Abstract

Isotropic optical focusing – the focusing of light with axial confinement that matches its lateral confinement, is important for a broad range of applications. Conventionally, such focusing is achieved by overlapping the focused beams from a pair of opposite-facing microscope objective lenses. However the exacting requirements for the alignment of the objective lenses and the method’s relative intolerance to sample turbidity have significantly limited its utility. In this paper, we present an optical phase conjugation (OPC)-assisted isotropic focusing method that can address both challenges. We exploit the time-reversal nature of OPC playback to naturally guarantee the overlap of the two focused beams even when the objective lenses are significantly misaligned (up to 140 microns transversely and 80 microns axially demonstrated). The scattering correction capability of OPC also enabled us to accomplish isotropic focusing through thick scattering samples (demonstrated with samples of ~7 scattering mean free paths). This method can potentially improve 4Pi microscopy and 3D microstructure patterning.

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References

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  1. S. W. Hell, “Far-Field optical nanoscopy,” Science316(5828), 1153–1158 (2007).
    [CrossRef] [PubMed]
  2. S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
    [CrossRef]
  3. J. Pawley, Handbook of biological confocal microscopy (Springer 2006).
  4. D. G. Grier, “A revolution in optical manipulation,” Nature424(6950), 810–816 (2003).
    [CrossRef] [PubMed]
  5. A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
    [CrossRef]
  6. S. Hell and E. H. K. Stelzer, “Properties of a 4Pi confocal fluorescence microscope,” J. Opt. Soc. Am. A9(12), 2159–2166 (1992).
    [CrossRef]
  7. K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
    [CrossRef] [PubMed]
  8. C. Sheppard and C. Cogswell, “Optics in medicine, biology and environmental research, edited by G. v,” Bally Elsevier, 310–315 (1993).
  9. M. Gu and C. J. R. Sheppard, “Three-dimensional transfer functions in 4Pi confocal microscopes,” J. Opt. Soc. Am. A11(5), 1619–1627 (1994).
    [CrossRef]
  10. M. Born and E. Wolf, Principles of optics (Cambridge University Press 1998).
  11. E. N. Leith and J. Upatnieks, “Holographic imagery through diffusing media,” J. Opt. Soc. Am.56(4), 523–523 (1966).
    [CrossRef]
  12. A. Yariv, “Phase conjugate optics and real-time holography,” IEEE J. Quantum Electron.14(9), 650–660 (1978).
    [CrossRef]
  13. Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
    [CrossRef] [PubMed]
  14. E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
    [CrossRef] [PubMed]
  15. M. Cui and C. Yang, “Implementation of a digital optical phase conjugation system and its application to study the robustness of turbidity suppression by phase conjugation,” Opt. Express18(4), 3444–3455 (2010).
    [CrossRef] [PubMed]
  16. E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
    [CrossRef] [PubMed]
  17. M. Cui, E. J. McDowell, and C. Yang, “An in vivo study of turbidity suppression by optical phase conjugation (TSOPC) on rabbit ear,” Opt. Express18(1), 25–30 (2010).
    [CrossRef] [PubMed]
  18. P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
    [CrossRef]
  19. H. J. van Staveren, C. J. M. Moes, J. van Marie, S. A. Prahl, and M. J. C. van Gemert, “Light scattering in Intralipid-10% in the wavelength range of 400-1100 nm,” Appl. Opt.30(31), 4507–4514 (1991).
    [CrossRef] [PubMed]
  20. M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
    [CrossRef]
  21. G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
    [CrossRef]
  22. M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
    [CrossRef]

2010

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

M. Cui and C. Yang, “Implementation of a digital optical phase conjugation system and its application to study the robustness of turbidity suppression by phase conjugation,” Opt. Express18(4), 3444–3455 (2010).
[CrossRef] [PubMed]

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

M. Cui, E. J. McDowell, and C. Yang, “An in vivo study of turbidity suppression by optical phase conjugation (TSOPC) on rabbit ear,” Opt. Express18(1), 25–30 (2010).
[CrossRef] [PubMed]

