Abstract

By exploring micro-optical design principles and technology, we have developed an artificial apposition compound eye. The overall thickness of the imaging system is only 320 μm, the diagonal field of view is 21°, and the f-number is 2.6. The monolithic device consists of an UV-replicated microlens array upon a thin silica substrate with a pinhole array in a metal layer on the back side. The pitch of the pinholes differs from that of the lens array to provide individual viewing angle for each channel. Theoretical limitations of resolution and sensitivity are discussed as well as fabrication issues and compared with experimental results. A method to generate nontransparent walls between optical channels to prevent cross talk is proposed.

© 2004 Optical Society of America

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References

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  1. R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
    [CrossRef]
  2. R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” presented at the Micro- and Nanoengineering International Conference, Lugano, Switzerland, 16–19 September 2002.
  3. G. A. Horridge, “The compound eye of insects,” Sci. Am. 237, 108–120 (1977).
    [CrossRef]
  4. A. W. Snyder, “Acuity of compound eyes: physical limitations and design,” J. Comp. Physiol. A 116, 161–182 (1977).
    [CrossRef]
  5. K. Kirschfeld, “The absolute sensitivity of lens and compound eyes,” Z. Naturforsch. 29, 592–596 (1974).
  6. R. Wehner, “Spatial vision in arthropods,” in Comparative Physiology and Evolution of Vision in Invertebrates—Handbook of Sensory Physiology, H. Autrum, ed. (Springer-Verlag, Berlin, 1981), Vol. VII/6C, Chap. 4, pp. 287–317.
    [CrossRef]
  7. M. F. Land, “Variations in structure and design of compound eyes,” in Facets of Vision, D. G. Stavenga, R. C. Hardie, eds. (Springer-Verlag, Berlin, 1989), Chap. 5, pp. 90–111.
    [CrossRef]
  8. G. A. Horridge, “Apposition eyes of large diurnal insects as organs adapted to seeing,” Proc. R. Soc. London Ser. B 207, 287–309 (1980).
    [CrossRef]
  9. J. S. Sanders, C. E. Halford, “Design and analysis of apposition compound eye optical sensors,” Opt. Eng. 34, 222–235 (1995).
    [CrossRef]
  10. K. Hamanaka, H. Koshi, “An artificial compound eye using a microlens array and its application to scale-invariant processing,” Opt. Rev. 3, 264–268 (1996).
    [CrossRef]
  11. S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
    [CrossRef]
  12. J. Tanida, T. Kumagai, K. Yamada, S. Miyatake, K. Ishida, T. Morimoto, N. Kondou, D. Miyazaki, Y. Ichioka, “Thin observation module by bound optics (TOMBO) concept and experimental verification,” Appl. Opt. 40, 1806–1813 (2001).
    [CrossRef]
  13. H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
    [CrossRef]
  14. P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.
  15. R. McCluney, Introduction to Radiometry and Photometry (Artech House, Boston, Mass., 1994).
  16. R. Kingslake, Optical System Design (Academic, London, 1983).
  17. P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.
  18. H. Naumann, G. Schröder, Bauelemente der Optik—Taschenbuch der technischen Optik, 6th ed. (Hanser-Verlag, Munich, 1992).
  19. M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
    [CrossRef]
  20. R. Rumpf, E. Johnson, “Micro-photonic systems utilizing SU-8,” in MOEMS and Miniaturized Systems IV, A. El-Fatatry, ed., Proc. SPIE5346, 64–72 (2004).
    [CrossRef]

2003 (2)

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
[CrossRef]

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

2001 (1)

1998 (1)

H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
[CrossRef]

1996 (1)

K. Hamanaka, H. Koshi, “An artificial compound eye using a microlens array and its application to scale-invariant processing,” Opt. Rev. 3, 264–268 (1996).
[CrossRef]

1995 (1)

J. S. Sanders, C. E. Halford, “Design and analysis of apposition compound eye optical sensors,” Opt. Eng. 34, 222–235 (1995).
[CrossRef]

1994 (1)

S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
[CrossRef]

1980 (1)

G. A. Horridge, “Apposition eyes of large diurnal insects as organs adapted to seeing,” Proc. R. Soc. London Ser. B 207, 287–309 (1980).
[CrossRef]

1977 (2)

G. A. Horridge, “The compound eye of insects,” Sci. Am. 237, 108–120 (1977).
[CrossRef]

A. W. Snyder, “Acuity of compound eyes: physical limitations and design,” J. Comp. Physiol. A 116, 161–182 (1977).
[CrossRef]

1974 (1)

K. Kirschfeld, “The absolute sensitivity of lens and compound eyes,” Z. Naturforsch. 29, 592–596 (1974).

Alda, J.

