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1. (WO2017139885) METHOD AND SYSTEM FOR IMPROVING LATERAL RESOLUTION IN OPTICAL SCANNING MICROSCOPY
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CLAIMS

1 . A method for improving lateral resolution in optical microscopy, the method comprising:

(a) generating a source optical beam;

(b) converting the source optical beam into an excitation Bessel-type beam having a central lobe and at least one side lobe, the converting comprising:

(i) passing the source optical beam through an axicon, thereby converting the source optical beam into an intermediate Bessel-type beam;

(ii) passing the intermediate Bessel-type beam through a Fourier-transform lens, thereby converting the intermediate Bessel-type beam into an annular beam; and

(iii) passing the annular beam through an objective, thereby converting the annular beam into the excitation Bessel-type beam;

(c) focusing the excitation Bessel-type beam onto a focal plane of the objective within or on a sample, thereby generating a sample light signal from the sample;

(d) spatially filtering the sample light signal, the spatial filtering comprising rejecting, from the sample light signal, light originating from outside of the focal plane of the objective and light generated by the at least one side lobe of the excitation Bessel-type beam, and permitting passage, as a filtered light signal, of light generated by the central lobe of the excitation Bessel-type beam; and

(e) detecting the filtered light signal.

2. The method of claim 1 , wherein step (a) comprises generating a laser beam as the source optical beam.

3. The method of claim 1 or 2, wherein step (a) comprises generating a Gaussian beam as the source optical beam, sub-step (i) of step (b) comprises generating a Bessel-Gauss beam as the intermediate Bessel-type beam, and sub-step (iii) of step (b) comprises generating a Bessel-Gauss beam as the excitation Bessel-type beam.

4. The method of any one of claims 1 to 3, wherein step (a) comprises generating the source optical beam in a wavelength range extending from 200 nanometers to 5 micrometers.

5. The method of any one of claims 1 to 4, further comprising a step of adjusting a focal length of the Fourier-transform lens so that a back focal plane of the Fourier-transform lens coincides with a center of the intermediate Bessel-type beam produced by the axicon.

6. The method of any one of claims 1 to 5, wherein step (d) comprises passing the sample light signal through an aperture.

7. The method of claim 6, wherein step (d) further comprises adjusting at least one of a size, a shape and a position of the aperture in accordance with a width and a position of the central lobe of the excitation Bessel-type beam.

8. The method of claim 7, wherein adjusting at least one of the size, the shape and the position of the aperture comprises adjusting a linear dimension of the aperture in a range from 1 micrometer to 1 millimeter.

9. The method of any one of claims 1 to 8, further comprising a step of scanning the excitation Bessel-type beam over the sample.

10. An optical microscopy system comprising:

an optical source configured to generate a source optical beam;

beam-conditioning optics disposed in a path of the source optical beam, the beam- conditioning optics comprising:

an axicon positioned and configured to convert the source optical beam into an intermediate Bessel-type beam; and

a Fourier-transform lens positioned and configured to convert the intermediate Bessel-type beam into an annular beam;

an objective disposed in a path of the annular beam for converting the annular beam into an excitation Bessel-type beam having a central lobe and at least one side lobe, the objective focusing the excitation Bessel-type beam onto a focal plane of the objective within or on a sample, thereby generating a sample light signal from the sample;

a spatial filter disposed in a path of the sample light signal, the spatial filter being configured to reject, from the sample light signal, light originating from outside of the focal plane of the objective and light generated by the at least one side lobe of the excitation Bessel-type beam, and permitting passage, as a filtered light signal, of light generated by the central lobe of the excitation Bessel-type beam; and

a detector configured to detect the filtered light signal.

1 1 . The optical microscopy system of claim 10, wherein the optical source is a laser source configured to generate a laser beam as the source optical beam.

12. The optical microscopy system of claim 1 1 , wherein the system is configured for one of confocal laser scanning microscopy and two-photon laser scanning microscopy.

13. The optical microscopy system of any one of claims 10 to 12, wherein the optical source is configured to generate a Gaussian beam as the source optical beam, the axicon is positioned and configured to generate a Bessel-Gauss beam as the intermediate Bessel-type beam, and the objective is positioned and configured to generate a Bessel-Gauss beam as the excitation Bessel-type beam.

14. The optical microscopy system of any one of claims 10 to 13, further comprising a switching module disposed between the optical source and the beam-conditioning optics, the switching module being configured for operation between a first operating mode, wherein the switching module directs the source optical beam onto the beam-conditioning optics, and a second operating mode, wherein the switching module directs the source optical beam along a path that bypasses the beam-conditioning optics.

15. The optical microscopy system of any one of claims 10 to 14, wherein the optical source is configured to generate the source optical beam in a wavelength range extending from 200 nanometers to 5 micrometers.

16. The optical microscopy system of any one of claims 10 to 15, wherein the axicon is a refractive axicon.

17. The optical microscopy system of claim 16, wherein the axicon has an axicon angle ranging from 1 ° to 5°.

18. The optical microscopy system of any one of claims 10 to 17, wherein the Fourier-transform lens has an adjustable focal length.

19. The optical microscopy system of any one of claims 10 to 18, further comprising a scanning module configured to relay the annular beam generated by the Fourier-transform lens to the objective and to scan the excitation Bessel-type beam over the sample.

20. The optical microscopy system of any one of claims 10 to 19, wherein the axicon and the Fourier-transform lens are separated from each other by a distance such that a back focal plane of the Fourier-transform lens coincides with a center of the intermediate Bessel-type beam produced by the axicon.

21 . The optical microscopy system of any one of claims 10 to 20, wherein the Fourier-transform lens has a front focal plane and the objective has a back-aperture plane, the front focal plane of the Fourier-transform lens being optically conjugate with the back-aperture plane of the objective.

22. The optical microscopy system of any one of claims 10 to 21 , wherein the spatial filter comprises a light-blocking portion surrounding an aperture, the light-blocking portion being configured to reject the light originating from outside of the focal plane and the light generated by the at least one side lobe of the excitation Bessel-type beam, and the aperture being configured to permit passage therethrough of the light generated by the central lobe of the excitation Bessel-type beam.

23. The optical microscopy system of claim 22, wherein the aperture has a size ranging from 1 micrometer to 1 millimeter.

24. The optical microscopy system of claim 22 or 23, wherein the aperture has at least one of an adjustable size, an adjustable shape and an adjustable position.

25. The optical microscopy system of any one of claims 22 to 24, wherein the aperture is circular.