Abstract

In this research, a unique freeform microlens array was designed and fabricated for a compact compound-eye camera to achieve a large field of view. This microlens array has a field of view of 48°×48°, with a thickness of only 1.6 mm. The freeform microlens array resides on a flat substrate, and thus can be directly mounted to a commercial 2D image sensor. Freeform surfaces were used to design the microlens profiles, thus allowing the microlenses to steer and focus incident rays simultaneously. The profiles of the freeform microlenses were represented using extended polynomials, the coefficients of which were optimized using ZEMAX. To reduce crosstalk among neighboring channels, a micro aperture array was machined using high-speed micromilling. The molded microlens array was assembled with the micro aperture array, an adjustable fixture, and a board-level image sensor to form a compact compound-eye camera system. The imaging tests using the compound-eye camera showed that the unique freeform microlens array was capable of forming proper images, as suggested by design. The measured field of view of ±23.5° also matches the initial design and is considerably larger compared with most similar camera designs using conventional microlens arrays. To achieve low manufacturing cost without sacrificing image quality, the freeform microlens array was fabricated using a combination of ultraprecision diamond broaching and a microinjection molding process.

© 2012 Optical Society of America

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  22. C. N. Huang, “Investigation of injection molding process for high precision polymer lens manufacturing,” Ph.D. dissertation, Ohio State University (2008, Columbus, Ohio).

2011

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

2010

2009

D. Cheng, Y. Wang, H. Hua, and M. M. Talha, “Design of an optical see-through head-mounted display with a low f-number and large field of view using a freeform prism,” Appl. Opt. 48, 2655–2668 (2009).
[CrossRef]

G. Druart, N. Guérineau, R. Haïdar, S. Thétas, J. Taboury, S. Rommeluére, J. Primot, and M. Fendler, “Demonstration of an infrared microcamera inspired by Xenos peckii vision,” Appl. Opt. 48, 3368–3374 (2009).
[CrossRef]

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

C. N. Huang, L. Li, and A. Y. Yi, “Design and fabrication of a micro Alvarez lens array with a variable focal length,” Microsys. Technol. 15, 559–563 (2009).
[CrossRef]

2008

2007

H. R. Fallah and A. Karimzadeh, “Design and simulation of a high-resolution superposition compound eye,” J. Mod. Opt. 54, 67–76 (2007).
[CrossRef]

2006

J. W. Duparré and F. C. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R6 (2006).
[CrossRef]

2005

2003

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

2001

Aikio, M.

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Araki, T.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Brady, D.

Bräuer, A.

Brückner, A.

Carriere, J.

Castro, J. M.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

Chen, C.

Cheng, D.

Collins, S. A.

L. Li, S. A. Collins, and A. Y. Yi, “Optical effects of surface finish by ultraprecision single point diamond machining,” J. Manuf. Sci. Eng. 132, 021002 (2010).
[CrossRef]

Dannberg, P.

Druart, G.

Duparré, J.

Duparré, J. W.

J. W. Duparré and F. C. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R6 (2006).
[CrossRef]

Eberhardt, R.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Eisner, M.

Fallah, H. R.

H. R. Fallah and A. Karimzadeh, “Design and simulation of a high-resolution superposition compound eye,” J. Mod. Opt. 54, 67–76 (2007).
[CrossRef]

Fendler, M.

Gao, W.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Gebhardt, A.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Gibbons, R.

Guérineau, N.

Haïdar, R.

Hua, H.

Huang, C. N.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

C. N. Huang, L. Li, and A. Y. Yi, “Design and fabrication of a micro Alvarez lens array with a variable focal length,” Microsys. Technol. 15, 559–563 (2009).
[CrossRef]

C. N. Huang, “Investigation of injection molding process for high precision polymer lens manufacturing,” Ph.D. dissertation, Ohio State University (2008, Columbus, Ohio).

Huang, H. X.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

Ichioka, Y.

Ishida, K.

Jin, G.

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Karimzadeh, A.

H. R. Fallah and A. Karimzadeh, “Design and simulation of a high-resolution superposition compound eye,” J. Mod. Opt. 54, 67–76 (2007).
[CrossRef]

Kiyono, S.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Kolste, R. T.

Kondou, N.

Kumagai, T.

Leitel, R.

Li, H.