H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
[CrossRef]

Bräuer, A.

P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.

Burgi, P.-Y.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Dannberg, P.

P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.

Eisner, M.

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
[CrossRef]

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” presented at the Micro- and Nanoengineering International Conference, Lugano, Switzerland, 16–19 September 2002.

Grenet, E.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Gyger, S.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Halford, C. E.

J. S. Sanders, C. E. Halford, “Design and analysis of apposition compound eye optical sensors,” Opt. Eng. 34, 222–235 (1995).
[CrossRef]

Hamanaka, K.

K. Hamanaka, H. Koshi, “An artificial compound eye using a microlens array and its application to scale-invariant processing,” Opt. Rev. 3, 264–268 (1996).
[CrossRef]

Heim, P.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Heitger, F.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Horridge, G. A.

G. A. Horridge, “Apposition eyes of large diurnal insects as organs adapted to seeing,” Proc. R. Soc. London Ser. B 207, 287–309 (1980).
[CrossRef]

G. A. Horridge, “The compound eye of insects,” Sci. Am. 237, 108–120 (1977).
[CrossRef]

Hurditch, R.

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

Ichioka, Y.

Ishida, J.

S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
[CrossRef]

Ishida, K.

Johnson, D.

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

Johnson, E.

R. Rumpf, E. Johnson, “Micro-photonic systems utilizing SU-8,” in MOEMS and Miniaturized Systems IV, A. El-Fatatry, ed., Proc. SPIE5346, 64–72 (2004).
[CrossRef]

Kaess, F.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Kamal, H.

H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
[CrossRef]

Kingslake, R.

R. Kingslake, Optical System Design (Academic, London, 1983).

Kirschfeld, K.

K. Kirschfeld, “The absolute sensitivity of lens and compound eyes,” Z. Naturforsch. 29, 592–596 (1974).

Kondou, N.

Koshi, H.

K. Hamanaka, H. Koshi, “An artificial compound eye using a microlens array and its application to scale-invariant processing,” Opt. Rev. 3, 264–268 (1996).
[CrossRef]

Kumagai, T.

Land, M. F.

M. F. Land, “Variations in structure and design of compound eyes,” in Facets of Vision, D. G. Stavenga, R. C. Hardie, eds. (Springer-Verlag, Berlin, 1989), Chap. 5, pp. 90–111.
[CrossRef]

Mann, G.

P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.

McCluney, R.

R. McCluney, Introduction to Radiometry and Photometry (Artech House, Boston, Mass., 1994).

Miyatake, S.

Miyazaki, D.

Morimoto, T.

Naumann, H.

H. Naumann, G. Schröder, Bauelemente der Optik—Taschenbuch der technischen Optik, 6th ed. (Hanser-Verlag, Munich, 1992).

Nawrocki, D.

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

Nussbaum, P.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Ogata, S.

S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
[CrossRef]

Rüedi, P.-F.

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

Rumpf, R.

R. Rumpf, E. Johnson, “Micro-photonic systems utilizing SU-8,” in MOEMS and Miniaturized Systems IV, A. El-Fatatry, ed., Proc. SPIE5346, 64–72 (2004).
[CrossRef]

Sanders, J. S.

J. S. Sanders, C. E. Halford, “Design and analysis of apposition compound eye optical sensors,” Opt. Eng. 34, 222–235 (1995).
[CrossRef]

Sasano, T.

S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
[CrossRef]

Schröder, G.

H. Naumann, G. Schröder, Bauelemente der Optik—Taschenbuch der technischen Optik, 6th ed. (Hanser-Verlag, Munich, 1992).

Shaw, M.

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

Snyder, A. W.

A. W. Snyder, “Acuity of compound eyes: physical limitations and design,” J. Comp. Physiol. A 116, 161–182 (1977).
[CrossRef]

Tanida, J.

Völkel, R.

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
[CrossRef]

H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
[CrossRef]

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” presented at the Micro- and Nanoengineering International Conference, Lugano, Switzerland, 16–19 September 2002.

Wagner, L.

P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.

Wehner, R.

R. Wehner, “Spatial vision in arthropods,” in Comparative Physiology and Evolution of Vision in Invertebrates—Handbook of Sensory Physiology, H. Autrum, ed. (Springer-Verlag, Berlin, 1981), Vol. VII/6C, Chap. 4, pp. 287–317.
[CrossRef]

Weible, K. J.

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
[CrossRef]

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” presented at the Micro- and Nanoengineering International Conference, Lugano, Switzerland, 16–19 September 2002.

Yamada, K.

