Abstract

We present results obtained with a computer-controlled low-coherence interference microscope featuring a modified optical layout that uses a pair of fast switchable achromatic phase-shifters. This layout makes it possible to use ferro-electric liquid-crystal devices made with readily available FLC materials having a switching angle of 45°, and obtain phase shifts of 0° and ±90°. The use of phase shifts of 0° and ±90° simplifies calculations of the fringe visibility and the fractional fringe-order and yields maximum accuracy.

© 2005 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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Appl. Opt. (1)

J. Mod. Opt. (2)

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

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

Opt Lett. (1)

S. S. C. Chim and G. S. Kino, �??Correlation microscope,�?? Opt Lett. 15, 579-581 (1990).
[CrossRef] [PubMed]

Opt. Eng. (2)

P. Hariharan, P. E. Ciddor, M. Roy, �??Improved switchable achromatic phase shifters 2,�?? Opt. Eng. accepted.

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

Opt. Express (1)

Opt. Lasers Eng. (1)

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

Opt. Lett. (1)

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Figures (3)

Fig. 1.
Fig. 1.

Modified LCI microscope using two QWPs and two FLC devices.

Fig. 2.
Fig. 2.

Closed path followed by the polarization state on the Poincare sphere.

Fig. 3.
Fig. 3.

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

Equations (2)

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V = [ ( I 90 I 90 ) 2 + ( I 0 I 90 I 90 ) 2 ] I 90 + I 90 1 / 2
tan ϕ = I 90 I 90 2 I 0 I 90 I 90

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