Li, L.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

L. Li, S. A. Collins, and A. Y. Yi, “Optical effects of surface finish by ultraprecision single point diamond machining,” J. Manuf. Sci. Eng. 132, 021002 (2010).
[CrossRef]

L. Li and A. Y. Yi, “Design and fabrication of a freeform prism array for 3D microscopy,” J. Opt. Soc. Am. A 27, 2613–2620 (2010).
[CrossRef]

L. Li and A. Y. Yi, “Development of a 3D artificial compound eye,” Opt. Express 18, 18125–18137 (2010).

C. N. Huang, L. Li, and A. Y. Yi, “Design and fabrication of a micro Alvarez lens array with a variable focal length,” Microsys. Technol. 15, 559–563 (2009).
[CrossRef]

A. Y. Yi and L. Li, “Design and fabrication of a microlens array using slow tool servo,” Opt. Lett. 30, 1707–1709 (2005).
[CrossRef]

Liu, X.

Loose, R.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Makinen, J. T.

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Mattes, A.

Miyatake, S.

Miyazaki, D.

Morimoto, T.

Okazaki, Y.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Pitsianis, N.

Prather, D.

Primot, J.

Pshenay-Severin, E.

Reimann, A.

Risse, S.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Rommeluére, S.

Scharf, T.

Scheiding, S.

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Schreiber, P.

Schulz, T.

Shankar, M.

Su, L. J.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

Taboury, J.

Talha, M. M.

Tanida, J.

Thétas, S.

Tünnermann, A.

Völkel, R.

Wang, Y.

D. Cheng, Y. Wang, H. Hua, and M. M. Talha, “Design of an optical see-through head-mounted display with a low f-number and large field of view using a freeform prism,” Appl. Opt. 48, 2655–2668 (2009).
[CrossRef]

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Willett, R.

Wippermann, F.

Wippermann, F. C.

J. W. Duparré and F. C. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R6 (2006).
[CrossRef]

Xu, L.

Yamada, K.

Yamanaka, M.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Yang, B.

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Yang, C.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

Yi, A. Y.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

L. Li, S. A. Collins, and A. Y. Yi, “Optical effects of surface finish by ultraprecision single point diamond machining,” J. Manuf. Sci. Eng. 132, 021002 (2010).
[CrossRef]

L. Li and A. Y. Yi, “Design and fabrication of a freeform prism array for 3D microscopy,” J. Opt. Soc. Am. A 27, 2613–2620 (2010).
[CrossRef]

L. Li and A. Y. Yi, “Development of a 3D artificial compound eye,” Opt. Express 18, 18125–18137 (2010).

C. N. Huang, L. Li, and A. Y. Yi, “Design and fabrication of a micro Alvarez lens array with a variable focal length,” Microsys. Technol. 15, 559–563 (2009).
[CrossRef]

A. Y. Yi and L. Li, “Design and fabrication of a microlens array using slow tool servo,” Opt. Lett. 30, 1707–1709 (2005).
[CrossRef]

Zheng, Z.

Adv. Polym. Technol.

C. Yang, L. J. Su, C. N. Huang, H. X. Huang, J. M. Castro, and A. Y. Yi, “Effect of packing pressure on refractive index variation in injection molding of precision plastic optical lens,” Adv. Polym. Technol. 30, 51–61 (2011).

Appl. Opt.

Bioinspir. Biomim.

J. W. Duparré and F. C. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R6 (2006).
[CrossRef]

J. Manuf. Sci. Eng.

L. Li, S. A. Collins, and A. Y. Yi, “Optical effects of surface finish by ultraprecision single point diamond machining,” J. Manuf. Sci. Eng. 132, 021002 (2010).
[CrossRef]

J. Mod. Opt.

H. R. Fallah and A. Karimzadeh, “Design and simulation of a high-resolution superposition compound eye,” J. Mod. Opt. 54, 67–76 (2007).
[CrossRef]

J. Opt. Soc. Am. A

Microsys. Technol.

C. N. Huang, L. Li, and A. Y. Yi, “Design and fabrication of a micro Alvarez lens array with a variable focal length,” Microsys. Technol. 15, 559–563 (2009).
[CrossRef]

Opt. Express

Opt. Lett.

Optik

B. Yang, J. T. Makinen, M. Aikio, G. Jin, and Y. Wang, “Free-form lens design for wide-angle imaging with an equidistance projection scheme,” Optik 120, 74–78 (2009).
[CrossRef]

Precis. Eng.

