Abstract

In this study, we presented a light-emitting diode-based (LED) miniaturized optical pattern imager for slim mobile phone application. To meet volume constraints, we designed a miniaturized compact illuminating and imaging optical component. The objective was to minimize optical loss using several nano- and micro-fabrication methods. After integration into a single optical body, the prototype imager–with dimensions of 6.8 × 2.2 × 2.5 mm and a weight of 0.4 g–demonstrated clear feasibility in measuring 2D micropatterns with widths of 50 and 10 μm.

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References

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  1. I. Fujieda, K. Tai, E. Matsuyama, and M. Kurita, “Dual-LED imaging system for secure fingerprint identification,” Proc. of SPIE 6049, 60490B–1- 60490B–9 (2005).
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    [CrossRef]
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    [CrossRef]
  5. L. Nguyen, “Wafer-Level chip-scale packaging,” in Proceedings of Professional Development Course 55th Electronic Components & Technology Conference, (Orlando, Florida, 2005), pp. 4–19.
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
  17. C. C. Sun, T. X. Lee, S. H. Ma, Y. L. Lee, and S. M. Huang, “Precise optical modeling for LED lighting verified by cross correlation in the midfield region,” Opt. Lett. 31(14), 2193–2195 (2006).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
  20. N. Maluf, and K. Williams, An Introduction to microelectromechanical systems engineering (Artech house Inc., Norwood, 2004).
  21. F. L. Pedrotti, and S. Leno, Introduction to optics (Prentice-Hall, New Jersey, 1987).
  22. D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
    [CrossRef]
  23. D. K. Woo, K. Hane, and S. K. Lee, “High order diffraction grating using v-shaped groove with refractive and reflective surfaces,” Opt. Express 16(25), 21004–21011 (2008).
    [CrossRef] [PubMed]
  24. J. S. Fender and J. E. Harvey, “Specifying surface finish and scattering tolerances of conical optical elements,” Opt. Eng. 21, 983–986 (1982).
  25. J. Y. Joo, C. S. Kang, S. S. Park, and S. K. Lee, “Fabrication of a beam shaping lens for chip scale packaged LEDs,” International Conference on Precision Engineering 2010 (to be published).
  26. S. H. Ng and Z. F. Wang, “Hot embossing on polymethyl methacrylate,” Singapore Inst. Manuf. Technol. Rep. 8(3), 174–177 (2007).
  27. M. T. Gale, “Replication techniques for diffractive optical elements,” Microelectron. Eng. 34(3-4), 321–339 (1997).
    [CrossRef]

2009 (3)

2008 (7)

I. Moreno and C. C. Sun, “Modeling the radiation pattern of LEDs,” Opt. Express 16(3), 1808–1819 (2008).
[CrossRef] [PubMed]

Y. Ding, X. Liu, Z. R. Zheng, and P. F. Gu, “Freeform LED lens for uniform illumination,” Opt. Express 16(17), 12958–12966 (2008).
[CrossRef] [PubMed]

D. K. Woo, K. Hane, and S. K. Lee, “High order diffraction grating using v-shaped groove with refractive and reflective surfaces,” Opt. Express 16(25), 21004–21011 (2008).
[CrossRef] [PubMed]

D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
[CrossRef]

F. Fournier and J. Rolland, “Design Methodology for High Brightness Projectors,” J. Disp. Technol. 4(1), 86–91 (2008).
[CrossRef]

T. Imamura, K. Kakutani, and I. Fujieda, “Imaging simulated smeared fingers with a sensor based on scattered-light detection,” Opt. Rev. 15(3), 143–147 (2008).
[CrossRef]

I. Moreno and C. C. Sun, “LED array: where does far-field begin?” Proc. SPIE 7058, 70580R (2008).
[CrossRef]

2007 (3)

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

S. H. Ng and Z. F. Wang, “Hot embossing on polymethyl methacrylate,” Singapore Inst. Manuf. Technol. Rep. 8(3), 174–177 (2007).

