Abstract

A two-degrees-of-freedom scanned beam imaging system with large dynamic range and dynamic focusing is demonstrated. The laser diode, photo-detector and the optical components are integrated on a moving platform that is made of FR4 (Flame-Retardant 4), a common polymeric substrate used in printed circuit boards. A scan angle of 52 degrees is demonstrated at 60Hz resonant frequency while the laser is moved 250um in the out-of-plane direction to achieve dynamic focusing. The laser is scanned by physically rotating the laser diode and the collection optics to achieve high signal-to-noise ratio and good ambient light rejection. The collection optics is engineered such that the collection efficiency decreases when collecting light from close distances to avoid detector saturation. The detection range is extended from contact distance up to 600mm while the collected power level varies only by a factor of 30 within this long range. Slight modifications will allow increasing the detection range up to one meter. This is the first demonstration of a laser scan engine with such a high degree of integration of electronics, optoelectronics, optics and micromechanics on the same platform.

© 2009 OSA

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References

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  1. A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
    [CrossRef]
  2. A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
    [CrossRef]
  3. H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).
  4. M. Rioux, “Laser range finder based on synchronized scanners,” Appl. Opt. 23(21), 3837–3844 (1984).
    [CrossRef] [PubMed]
  5. E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
    [CrossRef]
  6. S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
    [CrossRef]
  7. S. Holmstrom, A. D. Yalcinkaya, S. O. Isikman, C. Ataman, and H. Urey, “FR-4 as a New MOEMS Platform”, IEEE/LEOS International Conference on Optical MEMS and Nanophotonics, pp.25–26 (2007)
  8. H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
    [CrossRef]
  9. C. A. Stan, “Liquid optics: Oscillating lenses focus fast,” Nat. Photonics 2(10), 595–596 (2008).
    [CrossRef]

2009 (1)

S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
[CrossRef]

2008 (2)

H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
[CrossRef]

C. A. Stan, “Liquid optics: Oscillating lenses focus fast,” Nat. Photonics 2(10), 595–596 (2008).
[CrossRef]

2007 (2)

A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
[CrossRef]

A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
[CrossRef]

2004 (2)

H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).

E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
[CrossRef]

1984 (1)

Ergeneman, O.

A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
[CrossRef]

Holmstrom, S.

H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
[CrossRef]

A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
[CrossRef]

Isikman, S. O.

S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
[CrossRef]

Katashiro, M.

H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).

Kushner, P. J.

E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
[CrossRef]

Miyajima, H.

H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).

Murakami, K.

H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).

Rioux, M.

Roberts, D. A.

E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
[CrossRef]

Sprague, R. B.

S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
[CrossRef]

Stan, C. A.

C. A. Stan, “Liquid optics: Oscillating lenses focus fast,” Nat. Photonics 2(10), 595–596 (2008).
[CrossRef]

Urey, H.

S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
[CrossRef]

H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
[CrossRef]

A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
[CrossRef]

A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
[CrossRef]

Yalcinkaya, A. D.

H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
[CrossRef]

A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
[CrossRef]

A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
[CrossRef]

Yeatman, E.

E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
[CrossRef]

Appl. Opt. (1)

IEEE J. of Sel. Topics in Quant. Elect. (1)

H. Miyajima, K. Murakami, and M. Katashiro, “MEMS Optical Scanners for Microscopes” IEEE J. of Sel. Topics in Quant. Elect. 10(3), (2004).

IEEE Photon. Technol. Lett. (3)

A. D. Yalcinkaya, H. Urey, and S. Holmstrom, “NiFe Plated Biaxial MEMS Scanner for 2-D Imaging,” IEEE Photon. Technol. Lett. 19(5), 330–332 (2007).
[CrossRef]

S. O. Isikman, R. B. Sprague, and H. Urey, “FR4 Laser Scanner with Dynamic Focus,” IEEE Photon. Technol. Lett. 21(4), 233–235 (2009).
[CrossRef]

H. Urey, S. Holmstrom, and A. D. Yalcinkaya, “Electromagnetically actuated FR4 Scanners,” IEEE Photon. Technol. Lett. 20(1), 30–32 (2008).
[CrossRef]

IEEE Trans. Instrum. Meas. (1)

E. Yeatman, P. J. Kushner, and D. A. Roberts, “Use of Scanned Detection in Optical Position Encoders,” IEEE Trans. Instrum. Meas. 53(1), 37–44 (2004).
[CrossRef]

