Abstract

The potassium dihydrogen phosphate (KDP) crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of an infrared laser light beam into an ultraviolet beam. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the backreflection beam, which exhibits a distinct characteristic shape. When a phase-plate device is introduced before the final assembly to increase the uniformity of the beam, the backreflection pattern changes drastically. The algorithm that is best for tracking the special-shaped beam is no longer suitable for tracking the phase-modified beam. We discuss our detection schemes for both situations. In particular, we demonstrate how the algorithm senses the modified beam by using a newly proposed criterion of correlation peak pedestal area and executes an alternate algorithm in real time without operator intervention. This new algorithm continuously tracks the beam pattern to guarantee reliable and repeatable sensing. Results from simulation and real-world implementation of the algorithm at the NIF facility are presented.

© 2006 Optical Society of America

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  1. E. I. Moses and C. Wuest, "The National Ignition Facility: status and plans for laser fusion and high-energy-density experimental studies," Fusion Sci. Technol. 43, pp. 420-427 (2003).
  2. M. Rahman, A. A. S. Awwal, and K. Gudmundsson, "Composite filters for search time reduction for 3D model based object recognition," in Photonic Devices and Algorithms for Computing V, K.M.Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5201, pp. 97-107 (2003).
  3. A. A. S. Awwal, M. A. Karim, and S. R. Jahan, "Improved correlation discrimination using an amplitude-modulated phase-only filter," Appl. Opt. 29, 233-236 (1990).
    [CrossRef] [PubMed]
  4. A. VanderLugt, "Signal detection by complex spatial filtering," IEEE Trans. Inf. Theory IT-10, 139-145 (1964).
    [CrossRef]
  5. J. L. Horner and J. Leger, "Pattern recognition with binary phase-only filters," Appl. Opt. 24, 609-611 (1985).
    [CrossRef] [PubMed]
  6. M. A. Karim and A. A. S. Awwal, Optical Computing: an Introduction (Wiley, 1992).
  7. K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
    [CrossRef]
  8. K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
    [CrossRef]
  9. P. Wegner, National Ignition Facility, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (2003).
  10. J. V. Beck and K. J. Arnold, Parameter Estimation in Engineering and Science (Wiley, 1977).
  11. M. Axelrod, "Modeling image noise that is both non-Gaussian and non-stationary," paper presented at the Photonic Devices and Algorithms for Computing VI Conference, Denver, Colo., 2-3 August 2004.
  12. J. P. Holman (in collaboration with W. J. Gajda), Experimental Methods for Engineers, 3rd. ed. (McGraw-Hill, 1978), Chaps. 3-11.
  13. A. A. S. Awwal and H. E. Michel, "Enhancing the discrimination capability of phase only filter," Asian J. Phys. 8, 381-384 (1999).
  14. F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
    [CrossRef]
  15. K. S. Gudmundsson and A. A. S. Awwal, "Sub-imaging technique to improve POF search capability," Appl. Opt. 42, 4709-4717 (2003).
    [CrossRef] [PubMed]
  16. A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

2003 (2)

E. I. Moses and C. Wuest, "The National Ignition Facility: status and plans for laser fusion and high-energy-density experimental studies," Fusion Sci. Technol. 43, pp. 420-427 (2003).

K. S. Gudmundsson and A. A. S. Awwal, "Sub-imaging technique to improve POF search capability," Appl. Opt. 42, 4709-4717 (2003).
[CrossRef] [PubMed]

1999 (1)

A. A. S. Awwal and H. E. Michel, "Enhancing the discrimination capability of phase only filter," Asian J. Phys. 8, 381-384 (1999).

1997 (1)

F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
[CrossRef]

1996 (2)

K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

1990 (1)

1985 (1)

1964 (1)

A. VanderLugt, "Signal detection by complex spatial filtering," IEEE Trans. Inf. Theory IT-10, 139-145 (1964).
[CrossRef]

Ahmed, F.

F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
[CrossRef]

Arnold, K. J.

J. V. Beck and K. J. Arnold, Parameter Estimation in Engineering and Science (Wiley, 1977).

Awwal, A. A. S.

K. S. Gudmundsson and A. A. S. Awwal, "Sub-imaging technique to improve POF search capability," Appl. Opt. 42, 4709-4717 (2003).
[CrossRef] [PubMed]

A. A. S. Awwal and H. E. Michel, "Enhancing the discrimination capability of phase only filter," Asian J. Phys. 8, 381-384 (1999).

F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
[CrossRef]

A. A. S. Awwal, M. A. Karim, and S. R. Jahan, "Improved correlation discrimination using an amplitude-modulated phase-only filter," Appl. Opt. 29, 233-236 (1990).
[CrossRef] [PubMed]

M. Rahman, A. A. S. Awwal, and K. Gudmundsson, "Composite filters for search time reduction for 3D model based object recognition," in Photonic Devices and Algorithms for Computing V, K.M.Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5201, pp. 97-107 (2003).