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

2009

S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
[CrossRef]

2008

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

2007

S. W. Hell, “Far-Field optical nanoscopy,” Science316(5828), 1153–1158 (2007).
[CrossRef] [PubMed]

2006

A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
[CrossRef]

2003

D. G. Grier, “A revolution in optical manipulation,” Nature424(6950), 810–816 (2003).
[CrossRef] [PubMed]

2001

K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
[CrossRef] [PubMed]

1998

P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
[CrossRef]

1995

M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
[CrossRef]

1994

1992

1991

1978

A. Yariv, “Phase conjugate optics and real-time holography,” IEEE J. Quantum Electron.14(9), 650–660 (1978).
[CrossRef]

1966

Bahlmann, K.

K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
[CrossRef] [PubMed]

Braat, J. J. M.

A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
[CrossRef]

Busch, K.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Chaumet, P. C.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Cui, M.

Dirac, H.

M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
[CrossRef]

Egner, A.

S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
[CrossRef]

Engelhardt, J.

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

Essig, S.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Feld, M. S.

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

Ferrand, P.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Grier, D. G.

D. G. Grier, “A revolution in optical manipulation,” Nature424(6950), 810–816 (2003).
[CrossRef] [PubMed]

Gu, M.

Hell, S.

Hell, S. W.

S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
[CrossRef]

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

S. W. Hell, “Far-Field optical nanoscopy,” Science316(5828), 1153–1158 (2007).
[CrossRef] [PubMed]

K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
[CrossRef] [PubMed]

Higdon, P. D.

P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
[CrossRef]

Jakobs, S.

K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
[CrossRef] [PubMed]

Lang, M. C.

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

Le Moal, E.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Ledermann, A.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Leith, E. N.

McDowell, E. J.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

M. Cui, E. J. McDowell, and C. Yang, “An in vivo study of turbidity suppression by optical phase conjugation (TSOPC) on rabbit ear,” Opt. Express18(1), 25–30 (2010).
[CrossRef] [PubMed]

Moes, C. J. M.

Mudry, E.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Müllenborn, M.

M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
[CrossRef]

Nes, A. S.

A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
[CrossRef]

Pereira, S. F.

A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
[CrossRef]

Petersen, J. W.

M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
[CrossRef]

Prahl, S. A.

Psaltis, D.

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

Schmidt, R.

S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
[CrossRef]

Senekerimyan, V.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

Sentenac, A.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Sheppard, C. J. R.

Staude, I.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Staudt, T.

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

Stelzer, E. H. K.

Thiel, M.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Török, P.

P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
[CrossRef]

Upatnieks, J.

van Gemert, M. J. C.

van Marie, J.

van Staveren, H. J.

Vellekoop, I. M.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

von Freymann, G.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Wegener, M.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Wilson, T.

P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
[CrossRef]

Yang, C.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

M. Cui, E. J. McDowell, and C. Yang, “An in vivo study of turbidity suppression by optical phase conjugation (TSOPC) on rabbit ear,” Opt. Express18(1), 25–30 (2010).
[CrossRef] [PubMed]

M. Cui and C. Yang, “Implementation of a digital optical phase conjugation system and its application to study the robustness of turbidity suppression by phase conjugation,” Opt. Express18(4), 3444–3455 (2010).
[CrossRef] [PubMed]

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

Yaqoob, Z.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

Yariv, A.

A. Yariv, “Phase conjugate optics and real-time holography,” IEEE J. Quantum Electron.14(9), 650–660 (1978).
[CrossRef]

Adv. Funct. Mater.

G. von Freymann, A. Ledermann, M. Thiel, I. Staude, S. Essig, K. Busch, and M. Wegener, “Three-dimensional nanostructures for photonics,” Adv. Funct. Mater.20(7), 1038–1052 (2010).
[CrossRef]

Appl. Opt.