Appl. Opt. (1)

J. Comp. Physiol. A (1)

A. W. Snyder, “Acuity of compound eyes: physical limitations and design,” J. Comp. Physiol. A 116, 161–182 (1977).
[CrossRef]

Microelectron. Eng. (1)

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” Microelectron. Eng. 67–68, 461–472 (2003).
[CrossRef]

Microsystems Technologies (1)

M. Shaw, D. Nawrocki, R. Hurditch, D. Johnson, “Improving the process capability of SU-8,” Microsystems Technologies 10, 1–6 (2003).
[CrossRef]

Opt. Eng. (3)

J. S. Sanders, C. E. Halford, “Design and analysis of apposition compound eye optical sensors,” Opt. Eng. 34, 222–235 (1995).
[CrossRef]

H. Kamal, R. Völkel, J. Alda, “Properties of moiré magnifiers,” Opt. Eng. 37, 3007–3014 (1998).
[CrossRef]

S. Ogata, J. Ishida, T. Sasano, “Optical sensor array in an artificial compound eye,” Opt. Eng. 33, 3649–3655 (1994).
[CrossRef]

Opt. Rev. (1)

K. Hamanaka, H. Koshi, “An artificial compound eye using a microlens array and its application to scale-invariant processing,” Opt. Rev. 3, 264–268 (1996).
[CrossRef]

Proc. R. Soc. London Ser. B (1)

G. A. Horridge, “Apposition eyes of large diurnal insects as organs adapted to seeing,” Proc. R. Soc. London Ser. B 207, 287–309 (1980).
[CrossRef]

Sci. Am. (1)

G. A. Horridge, “The compound eye of insects,” Sci. Am. 237, 108–120 (1977).
[CrossRef]

Z. Naturforsch. (1)

K. Kirschfeld, “The absolute sensitivity of lens and compound eyes,” Z. Naturforsch. 29, 592–596 (1974).

Other (9)

R. Wehner, “Spatial vision in arthropods,” in Comparative Physiology and Evolution of Vision in Invertebrates—Handbook of Sensory Physiology, H. Autrum, ed. (Springer-Verlag, Berlin, 1981), Vol. VII/6C, Chap. 4, pp. 287–317.
[CrossRef]

M. F. Land, “Variations in structure and design of compound eyes,” in Facets of Vision, D. G. Stavenga, R. C. Hardie, eds. (Springer-Verlag, Berlin, 1989), Chap. 5, pp. 90–111.
[CrossRef]

R. Völkel, M. Eisner, K. J. Weible, “Miniaturized imaging systems,” presented at the Micro- and Nanoengineering International Conference, Lugano, Switzerland, 16–19 September 2002.

R. Rumpf, E. Johnson, “Micro-photonic systems utilizing SU-8,” in MOEMS and Miniaturized Systems IV, A. El-Fatatry, ed., Proc. SPIE5346, 64–72 (2004).
[CrossRef]

P.-F. Rüedi, P. Heim, F. Kaess, E. Grenet, F. Heitger, P.-Y. Burgi, S. Gyger, P. Nussbaum, “A 128 × 128 pixel 120 dB dynamic range vision sensor chip for image contrast and orientation extraction,” in IEEE International Solid-State Circuits Conference (Institute of Electrical and Electronics Engineers, Piscataway, N.J., 2003), paper 12.8.

R. McCluney, Introduction to Radiometry and Photometry (Artech House, Boston, Mass., 1994).

R. Kingslake, Optical System Design (Academic, London, 1983).

P. Dannberg, G. Mann, L. Wagner, A. Bräuer, “Polymer UV-molding for micro-optical systems and O/E-integration,” in Micromachining for Micro-Optics, S. H. Lee, E. G. Johnson, eds., Proc. SPIE4179, page 137 ff. SPIE, 2000.

H. Naumann, G. Schröder, Bauelemente der Optik—Taschenbuch der technischen Optik, 6th ed. (Hanser-Verlag, Munich, 1992).

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Figures (12)

Fig. 1
Fig. 1

Cross section of natural apposition compound eye with radius R and diameter of lenslets D. Interommatidial angle ΔΦ and acceptance angles of the individual channels Δϕ are shown.

Fig. 2
Fig. 2

Simplest setup of an artificial apposition compound eye. The optical axes and thus the directions of view of the ommatidia are directed outward owing to a difference in pitch Δp of microlens and pinhole arrays. The length of the objective is L; the pinhole array in a metal layer is located in the focal plane of the lens array. p, pitch of the optical channels; D, diameter of the lenslets. The size of each of the sampled microimages is a. ΔΦ defines the angular sampling of the FOV and is known as the interommatidial angle. Δϕ is the acceptance angle of an individual channel and is partly determined by pinhole diameter d. It is a measure of which solid angle in object space is represented by the optical system as one image point.