X. Zhao, Z. L. Fang, J. C. Cui, X. Zhang, and G. G. Mu, “Illumination system using LED sources for pocket-size projectors,” Appl. Opt. 46(4), 522–526 (2007).
[CrossRef] [PubMed]

2006 (2)

2005 (1)

2002 (1)

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

1997 (1)

M. T. Gale, “Replication techniques for diffractive optical elements,” Microelectron. Eng. 34(3-4), 321–339 (1997).
[CrossRef]

1982 (1)

J. S. Fender and J. E. Harvey, “Specifying surface finish and scattering tolerances of conical optical elements,” Opt. Eng. 21, 983–986 (1982).

Abe, S.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Chien, W. T.

Cui, J. C.

Ding, Y.

Fang, Z. L.

Fender, J. S.

J. S. Fender and J. E. Harvey, “Specifying surface finish and scattering tolerances of conical optical elements,” Opt. Eng. 21, 983–986 (1982).

Fournier, F.

F. Fournier and J. Rolland, “Design Methodology for High Brightness Projectors,” J. Disp. Technol. 4(1), 86–91 (2008).
[CrossRef]

Fujieda, I.

T. Imamura, K. Kakutani, and I. Fujieda, “Imaging simulated smeared fingers with a sensor based on scattered-light detection,” Opt. Rev. 15(3), 143–147 (2008).
[CrossRef]

K. Tai, E. Matsuyama, M. Kurita, and I. Fujieda, “Dual-LED imaging for finger liveliness detection and its evaluation with replicas,” Appl. Opt. 45(24), 6263–6269 (2006).
[CrossRef] [PubMed]

Fujimoto, M.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Gale, M. T.

M. T. Gale, “Replication techniques for diffractive optical elements,” Microelectron. Eng. 34(3-4), 321–339 (1997).
[CrossRef]

Gu, P. F.

Hane, K.

D. K. Woo, K. Hane, and S. K. Lee, “High order diffraction grating using v-shaped groove with refractive and reflective surfaces,” Opt. Express 16(25), 21004–21011 (2008).
[CrossRef] [PubMed]

D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
[CrossRef]

Harvey, J. E.

J. S. Fender and J. E. Harvey, “Specifying surface finish and scattering tolerances of conical optical elements,” Opt. Eng. 21, 983–986 (1982).

Ho, Y. L.

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

Hsieh, C. C.

Hu, F.

Huang, H. C.

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

Huang, S. M.

Iijima, R.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Imamura, T.

T. Imamura, K. Kakutani, and I. Fujieda, “Imaging simulated smeared fingers with a sensor based on scattered-light detection,” Opt. Rev. 15(3), 143–147 (2008).
[CrossRef]

Inui, T.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Joo, J. Y.

J. Y. Joo and S. K. Lee, “Miniaturized TIR Fresnel lens for miniature optical LED applications,” Int. J. Precis. Eng. Manuf. 10(2), 137–140 (2009).
[CrossRef]

J. Y. Joo, C. S. Kang, S. S. Park, and S. K. Lee, “LED beam shaping lens based on the near-field illumination,” Opt. Express 17(26), 23449–23458 (2009).
[CrossRef]

Kakutani, K.

T. Imamura, K. Kakutani, and I. Fujieda, “Imaging simulated smeared fingers with a sensor based on scattered-light detection,” Opt. Rev. 15(3), 143–147 (2008).
[CrossRef]

Kang, C. S.

Kurita, M.

Kwok, H. S.

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

Lee, S. K.

J. Y. Joo and S. K. Lee, “Miniaturized TIR Fresnel lens for miniature optical LED applications,” Int. J. Precis. Eng. Manuf. 10(2), 137–140 (2009).
[CrossRef]

J. Y. Joo, C. S. Kang, S. S. Park, and S. K. Lee, “LED beam shaping lens based on the near-field illumination,” Opt. Express 17(26), 23449–23458 (2009).
[CrossRef]

D. K. Woo, K. Hane, and S. K. Lee, “High order diffraction grating using v-shaped groove with refractive and reflective surfaces,” Opt. Express 16(25), 21004–21011 (2008).
[CrossRef] [PubMed]

D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
[CrossRef]

Lee, T. X.

Lee, Y. L.

Liu, X.