Appl. Surf. Sci.

M. Müllenborn, H. Dirac, and J. W. Petersen, “Three-dimensional nanostructures by direct laser etching of Si,” Appl. Surf. Sci.86(1-4), 568–576 (1995).
[CrossRef]

IEEE J. Quantum Electron.

A. Yariv, “Phase conjugate optics and real-time holography,” IEEE J. Quantum Electron.14(9), 650–660 (1978).
[CrossRef]

J. Biomed. Opt.

E. J. McDowell, M. Cui, I. M. Vellekoop, V. Senekerimyan, Z. Yaqoob, and C. Yang, “Turbidity suppression from the ballistic to the diffusive regime in biological tissues using optical phase conjugation,” J. Biomed. Opt.15(2), 025004 (2010).
[CrossRef] [PubMed]

J. Opt. Soc. Am.

J. Opt. Soc. Am. A

Nat. Photonics

Z. Yaqoob, D. Psaltis, M. S. Feld, and C. Yang, “Optical phase conjugation for turbidity suppression in biological samples,” Nat. Photonics2(2), 110–115 (2008).
[CrossRef] [PubMed]

S. W. Hell, R. Schmidt, and A. Egner, “Diffraction-unlimited three-dimensional optical nanoscopy with opposing lenses,” Nat. Photonics3(7), 381–387 (2009).
[CrossRef]

Nature

D. G. Grier, “A revolution in optical manipulation,” Nature424(6950), 810–816 (2003).
[CrossRef] [PubMed]

New J. Phys.

M. C. Lang, T. Staudt, J. Engelhardt, and S. W. Hell, “4Pi microscopy with negligible sidelobes,” New J. Phys.10(4), 043041 (2008).
[CrossRef]

Opt. Commun.

P. Török, P. D. Higdon, and T. Wilson, “On the general properties of polarised light conventional and confocal microscopes,” Opt. Commun.148(4-6), 300–315 (1998).
[CrossRef]

Opt. Express

Phys. Rev. Lett.

E. Mudry, E. Le Moal, P. Ferrand, P. C. Chaumet, and A. Sentenac, “Isotropic diffraction-limited focusing using a single objective lens,” Phys. Rev. Lett.105(20), 203903 (2010).
[CrossRef] [PubMed]

Rep. Prog. Phys.

A. S. Nes, J. J. M. Braat, and S. F. Pereira, “High-density optical data storage,” Rep. Prog. Phys.69(8), 2323–2363 (2006).
[CrossRef]

Science

S. W. Hell, “Far-Field optical nanoscopy,” Science316(5828), 1153–1158 (2007).
[CrossRef] [PubMed]

Ultramicroscopy

K. Bahlmann, S. Jakobs, and S. W. Hell, “4Pi-confocal microscopy of live cells,” Ultramicroscopy87(3), 155–164 (2001).
[CrossRef] [PubMed]

Other

C. Sheppard and C. Cogswell, “Optics in medicine, biology and environmental research, edited by G. v,” Bally Elsevier, 310–315 (1993).

M. Born and E. Wolf, Principles of optics (Cambridge University Press 1998).

J. Pawley, Handbook of biological confocal microscopy (Springer 2006).

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Figures (8)

Fig. 1
Fig. 1

(a) Conventional unidirectional focusing scheme with single lens. (b) Conventional isotropic focusing scheme with two aligned lenses. The aperture angle (contributing k-vector components) for the focused light beam is doubled in the isotropic focusing scheme. (c-f) Conventional and OPC-assisted isotropic focusing in two circumstances – (c and d) with lateral misalignment (e and f) and through inhomogeneous media. The conventional system fails to maintain isotropic focusing for both cases, while the OPC-assisted system adaptively corrects the aberrations.

