Abstract

The system design of front-projection systems for free-form screens utilizing conventional single-aperture optical layouts always requires a trade-off between system complexity and achievable luminous output. This article presents novel slide pre-processing algorithms based on array projection technology that are able to resolve the design drawbacks for both free-form as well as strongly-inclined planar screen applications by breaking the common contradiction between system simplicity and flux. Starting from describing common design strategies and their drawbacks, the theoretical basics of the novel concept are investigated and applied to raytracing simulations. Experimental results are shown and evaluated regarding their optical performance.

© 2013 Optical Society of America

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References

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  1. Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
    [CrossRef]
  2. M. Sieler, P. Schreiber, P. Dannberg, A. Bräuer, and A. Tünnermann, “Ultraslim fixed pattern projectors with inherent homogenization of illumination,” Appl. Opt.51(1), 64–74 (2012).
    [CrossRef] [PubMed]
  3. M. Sieler, P. Schreiber, P. Dannberg, and A. Bräuer, “Design and realization of an ultra-slim array projector,” Microopics Conference (MOC), 2011 (IEEE, 2011).
  4. W. J. Smith, Modern Optical Engineering (McGraw-Hill, 1990).
  5. N. Lindlein and H. P. Herzig, “Design and modeling of a miniature system containing micro-optics,” Proc. SPIE4437, 1–13 (2001).
    [CrossRef]
  6. T. Scheimpflug, “Improved method and apparatus for the systematic alternation or distortion of plane pictures and images by means of lenses and mirrors for photography and for other purposes,” GB patent 190401196 (A), (1904).
  7. P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
    [CrossRef]
  8. M. Salt and M. Rossi, “Replicated micro-optics for multimedia products,” Proc. SPIE6196, 61960F (2006).
    [CrossRef]

2012

2008

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

2006

M. Salt and M. Rossi, “Replicated micro-optics for multimedia products,” Proc. SPIE6196, 61960F (2006).
[CrossRef]

2001

N. Lindlein and H. P. Herzig, “Design and modeling of a miniature system containing micro-optics,” Proc. SPIE4437, 1–13 (2001).
[CrossRef]

2000

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

Bräuer, A.

M. Sieler, P. Schreiber, P. Dannberg, A. Bräuer, and A. Tünnermann, “Ultraslim fixed pattern projectors with inherent homogenization of illumination,” Appl. Opt.51(1), 64–74 (2012).
[CrossRef] [PubMed]

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

Cheng, J.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Chung, R.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Dannberg, P.

M. Sieler, P. Schreiber, P. Dannberg, A. Bräuer, and A. Tünnermann, “Ultraslim fixed pattern projectors with inherent homogenization of illumination,” Appl. Opt.51(1), 64–74 (2012).
[CrossRef] [PubMed]

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

Fung, K. S. M.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Herzig, H. P.

N. Lindlein and H. P. Herzig, “Design and modeling of a miniature system containing micro-optics,” Proc. SPIE4437, 1–13 (2001).
[CrossRef]

Lam, E. Y.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Lindlein, N.

N. Lindlein and H. P. Herzig, “Design and modeling of a miniature system containing micro-optics,” Proc. SPIE4437, 1–13 (2001).
[CrossRef]

Mann, G.

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

Rossi, M.

M. Salt and M. Rossi, “Replicated micro-optics for multimedia products,” Proc. SPIE6196, 61960F (2006).
[CrossRef]

Salt, M.

M. Salt and M. Rossi, “Replicated micro-optics for multimedia products,” Proc. SPIE6196, 61960F (2006).
[CrossRef]

Schreiber, P.

Shu, Y.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Sieler, M.

Tan, Z.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Tünnermann, A.

Wagner, L.

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

Wang, F.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Appl. Opt.

Opt. Eng.

Z. Tan, J. Cheng, E. Y. Lam, K. S. M. Fung, Y. Shu, R. Chung, and F. Wang, “Projection optics design for tilted projection of fringe patterns,” Opt. Eng.47(5), 053002 (2008).
[CrossRef]

Proc. SPIE

P. Dannberg, G. Mann, L. Wagner, and A. Bräuer, “Polymer UV-moulding for micro-optical systems and O/E integration,” Proc. SPIE4179, 137–145 (2000).
[CrossRef]

M. Salt and M. Rossi, “Replicated micro-optics for multimedia products,” Proc. SPIE6196, 61960F (2006).
[CrossRef]

N. Lindlein and H. P. Herzig, “Design and modeling of a miniature system containing micro-optics,” Proc. SPIE4437, 1–13 (2001).
[CrossRef]

Other

T. Scheimpflug, “Improved method and apparatus for the systematic alternation or distortion of plane pictures and images by means of lenses and mirrors for photography and for other purposes,” GB patent 190401196 (A), (1904).

