Abstract

Inspired by the biomechanics of the human eye, which includes a crystalline lens, ciliary muscles, and zonular fibers, the proposed variable-focus lens system consists of a PDMS lens, winding-type SMA actuator, and load arms. The PDMS lens is encircled and stretched by the load arms joined to an outer ring that is rotated by the winding-type SMA actuator, thereby changing the focal length of the lens. In contrast to other single tunable-focus lenses, the proposed system uses a gel-type PDMS lens, which is insensitive to gravity and external vibration, and can be made into a biconvex or aspheric shape. The design of the proposed system is described in detail, and experimental results demonstrate the validity of the proposed system.

© 2009 Optical Society of America

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References

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  1. T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
    [CrossRef]
  2. M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
    [CrossRef]
  3. B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159-163 (2000).
    [CrossRef]
  4. H. Ren and S. T. Wu, "Variable-focus liquid lens," Opt. Express 15, 5931-5936 (2007).
    [CrossRef] [PubMed]
  5. H. Ren, D. Fox, P. Anderson, B. Wu, and S. T. Wu, "Tunable-focus liquid lens controlled using a servo motor," Opt. Express 14, 8031-8036 (2006).
    [CrossRef] [PubMed]
  6. A. Werber and H. Zappe, "Tunable pneumatic microoptics," J. Microelectromech. Syst. 17, 1218-1227 (2008).
    [CrossRef]
  7. J. M. Choi, H. M. Son, and Y. J. Lee, "Design of biomimetic robot-eye system with single vari-focal lens and winding-type SMA actuator," International Conference on Control, Automation and Systems 2533-2537 (2008).
    [CrossRef]
  8. http://projects.cbe.ab.ca/Diefenbaker/Biology/Bio%20Website%20Final/notes/nervous_system/8_eye_notes.html
  9. Y. J. Lee, H. M. Son J. B. Gu, and T. H. Nam, "Design and control of a multistep SMA actuator," Int. J. Appl. Electromagn. Mech.  23, 119-124 (2006).
  10. Korean Industrial Standards, KS B 5408, http://www.kats.go.kr.
  11. HyVISION SYSTEM Inc., http://www.hyvision.co.kr.

2008 (2)

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

A. Werber and H. Zappe, "Tunable pneumatic microoptics," J. Microelectromech. Syst. 17, 1218-1227 (2008).
[CrossRef]

2007 (1)

2006 (3)

H. Ren, D. Fox, P. Anderson, B. Wu, and S. T. Wu, "Tunable-focus liquid lens controlled using a servo motor," Opt. Express 14, 8031-8036 (2006).
[CrossRef] [PubMed]

Y. J. Lee, H. M. Son J. B. Gu, and T. H. Nam, "Design and control of a multistep SMA actuator," Int. J. Appl. Electromagn. Mech.  23, 119-124 (2006).

T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
[CrossRef]

2000 (1)

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159-163 (2000).
[CrossRef]

Anderson, P.

Berge, B.

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159-163 (2000).
[CrossRef]

Fox, D.

Lee, Y. J.

Y. J. Lee, H. M. Son J. B. Gu, and T. H. Nam, "Design and control of a multistep SMA actuator," Int. J. Appl. Electromagn. Mech.  23, 119-124 (2006).

Peseux, J.

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159-163 (2000).
[CrossRef]

Ren, H.

Sato, S.

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
[CrossRef]

Takahash, T.

T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
[CrossRef]

Wang, B.

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

Werber, A.

A. Werber and H. Zappe, "Tunable pneumatic microoptics," J. Microelectromech. Syst. 17, 1218-1227 (2008).
[CrossRef]

Wu, B.

Wu, S. T.

Yanase, S.

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

Ye, M.

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
[CrossRef]

Zappe, H.

