Abstract

We have constructed a scanning confocal laser-feedback microscope that determines surface profiles in the range of 5 nm to 3 μm with ~200-nm lateral discrimination. A direct comparison is made with scanning electron microscopy, and an image of a silicon resolution standard with 40-nm-high structures is shown. The device is also capable of characterizing surface motion with a sensitivity of <1 pm (Hz)−1/2 across a bandwidth of several megahertz. Vibrational analysis of a miniature piezoelectric microphone is demonstrated from 50 Hz to 50 kHz. An operational description of the device is presented in addition to a generalization of laser-feedback theory that includes gas-laser dynamics.

© 1993 Optical Society of America

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References

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  1. P. Hariharan, in Progress in Optics, E. Wolf, ed. (North-Holland, Amsterdam, 1987), Vol. 24, p. 103.
    [CrossRef]
  2. P. G. R. King, G. J. Steward, New Sci. 17, 180 (1963).
  3. P. G. R. King, G. J. Steward, U.S. patent3,409,370 (November5, 1968).
  4. J. W. Campbell, V. Erbert, Appl. Opt. 6, 1128 (1967).
    [CrossRef] [PubMed]
  5. T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
    [CrossRef]
  6. M. J. Rudd, J. Sci. Instrum. 1, 723 (1968).
    [CrossRef]
  7. N. Brown, Appl. Opt. 20, 3711 (1981).
    [CrossRef] [PubMed]
  8. D. Sarid, D. Iams, V. Weissenberger, L. S. Bell, Opt. Lett. 13, 1057 (1988).
    [CrossRef] [PubMed]
  9. P. J. de Groot, J. Mod. Opt. 37, 1199 (1990).
    [CrossRef]
  10. The dependence of K on the laser operating parameters and the degree of feedback coupling can be derived from the more fundamental approach leading to Eq. (2). Following the notation of Ref. 13 below:K=2γtp(N/Nth−1)−1,γ=c2ncLc1−R22R2(fR3),where tp is the average photon lifetime in the cavity, N is the population inversion (Nth its value at threshold), c is the speed of light, nc is the effective index of refraction inside the laser cavity, Lc is the length of the laser gain medium, R2 is the amplitude reflectivity of M2, the laser output mirror, f is the factor between 0 and 1 representing the degree of coupling of the backreflected field to the oscillating laser mode, and R3 is the reflectivity of M3, the target.
  11. D. M. Clunie, N. H. Rock, J. Sci. Instrum. 41, 489 (1964).
    [CrossRef]
  12. G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
    [CrossRef]
  13. D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
    [CrossRef]
  14. A. Yariv, Quantum Electronics (Wiley, New York, 1989), p. 584.
  15. E. S. Kim, R. S. Muller, IEEE Electron Device Lett. EDL-8, 401 (1987).
  16. S. W. Wenzel, R. M. White, IEEE Trans. Electron Devices 35, 735 (1988).
    [CrossRef]
  17. R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.
  18. A. J. Bearden, M. P. O’Neill, U.S. patent5,029,023 (July2, 1991).
  19. A. J. Bearden, M. P. O’Neill, Biophys. J. 59, 169A (1990).
  20. M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

1990 (3)

P. J. de Groot, J. Mod. Opt. 37, 1199 (1990).
[CrossRef]

A. J. Bearden, M. P. O’Neill, Biophys. J. 59, 169A (1990).

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

1989 (1)

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

1988 (2)

S. W. Wenzel, R. M. White, IEEE Trans. Electron Devices 35, 735 (1988).
[CrossRef]

D. Sarid, D. Iams, V. Weissenberger, L. S. Bell, Opt. Lett. 13, 1057 (1988).
[CrossRef] [PubMed]

1987 (1)

E. S. Kim, R. S. Muller, IEEE Electron Device Lett. EDL-8, 401 (1987).

1984 (1)

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

1981 (1)

1968 (1)

M. J. Rudd, J. Sci. Instrum. 1, 723 (1968).
[CrossRef]

1967 (2)

J. W. Campbell, V. Erbert, Appl. Opt. 6, 1128 (1967).
[CrossRef] [PubMed]

T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
[CrossRef]

1964 (1)

D. M. Clunie, N. H. Rock, J. Sci. Instrum. 41, 489 (1964).
[CrossRef]

1963 (1)

P. G. R. King, G. J. Steward, New Sci. 17, 180 (1963).

Acket, G. A.