M. Sieler, P. Schreiber, P. Dannberg, and A. Bräuer, “Design and realization of an ultra-slim array projector,” Microopics Conference (MOC), 2011 (IEEE, 2011).

W. J. Smith, Modern Optical Engineering (McGraw-Hill, 1990).

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Figures (10)

Fig. 1
Fig. 1

Current optical approaches to project sharp images onto free-form screen surfaces.

Fig. 2
Fig. 2

Layout of an array projection optics for a perpendicular planar screen setup. A tandem-reflow lens array is molded on both sides of a common glass substrate. A buried chromium layer on the backside of the glass substrate contains a transmissive slide array. A pre-calculated pitch difference of the array of identical subimages w.r.t. the projection lens array generates an integral image in a predefined screen distance according to paraxial considerations [2].

Fig. 3
Fig. 3

a. Monolithic array projection optics containing 149 hexagonally packed projectorlets illuminated by a collimated green LED. Each projectorlet has an aperture diameter of 790µm while having a focal width of 2mm. The lateral size of the array is 11x11mm2. The total thickness of the projector is 3mm, which corresponds to a system volume of only 14% compared to a flux-equivalent single aperture projector [2]. Fig. 3b. The microoptical element shown in Fig. 3a is illuminated by a white LED and projects a virtual keyboard to a planar screen in 530mm distance. The brightness of the integral image is sufficient for daylight visibility [2].

Fig. 4
Fig. 4

Paraxial system layout of an array projection setup, consisting of an array of illuminated subslides with a corresponding array of projection lenses, projecting onto a free-form screen. The large screen sided f-number of each projectorlet leads to a very large depth of focus of the subimages. A well-defined slide array manipulation provides a perfect superimposing of all subimages onto an arbitrary screen surface. Please note that α’ is negative for both exemplary rays.

Fig. 5
Fig. 5

a) Simulated projector setup projecting a line test pattern onto a 70° tilted planar screen surface. The overlaid rectangle corresponds to the region of contrast measurements shown in b. c) Simulated contrast transfer for both, an uncorrected array projector (b1) and an array projector with pre-processed slide array (b2) for various screen distances. Accepting a minimum relative contrast transfer of 70%, the distance range is tripled and becomes 300mm to 600mm compared to a range of 330mm to 430mm when using a conventional single aperture projector working for an orthogonal screen. It can be seen that the projector with pre-corrected slides creates a much wider range of image sharpness.

Fig. 6
Fig. 6

a) Upper half of an object data array. b) Overlay of the object of the central (black) and a marginal channel (red) showing the geometrical mismatch of both slides resulting from the slide pre-processing algorithm.

Fig. 7
Fig. 7

Subsequent steps of manufacturing process: a) Detailed view of a single slide in a chromium layer on a floatglass substrate. b) Produced wafer containing 52 different array projection optics. c) Three diced MLAs in size comparison with a 1 euro cent coin.

Fig. 8
Fig. 8

a) Projection setup utilizing an array projector with pre-corrected slides for 70° screen inclination. b) Projected images of an array projector without and with pre-corrected slides. In comparison to the uncorrected system (upper image), the corrected system (lower image) conserves image sharpness over the entire image.

Fig. 9
Fig. 9

Results of contrast transfer measurements (1a, 2a) and simulations (1b, 2b) of two array projectors projecting the same test pattern, uncorrected (1a) and corrected (2a) containing equidistant lines with 2.84mm period. While the uncorrected array projector shows an inter-line-contrast larger than 20% from 375mm to 425mm distance, the array projector with a pre-corrected slide array shows a minimum of 20% contrast from 310mm to 500mm. Consequently, the distance range of sufficient image contrast is enhanced by a factor of four. While the curve of simulated and measured values correspond in shape, their absolute values deviate resulting from additional stray light of the real LED source and ghosting effects caused by the uncoated or reflective optical surfaces.

Fig. 10
Fig. 10

(a) Facetted perpendicular screen setup containing three planar perpendicular subscreens in 200mm, 400mm, and 600mm distance. The image information projected onto each facet corresponds to the distance of this facet to the projector. (b). Projected images of the manufactured prototype captured on a single planar screen at several distances L. Each sharp font represents the corresponding distance of the projector to the screen whereas the blurred projections correspond to intermediate distances. All 149 projectorlets are focused to 400mm screen distance and project all three distance information.

Equations (3)

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( x α )=( 1 s 0 1 )( 1 0 1/f 1 )[ ( Δx 0 )+( 1 L n 0 1 )( x' α' ) ] =( fLα' fL +( 1+ L fL )( x' L n α'Δx ) α'+ x' L n α'Δx f ).
α'= x'Δx L n .
( x α )=( f L n L fL (x'Δx) x'Δx L n )( f L n (x'Δx) x'Δx L n ).

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