Lo, Y. C.

Luo, Y.

Ma, S. H.

Maruo, Y.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Matsuyama, E.

Moreno, I.

Mu, G. G.

Nakatsuka, M.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Ng, S. H.

S. H. Ng and Z. F. Wang, “Hot embossing on polymethyl methacrylate,” Singapore Inst. Manuf. Technol. Rep. 8(3), 174–177 (2007).

Park, S. S.

Qian, K. Y.

Rolland, J.

F. Fournier and J. Rolland, “Design Methodology for High Brightness Projectors,” J. Disp. Technol. 4(1), 86–91 (2008).
[CrossRef]

Sun, C. C.

Tai, K.

Tan, L.

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

Unuma, Y.

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Wang, Z. F.

S. H. Ng and Z. F. Wang, “Hot embossing on polymethyl methacrylate,” Singapore Inst. Manuf. Technol. Rep. 8(3), 174–177 (2007).

Woo, D. K.

D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
[CrossRef]

D. K. Woo, K. Hane, and S. K. Lee, “High order diffraction grating using v-shaped groove with refractive and reflective surfaces,” Opt. Express 16(25), 21004–21011 (2008).
[CrossRef] [PubMed]

Yu, X. J.

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

Zhang, X.

Zhao, X.

Zheng, Z. R.

Appl. Opt. (3)

Int. J. Precis. Eng. Manuf. (1)

J. Y. Joo and S. K. Lee, “Miniaturized TIR Fresnel lens for miniature optical LED applications,” Int. J. Precis. Eng. Manuf. 10(2), 137–140 (2009).
[CrossRef]

J. Disp. Technol. (2)

X. J. Yu, Y. L. Ho, L. Tan, H. C. Huang, and H. S. Kwok, “LED Based Projection Systems,” J. Disp. Technol. 3(3), 295–303 (2007).
[CrossRef]

F. Fournier and J. Rolland, “Design Methodology for High Brightness Projectors,” J. Disp. Technol. 4(1), 86–91 (2008).
[CrossRef]

J. Opt. A, Pure Appl. Opt. (1)

D. K. Woo, K. Hane, and S. K. Lee, “Fabrication of a multi-level lens using independent-exposure lithography and FAB plasma etching,” J. Opt. A, Pure Appl. Opt. 10(4), 044001 (2008).
[CrossRef]

Microelectron. Eng. (1)

M. T. Gale, “Replication techniques for diffractive optical elements,” Microelectron. Eng. 34(3-4), 321–339 (1997).
[CrossRef]

Opt. Eng. (2)

J. S. Fender and J. E. Harvey, “Specifying surface finish and scattering tolerances of conical optical elements,” Opt. Eng. 21, 983–986 (1982).

R. Iijima, M. Fujimoto, Y. Maruo, M. Nakatsuka, T. Inui, S. Abe, and Y. Unuma, “Document scanner using polymer waveguides with a microlens array,” Opt. Eng. 41(11), 2743–2748 (2002).
[CrossRef]

Opt. Express (5)

Opt. Lett. (1)

Opt. Rev. (1)

T. Imamura, K. Kakutani, and I. Fujieda, “Imaging simulated smeared fingers with a sensor based on scattered-light detection,” Opt. Rev. 15(3), 143–147 (2008).
[CrossRef]

Proc. SPIE (1)

I. Moreno and C. C. Sun, “LED array: where does far-field begin?” Proc. SPIE 7058, 70580R (2008).
[CrossRef]

Singapore Inst. Manuf. Technol. Rep. (1)

S. H. Ng and Z. F. Wang, “Hot embossing on polymethyl methacrylate,” Singapore Inst. Manuf. Technol. Rep. 8(3), 174–177 (2007).

Other (8)

J. Y. Joo, C. S. Kang, S. S. Park, and S. K. Lee, “Fabrication of a beam shaping lens for chip scale packaged LEDs,” International Conference on Precision Engineering 2010 (to be published).

N. Maluf, and K. Williams, An Introduction to microelectromechanical systems engineering (Artech house Inc., Norwood, 2004).