Nat. Photonics (1)

C. A. Stan, “Liquid optics: Oscillating lenses focus fast,” Nat. Photonics 2(10), 595–596 (2008).
[CrossRef]

Sens. Act. A (1)

A. D. Yalcinkaya, O. Ergeneman, and H. Urey, “Polymer Magnetic Scanners for Bar Code Applications,” Sens. Act. A 135(1), 236–243 (2007).
[CrossRef]

Other (1)

S. Holmstrom, A. D. Yalcinkaya, S. O. Isikman, C. Ataman, and H. Urey, “FR-4 as a New MOEMS Platform”, IEEE/LEOS International Conference on Optical MEMS and Nanophotonics, pp.25–26 (2007)

Supplementary Material (2)

» Media 1: MOV (4415 KB)     
» Media 2: MOV (3122 KB)     

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Figures (11)

Fig. 1
Fig. 1

(a) Staring detection: Static detector and imaging optics view the entire barcode regardless of the position of the flying spot on the barcode. (b) Scanned detection: The collection optics of the scanner is placed on the scanning element. This makes sure that the detector receives the image of the flying spot, and the reflection from the barcode is imaged at the same position in space at all times.

Fig. 2
Fig. 2

Photodiode output signals obtained by scanning the same barcode pattern using conventional staring detection (left), and scanned detection (right) under the same ambient light conditions. The SNR of scanned detection system is observed to be increased approximately 8 times.

Fig. 3
Fig. 3

(a) 300um thick FR4 board fabricated using conventional PCB cutting and routing. The folded arm structure inside the larger scanning frame is the out-of-plane moving dynamic focusing element (laser plunger), which carries the laser diode at its tip. (b) Scanline generated with the barcode scanner. 52° total optical scan angle is achieved with approximately 100mW power consumption at 60Hz resonance. (Media 1)

Fig. 4
Fig. 4

The optical design of the imaging system. A relatively large lens is employed for collecting the scattered light from the barcode. Two flat mirrors are utilized to fold the collected beam, which allows placing the lens closer to the scanner surface so as to minimize the total inertia significantly.

Fig. 5
Fig. 5

Full assembly of the barcode scanner. An opto-mechanical piece is mounted on the scanning frame for carrying the focusing and collecting lenses. The laser diode is translated in the out-of-plane direction towards or away from the focusing lens for dynamic focusing. Collection optics is synchronously scanned with the laser.

Fig. 6
Fig. 6

Illustrates the beam-walk on the detector as a function of the barcode distance. The reflected light is focused at a different position on the detector as the barcode is moved further away.

Fig. 7
Fig. 7

Zemax simulations of the collected light on the detector. Each view is for a different barcode distance. The image on the PD gets defocused as the barcode gets closer. Beam-walk is also observed as a function of distance. Exploiting both beam-walk and image defocus, excessive light collection is prevented when barcode is close. In this configuration, a circular mask is also used to block light. (the shadow of this circular aperture can be seen for cases 30mm and 100mm) The size of the PD is 1.2mm x 1.2mm.

Fig. 8
Fig. 8

Simulation and experimental results showing the light collection efficiency of the system. The efficiency for close distances is designed to be lower, which prevents detector saturation and increases the dynamic range of the imaging system.

Fig. 9
Fig. 9

Shows both the simulation and experimental collected optical power as a function of barcode distance. The sharp decrease in the curves for close distances shows the intentional efficiency decrease in the collection optics. It is also seen that for distances above 200-300mm, optical power on the PD follows a 1/r2 behavior.

Fig. 10
Fig. 10

Shows the experimental results for spot size as a function of distance from the scanner. Each set of data is taken for a specific laser-to-lens distance shown in the legend, where the beam waist is shifted to a different location. Dashed line illustrates the minimum waist line that can be obtained with dynamic focusing. (Media 2)

Fig. 11
Fig. 11

The experimental reading range of the barcode reader for 5, 7.5, 10 and 20mil barcodes (1 mil = 25.4 microns). The plunger oscillates at 10Hz, with 250μm peak-to-peak deflection. For 20mil barcodes, the signal decoding range extends up to 600mm.

Equations (1)

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η (%)=(Power incident on the detector)(Power incident on the collecting lens)x100

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