Abstract

High-speed two-wavelength phase-shifting interferometry is presented. The technique is aimed at high-speed in-line inspection of spacers in liquid crystal display panels or wafer bumps where the measuring range is well determined and high-speed measurements are essential. With our test setup, the measuring range is extended to 10μm by using two injection locked frequency scanning lasers that offer fast and equidistant phase shifting of interference fringes. A technique to determine the unwrapped phase map in a frequency scanning phase-shifting interferometry without the ordinary phase-unwrapping process is proposed.

© 2011 Optical Society of America

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References

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2009

2008

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

2007

2005

2000

Y. Bitou and K. Seta, “Gauge block measurement using a wavelength scanning interferometer,” Jpn. J. Appl. Phys. 39, 6084–6088 (2000).
[CrossRef]

A. Harasaki, J. Schmit, and J. C. Wyant, “Improved vertical-scanning interferometry,” Appl. Opt. 39, 2107–2115 (2000).
[CrossRef]

1997

1996

S. Tang, “Generalized algorithm for phase shifting interferometry,” Proc. SPIE 2860, 27–32 (1996).
[CrossRef]

1986

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1–8 (1986).
[CrossRef]

1985

1984

Baik, S. H.

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

Basila, D.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1–8 (1986).
[CrossRef]

Bhushan, B.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1–8 (1986).
[CrossRef]

Bitou, Y.

Y. Bitou and K. Seta, “Gauge block measurement using a wavelength scanning interferometer,” Jpn. J. Appl. Phys. 39, 6084–6088 (2000).
[CrossRef]

Brock, N.

Campbell, D. P.

P. A. Karasev, D. P. Campbell, and M. A. Richards, “Obtaining a 35× speedup in 2D phase unwrapping using commodity graphics processors,” in Proceedings of IEEE Conference on Radar (IEEE, 2007), pp. 574–578.

Cheng, Y.-Y.

Eom, T. B.

Harasaki, A.

Hayes, J.

Huntley, J. M.

Jang, R.

Kang, C.-S.

Kang, S. J.

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

Kang, Y. J.

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

Karasev, P. A.

P. A. Karasev, D. P. Campbell, and M. A. Richards, “Obtaining a 35× speedup in 2D phase unwrapping using commodity graphics processors,” in Proceedings of IEEE Conference on Radar (IEEE, 2007), pp. 574–578.

Kim, J. W.

Kim, J.-A.

Koliopoulos, C. L.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1–8 (1986).
[CrossRef]

Lee, W.-K.

Millerd, J.

North-Morris, M.

Novak, M.

Park, H. Y.

Richards, M. A.

P. A. Karasev, D. P. Campbell, and M. A. Richards, “Obtaining a 35× speedup in 2D phase unwrapping using commodity graphics processors,” in Proceedings of IEEE Conference on Radar (IEEE, 2007), pp. 574–578.

Ryu, W. J.

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

Saldner, H. O.

Schmit, J.

Seta, K.

Y. Bitou and K. Seta, “Gauge block measurement using a wavelength scanning interferometer,” Jpn. J. Appl. Phys. 39, 6084–6088 (2000).
[CrossRef]

Suh, H. S.

Tang, S.

S. Tang, “Generalized algorithm for phase shifting interferometry,” Proc. SPIE 2860, 27–32 (1996).
[CrossRef]

Wyant, J.

Wyant, J. C.

Appl. Opt.

Chin. Opt. Lett.

J. Tribol.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1–8 (1986).
[CrossRef]

Jpn. J. Appl. Phys.

Y. Bitou and K. Seta, “Gauge block measurement using a wavelength scanning interferometer,” Jpn. J. Appl. Phys. 39, 6084–6088 (2000).
[CrossRef]

Opt. Express

Optik

W. J. Ryu, Y. J. Kang, S. H. Baik, and S. J. Kang, “A study on the 3-D measurement by using digital projection moire method,” Optik 119, 453–458 (2008).
[CrossRef]

Proc. SPIE

S. Tang, “Generalized algorithm for phase shifting interferometry,” Proc. SPIE 2860, 27–32 (1996).
[CrossRef]

Other

P. A. Karasev, D. P. Campbell, and M. A. Richards, “Obtaining a 35× speedup in 2D phase unwrapping using commodity graphics processors,” in Proceedings of IEEE Conference on Radar (IEEE, 2007), pp. 574–578.

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Figures (6)

Fig. 1
Fig. 1

Schematic diagram of the ILFSL. LD, laser diode; M, mirror; CFPC, confocal Fabry–Perot cavity; PD, photodiode; PH, pinhole; L, lens; BS, beam splitter; PC, personal computer.

Fig. 2
Fig. 2

Schematic diagram of the HSTWPSI. LD 1 , LD 2 , laser diodes; M, mirror; CFPC, confocal Fabry–Perot cavity; PD, photodiode; PH, pinhole; OS, optical switch; RD, rotational diffuser; SMF, single-mode fiber; MMF, multimode fiber; L, lens; BS, beam splitter; FCL, fiber collimating lens; RM, reference mirror; AP, aperture; PC, personal computer, FPGA, field-programmable gate array.

Fig. 3
Fig. 3

Schematic diagram showing the synchronization of the currents and frequencies of the two LDs, and the trigger signal of the camera. The current and frequency are shown in black when the LD is selected, and gray if not.

Fig. 4
Fig. 4

Procedure of profiling a flat mirror with the HSTWPSI. Phase maps of ϕ 1 and ϕ 2 are presented in (a) and (b), respectively. In (c), the bold curve comes from ϕ 1 ϕ 2 and the hairline curve is the wrapped phase ϕ eq . The SOPD including the amplified error is plotted in graph (d). The differences between the right-hand side value of Eq. (7) and its nearest integer are presented in (e) and (f) when ϕ 0 is substituted with 0 and 0.496 × 2 π , respectively. The calculated integer order of λ 1 , m 1 m 01 , is plotted in (g). The SOPD determined from Eq. (5) is shown in (h).

Fig. 5
Fig. 5

Phase-shifted interferograms from the laser wavelengths of (a) 637 and (b)  657 nm , respectively.

Fig. 6
Fig. 6

Measured profiles of a four-step standard specimen: (a) the 3-D surface profile and (b) the cross-sectional profile of the center of the specimen.

Tables (1)

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Table 1 Results of Repeatedly Measured Step Heights with Different Speeds

Equations (8)

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Δ ϕ = 4 π n Δ L c × FSR = n Δ L n c l × π ,
OPD = ( m i + ϕ i 2 π ) λ i ( i = 1 , 2 ) ,
OPD = ( N + ϕ eq 2 π ) λ eq ,
N λ eq = ( m 0 i + ϕ 0 2 π ) λ i ( i = 1 , 2 ) ,
SOPD = ( ( m i m 0 i ) + ϕ i ϕ 0 2 π ) λ i ( i = 1 , 2 ) ,
SOPD = ( ϕ eq 2 π ) λ eq .
m i m i 0 = 1 2 π ( ϕ eq λ eq λ i ϕ i + ϕ 0 ) ( i = 1 , 2 ) .
h e = ( ϕ 1 e ϕ 2 e 4 π ) λ eq ,

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