F. L. Pedrotti, and S. Leno, Introduction to optics (Prentice-Hall, New Jersey, 1987).

I. Ashdown, and M. Salsbury, “A Near-field Goniospectroradiometer for LED Measurements,” Proc. SPIE 6342, 634215–1 - 634215–11 (2006).

I. Fujieda, K. Tai, E. Matsuyama, and M. Kurita, “Dual-LED imaging system for secure fingerprint identification,” Proc. of SPIE 6049, 60490B–1- 60490B–9 (2005).

http://www.crucialtec.com/ .

L. Nguyen, “Wafer-Level chip-scale packaging,” in Proceedings of Professional Development Course 55th Electronic Components & Technology Conference, (Orlando, Florida, 2005), pp. 4–19.

P. Schreiber, S. Kudaev, P. Dannberg, and A. Gebhardt, “Microoptics for homogeneous LED-illumination,” Proc. SPIE 6196, 61960–1 - 61960–9 (2006).

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Figures (12)

Fig. 1
Fig. 1

Schematic of a LED-based étendue-limited optical system: miniaturized pocket projector (left) and imager (right).

Fig. 2
Fig. 2

Schematic of ray paths in the miniaturized 2D optical imager.

Fig. 3
Fig. 3

(a) Physical dimensions of the LED and the precisely modeled LED, (b) molded LED and measurement coordinates, (c) comparison of light distributions between molded LED and actual LED in polar coordinates, tracing of a hundred million rays.

Fig. 4
Fig. 4

(a) Schematic of a diffractive Fresnel imaging lens design, (b) MTF performance of the designed imaging lens.

Fig. 5
Fig. 5

(a) Designed miniaturized 2D optical imager in the optical software, (b) image formed on the detector, (c) illuminance distribution on the imaging area without imaging object, (d) total luminous flux variation on the imaging area based on assembly errors. (a hundred-million rays being traced during simulation)

Fig. 6
Fig. 6

(a) Assembled fabricated optical component on silicon wafer in the top core, (b) surface quality of the bottom core after EDM, (c) enhanced surface quality after mechanical polishing.

Fig. 7
Fig. 7

(a) Photography of machined NBSL and microscope image of facets ( × 50), (b) optical performance of the CSP LED with/without NBSL in logarithmic.

Fig. 8
Fig. 8

(a) Assembled mold set with hot embossing equipment, (b) fabricated optical system by thermal nano-imprint (4 Mpa, 160° C).

Fig. 9
Fig. 9

(a) Aluminum-coated integrated custom microprism, (b) schematic of aluminum coating on PMMA.

Fig. 10
Fig. 10

(a) Assembled and fabricated optical components with measurement jigs, (b) image tester setup of an LED-based micro pattern recognizer and side view of all assembled optics and jigs.

Fig. 11
Fig. 11

(a) Physical dimension of the target specimen, (b) formed images on image plane for target specimen through microscopes.

Fig. 12
Fig. 12

(a) Physical dimension of the micropattern, (b) formed images on an image plane as the target specimen via a microscope.

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

E ˙ t e n d u e ( m m 2 s r ) = π ( r e f r a c t i v e ​   i n d e x ) 2 ( I l l u min a t e d a r e a o f t h e i m a g e r ) sin 2 θ
I s e n s o r = G i m a g e r × A i m a g e r A s e n s o r × N A 2 × η p r i s m × η B S L × L L E D ,       where        N A = l e n s d i a m e t e r 2 f o c a l l e n g t h
ν = 54.74 ° + s i n 1 ( n a i r s i n ( 15.78 ° + θ ) n P M M A )
R i m a g e e ( A l e n s A i m a g e r ) = H tan ( 45 ° v / 2 ) H / tan v = tan ( v ) tan ( 45 ° v / 2 )
1 S s e n s o r 1 S i m a g e = ( n P M M A n a i r ) ( C 1 C 2 ) , ​ ​ ​                         where               S i m a g e = H cos ( 45 ° v / 2 )
T I S = 1 R s c a t t e r R o = 1 E X P [ ( 4 π R q cos v λ ) 2 ]
δ 35.26 ° + tan 1 ( D e d t ) + α

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