Fig. 2
Fig. 2

Schematic diagram of the OPC-assisted isotropic focusing system. 532nm laser beam was split into two paths. Both beams were spatially filtered as coupled to single mode fiber and collimated by bulk lenses. One path passing EOM formed an original focal spot through OBJ1 and entered DOPC system, the other path was split into two beams – a reference beam for phase-shifting holography and an OPC beam retracing the original focal spot back. ND, continuous neutral density filter; SF, spatial filter; 1X TS, 1X telescope; PH, pinhole; MFW, motorized filter wheel; OBJ, objective lens; EOM, Electro-optical phase modulator; SLM, spatial light modulator; SCMOS, scientific CMOS camera; CCD, CCD camera; APD, avalanche photo diode.

Fig. 3
Fig. 3

PSF of unidirectional and isotropic focusing system. (a and c) Unidirectional and isotropic focusing schemes with single lens and two aligned lenses. (b and d) Transverse and longitudinal section of the measured PSF in conjunction with confocal detection system. 1D profiles presents the axial and transverse PSF. (red line: measured profile, blue line: theoretical profile). All graphs plotted on a micron scale.

Fig. 4
Fig. 4

Measured wave front (phase map) exiting transversely/axially misaligned objective lens (OBJ2 in Fig. 2). (a) Phase map of the wave front exiting well-aligned objective lens. Flat pattern (plane light beam) was observed. (b1-b3) Phase map of the wave front exiting transversely misaligned objective lens with an incremental displacement. Fringe patterns (angularly deviated light beam) with different frequency were detected. (c1-c3) Phase map of the wave front exiting axially misaligned objective lens with an incremental displacement. Bull’s eye patterns (converging light beam) were emerged. With severe misalignment, some higher spatial frequency information was missed.

Fig. 5
Fig. 5

PSF of OPC-assisted and conventional isotropic focusing system with a 10 microns transverse misalignment. (a and d) OPC-assisted and conventional isotropic focusing schemes. (b and e) Transverse and longitudinal section of the measured PSFs in conjunction with confocal detection system. (c1-c3) 1D axial PSFs of OPC-assisted isotropic focusing system with incremental transverse misalignment. The OPC-assisted system robustly provided the identical PSFs with marginal errors (FWHM of 120nm ). (f1-f3) 1D axial PSFs of conventional isotropic focusing system. As two objective lenses formed two far-distant foci, the system presented the elongated profile (FWHM of 500nm ). (c4 and f4) 1D axial PSFs of two systems with well-aligned objective lenses. As a control set of experiments, axially sharpened profiles were measured for both systems. All graphs plotted on a micron scale.

Fig. 6
Fig. 6

PSF of OPC-assisted and conventional isotropic focusing system with a 10 microns axial misalignment. (a and d) OPC-assisted and conventional isotropic focusing schemes. (b and e) Transverse and longitudinal section of the measured PSFs in conjunction with confocal detection system. (c1-c3 and f1-f3) 1D axial PSFs of OPC-assisted isotropic focusing system and conventional isotropic focusing system with incremental axial misalignment. (c4 and f4) 1D axial PSFs of two systems with well-aligned objective lenses. All graphs plotted on a micron scale.

Fig. 7
Fig. 7

(a) Measured wave front (phase map) propagated through an inhomogeneous media with μ s l7 . As the light experienced multiple scatterings, disordered wave front was measured. (b-c) Light intensity distribution emerged from objective lens on the side of DOPC (OBJ2 in Fig. 2). Those were captured from additional CCD sensor through OBJ1 (Fig. 2). (b) With an aid of DOPC, sharp focal spot was reconstructed. (c) Without and aid of DOPC (plane light beam from DOPC), focal spot was significantly degraded.

Fig. 8
Fig. 8

PSF of OPC-assisted and conventional isotropic focusing system through the optically inhomogeneous media ( μ s l7 ). (a and c) OPC-assisted and conventional isotropic focusing schemes. (b and d) Transverse and longitudinal section of the measured PSFs in conjunction with confocal detection system. 1D axial PSFs clearly showed the recovery of isotropic focusing with an aid of DOPC. All graphs plotted on a micron scale.

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