Abstract

Laser scanning picoprojectors present a new challenge in the field of laser safety with methods of calculating accessible emission limits still in their infancy. We present a laser safety analysis and a calculation of an example picoprojector. We show that, due to its scanning operation, a picoprojector should be considered an extended laser source, and we also show that a picoprojector with two separate one-axis microelectromechanical systems mirrors offers a higher safe power limit than a projector with a single scanning mirror. Finally, a safety analysis is done under conditions of mirror failure. We show that, if the projector fails to scan in just one of the axes, the ocular hazard rises sharply, highlighting the need for a fail-safe system to be built into laser scanning picoprojectors.

© 2012 Optical Society of America

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References

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  1. European norm EN 60825 and the U.S. ANSI Z136 series of standards.
  2. International Commission on Non-Ionizing Radiation Protection, “Revision of guidelines on limits of exposure to laser radiation of wavelengths between 400 nm and 1∶4  μm,” Health Phys. 79, 431–440 (2000).
    [CrossRef]
  3. G. Forrest, “Laser safety standards and fiber optics: an update,” Opt. Photon. News 9(2), 39–41 (1998).
    [CrossRef]
  4. D. L. Fried, “Laser eye safety: the implications of ordinary speckle statistics and of speckled-speckle statistics,” J. Opt. Soc. Am. 71, 914–916 (1981).
    [CrossRef]
  5. R. C. Petersen and D. H. Sliney, “Toward the development of laser safety standards for fiber-optic communication systems,” Appl. Opt. 25, 1038–1047 (1986).
    [CrossRef]
  6. W. J. Marshall, “Determining hazard distances from non-Gaussian lasers,” Appl. Opt. 30, 696–698 (1991).
    [CrossRef]
  7. R. T. Hitchcock, “Laser safety standards and regulations,” presented at SPAR 2006: Capturing and Documenting Existing-Conditions Data for Design, Construction and Operations, Houston, Texas, 27–28March2006.
  8. W. J. Ertle and R. J. Rockwell, “Safety fundamentals for today’s industrial lasers,” The Fabricator (December1998), http://www.thefabricator.com/article/safety/safety-fundementals-for-todays-industrial-lasers .
  9. C. T. Meneely, “Calculating the laser safety hazard for scanning systems,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.
  10. P. Murphy and G. Makhov, “Scanning audiences at laser shows: theory and practice,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.
  11. J. O’Hagan, “A risk assessment methodology for the use of lasers in the entertainment industry,” Ph.D. thesis (Loughborough University, 1998).
  12. W. R. Benner and J. P. Turner, “Laser projector having safety lens for audience scanning,” U.S. patent US2011/0279880 A1 (17November2011).
  13. K. V. Chellappan, E. Erden, and H. Urey, “Laser-based displays: a review,” Appl. Opt. 49, F79–F98 (2010).
    [CrossRef]
  14. E. Buckley, “Eye-safety analysis of current laser-based scanned-beam projection systems,” J. Soc. Inf. Disp. 18, 944–951 (2010).
    [CrossRef]
  15. Microvision, http://www.microvision.com .
  16. PicoDiCon, http://www.picodicon.com .
  17. Lemoptix, http://www.lemoptix.com .
  18. J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
    [CrossRef]
  19. M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).
  20. N. Abelé, “Laser micro-projector based on MEMS mirror, for high brightness environment,” presented at the Comission for Technology and Innovation Micro and Nano Technologies Event, Neuchatel, 11November2009.

2012 (1)

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

2010 (2)

K. V. Chellappan, E. Erden, and H. Urey, “Laser-based displays: a review,” Appl. Opt. 49, F79–F98 (2010).
[CrossRef]

E. Buckley, “Eye-safety analysis of current laser-based scanned-beam projection systems,” J. Soc. Inf. Disp. 18, 944–951 (2010).
[CrossRef]

2000 (1)

International Commission on Non-Ionizing Radiation Protection, “Revision of guidelines on limits of exposure to laser radiation of wavelengths between 400 nm and 1∶4  μm,” Health Phys. 79, 431–440 (2000).
[CrossRef]

1998 (1)

G. Forrest, “Laser safety standards and fiber optics: an update,” Opt. Photon. News 9(2), 39–41 (1998).
[CrossRef]

1991 (1)

1986 (1)

1981 (1)

Abelé, N.

