Abstract

Endoscopic imaging through a multicore fiber (MCF) is widely used but is affected by pixelated images, which limits its resolution to a few micrometers. This is due to the spacing between the cores in the MCF, which is large enough to avoid core-to-core light coupling. Wavefront shaping techniques have been shown to focus light to a resolution finer than the inter core spacing, however a long calibration procedure is needed. Moreover the calibration depends on the optical fiber conformation. Here, we show a calibration method using only one digital hologram. The method is based on digital phase conjugation and the memory effect of the MCF to focus and scan a spot. In addition, we show how simple patterns can be projected using the same multicore fiber.

© 2015 Optical Society of America

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References

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    [Crossref]
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    [Crossref] [PubMed]
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    [Crossref] [PubMed]
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    [Crossref] [PubMed]

2015 (2)

2014 (1)

2013 (6)

2012 (4)

I. N. Papadopoulos, S. Farahi, C. Moser, and D. Psaltis, “Focusing and scanning light through a multimode optical fiber using digital phase conjugation,” Opt. Express 20(10), 10583–10590 (2012).
[Crossref] [PubMed]

S. Bianchi and R. Di Leonardo, “A multi-mode fiber probe for holographic micromanipulation and microscopy,” Lab Chip 12(3), 635–639 (2012).
[Crossref] [PubMed]

T. Čižmár and K. Dholakia, “Exploiting multimode waveguides for pure fibre-based imaging,” Nat. Commun. 3, 1027 (2012).
[Crossref] [PubMed]

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

2011 (1)

2008 (2)

2007 (2)

2005 (1)

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

1988 (2)

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

I. Freund, M. Rosenbluh, and S. Feng, “Memory effects in propagation of optical waves through disordered media,” Phys. Rev. Lett. 61(20), 2328–2331 (1988).
[Crossref] [PubMed]

1954 (1)

H. H. Hopkins and N. S. Kapany, “A flexible fibrescope, using static scanning,” Nature 173(4392), 39–41 (1954).
[Crossref]

Amitonova, L. V.

Andresen, E. R.

Bellanger, C.

Bianchi, S.

S. Bianchi and R. Di Leonardo, “A multi-mode fiber probe for holographic micromanipulation and microscopy,” Lab Chip 12(3), 635–639 (2012).
[Crossref] [PubMed]

Bouwmans, G.

Brignon, A.

Caravaca-Aguirre, A. M.

Chen, X.

Cheung, E. L. M.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Choi, W.

D. Kim, J. Moon, M. Kim, T. D. Yang, J. Kim, E. Chung, and W. Choi, “Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle,” Opt. Lett. 39(7), 1921–1924 (2014).
[Crossref] [PubMed]

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Choi, Y.

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Chung, E.

D. Kim, J. Moon, M. Kim, T. D. Yang, J. Kim, E. Chung, and W. Choi, “Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle,” Opt. Lett. 39(7), 1921–1924 (2014).
[Crossref] [PubMed]

G. Oh, E. Chung, and S. H. Yun, “Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging,” Opt. Fiber Technol. 19(6), 760–771 (2013).
[Crossref]

Cižmár, T.

T. Čižmár and K. Dholakia, “Exploiting multimode waveguides for pure fibre-based imaging,” Nat. Commun. 3, 1027 (2012).
[Crossref] [PubMed]

Cocker, E. D.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Colineau, J.

Conkey, D. B.

Dasari, R. R.

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Dholakia, K.

T. Čižmár and K. Dholakia, “Exploiting multimode waveguides for pure fibre-based imaging,” Nat. Commun. 3, 1027 (2012).
[Crossref] [PubMed]

Di Leonardo, R.

S. Bianchi and R. Di Leonardo, “A multi-mode fiber probe for holographic micromanipulation and microscopy,” Lab Chip 12(3), 635–639 (2012).
[Crossref] [PubMed]

Dunsby, C.

Fang-Yen, C.

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Farahi, S.

Feng, S.