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

Alkemade, C. T. H.

T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
[CrossRef]

Bearden, A.

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

Bearden, A. J.

A. J. Bearden, M. P. O’Neill, Biophys. J. 59, 169A (1990).

A. J. Bearden, M. P. O’Neill, U.S. patent5,029,023 (July2, 1991).

Bell, L. S.

Bolwijn, P. T.

T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
[CrossRef]

Brown, N.

Campbell, J. W.

Clunie, D. M.

D. M. Clunie, N. H. Rock, J. Sci. Instrum. 41, 489 (1964).
[CrossRef]

de Groot, P. J.

P. J. de Groot, J. Mod. Opt. 37, 1199 (1990).
[CrossRef]

Den Boef, A. J.

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

Erbert, V.

Hariharan, P.

P. Hariharan, in Progress in Optics, E. Wolf, ed. (North-Holland, Amsterdam, 1987), Vol. 24, p. 103.
[CrossRef]

Hong, D. M.

R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.

Iams, D.

Iams, D. A.

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

Ingle, J. T.

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

Kim, E. S.

E. S. Kim, R. S. Muller, IEEE Electron Device Lett. EDL-8, 401 (1987).

R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.

King, P. G. R.

P. G. R. King, G. J. Steward, New Sci. 17, 180 (1963).

P. G. R. King, G. J. Steward, U.S. patent3,409,370 (November5, 1968).

Lenstra, D.

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

Muller, R. S.

E. S. Kim, R. S. Muller, IEEE Electron Device Lett. EDL-8, 401 (1987).

R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.

O’Neill, M. P.

A. J. Bearden, M. P. O’Neill, Biophys. J. 59, 169A (1990).

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

A. J. Bearden, M. P. O’Neill, U.S. patent5,029,023 (July2, 1991).

Osborne, L. C.

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

Peek, T. H. H.

T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
[CrossRef]

Ried, R. P.

R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.

Rock, N. H.

D. M. Clunie, N. H. Rock, J. Sci. Instrum. 41, 489 (1964).
[CrossRef]

Rudd, M. J.

M. J. Rudd, J. Sci. Instrum. 1, 723 (1968).
[CrossRef]

Sarid, D.

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

D. Sarid, D. Iams, V. Weissenberger, L. S. Bell, Opt. Lett. 13, 1057 (1988).
[CrossRef] [PubMed]

Steward, G. J.

P. G. R. King, G. J. Steward, New Sci. 17, 180 (1963).

P. G. R. King, G. J. Steward, U.S. patent3,409,370 (November5, 1968).

Verbeek, B. H.

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

Weissenberger, V.

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

D. Sarid, D. Iams, V. Weissenberger, L. S. Bell, Opt. Lett. 13, 1057 (1988).
[CrossRef] [PubMed]

Wenzel, S. W.

S. W. Wenzel, R. M. White, IEEE Trans. Electron Devices 35, 735 (1988).
[CrossRef]

White, R. M.

S. W. Wenzel, R. M. White, IEEE Trans. Electron Devices 35, 735 (1988).
[CrossRef]

Wong, T. L.

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

Yariv, A.

A. Yariv, Quantum Electronics (Wiley, New York, 1989), p. 584.

Am. J. Phys. (1)

T. H. H. Peek, P. T. Bolwijn, C. T. H. Alkemade, Am. J. Phys. 35, 820 (1967).
[CrossRef]

Appl. Opt. (2)

Biophys. J. (2)

A. J. Bearden, M. P. O’Neill, Biophys. J. 59, 169A (1990).

M. P. O’Neill, L. C. Osborne, T. L. Wong, A. Bearden, Biophys. J. 59, 169A (1990).

IEEE Electron Device Lett. (1)

E. S. Kim, R. S. Muller, IEEE Electron Device Lett. EDL-8, 401 (1987).

IEEE J. Quantum Electron. (2)

G. A. Acket, D. Lenstra, A. J. Den Boef, B. H. Verbeek, IEEE J. Quantum Electron. QE-20, 1163 (1984).
[CrossRef]

D. Sarid, V. Weissenberger, D. A. Iams, J. T. Ingle, IEEE J. Quantum Electron. 25, 1968 (1989).
[CrossRef]

IEEE Trans. Electron Devices (1)

