Abstract

We investigate the performance of a widefield imaging system employing an aplanatic solid immersion lens. Off-axis imaging quality is examined theoretically at different radii and thicknesses of the aplanatic solid immersion lens. It is found that field curvature is the major aberration affecting the imaging quality. Aberrations are measured experimentally, and the results are in very good agreement with those obtained from simulations and demonstrate the situations where high quality images can be obtained with the aplanatic solid immersion lens.

© 2007 Optical Society of America

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  1. Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
    [CrossRef]
  2. M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
    [CrossRef]
  3. S. M. Mansfield and G. S. Kino, "Solid immersion microscope," Appl. Phys. Lett. 57, 2615 (1990).
    [CrossRef]
  4. I. Ichimura, S. Hayashi, and G. S. Kino, "High-density optical recording using a solid immersion lens," Appl. Opt. 36, 4339-4348 (1997).
    [CrossRef] [PubMed]
  5. B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
    [CrossRef]
  6. B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
    [CrossRef]
  7. L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
    [CrossRef]
  8. S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
    [CrossRef]
  9. K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
    [CrossRef]
  10. J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
    [CrossRef]
  11. J. Zhang, M. C. Pitter, S. Liu, C. See, and M. G. Somekh, "Surface-plasmon microscopy with a two-piece solid immersion lens: bright and dark fields," Appl. Opt. 45, 7977-7986 (2006).
    [CrossRef] [PubMed]
  12. M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 2003).
  13. Winlens 4.3, Linos Photonics Gmbh & Co. KG.
  14. D. Axelrod, "Total internal reflection fluorescence microscopy in cell biology," Method Enzymol. 361, 1-33 (2003).
    [CrossRef]
  15. M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
    [CrossRef]
  16. R. Kingslake, Lens Design Fundamentals (Academic, 1978).
  17. J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, 1996).

2006 (1)

2004 (1)

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

2003 (1)

D. Axelrod, "Total internal reflection fluorescence microscopy in cell biology," Method Enzymol. 361, 1-33 (2003).
[CrossRef]

2001 (1)

S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
[CrossRef]

2000 (1)

Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
[CrossRef]

1999 (3)

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

1998 (1)

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

1997 (1)

1996 (1)

B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
[CrossRef]

1994 (1)

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

1990 (1)

S. M. Mansfield and G. S. Kino, "Solid immersion microscope," Appl. Phys. Lett. 57, 2615 (1990).
[CrossRef]

Akiyama, H.

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

Axelrod, D.

D. Axelrod, "Total internal reflection fluorescence microscopy in cell biology," Method Enzymol. 361, 1-33 (2003).
[CrossRef]

Baba, M.

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

Born, M.

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 2003).

Clark, M.

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

Crozier, K. B.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Elings, V. B.

Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
[CrossRef]

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Ghislain, L. P.

Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
[CrossRef]

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Goldberg, B. B.

S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
[CrossRef]

Goodman, J. W.

J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, 1996).

Hayashi, S.

Ichimura, I.

Ippolito, S. B.

S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
[CrossRef]

Kingslake, R.

R. Kingslake, Lens Design Fundamentals (Academic, 1978).

Kino, G. S.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

I. Ichimura, S. Hayashi, and G. S. Kino, "High-density optical recording using a solid immersion lens," Appl. Opt. 36, 4339-4348 (1997).
[CrossRef] [PubMed]

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

S. M. Mansfield and G. S. Kino, "Solid immersion microscope," Appl. Phys. Lett. 57, 2615 (1990).
[CrossRef]

Koyama, K.

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

Liu, S.

Liu, S. G.

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

Mamin, H. J.

B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
[CrossRef]

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

Manalis, S. R.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Mansfield, S. M.

S. M. Mansfield and G. S. Kino, "Solid immersion microscope," Appl. Phys. Lett. 57, 2615 (1990).
[CrossRef]

Minne, S. C.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Pitter, M. C.