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

I. Freund, M. Rosenbluh, and S. Feng, “Memory effects in propagation of optical waves through disordered media,” Phys. Rev. Lett. 61(20), 2328–2331 (1988).
[Crossref] [PubMed]

Flusberg, B. A.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

French, P. M. W.

Freund, I.

I. Freund, M. Rosenbluh, and S. Feng, “Memory effects in propagation of optical waves through disordered media,” Phys. Rev. Lett. 61(20), 2328–2331 (1988).
[Crossref] [PubMed]

Hopkins, H. H.

H. H. Hopkins and N. S. Kapany, “A flexible fibrescope, using static scanning,” Nature 173(4392), 39–41 (1954).
[Crossref]

Huignard, J. P.

Jung, J. C.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Kane, C.

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

Kapany, N. S.

H. H. Hopkins and N. S. Kapany, “A flexible fibrescope, using static scanning,” Nature 173(4392), 39–41 (1954).
[Crossref]

Kim, D.

Kim, J.

Kim, M.

D. Kim, J. Moon, M. Kim, T. D. Yang, J. Kim, E. Chung, and W. Choi, “Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle,” Opt. Lett. 39(7), 1921–1924 (2014).
[Crossref] [PubMed]

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Lee, K. J.

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Lee, P. A.

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

Monneret, S.

Moon, J.

Morales-Delgado, E. E.

Moser, C.

Mosk, A. P.

Neil, M. A. A.

Niv, E.

Oh, G.

G. Oh, E. Chung, and S. H. Yun, “Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging,” Opt. Fiber Technol. 19(6), 760–771 (2013).
[Crossref]

Papadopoulos, I. N.

Paterson, C.

Piestun, R.

Pinkse, P. W. H.

Piyawattanametha, W.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Psaltis, D.

Reichenbach, K. L.

Rigneault, H.

Rosenbluh, M.

I. Freund, M. Rosenbluh, and S. Feng, “Memory effects in propagation of optical waves through disordered media,” Phys. Rev. Lett. 61(20), 2328–2331 (1988).
[Crossref] [PubMed]

Schnitzer, M. J.

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Stone, A. D.

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

Thompson, A. J.

Vellekoop, I. M.

Xu, C.

Yang, T. D.

D. Kim, J. Moon, M. Kim, T. D. Yang, J. Kim, E. Chung, and W. Choi, “Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle,” Opt. Lett. 39(7), 1921–1924 (2014).
[Crossref] [PubMed]

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Yoon, C.

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Yun, S. H.

G. Oh, E. Chung, and S. H. Yun, “Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging,” Opt. Fiber Technol. 19(6), 760–771 (2013).
[Crossref]

Ziegler, D.

Biomed. Opt. Express (1)

Lab Chip (1)

S. Bianchi and R. Di Leonardo, “A multi-mode fiber probe for holographic micromanipulation and microscopy,” Lab Chip 12(3), 635–639 (2012).
[Crossref] [PubMed]

Nat. Commun. (1)

T. Čižmár and K. Dholakia, “Exploiting multimode waveguides for pure fibre-based imaging,” Nat. Commun. 3, 1027 (2012).
[Crossref] [PubMed]

Nat. Methods (1)

B. A. Flusberg, E. D. Cocker, W. Piyawattanametha, J. C. Jung, E. L. M. Cheung, and M. J. Schnitzer, “Fiber-optic fluorescence imaging,” Nat. Methods 2(12), 941–950 (2005).
[Crossref] [PubMed]

Nature (1)

H. H. Hopkins and N. S. Kapany, “A flexible fibrescope, using static scanning,” Nature 173(4392), 39–41 (1954).
[Crossref]

Opt. Express (8)

S. Farahi, D. Ziegler, I. N. Papadopoulos, D. Psaltis, and C. Moser, “Dynamic bending compensation while focusing through a multimode fiber,” Opt. Express 21(19), 22504–22514 (2013).
[Crossref] [PubMed]

E. E. Morales-Delgado, S. Farahi, I. N. Papadopoulos, D. Psaltis, and C. Moser, “Delivery of focused short pulses through a multimode fiber,” Opt. Express 23(7), 9109–9120 (2015).
[Crossref] [PubMed]

