Measurement probe and biological optical measurement system

1. A measurement probe configured to be detachably connected to a biological optical measurement apparatus that performs an optical measurement on body tissue, the measurement probe comprising:

an illumination fiber configured to irradiate the body tissue with illumination light, the illumination fiber having a distal end from which the illumination light emits; and

a plurality of detection fibers configured to detect return light of at least one of the illumination light reflected from the body tissue and the illumination light scattered from the body tissue, each of the plurality of detection fibers having a distal end that receives the return light, wherein at least two of the distal ends of the detection fibers are spaced a different distance from the distal end of the illumination fiber, wherein

on a plane which is spaced from the distal end of the illumination fiber and the distal ends of the plurality of detection fibers and through which the illumination light and the return light can pass, a detection area of the return light in each of the plurality of detection fibers is identical with an illumination area of the illumination fiber.

2. The measurement probe according to claim 1 , further comprising:

an optical element located at the distal ends of the detecting fibers and the distal end of the illumination fiber and having a columnar shape and a distal end; and

a stop at the distal end of the optical element and having an opening, wherein the illumination light can only pass through the opening.

3. The measurement probe according to claim 2 , further comprising a fiber retainer that retains the illumination fiber and the plurality of detection fibers, a distal end of the fiber retainer having a spherical surface.

4. The measurement probe according to claim 2 , wherein a numerical aperture of each of the plurality of detection fibers is larger than a numerical aperture of the illumination fiber.

5. The measurement probe according to claim 1 , further comprising an optical element located at the distal ends of the detection fibers and the distal end of the illumination fiber and having a columnar shape, wherein

the optical element has an outer diameter that defines an outer diameter of the illumination area.

6. The measurement probe according to claim 5 , further comprising a fiber retainer that retains the illumination fiber and the plurality of detection fibers, a distal end of the fiber retainer having a spherical surface.

7. The measurement probe according to claim 5 , wherein a numerical aperture of each of the plurality of detection fibers is larger than a numerical aperture of the illumination fiber.

8. The measurement probe according to claim 1 , wherein a numerical aperture of the illumination fiber is smaller than a numerical aperture of each of the plurality of detection fibers.

9. The measurement probe according to claim 1 , further comprising a stress application unit configured to apply stress to the plurality of detection fibers.

10. The measurement probe according to claim 9 , wherein the stress application unit includes one or more members each having a lateral surface of a radius smaller than an allowable bending radius of each of the plurality of detection fibers.

11. The measurement probe according to claim 1 , further comprising a fiber retainer that retains the illumination fiber and the plurality of detection fibers, a distal end of the fiber retainer having a spherical surface.

12. The measurement probe according to claim 1 , wherein the distal end of the illumination fiber and the distal ends of the detection fibers are in the same plane.

13. A biological optical measurement system, comprising:

the measurement probe according to claim 1 ; and

an optical measurement apparatus to which the measurement probe is detachably connected and which is configured to supply the measurement probe with the illumination light and to receive the return light emitted from the measurement probe to perform an optical measurement on the body tissue.

14. A measurement probe configured to be detachably connected to a biological optical measurement apparatus that performs an optical measurement on body tissue, the measurement probe comprising:

an illumination fiber configured to irradiate the body tissue with illumination light, the illumination fiber having a distal end from which the illumination light emits; and

a plurality of detection fibers configured to detect return light of at least one of the illumination light reflected from the body tissue and the illumination light scattered from the body tissue, each of the plurality of detection fibers having a distal end that receives the return light, wherein at least two of the distal ends of the detection fibers are spaced radially a different distance from the distal end of the illumination fiber, wherein

on a plane which is spaced from the distal end of the illumination fiber and the distal ends of the plurality of detection fibers and through which the illumination light and the return light can pass, a detection area of the return light in each of the plurality of detection fibers is identical with an illumination area of the illumination fiber.

15. The measurement probe according to claim 14 , further comprising:

an optical element located at the distal ends of the detecting fibers and the distal end of the illumination fiber and having a columnar shape and a distal end; and

a stop at the distal end of the optical element and having an opening, wherein the illumination light can only pass through the opening.

16. The measurement probe according to claim 14 , further comprising an optical element located at the distal ends of the detection fibers and the distal end of the illumination fiber and having a columnar shape, wherein

the optical element has an outer diameter that defines an outer diameter of the illumination area.

17. The measurement probe according to claim 14 , further comprising a fiber retainer that retains the illumination fiber and the plurality of detection fibers, a distal end of the fiber retainer having a spherical surface.

18. The measurement probe according to claim 14 , wherein a numerical aperture of each of the plurality of detection fibers is larger than a numerical aperture of the illumination fiber.

19. The measurement probe according to claim 14 , further comprising a stress application unit configured to apply stress to the plurality of detection fibers.

20. The measurement probe according to claim 19 , wherein the stress application unit includes one or more members each having a lateral surface of a radius smaller than an allowable bending radius of each of the plurality of detection fibers.

21. A biological optical measurement system, comprising:

the measurement probe according to claim 14 ; and

an optical measurement apparatus to which the measurement probe is detachably connected and which is configured to supply the measurement probe with the illumination light and to receive the return light emitted from the measurement probe to perform an optical measurement on the body tissue.

22. A measurement probe configured to be detachably connected to a biological optical measurement apparatus that performs an optical measurement on body tissue, the measurement probe having a longitudinal axis and comprising:

an illumination fiber (1) configured to irradiate the body tissue with illumination light, (2) extending along the longitudinal axis, and (3) having a distal end from which the illumination light emits; and

a plurality of detection fibers (1) configured to detect return light of at least one of the illumination light reflected from the body tissue and the illumination light scattered from the body tissue and (2) extending along the longitudinal axis; wherein:

each of the plurality of detection fibers includes a distal end that receives the return light;

each of the distal ends of the detection fibers is spaced a different distance from the distal end of the illumination fiber along the longitudinal axis; and

on a plane which is spaced from the distal end of the illumination fiber and the distal ends of the plurality of detection fibers and through which the illumination light and the return light can pass, a detection area of the return light in each of the plurality of detection fibers is identical with an illumination area of the illumination fiber.