M. A. Karim and A. A. S. Awwal, Optical Computing: an Introduction (Wiley, 1992).

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

Axelrod, M.

M. Axelrod, "Modeling image noise that is both non-Gaussian and non-stationary," paper presented at the Photonic Devices and Algorithms for Computing VI Conference, Denver, Colo., 2-3 August 2004.

Beck, J. V.

J. V. Beck and K. J. Arnold, Parameter Estimation in Engineering and Science (Wiley, 1977).

Candy, J.

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

Eloe, P. W.

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

Ferguson, W.

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

Gudmundsson, K.

M. Rahman, A. A. S. Awwal, and K. Gudmundsson, "Composite filters for search time reduction for 3D model based object recognition," in Photonic Devices and Algorithms for Computing V, K.M.Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5201, pp. 97-107 (2003).

Gudmundsson, K. S.

Holman, J. P.

J. P. Holman (in collaboration with W. J. Gajda), Experimental Methods for Engineers, 3rd. ed. (McGraw-Hill, 1978), Chaps. 3-11.

Horner, J. L.

Iftekharuddin, K. M.

K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

Jahan, S. R.

Karim, M. A.

F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
[CrossRef]

A. A. S. Awwal, M. A. Karim, and S. R. Jahan, "Improved correlation discrimination using an amplitude-modulated phase-only filter," Appl. Opt. 29, 233-236 (1990).
[CrossRef] [PubMed]

M. A. Karim and A. A. S. Awwal, Optical Computing: an Introduction (Wiley, 1992).

Leger, J.

Mcclay, W.

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

Michel, H. E.

A. A. S. Awwal and H. E. Michel, "Enhancing the discrimination capability of phase only filter," Asian J. Phys. 8, 381-384 (1999).

Moses, E. I.

E. I. Moses and C. Wuest, "The National Ignition Facility: status and plans for laser fusion and high-energy-density experimental studies," Fusion Sci. Technol. 43, pp. 420-427 (2003).

Rahman, M.

M. Rahman, A. A. S. Awwal, and K. Gudmundsson, "Composite filters for search time reduction for 3D model based object recognition," in Photonic Devices and Algorithms for Computing V, K.M.Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5201, pp. 97-107 (2003).

Salmon, T.

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

VanderLugt, A.

A. VanderLugt, "Signal detection by complex spatial filtering," IEEE Trans. Inf. Theory IT-10, 139-145 (1964).
[CrossRef]

Wegner, P.

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

P. Wegner, National Ignition Facility, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (2003).

Wuest, C.

E. I. Moses and C. Wuest, "The National Ignition Facility: status and plans for laser fusion and high-energy-density experimental studies," Fusion Sci. Technol. 43, pp. 420-427 (2003).

Appl. Opt. (3)

Asian J. Phys. (1)

A. A. S. Awwal and H. E. Michel, "Enhancing the discrimination capability of phase only filter," Asian J. Phys. 8, 381-384 (1999).

Fusion Sci. Technol. (1)

E. I. Moses and C. Wuest, "The National Ignition Facility: status and plans for laser fusion and high-energy-density experimental studies," Fusion Sci. Technol. 43, pp. 420-427 (2003).

IEEE Trans. Inf. Theory (1)

A. VanderLugt, "Signal detection by complex spatial filtering," IEEE Trans. Inf. Theory IT-10, 139-145 (1964).
[CrossRef]

Math. Comput. Modell. (1)

K. M. Iftekharuddin, M. A. Karim, and A. A. S. Awwal, "Optimization of amplitude modulated inverse filter," Math. Comput. Modell. 24, 103-112 (1996).
[CrossRef]

Microwave Opt. Technol. Lett. (1)

F. Ahmed, A. A. S. Awwal, and M. A. Karim, "Improved recognition performance with synthetic correlator," Microwave Opt. Technol. Lett. 14, 274-278 (1997).
[CrossRef]

Opt. Laser Technol. (1)

K. M. Iftekharuddin, M. A. Karim, P. W. Eloe, and A. A. S. Awwal, "Discretized amplitude-modulated phase-only filter," Opt. Laser Technol. 28, 93-100 (1996).
[CrossRef]

Other (7)

P. Wegner, National Ignition Facility, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (2003).

J. V. Beck and K. J. Arnold, Parameter Estimation in Engineering and Science (Wiley, 1977).

M. Axelrod, "Modeling image noise that is both non-Gaussian and non-stationary," paper presented at the Photonic Devices and Algorithms for Computing VI Conference, Denver, Colo., 2-3 August 2004.