A. M. Caravaca-Aguirre, E. Niv, D. B. Conkey, and R. Piestun, “Real-time resilient focusing through a bending multimode fiber,” Opt. Express 21(10), 12881–12887 (2013).
[Crossref] [PubMed]

I. N. Papadopoulos, S. Farahi, C. Moser, and D. Psaltis, “Focusing and scanning light through a multimode optical fiber using digital phase conjugation,” Opt. Express 20(10), 10583–10590 (2012).
[Crossref] [PubMed]

L. V. Amitonova, A. P. Mosk, and P. W. H. Pinkse, “The rotational memory effect of a multimode fiber,” Opt. Express 23(16), 20569–20575 (2015).
[Crossref] [PubMed]

E. R. Andresen, G. Bouwmans, S. Monneret, and H. Rigneault, “Two-photon lensless endoscope,” Opt. Express 21(18), 20713–20721 (2013).
[Crossref] [PubMed]

K. L. Reichenbach and C. Xu, “Numerical analysis of light propagation in image fibers or coherent fiber bundles,” Opt. Express 15(5), 2151–2165 (2007).
[Crossref] [PubMed]

X. Chen, K. L. Reichenbach, and C. Xu, “Experimental and theoretical analysis of core-to-core coupling on fiber bundle imaging,” Opt. Express 16(26), 21598–21607 (2008).
[Crossref] [PubMed]

Opt. Fiber Technol. (1)

G. Oh, E. Chung, and S. H. Yun, “Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging,” Opt. Fiber Technol. 19(6), 760–771 (2013).
[Crossref]

Opt. Lett. (5)

Phys. Rev. Lett. (3)

S. Feng, C. Kane, P. A. Lee, and A. D. Stone, “Correlations and fluctuations of coherent wave transmission through disordered media,” Phys. Rev. Lett. 61(7), 834–837 (1988).
[Crossref] [PubMed]

I. Freund, M. Rosenbluh, and S. Feng, “Memory effects in propagation of optical waves through disordered media,” Phys. Rev. Lett. 61(20), 2328–2331 (1988).
[Crossref] [PubMed]

Y. Choi, C. Yoon, M. Kim, T. D. Yang, C. Fang-Yen, R. R. Dasari, K. J. Lee, and W. Choi, “Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber,” Phys. Rev. Lett. 109(20), 203901 (2012).
[Crossref] [PubMed]

Other (2)

K. Okamoto, Fundamentals of Optical Waveguides (Academic Press, 2006).

A. Yariv and P. Yeh, Photonics: Optical Electronics in Modern Communications (The Oxford Series in Electrical and Computer Engineering) (Oxford University Press, Inc., 2006).

Supplementary Material (1)

NameDescription
» Visualization 1: AVI (527 KB)      Focusing and scanning using digital phase conjugation and memory effect in a multicore fiber.

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Figures (9)

