Optical fiber arrangement for endoscope

1. An endoscopic probe extending from a proximal end to a distal end thereof, and configured to observe a sample, the probe comprising:

a first waveguide enclosed within an inner sheath and extending from the proximal end to the distal end along an axis of the inner sheath;

a plurality of second waveguides having at least the distal ends thereof arranged in a first ring pattern around the inner sheath to surround the distal end of the first waveguide,

wherein, at the distal end of the inner sheath, the axis of each of the second waveguides is tilted with respect to the axis of the first waveguide by a predetermined angle,

wherein the axis of each of the second waveguides is tilted with respect to the axis of the inner sheath,

wherein one or more of the second waveguides has its distal end polished perpendicular to the axis of the inner sheath, and

wherein the axis of a cone of acceptance for each of the second waveguides is tilted with respect to the axis of the first waveguide by an angle larger than the predetermined angle.

2. The probe of claim 1 , wherein the distal end of each of the second waveguides is tilted with respect to the axis of the inner sheath.

3. The probe of claim 1 ,

wherein the plurality of second waveguides is a plurality of optical fibers, and

wherein one or more of the second waveguides has its distal end polished perpendicular to its fiber axis.

4. The probe of claim 1 ,

wherein, at the distal end of the inner sheath, the distal ends of the plurality of second waveguides are arranged symmetrically in the first ring pattern around the inner sheath to surround the distal end of the first waveguide.

5. The probe of claim 1 , further comprising:

a locking mechanism having a plurality of openings, each opening configured to fit therein one or more of the plurality of second waveguides,

wherein the locking mechanism is configured to lock the plurality of second waveguides with a predetermined tilt configuration around the distal end of the inner sheath.

6. The probe of claim 1 , further comprising:

an angle adjusting mechanism having a plurality of openings, each opening configured to loosely fit therein one or more of the plurality of second waveguides;

wherein the angle adjusting mechanism is configured to adjust, at the distal end of the inner sheath, a tilt angle between the axis of each of the second waveguides with respect to the axis of the first waveguide.

7. The probe of claim 6 , further comprising:

an outer sheath extending from the proximal end to the distal end; and

the angle adjusting mechanism arranged concentric with the inner sheath and the outer sheath,

wherein the angle adjusting mechanism is attached at the distal end of either the inner sheath or outer sheath, and the distal ends of the second waveguides are arranged to surround the distal end of either the inner sheath or the outer sheath, and

wherein the adjusting mechanism adjusts the tilt angle, by rotating one of the outer sheath and the inner sheath with respect to the other.

8. The probe of claim 6 , further comprising:

an outer sheath extending from the proximal end to the distal end; and

a middle rotatable tube arranged concentric with the inner sheath and the outer sheath,

wherein the angle adjusting mechanism is formed at the proximal end of the middle rotatable tube along an outer surface thereof, and a locking mechanism having a plurality of openings configured to fit in each opening one or more of the plurality of second waveguides is formed at the distal end of the outer sheath in the inner surface thereof, and

wherein the angle adjusting mechanism adjusts the tilt angle by rotating the middle rotatable tube with respect to either one of the inner sheath and the outer sheath to which waveguides are attached at a portion proximal to the locking mechanism.

9. The probe of claim 1 , further comprising:

a plurality of third waveguides having at least the distal ends thereof arranged in a second ring pattern around the plurality of second waveguides to surround the distal end of the first waveguide,

wherein, at the distal end of the inner sheath, the axis of each of the third waveguides is tilted with respect to the axis of the first waveguide by the predetermined angle.

10. The probe of claim 9 , wherein, at the distal end of the inner sheath,

the axis of each of the second waveguides is tilted with respect to the axis of the first waveguide by the predetermined angle in a first direction, and

the axis of each of the third waveguides is tilted with respect to the axis of the first waveguide by the predetermined angle in a second direction intersecting the first direction.

11. The probe of claim 9 , wherein, at the distal end of the inner sheath,

the axis of each of the second waveguides is tilted with respect to the axis of the first waveguide by the predetermined angle in a first direction, and

the axis of each of the third waveguides is tilted with respect to the axis of the first waveguide by the predetermined angle in a second direction same as the first direction.

12. The probe of claim 1 , wherein the plurality of second waveguides are multi-modal (MM) optical fibers used as illumination fibers to transmit light from a light source to the sample.

13. The probe of claim 1 , wherein the plurality of second waveguides are multi-modal (MM) optical fibers used as detection fibers to transmit light from the sample to a detector.

14. The probe of claim 1 , wherein the plurality of second waveguides is a plurality of multi-mode (MM) optical fibers,

wherein, at the distal end of the probe, a resultant numerical aperture (NAr) of the MM optical fibers is given by NAr=sin(arcsin(NAf)+T),

where NAf is the numerical aperture of each fiber of the MM optical fibers, and T is the predetermined angle of tilt between the axis of each fiber tilted with respect to the axis of the first waveguide.

15. The probe of claim 1 ,

wherein one or more of the following conditions is satisfied:

0< T< 22 degrees,

0.25< NAr< 0.82,

where T is the predetermined angle of tilt between the axis of each of the second waveguides with respect to the axis of the first waveguide,

where NAr is a resultant numerical aperture (NAr) at the distal end of the probe, resulting from the plurality second waveguides, and

where NAr=sin(arcsin(NAf)+T) and NAf is the numerical aperture of each of the second waveguides.

16. The probe of claim 1 , wherein the second waveguides are optical fibers wrapped around the inner sheath in a helical manner such that, at the distal end of the inner sheath, the axis of each fiber is tilted in a plane which is substantially tangent to the outer surface of the inner sheath.

17. The probe of claim 1 , wherein the second waveguides are optical fibers arranged on the outer surface of the inner sheath, and wherein the distal ends of the optical fibers are tilted with respect to the axis of the inner sheath in a manner such that, at the distal end of the inner sheath, the axis of each fiber is substantially tangent to the distal edge of the inner sheath, in the plane perpendicular to the axis of inner sheath.

18. The probe of claim 1 , further comprising:

a plurality of third waveguides having at least the distal ends thereof arranged in a second ring pattern around the inner sheath to surround the distal end of the first waveguide, the second ring pattern being concentric to first ring pattern,

wherein, at the distal end of the inner sheath, the axis of each of the second waveguides is tilted with respect to the axis of the first waveguide by a first tilt angle T 1 , and the axis of each of the third waveguides is tilted with respect to the axis of the first waveguide by a second tilt angle T 2 , where T 2 >T 1 .

19. An endoscopic system comprising:

a processor,

a first waveguide enclosed within an inner sheath and extending from the proximal end to the distal end along an axis of the inner sheath, the first waveguide configured to irradiate a sample with light from a light source;

a plurality of second waveguides having at least the distal ends thereof arranged in one or more ring patterns around the inner sheath to concentrically surround the distal end of the first waveguide,

wherein, at the distal end of the inner sheath, the axis of each of the second waveguides is tilted with respect to the axis of the first waveguide by a tilt angle T where 0<T≤22 degrees,

wherein the plurality of second waveguides are configured to collect light from the sample and deliver the collected light to a detector or an spectrometer; and

wherein the processor is configured to process data from the spectrometer or detector and form an image.