luminescent sample at a first intensity
level and for a first duration so as to photobleach said sample, wherein said first intensity level is slightly lower than a photodamage threshold of said
sample;
means for applying said laser illumination to said sample at a second intensity level and for a second duration after said first duration without changing
wavelength of said illumination, wherein said second intensity level is
substantially lower than said first intensity level; and
means for measuring a spectral response of said sample when said laser illumination is applied to said sample at said second intensity level.

25. The system of claim 24, wherein said means for measuring said spectral response includes means for measuring a Raman spectrum of said sample from photons scattered from said sample in response to said laser illumination at said second intensity level.