Fig. 1
Fig. 1 Experimental optical setup. The output of a He-Ne laser is expanded is split by the polarizing beam splitter PBS into the calibration and reference arms. The objective OBJ2 focuses the calibration beam in a plane S in front of the distal end of the multicore fiber (MCF). The proximal end facet of the MCF is imaged on the CMOS sensor through the 4f imaging system OBJ3-L3. Using the non-polarizing beam splitter BS2, the reference arm is combined with the image on the CMOS to form a digital hologram. The phase extracted from the digital hologram is conjugated and projected on the spatial light modulator (SLM), which modulates and reflects the reference beam towards the MCF through BS2. A focus spot forms in the plane S and is imaged using the 4f system OBJ2-L2 on the CCD camera. The translational stage TS bends the fiber in a controllable way. OBJ1 = 10 × , NA = 0.25, Newport, OBJ2 = OBJ3 = 20 × , NA = 0.4, Newport. Focal length lenses: L1 = 150 mm, L2 = 100 mm, L3 = 200 mm.
Fig. 2
Fig. 2 DPC focus spot characterization. (a) Focus spot size (FWHM, blue points) and enhancement (red points) as a function of the working distance. The lines are drawn only for clarity. (b) Example of DPC focus spot imaged on the CCD camera. (c) The same focus spot of (b) with the CCD exposure time increased 100 times. The six bright speckle areas around the main lobe are a result of the quasi-periodicity of the MCF. Scale bars are 20 μm.
Fig. 3
Fig. 3 Digital scanning of the focus spot using a single calibration hologram. (a) The phase conjugation pattern is combined with a linear phase gradient and projected on the SLM. By changing the direction and the strength of the gradient it is possible to scan the focus spot in a regular grid. The image is a combination of several DPC projections (see Visualization 1). (b) The square markers represent the peak intensities of the DPC spots along the red dashed line in (a). Scale bar 20 μm.
Fig. 4
Fig. 4 Using a pulsed laser it is possible to independently phase conjugate distinct modes of the MCF cores. The scanning range of the fundamental LP01 mode is larger than the one of the higher order modes because of the limited core-to-core coupling.
Fig. 5
Fig. 5 Axial shifting of the DPC focus spot using a single calibration hologram. The central row of images shows a phase-conjugated spot observed at different planes. The calibration hologram was taken focusing at a distance of 400 μm from the fiber facet. By adding a negative lens phase to the phase hologram, the focus shifts towards the fiber. The images above and below the central row show the axial shift of the focus with the increasingly positive or negative lens phases.
Fig. 6
Fig. 6 Pattern projection using a single calibration hologram: (a) cross obtained as a combination of shifted spots; (b) the same pattern as (a) except the spots of one arm are in opposite phase to those of the other arm; (c) multiple spot projection, in this case nine spots are projected simultaneously in a regular grid. Scale bars are 5 μm. (d) Simulation of the cross-pattern projection with phase only modulation; (e) simulation of the cross-pattern projection with amplitude and phase modulation.
Fig. 7
Fig. 7 Focusing through a waveguide array in no-coupling and coupling conditions. The propagation in the waveguide array was simulated using coupled mode theory and the free space propagation with the beam propagation method. (a) Focusing in no coupling conditions is possible by assigning a quadratic phase at the input of the waveguide array. The phase relationship between the cores is preserved along the waveguide and it is possible to focus at a given distance for the waveguide facet (400 μm in this case). Focusing using DPC gives equivalent results. (b) In coupling conditions, the phase relationship between cores is not preserved along the waveguide and focusing using a quadratic phase pattern is no longer possible. DPC allows focusing in severe coupling conditions.
Fig. 8
Fig. 8 Scanning range using DPC in a waveguide array with different coupling conditions by tuning the distance between the cores. Increased coupling decreases the scanning range. The green curve represents the no-coupling conditions, which yields the maximum scanning range.
Fig. 9
Fig. 9 Bending of a MCF with DPC. (a) The translational stage where one end of the MCF is mounted is shifted to three different positions to increase fiber bending. The red arrows indicate the MCF. (b) For each bending position, a digital hologram is recorded on the CMOS: the three figures represent the difference between the extracted phase for each hologram and the phase obtained when the fiber is not bent. The insets show the color code used to represent the phase value. Scale bars are 100 μm. (c) The induced linear phase gradient across the fiber leads to a transverse shift of the focus spot in the plane S during DPC. The dashed red line indicates the position of the focus spot of an unbent fiber. Scale bars are 5 μm.

Equations (8)

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ϕ SLM ( x,y )=arg[ e j ϕ DPC ( x,y ) e j( k x x+ k y y ) ],
ϕ SLM ( x,y )=arg[ e j ϕ DPC ( x,y ) e j π λF ( x 2 + y 2 ) ],
ϕ SLM ( x,y )=arg[ e j ϕ DPC ( x,y ) i e j( k xi x+ k yi y ) ].
A( x )=comb( Λ x x ) E a ( x ),
A ˜ ( f x )=FT{ A( x ) }=FT{ comb( Λ x x ) }FT{ E a ( x ) }.
w MAX =w( f )= w 2 ( 0 )+ f 2 N A 2 .
p x f λ Λ x .
Δϕ= ϕ 1 ( x,y ) ϕ i ( x,y ).

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