W. Gao, T. Araki, S. Kiyono, Y. Okazaki, and M. Yamanaka, “Precision nano-fabrication and evaluation of a large area sinusoidal grid surface for a surface encoder,” Precis. Eng. 27, 289–298 (2003).
[CrossRef]

Proc. SPIE

S. Scheiding, A. Y. Yi, A. Gebhardt, R. Loose, L. Li, S. Risse, R. Eberhardt, and A. Tünnermann, “Diamond milling or turning for the fabrication of micro lens arrays: comparing different diamond machining technologies,” Proc. SPIE 7927, 79270N (2011).

Other

C. N. Huang, “Investigation of injection molding process for high precision polymer lens manufacturing,” Ph.D. dissertation, Ohio State University (2008, Columbus, Ohio).

ZEMAX, Optical Design Program User’s Manual, ZEMAX Development Corporation (2009).

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Figures (13)

Fig. 1.
Fig. 1.

Schematic of the basic structure of the freeform microlens array based camera.

Fig. 2.
Fig. 2.

The layout of the freeform microlens array. The viewing directions of the microlenses are symmetric to X and Y axes; therefore, only the viewing directions of the microlenses in the upper-right quadrant are shown (dimensions are in mm).

Fig. 3.
Fig. 3.

The layout of one of the freeform microlenses and the ray tracing for three fields, i.e., 0°, 3.2° in X, and 3.2° in Y direction.

Fig. 4.
Fig. 4.

Spot diagrams of the microlens with X direction viewing angle of 15° and Y direction viewing angle of 15°. (a) Simulation in this case starts from a parallel plate using an extended polynomial of nine terms. (b) Simulation starts from a parallel plate using an extended polynomial of 20 terms. (c) Simulation starts from a prism using an extended polynomial of nine terms. (d) Simulation starts from a prism using an extended polynomial of 20 terms.

Fig. 5.
Fig. 5.

Surface profiles of the 8×8 freeform microlens array. Each microlens in this array is designed to aim in a specific direction. Only the top surfaces of the microlenses are shown, since the bottom surfaces are symmetric to the top surfaces about the X-Y plane.

Fig. 6.
Fig. 6.

Influence of the tool shape to the machining process and design of the freeform microlens array. (a) Geometry of a typical diamond cutter with a spherical cutting edge. (b) The relationship of the tool and the features to be machined, as shown in the X-Z plane. (c) The relationship of the tool and the features to be machined, as shown in the Y-Z plane.

Fig. 7.
Fig. 7.

Layouts of the microlens array (a) arranged in the order of viewing angle, and (b) In an alternate arrangement to alleviate the effect of the steep edges.

Fig. 8.
Fig. 8.

Tool path for freeform microlens array mold fabrication. In the broaching process, the diamond tool cuts along the precalculated tool path (the parallel lines). In this figure, the total number of passes was reduced for clarity. The profile of the lens was machined by raster cutting the surface.

Fig. 9.
Fig. 9.

(a) The aluminum optical mold for the freeform microlens array fabricated using ultraprecision diamond machining and (b) The molded freeform microlens array. To assist for alignment, four straight lines were machined on the mold as the alignment fiducial marks.

Fig. 10.
Fig. 10.

Surface profile of the injection molded freeform microlens. (a) 3D surface profile measured by Wyko. (b) Surface profile error compared with design.

Fig. 11.
Fig. 11.

Assembly of the freeform microlens array camera: (a) The freeform microlens array with the aperture array, (b) The front side of the assembled freeform microlens array camera, and (c) The back side of the assembled freeform microlens array camera.

Fig. 12.
Fig. 12.

(a) The test target and (b) the image formed on the CMOS sensor by using the device shown in Fig. 11.

Fig. 13.
Fig. 13.

(a) Object and (b) the image formed on the CMOS sensor by using the freeform microlens array and the relay optics.

Tables (2)

Tables Icon

Table 1. Configuration of the Freeform Microlens

Tables Icon

Table 2. Coefficient of One of the Microlenses with Viewing Angle of 15° in both X and Y Directions

Equations (2)

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z(x,y)=cr21+1(1+k)c2r2+i=1NAiEi(x,y)
i=1NAiEi(x,y)=A1x1y0+A2x0y1+A3x2y0+A4x1y1+A5x0y2+.

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