J. Zhang, M. C. Pitter, S. Liu, C. See, and M. G. Somekh, "Surface-plasmon microscopy with a two-piece solid immersion lens: bright and dark fields," Appl. Opt. 45, 7977-7986 (2006).
[CrossRef] [PubMed]

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

Quate, C. F.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Rugar, D.

B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
[CrossRef]

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

Sasaki, T.

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

See, C.

See, C. W.

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

Sharples, S. D.

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

Somekh, M. G.

J. Zhang, M. C. Pitter, S. Liu, C. See, and M. G. Somekh, "Surface-plasmon microscopy with a two-piece solid immersion lens: bright and dark fields," Appl. Opt. 45, 7977-7986 (2006).
[CrossRef] [PubMed]

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

Studenmund, W. R.

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

Suemoto, T.

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

Terris, B. D.

B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
[CrossRef]

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

Unlu, M. S.

S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
[CrossRef]

Wilder, K.

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

Wolf, E.

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 2003).

Wu, Q.

Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
[CrossRef]

Yoshita, M.

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

Zhang, J.

J. Zhang, M. C. Pitter, S. Liu, C. See, and M. G. Somekh, "Surface-plasmon microscopy with a two-piece solid immersion lens: bright and dark fields," Appl. Opt. 45, 7977-7986 (2006).
[CrossRef] [PubMed]

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

Appl. Opt. (2)

Appl. Phys. Lett. (8)

M. Yoshita, T. Sasaki, M. Baba, and H. Akiyama, "Application of solid immersion lens to high-spatial resolution photoluminescence imaging of GaAs quantum wells at low temperatures," Appl. Phys. Lett. 73, 635-637 (1998).
[CrossRef]

S. M. Mansfield and G. S. Kino, "Solid immersion microscope," Appl. Phys. Lett. 57, 2615 (1990).
[CrossRef]

B. D. Terris, H. J. Mamin, and D. Rugar, "Near-field optical data storage," Appl. Phys. Lett. 68, 141-143 (1996).
[CrossRef]

B. D. Terris, H. J. Mamin, D. Rugar, W. R. Studenmund, and G. S. Kino, "Near-field optical-data storage using a solid immersion lens," Appl. Phys. Lett. 65, 388-390 (1994).
[CrossRef]

L. P. Ghislain, V. B. Elings, K. B. Crozier, S. R. Manalis, S. C. Minne, K. Wilder, G. S. Kino, and C. F. Quate, "Near-field photolithography with a solid immersion lens," Appl. Phys. Lett. 74, 501-503 (1999).
[CrossRef]

S. B. Ippolito, B. B. Goldberg, and M. S. Unlu, "High spatial resolution subsurface microscopy," Appl. Phys. Lett. 78, 4071-4073 (2001).
[CrossRef]

K. Koyama, M. Yoshita, M. Baba, T. Suemoto, and H. Akiyama, "High collection efficiency in fluorescence microscopy with a solid immersion lens," Appl. Phys. Lett. 75, 1667-1669 (1999).
[CrossRef]

J. Zhang, C. W. See, M. G. Somekh, M. C. Pitter, and S. G. Liu, "Wide-field surface plasmon microscopy with solid immersion lens excitation," Appl. Phys. Lett. 85, 5451-5453 (2004).
[CrossRef]

Electron. Lett. (1)

M. G. Somekh, S. D. Sharples, M. Clark, and C. W. See, "Lamb wave contrast in noncontacting surface acoustic wave microscopy," Electron. Lett. 35, 1886-1887 (1999).
[CrossRef]

Method Enzymol. (1)

D. Axelrod, "Total internal reflection fluorescence microscopy in cell biology," Method Enzymol. 361, 1-33 (2003).
[CrossRef]

Proc. IEEE (1)

Q. Wu, L. P. Ghislain, and V. B. Elings, "Imaging with solid immersion lenses, spatial resolution, and applications," Proc. IEEE 88, 1491-1498 (2000).
[CrossRef]

Other (4)

R. Kingslake, Lens Design Fundamentals (Academic, 1978).

J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, 1996).

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 2003).

Winlens 4.3, Linos Photonics Gmbh & Co. KG.