J. P. Holman (in collaboration with W. J. Gajda), Experimental Methods for Engineers, 3rd. ed. (McGraw-Hill, 1978), Chaps. 3-11.

M. Rahman, A. A. S. Awwal, and K. Gudmundsson, "Composite filters for search time reduction for 3D model based object recognition," in Photonic Devices and Algorithms for Computing V, K.M.Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5201, pp. 97-107 (2003).

M. A. Karim and A. A. S. Awwal, Optical Computing: an Introduction (Wiley, 1992).

A. A. S. Awwal, W. Mcclay, W. Ferguson, J. Candy, T. Salmon, and P. Wegner, "Composite amplitude modulated phase-only filter based detection and tracking of the back-reflection of KDP images," in Photonic Devices and Algorithms for Computing VI, K. M. Iftekharuddin and A. A. S. Awwal, eds., Proc. SPIE 5556, 180-190 (2004).

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Figures (16)

Fig. 1
Fig. 1

Example of a real KDP backreflection pattern: (a) image without a phase plate and (b) image in the presence of a phase plate.

Fig. 2
Fig. 2

Optical setup for KDP beam alignment.

Fig. 3
Fig. 3

Block diagram of the beam-position detection algorithm. Numbers in parenthesis correspond to equation numbers.

Fig. 4
Fig. 4

Comparison of the matched filtering method with the binary centroid-based method for the x-position data.

Fig. 5
Fig. 5

(a) AMPOF correlation peak and (b) CMF peak with a broad base.

Fig. 6
Fig. 6

Scatterplot of 49 image positions (for beam 315) taken over six months.

Fig. 7
Fig. 7

(a) Amplitude maximum of 200, noise of 20 rms; (b) amplitude maximum of 200, noise of 50 rms; (c) amplitude of 200, interference of 20, period of λ∕2; (d) amplitude of 200, interference of 20, period of λ.

Fig. 8
Fig. 8

Noise (in rms counts) versus uncertainty (in pixels) of (a) the old KDP centroid-based algorithm and (b) the new KDP algorithm.

Fig. 9
Fig. 9

(a) Original image; (b) amplitude of 100, interference amplitude of 50, 2λ; (c) amplitude of 50, interference amplitude of 50, 1λ; (d) amplitude of 50, interference amplitude of 50, λ∕2.

Fig. 10
Fig. 10

Correlation output for an image corrupted by a diffraction amplitude of 50. Signal, λ∕2; amplitude, 50; noise, 50; peak amplitude, 1048.

Fig. 11
Fig. 11

(a) Noise versus uncertainty with AMPOF and (b) noise uncertainty for various wave distortions of the algorithm for the amplitude signal and the rms noise for various wave amplitudes.

Fig. 12
Fig. 12

(a) Noise versus uncertainty with the new KDP algorithm. Image amplitude, 100. (b) Noise uncertainty for various wave distortions of the algorithm for various amplitude signals and rms noise for various wave amplitudes. Image amplitude, 50.

Fig. 13
Fig. 13

(a) Displacement between the average and the true centroids. (b) Scatterplot for an amplitude of 200 for centroids with a rms noise count of 20.

Fig. 14
Fig. 14

Pedestal experiment performed by correlating the square and the circle. The background is set at 0, and the white region is set at 255.

Fig. 15
Fig. 15

Pedestal area for in-class and out-of-class beams.

Fig. 16
Fig. 16

Block diagram of the beam-position detection algorithm.

Tables (1)

Tables Icon

Table 1 Pedestal Experiments Comprising Circular and Square Objects a

Equations (10)

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F ( U x , U y ) = | F ( U x , U y ) | exp [ j Φ ( U x , U y ) ] .
H ( U x , U y ) CMF = F ( U x , U y )
= | F ( U x , U y ) | exp [ j Φ ( U x , U y ) ] .
H POF ( U x , U y ) = exp [ j Φ ( U x , U y ) ] .
H AMPOF ( U x , U y ) = a F ( U x , U y ) [ b + c | F ( U x , U y ) | + d | F ( U x , U y ) | 2 ] m .
C AMPOF ( Δ x , Δ y ) = F 1 { F ( U x , U y ) H AMPOF ( U x , U y ) } .
x pos = x cross x auto + x c ,
y pos = y cross y auto + y c ,
X cross = 0.5 f 0 ( x 1 + x 2 ) + 0.5 f 2 ( x 0 + x 1 ) 0.5 f 1 ( x 0 + x 2 ) f 0 2 f 1 + f 2 ,
Y cross = 0.5 f 0 ( y 1 + y 2 ) + 0.5 f 2 ( y 0 + y 1 ) 0.5 f 1 ( y 0 + y 2 ) f 0 2 f 1 + f 2 .

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