S. W. Wenzel, R. M. White, IEEE Trans. Electron Devices 35, 735 (1988).
[CrossRef]

J. Mod. Opt. (1)

P. J. de Groot, J. Mod. Opt. 37, 1199 (1990).
[CrossRef]

J. Sci. Instrum. (2)

M. J. Rudd, J. Sci. Instrum. 1, 723 (1968).
[CrossRef]

D. M. Clunie, N. H. Rock, J. Sci. Instrum. 41, 489 (1964).
[CrossRef]

New Sci. (1)

P. G. R. King, G. J. Steward, New Sci. 17, 180 (1963).

Opt. Lett. (1)

Other (6)

P. G. R. King, G. J. Steward, U.S. patent3,409,370 (November5, 1968).

P. Hariharan, in Progress in Optics, E. Wolf, ed. (North-Holland, Amsterdam, 1987), Vol. 24, p. 103.
[CrossRef]

The dependence of K on the laser operating parameters and the degree of feedback coupling can be derived from the more fundamental approach leading to Eq. (2). Following the notation of Ref. 13 below:K=2γtp(N/Nth−1)−1,γ=c2ncLc1−R22R2(fR3),where tp is the average photon lifetime in the cavity, N is the population inversion (Nth its value at threshold), c is the speed of light, nc is the effective index of refraction inside the laser cavity, Lc is the length of the laser gain medium, R2 is the amplitude reflectivity of M2, the laser output mirror, f is the factor between 0 and 1 representing the degree of coupling of the backreflected field to the oscillating laser mode, and R3 is the reflectivity of M3, the target.

A. Yariv, Quantum Electronics (Wiley, New York, 1989), p. 584.

R. P. Ried, E. S. Kim, D. M. Hong, R. S. Muller, in 1992 ASME Winter Annual Meeting (American Society for Mechanical Engineering, New York, 1992), paper DSC-40, pp. 23–32.

A. J. Bearden, M. P. O’Neill, U.S. patent5,029,023 (July2, 1991).

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Figures (4)

Fig. 1
Fig. 1

Schematic of a laser-feedback microscope. PZT, piezoelectric transducer.

Fig. 2
Fig. 2

Top: three-dimensional projection view of a Si resolution standard where the central pit is 400 nm × 2200 nm and 100 nm deep. The field of view is 5 μm × 10 μm. Bottom: the same structure imaged with SEM.

Fig. 3
Fig. 3

Three-dimensional projection view of a Si resolution standard. The field of view is 25 μm × 25 μm. The small dots are 800 nm in diameter, spaced 800 nm apart, and are 400 nm high.

Fig. 4
Fig. 4

Diaphragm vibration amplitude versus frequency. The LFM was focused onto the microphone diaphragm with a 10 × 0.3-N.A. microscope objective. The noise floor was obtained while focused on the center with no signal input. The other response amplitudes were measured while a 250-mV peak sine wave was applied to the device and scanned from Ω′ ≅ 50 Hz to 53 kHz. An audio-frequency spectrum analyzer set to a bandwidth of 30 Hz was used to monitor η(Ω′) in all cases. The peaks in the noise floor at 16 and 21 kHz are due to interference from a video monitor and the laser switching power supply, respectively.

Equations (3)

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η ( t ) = K cos [ 4 π λ L ( t ) ] ,
η ( t , Ω ) = [ 2 γ ν L k = 1 ( R 2 R 3 ) k 1 cos ( k 4 π λ L 0 ) J 0 ( k 4 π λ a ) 4 γ ν L 2 + Ω 2 k = 1 ( R 2 R 3 ) k 1 sin ( k 4 π λ L 0 ) × J 1 ( k 4 π λ a ) sin ( Ω t ϕ 1 ) + 4 γ ν L 2 + ( 2 Ω ) 2 k = 1 ( R 2 R 3 ) k 1 cos ( k 4 π λ L 0 ) × J 2 ( k 4 π λ a ) sin ( 2 Ω t + ϕ 2 ) ] ,
K = 2 γ t p ( N / N t h 1 ) 1 , γ = c 2 n c L c 1 R 2 2 R 2 ( f R 3 ) ,

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