Abstract

We describe a computer-controlled low-coherence interference microscope, based on a Linnik interferometer configuration that can rapidly and accurately map the shape of micro-machined surfaces exhibiting steps and discontinuities. The novel feature of the system is a fast, switchable achromatic phase-modulator operating on the geometric phase, using a pair of ferro-electric liquid crystal devices.

© 2004 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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  9. P. Hariharan, and P. E. Ciddor, �??Achromatic phase-shifters:2. A quantized ferroelectric liquid-crystal system,�?? Opt. Comm. 117, 13-15 (1995).
    [CrossRef]
  10. P. Hariharan, �??Fast, common-path switchable, achromatic phase-shifter for polarization interferometry,�?? J. Mod. Opt. 44, 857-861 (1997).
    [CrossRef]
  11. P. Hariharan and P. E. Ciddor, �??Improved switchable achromatic phase shifters,�?? Opt. Eng. 38, 1078-1080 (1999).
    [CrossRef]
  12. P. Hariharan and M. Roy, �??White-light phase-stepping interferometry: measurement of the fractional interference order,�?? J. Mod. Opt. 42, 2357-2360 (1995).
    [CrossRef]

Appl. Opt.

J. Mod. Opt.

P. Hariharan, K. G. Larkin and M.Roy, �??The geometric phase: interferometric observations with white light,�?? J. Mod. Opt. 41, 663-667 (1994).
[CrossRef]

P. Hariharan and M.Roy, �??White-light phase-steppping interferometry for surface profiling,�?? J. Mod. Opt. 41, 2197-2201(1994).
[CrossRef]

P. Hariharan, �??Fast, common-path switchable, achromatic phase-shifter for polarization interferometry,�?? J. Mod. Opt. 44, 857-861 (1997).
[CrossRef]

P. Hariharan and M. Roy, �??White-light phase-stepping interferometry: measurement of the fractional interference order,�?? J. Mod. Opt. 42, 2357-2360 (1995).
[CrossRef]

Opt. and Lasers in Eng.

M. Roy, P. Svahn, L. Cherel, and C.J.R. Sheppard, �??Geometric phase-shifting for low-coherence interference microscopy,�?? Opt. and Lasers in Eng. 37, 631-641 (2002).
[CrossRef]

Opt. Comm.

G. D. Love, and R. Bhandari, �??Optical properties of a QHQ ferroelectric liquid crystal phase modulator,�?? Opt. Comm. 110, 475-478 (1994).
[CrossRef]

P. Hariharan, and P. E. Ciddor, �??Achromatic phase-shifters:2. A quantized ferroelectric liquid-crystal system,�?? Opt. Comm. 117, 13-15 (1995).
[CrossRef]

Opt. Eng.

P. Hariharan and P. E. Ciddor, �??Improved switchable achromatic phase shifters,�?? Opt. Eng. 38, 1078-1080 (1999).
[CrossRef]

Proc. SPIE

M. Davidson, K. Kaufman, I. Mazor, and F. Cohen, �??An application of interference microscopy to integrated circuit inspection and metrology,�?? Integrated Circuit, Metrology, Inspection and Process Control, Proc. SPIE 775 (Bellingham, Washington: SPIE), 233-247 (1987).
[CrossRef]

Science

D. Huang, E. A. Swanson, C. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M.R. Lee, T. Flotte, K. Gregory, C.A. Puliafito, and J.G. Fujimoto, �??Optical coherence tomography,�?? Science 254, 1178-1181 (1991).
[CrossRef] [PubMed]

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Figures (4)

Fig.1.
Fig.1.

GPM with FLC devices. Two FLC devices are sandwiched between two quarter-wave plates.

Fig. 2.
Fig. 2.

Schematic of the low coherence interference microscope using an FLC phase modulator.

Fig. 3.
Fig. 3.

Visibility of the interference fringes as a function of the position of the sample along the z axis.

Fig. 4.
Fig. 4.

Surface profile of an integrated circuit measured with our system. The lateral dimensions of the object are 25 µm×43 µm, height 1 µm.

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