Abstract

High-power phosphor-based LEDs are replacing conventional white-light sources for vertical scanning interferometry, but the spectrum of the phosphor-based LED is different from that of the conventional light source. The phosphor-based LED has two peaks in its spectrum, while the conventional light source has only one peak in the Gaussian distribution. In this Letter, we investigate the effects of phosphor-based LEDs on vertical scanning interferometry. Our result shows that the use of a phosphor-based LED changes the fringe contrast function significantly, such that measurement repeatability decreases. We propose and demonstrate that a constraint on the input to the existing reconstruction algorithm improves the repeatability of the vertical scanning interferometer with a phosphor-based LED.

© 2010 Optical Society of America

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References

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  1. L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
    [CrossRef]
  2. I. Gurov, E. Ermolaeva, and A. Zakharov, J. Opt. Soc. Am. A 21, 242 (2004).
    [CrossRef]
  3. C. Ai and E. K. Novak, “Centroid approach for estimating modulation peak in broad-bandwidth interferometry,” U.S. patent 5,633,715 (May 27, 1997).
  4. P. J. de Groot and L. L. Deck, Proc. SPIE 2248, 101 (1994).
    [CrossRef]
  5. P. de Groot and L. Deck, J. Mod. Opt. 42, 389 (1995).
    [CrossRef]

2005

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

2004

1995

P. de Groot and L. Deck, J. Mod. Opt. 42, 389 (1995).
[CrossRef]

1994

P. J. de Groot and L. L. Deck, Proc. SPIE 2248, 101 (1994).
[CrossRef]

Ai, C.

C. Ai and E. K. Novak, “Centroid approach for estimating modulation peak in broad-bandwidth interferometry,” U.S. patent 5,633,715 (May 27, 1997).

Chenggen, Q.

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

de Groot, P.

P. de Groot and L. Deck, J. Mod. Opt. 42, 389 (1995).
[CrossRef]

de Groot, P. J.

P. J. de Groot and L. L. Deck, Proc. SPIE 2248, 101 (1994).
[CrossRef]

Deck, L.

P. de Groot and L. Deck, J. Mod. Opt. 42, 389 (1995).
[CrossRef]

Deck, L. L.

P. J. de Groot and L. L. Deck, Proc. SPIE 2248, 101 (1994).
[CrossRef]

Ermolaeva, E.

Gurov, I.

Ivan, R.

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

Jui, T. C.

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

Mingzhou, L.

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

Novak, E. K.

C. Ai and E. K. Novak, “Centroid approach for estimating modulation peak in broad-bandwidth interferometry,” U.S. patent 5,633,715 (May 27, 1997).

Shihua, W.

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

Zakharov, A.

J. Mod. Opt.

P. de Groot and L. Deck, J. Mod. Opt. 42, 389 (1995).
[CrossRef]

J. Opt. Soc. Am. A

Proc. SPIE

L. Mingzhou, Q. Chenggen, T. C. Jui, R. Ivan, and W. Shihua, Proc. SPIE 5852, 401 (2005).
[CrossRef]

P. J. de Groot and L. L. Deck, Proc. SPIE 2248, 101 (1994).
[CrossRef]

Other

C. Ai and E. K. Novak, “Centroid approach for estimating modulation peak in broad-bandwidth interferometry,” U.S. patent 5,633,715 (May 27, 1997).

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Figures (5)

Fig. 1
Fig. 1

(a) Spectrum of a phosphor-based LED, LXHL-LW6C. (b) Simulated correlogram based on spectrum of (a).

Fig. 2
Fig. 2

Experiment data: intensity response based on light source of phosphor-based LED (LXHL-LW6C by LumiLEDs). The distinctive feature is consistent with the simulation result.

Fig. 3
Fig. 3

Comparing performance of different algorithms between different light sources: (a) standard deviation of a perfectly flat surface; the ideal value is zero and (b) height measurement; the ideal value is 1 μm .

Fig. 4
Fig. 4

Illustrating the effects of selecting (a) 80 data and (b) 20 data in the spatial frequency domain. According to the FDA approach, there should be only one peak (in the region around 20 to 30 rad / μm ); this assumption is met in (b).

Fig. 5
Fig. 5

Experimental verification on the proposed modification for a phosphor-based LED: comparing standard deviation of measuring an optically flat surface reconstructed with and without the proposed modification.

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