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Figures (11)

Fig. 1
Fig. 1

Configurations of (a) the hemispherical SIL and (b) the aplanatic SIL. Q and Q represent the aplanatic points, where the point source and its image are located. NA obj and NA img are numerical apertures at the object and the image space, respectively. (a) HSIL, NA obj = n  sin  u , NA img = sin  u , and (b) ASIL, NA obj = n 2  sin  u , NA img = sin  u .

Fig. 2
Fig. 2

Off-axis spot diagrams of (a) the HSIL and (b) the ASIL. The middle one in each matrix is the best imaging plane of that SIL. The Airy disk is 1.3 μ m in radius at the image space. (a) Simulated ray distributions of a HSIL at 0.1   mm field (radius), imaging NA obj = 0.3 . The solid circle is the Airy disk at the imaging space, and the value below each square is the distance from the paraxial imaging plane. (b) Simulated ray distributions by an ASIL at a 0.1   mm field (radius), imaging NA obj = 0.3 . The solid circle is the Airy disk at the imaging plane, the value below each square is the distance from the paraxial imaging plane.

Fig. 3
Fig. 3

Ray diagram of computer model.

Fig. 4
Fig. 4

Simulated results (left to right) are the PSF, the spot diagram, and the line profiles of the PSF in the x (solid curve) and y (dashed curve) directions (Fig. 3): (a) ideal thickness—on axis ( Δ H = 0 , Δ x = 0 ), (b) nonideal thickness—on axis ( Δ H = 10 μ m , Δ x = 0 ), (c) ideal thickness—off axis ( Δ H = 0 μ m , Δ x = 132 μ m ), and (d) nonideal thickness—off axis ( Δ H = 10 μ m , Δ x = 132 μ m ).

Fig. 5
Fig. 5

Simulated the relationship between the field radius (horizontal) and the defocus distance using computer model at different thickness of the ASIL.

Fig. 6
Fig. 6

Simulated result by ray tracing, the ASIL diameter (horizontal) against the defocus (vertical) at 10 μ m field radius with the ASIL thickness of ideal H 0 (solid curve), 5 μm smaller (dotted–dashed curve) and 5 μ m larger (dashed curve) than H 0 .

Fig. 7
Fig. 7

The setup of the ASIL microscope, consisting of the Mitutoyu 0.42NA, 20 × objective and the ASIL r = 2.5   mm , n = 1.845 (dashed square). The sample is placed in contact with the ASIL flat surface and imaged by the CCD with the coordinates shown on its right-hand side.

Fig. 8
Fig. 8

Images of a grating object of the period 1 μm. Illumination wavelength is 0.6328 μ m , (a) by 0.42NA 20× Mitutoyo objective only and (b) by the Mitutoyo objective employing an ASIL with r = 2.5 , n = 1.845 . The image size is 25 μ m .

Fig. 9
Fig. 9

Experimental results of widefield images (left, size 20 μ m ) and the normalized intensities (right) by three objectives: (from top to bottom) 100× oil 1.25NA (Zeiss), ASIL objective and 60× 0.8NA (Olympus), respectively. The object is a grating with the period of 2 μ m .

Fig. 10
Fig. 10

(a) Experimental and (b) simulated ratio of the spatial frequencies (third harmonic to the fundamental frequency). (a) Experimental result: the ASIL image quality (normalized) is represented by the normalized ratio of the spatial frequencies (third harmonic to the fundamental frequency) of the sample. The dashed curve (0.74) is the ratio when the sample is located at the defocus corresponding to a 90° phase shift. (b) Simulated ratio of the spatial frequencies (third harmonic to the fundamental frequency) using the model at the ideal thickness (solid curve) and 5 μ m apart from the ideal thickness of the ASIL.

Fig. 11
Fig. 11

Experimental results (dashed curve) describe the relationship between the field size (horizontal) and the defocus distance (vertical). The others are the simulations as shown in Fig. 5.

Tables (1)

Tables Icon

Table 1 Normalized FWHM of the PSF at Four Cases (Fig. 4) Using Computer Model

Equations (1)

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H 0 = r ( 1 + 1 n ) ,

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