N. Abelé, “Laser micro-projector based on MEMS mirror, for high brightness environment,” presented at the Comission for Technology and Innovation Micro and Nano Technologies Event, Neuchatel, 11November2009.

Benner, W. R.

W. R. Benner and J. P. Turner, “Laser projector having safety lens for audience scanning,” U.S. patent US2011/0279880 A1 (17November2011).

Bovee, J.

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

Brown, M.

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

Buckley, E.

E. Buckley, “Eye-safety analysis of current laser-based scanned-beam projection systems,” J. Soc. Inf. Disp. 18, 944–951 (2010).
[CrossRef]

Chellappan, K. V.

Dallmann, H. G.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Erden, E.

Ertle, W. J.

W. J. Ertle and R. J. Rockwell, “Safety fundamentals for today’s industrial lasers,” The Fabricator (December1998), http://www.thefabricator.com/article/safety/safety-fundementals-for-todays-industrial-lasers .

Forrest, G.

G. Forrest, “Laser safety standards and fiber optics: an update,” Opt. Photon. News 9(2), 39–41 (1998).
[CrossRef]

Freeman, M.

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

Fried, D. L.

Gerwig, C.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Grahmann, J.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Grasshoff, T.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Hitchcock, R. T.

R. T. Hitchcock, “Laser safety standards and regulations,” presented at SPAR 2006: Capturing and Documenting Existing-Conditions Data for Design, Construction and Operations, Houston, Texas, 27–28March2006.

Lewis, J. R.

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

Makhov, G.

P. Murphy and G. Makhov, “Scanning audiences at laser shows: theory and practice,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.

Marshall, W. J.

Meneely, C. T.

C. T. Meneely, “Calculating the laser safety hazard for scanning systems,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.

Murphy, P.

P. Murphy and G. Makhov, “Scanning audiences at laser shows: theory and practice,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.

O’Hagan, J.

J. O’Hagan, “A risk assessment methodology for the use of lasers in the entertainment industry,” Ph.D. thesis (Loughborough University, 1998).

Petersen, R. C.

Rockwell, R. J.

W. J. Ertle and R. J. Rockwell, “Safety fundamentals for today’s industrial lasers,” The Fabricator (December1998), http://www.thefabricator.com/article/safety/safety-fundementals-for-todays-industrial-lasers .

Shenk, H.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Sliney, D. H.

Sprague, R.

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

Turner, J. P.

W. R. Benner and J. P. Turner, “Laser projector having safety lens for audience scanning,” U.S. patent US2011/0279880 A1 (17November2011).

Urey, H.

Wildenhain, M.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Wolter, A.

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Appl. Opt. (3)

Health Phys. (1)

International Commission on Non-Ionizing Radiation Protection, “Revision of guidelines on limits of exposure to laser radiation of wavelengths between 400 nm and 1∶4  μm,” Health Phys. 79, 431–440 (2000).
[CrossRef]

J. Opt. Soc. Am. (1)

J. Soc. Inf. Disp. (1)

E. Buckley, “Eye-safety analysis of current laser-based scanned-beam projection systems,” J. Soc. Inf. Disp. 18, 944–951 (2010).
[CrossRef]

Opt. Photon. News (1)

G. Forrest, “Laser safety standards and fiber optics: an update,” Opt. Photon. News 9(2), 39–41 (1998).
[CrossRef]

Proc. SPIE (1)

J. Grahmann, M. Wildenhain, T. Grasshoff, C. Gerwig, H. G. Dallmann, A. Wolter, and H. Shenk, “Laser projector solution based on two 1D resonant micro scanning mirrors assembled in a low vertical distortion scan head,” Proc. SPIE 8252, 825205 (2012).
[CrossRef]

Other (12)

M. Brown, M. Freeman, J. R. Lewis, J. Bovee, and R. Sprague, “Apparatus and method for bi-directionally sweeping an image beam in the vertical dimension and related apparati and methods,” U.S. patent 7,580,007 (25August2009).