A. Werber and H. Zappe, "Tunable pneumatic microoptics," J. Microelectromech. Syst. 17, 1218-1227 (2008).
[CrossRef]

E (1)

M. Ye, B. Wang, S. Yanase, and S. Sato, "Variable-focus liquid crystal lenses used in imagine systems as focusing elements," IEICE Trans. Electron.E 91-C, 1599-1603 (2008).
[CrossRef]

Eur. Phys. J. E (1)

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159-163 (2000).
[CrossRef]

IEE Electron. Lett. (1)

T. Takahash, M. Ye, and S. Sato, "Aberrations of liquid crystal lens," IEE Electron. Lett. 42,1476-1477 (2006).
[CrossRef]

Int. J. Appl. Electromagn. Mech. (1)

Y. J. Lee, H. M. Son J. B. Gu, and T. H. Nam, "Design and control of a multistep SMA actuator," Int. J. Appl. Electromagn. Mech.  23, 119-124 (2006).

J. Microelectromech. Syst. (1)

A. Werber and H. Zappe, "Tunable pneumatic microoptics," J. Microelectromech. Syst. 17, 1218-1227 (2008).
[CrossRef]

Opt. Express (2)

Other (4)

J. M. Choi, H. M. Son, and Y. J. Lee, "Design of biomimetic robot-eye system with single vari-focal lens and winding-type SMA actuator," International Conference on Control, Automation and Systems 2533-2537 (2008).
[CrossRef]

http://projects.cbe.ab.ca/Diefenbaker/Biology/Bio%20Website%20Final/notes/nervous_system/8_eye_notes.html

Korean Industrial Standards, KS B 5408, http://www.kats.go.kr.

HyVISION SYSTEM Inc., http://www.hyvision.co.kr.

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Figures (16)

Fig. 1.
Fig. 1.

Accommodation of human eye: (a) to view distant object and (b) to view nearby object [8].

Fig. 2.
Fig. 2.

Cross-sectional view of proposed lens system, where physical curvature is changed by applying tensile strength: (a) before applying tensile strength and (b) after applying tensile strength.

Fig. 3.
Fig. 3.

Conceptual drawing: (a) before applying tensile strength and (b) after applying tensile strength.

Fig. 4.
Fig. 4.

CAD drawing of KNU eye-II.

Fig. 5.
Fig. 5.

Schematic of PDMS lens for calculating initial focal length.

Fig. 6.
Fig. 6.

Vari-focal PDMS lens: (a) top view and (b) skew view.

Fig. 7.
Fig. 7.

Mechanical parts of KNU eye-II.

Fig. 8.
Fig. 8.

KNU eye-II: (a) overall view, (b) inner structure except for upper part, and (c) side view.

Fig. 9.
Fig. 9.

Operation of KNU eye-II: (a) before pulling PDMS lens and (b) after pulling PDMS lens.

Fig. 10.
Fig. 10.

Results of simulated and measured displacement of load arm versus displacement of winding-type SMA actuator.

Fig. 11.
Fig. 11.

Schematic of experimental setup for measuring focal length of PDMS lens.

Fig. 12.
Fig. 12.

Results of focal length of PDMS lens versus displacement of SMA actuator.

Fig. 13.
Fig. 13.

Step response of SMA actuator.

Fig. 14.
Fig. 14.

Experimental setup for measuring focusing ability.

Fig. 15.
Fig. 15.

Controller: (a) microcontroller board and (b) SMA actuator controller.

Fig. 16.
Fig. 16.

Images taken by vari-focal PDMS lens with four focal lengths: (a) f = 17.2 mm and (b) f = 18.0 mm.

Tables (3)

Tables Icon

Table 1. Specifications of vari-focal PDMS lens.

Tables Icon

Table 2. Specifications of KNU eye-II

Tables Icon

Table 3. Specifications of winding-type SMA actuator.

Equations (3)

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1f=(nPDMS1)(1R11R2)
ΔLarm=Lb·RringLa·RSMA Δ LSMA
f=fo·yy

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