Fig. 3
Fig. 3

Simulated angular sensitivity function for a single ommatidium with lens diameter 85 μm and 300-μm focal-length in glass. The sagittal (x+) and the tangential (y±) sensitivity functions are given; several pinholes sizes and field angles are examined. In the simulations the system is perfectly focused. One simulation, with 11-μm defocusing on axis with a 3-μm pinhole, is presented for comparison with experimental results. Free-space wave propagation was used between the lens and the pinhole to account for diffraction effects.

Fig. 4
Fig. 4

Resolution of artificial compound eyes versus sensitivity to an extended source. For a given set of NA and system length there is a trade-off between sensitivity and resolution that is determined mainly by pinhole diameter d.

Fig. 5
Fig. 5

Schematic side view of the fabricated artificial compound eye consisting of a lens array layer, a substrate, and a metal layer.

Fig. 6
Fig. 6

Photograph of the front view of a demonstration wafer in the corner of a junction of four different cameras. The overlap of the metal layer and the lens array layer is presented to show the precision of replication. The lens array fills the whole substrate with identical lenses. The metal layer with the pinholes determines camera size, channel number, and increment of viewing direction of the individual cameras.

Fig. 7
Fig. 7

Response to a point source: Image of the single-mode fiber end face obtained with a camera with 51 × 51 optical channels and 3-μm pinhole diameter. The separation of viewing directions of the individual channels is 0.3°. The response of several ommatidia in the camera to one source point gives an idea of the possible resolution of the device.

Fig. 8
Fig. 8

Measured on-axis angular sensitivity function for ommatidia with lens diameter 85 μm and 300-μm focal length in glass. Pinhole diameter, 3 μm. Results of direct measurement for a single ommatidium while the point source was moved in front of it are presented. Additionally measured and normalized energies in images taken with a 51 × 51 channel camera for a point source and relayed with a microscope objective and a C-mount objective, respectively, on a CCD camera were analyzed. A Gaussian fit to the curves was made to quantify the curve shape.

Fig. 9
Fig. 9

Bar targets of different frequencies (in LPs/FOV) imaged by apposition-eye cameras with 101 × 101 channels, 15° horizontal FOV, and 3-μm pinhole diameter and relayed by a short working distance C-mount objective onto a CCD: (a) 2.5 LP/FOV, (b) 5 LP/FOV, (c) 10 LP/FOV, (c) 20 LP/FOV, (c) 28 LP/FOV. Image processing as Gaussian blurring (2 CCD pixels), brightness, contrast, and intensity were applied to enhance image quality, as done also by commercial digital cameras.

Fig. 10
Fig. 10

Calculated MTF and measured CTF. The MTF was calculated from Eq. (12) with σ = 0.85°. The CTF was measured for the imaged bar targets presented above but acquired without any subsequent image processing except Gaussian blurring with 2 CCD pixels for smoothing of the images determined by the CCD resolution. For reasons of simplicity and unambiguousness over the progression of the curve the CTF is opposed to the MTF.

Fig. 11
Fig. 11

Test patterns imaged by the same apposition-eye cameras as in Fig. 9. (a) Image of a passport photograph of J. Duparré. (b) Image of the Fraunhofer-Institut für Angewandte Optik und Feinmechanik logo. Test objects fill the FOV of the camera under test. Object distance has no noticeable influence on image quality.

Fig. 12
Fig. 12

Layout of a monolithic artificial apposition eye with optical isolation of the individual channels. Fabrication steps: (a) pinhole array upon a substrate, which works only as a carrier and can later be replaced by the electronics chip. (b) SU8 photopolymer pedestals with correct height structured on top. (c) Spaces between pedestals are filled with an absorbing polymer, and a microlens array, aligned to the pinholes, is embossed on the top in an UV-curing polymer.

Tables (1)

Tables Icon

Table 1 Parameters of Fabricated Artificial Apposition Eye Wafers

Equations (13)

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ΔΦ=arctanΔp/f,
Δϕ=arctanFWHMdˆPSFf,
Δϕ=df2+λD21/2,
dAiry=2.44λf/D.
FOV=arctana/f,
Δp=a1-NN+1.
II=πτLO4F/#2,
IIIO=τ4F/#2=τNA2,
PI=τIONA2πd2/4.
PI=9π128 τIONA2L211/Δϕ2
fx=fmax exp-x2σ2,
MTFx˜=exp-2π x˜2σ24FOV2,
CTFx˜=Imax-IminImax+Imin,

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