N. Abelé, “Laser micro-projector based on MEMS mirror, for high brightness environment,” presented at the Comission for Technology and Innovation Micro and Nano Technologies Event, Neuchatel, 11November2009.

European norm EN 60825 and the U.S. ANSI Z136 series of standards.

Microvision, http://www.microvision.com .

PicoDiCon, http://www.picodicon.com .

Lemoptix, http://www.lemoptix.com .

R. T. Hitchcock, “Laser safety standards and regulations,” presented at SPAR 2006: Capturing and Documenting Existing-Conditions Data for Design, Construction and Operations, Houston, Texas, 27–28March2006.

W. J. Ertle and R. J. Rockwell, “Safety fundamentals for today’s industrial lasers,” The Fabricator (December1998), http://www.thefabricator.com/article/safety/safety-fundementals-for-todays-industrial-lasers .

C. T. Meneely, “Calculating the laser safety hazard for scanning systems,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.

P. Murphy and G. Makhov, “Scanning audiences at laser shows: theory and practice,” presented at the International Laser Safety Conference, Nevada, USA, 23–26March2009.

J. O’Hagan, “A risk assessment methodology for the use of lasers in the entertainment industry,” Ph.D. thesis (Loughborough University, 1998).

W. R. Benner and J. P. Turner, “Laser projector having safety lens for audience scanning,” U.S. patent US2011/0279880 A1 (17November2011).

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Figures (11)

Fig. 1.
Fig. 1.

Example Lissajous figure of an LBS projector. Note that the frequency used in the horizontal scan has been decreased in order to show more clearly the nature of the Lissajous scan. The different lines represent four passes across the screen for each frame.

Fig. 2.
Fig. 2.

Example exposure to an LBS picoprojector. A series of 30.2 pulses is repeated 50 times.

Fig. 3.
Fig. 3.

Three cases of simulation of retinal illumination from an LBS projector under various conditions: a. projector and eye focus at infinity, b. projector located 100 mm from the eye with the eye focused at infinity, and c. projector located at 100 mm and eye focused at 100 mm.

Fig. 4.
Fig. 4.

Layout of the extended source condition.

Fig. 5.
Fig. 5.

For up=uf (observer focusing on the scan mirror), (top) C6 factor versus distance up, and (bottom) laser power limit versus distance up.

Fig. 6.
Fig. 6.

a. One of the possible implementations of a two-mirror scanning system; b. the retinal illumination if an observer focuses on the slow mirror and c. fast mirror of a two-mirror scanner.

Fig. 7.
Fig. 7.

For an observer focusing on one of the scan mirrors of a two-mirror system compared with focusing on the scan mirror of a single-mirror system. Mirror separation is 5 mm: a. C6 factor versus distance up, b. laser power limit versus distance up.

Fig. 8.
Fig. 8.

Laser power profile throughout a vertical scan.

Fig. 9.
Fig. 9.

Laser power limit versus distance up for up=uf (observer focusing on the fast scan mirror) in the case of a slow mirror failure.

Fig. 10.
Fig. 10.

Laser power profile throughout three horizontal scans.

Fig. 11.
Fig. 11.

Laser power limit versus distance up for up=uf (observer focusing on the slow scan mirror) in the case of fast mirror failure.

Tables (1)

Tables Icon

Table 1. Summary of AELs

Equations (15)

Equations on this page are rendered with MathJax. Learn more.

H=1.8×103t0.75J/cm2.
H=5×107N0.25J/cm2.
AELrp=2×107N0.25nsTpW.
AELrp=2×107N0.25nsTpπ/4W.
AELrp=C62×107N0.25nsTpπ/4W.
C6=ααmin,
α=dmup,
αstatic=dmup.
1f=1uf+1vf,1f=1up+1vp.
αdyn=|D(1up1uf)|.
α=dmup+|D(1up1uf)|,
Plim=2×107ααminN0.25nsTpπ/4.
Plim=1×106ααminN0.25nsTpπ/4,
α=dmup+12|D(1up1ufsm)|,
AELrp=C62×107N0.25nsTpW.

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