Abstract

A high peak-power Q-switched laser has been used to monitor the ion beam profiles in the superconducting linac at the Spallation Neutron Source (SNS). The laser beam suffers from position drift due to movement, vibration, or thermal effects on the optical components in the 250-meter long laser beam transport line. We have designed, bench-tested, and implemented a beam position stabilization system by using an Ethernet CMOS camera, computer image processing and analysis, and a piezo-driven mirror platform. The system can respond at frequencies up to 30 Hz with a high position detection accuracy. With the beam stabilization system, we have achieved a laser beam pointing stability within a range of 2 μrad (horizontal) to 4 μrad (vertical), corresponding to beam drifts of only 0.5 mm × 1 mm at the furthest measurement station located 250 meters away from the light source.

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References

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2010 (3)

J. Liu, Y. Kida, T. Teramoto, and T. Kobayashi, “Generation of stable sub-10 fs pulses at 400 nm in a hollow fiber for UV pump-probe experiment,” Opt. Express 18(5), 4664–4672 (2010).
[CrossRef] [PubMed]

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Y. Wu, D. French, and I. Jovanovic, “Passive beam pointing stabilization,” Opt. Lett. 35(2), 250–252 (2010).
[CrossRef] [PubMed]

2008 (1)

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

2007 (1)

2006 (1)

2001 (1)

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

1998 (1)

1995 (1)

Aleksandrov, A.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Assadi, S.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Blokland, W.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Bohman, S.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Breitling, F.

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

Cassou, K.

de Rossi, S.

Deibele, C.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Downer, M. C.

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

Drummond, J. R.

French, D.

Fritschel, P.

González, G.

Grice, W.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Hertel, I. V.

Jamelot, G.

Jovanovic, I.

Joyeux, D.

Kaku, M.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Kanai, T.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Kazamias, S.

Kida, Y.

Klisnick, A.

Kobayashi, T.

Kühl, T.

Lindau, F.

Liu, J.

Liu, Y.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Long, C.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Lundh, O.

Mavalvala, N.

May, A. D.

Midorikawa, K.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Pelaia, T.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Persson, A.

Plé, F.

Ros, D.

Schmid, K.

Shoemaker, D.

Sigg, D.

Sinclair, P. M.

Stalmashonak, A.

Suda, A.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Tajima, T.

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

Teramoto, T.

Ursescu, D.

Vetrov, S.

Wahlström, C. G.

Webster, A.

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Weigel, R. S.

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

Wu, Y.

Yamaguchi, S.

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Zhavoronkov, N.

Zielbauer, B.

Zucker, M.

Appl. Opt. (3)

Appl. Phys. Lett. (1)

T. Kanai, A. Suda, S. Bohman, M. Kaku, S. Yamaguchi, and K. Midorikawa, “Pointing stabilization of a high-repetition-rate high-power femtosecond laser for intense few-cycle pulse generation,” Appl. Phys. Lett. 92(6), 061106 (2008).
[CrossRef]

Nucl. Instr. Meth. A (1)

Y. Liu, A. Aleksandrov, S. Assadi, W. Blokland, C. Deibele, W. Grice, C. Long, T. Pelaia, and A. Webster, “Laser wire beam profile monitor in the spallation neutron source (SNS) superconducting linac,” Nucl. Instr. Meth. A 612(2), 241–253 (2010).
[CrossRef]

Opt. Express (2)

Opt. Lett. (1)

Rev. Sci. Instrum. (1)

F. Breitling, R. S. Weigel, M. C. Downer, and T. Tajima, “Laser pointing stabilization and control in the submicroradian regime with neural networks,” Rev. Sci. Instrum. 72(2), 1339–1342 (2001).
[CrossRef]

Other (4)

W. Blokland, A. Barker, and W. Grice, “Drift Compensation for the SNS Laserwire,” Proceedings of ICALEPCS 2007, Knoxville, Tennessee, USA (2007).

D. A. Neamen, Electronic Circuit Analysis and Design (McGraw-Hill, 2001).

J. DiStefano, A. Stubberud, and I. Williams, Schaum’s Outlines: Feedback and Control Systems, 2nd Edition. (McGraw-Hill, 1990).

E. Ott, Chaos in Dynamical System (Cambridge University Press, 2002).

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Figures (11)

Fig. 1
Fig. 1

(Top) Measured beam position as a function of time for the SNS laser wire system and the (Bottom) frequency spectrum of those positions.

Fig. 3
Fig. 3

Nyquist stability diagram for gain factors of 0.1, 0.5, 1, 1.5, 2, and 3 as a function of frequency for f d = 20 Hz.

Fig. 2
Fig. 2

Transfer function magnitudes for gain factors of 0.1, 0.5, 1, 1.5, 2, and 3 as a function of frequency for f d=20 Hz.

Fig. 4
Fig. 4

Bench test experimental setup. FBM is the feedback mirror, DM is the driving mirror, and VS is the view screen.

Fig. 5
Fig. 5

Mirror response to sinusoidal driving as a function of frequency.

Fig. 6
Fig. 6

Reduction Ratio experimental data and model comparison. Marks are the bench test data and lines are modeling results.

Fig. 7
Fig. 7

SNS laser wire system schematic. Camera A is 143 meters from the FBM and Camera B is 225 meters from the feedback mirror (FBM). BS is the beam splitter, VS is the view screen, M is the mirror, and LWS indicates the laser wire measurement station from the LWS1 (furthest) to the LWS9 (nearest).

Fig. 8
Fig. 8

Beam position standard deviations for two unique position set points with the feedback on for cameras A and B as a function of gain factors.

Fig. 9
Fig. 9

Spatial distribution maps for Camera B (a) feedback off, (b) feedback on, and Camera A (c) feedback off, (d) feedback on. The feedback on plots (b) and (d) have gain factors of 1.0.

Fig. 10
Fig. 10

Distribution of the shot-to-shot laser pulse energy measured at the furthest laser wire measurement station for (a) feedback off, (b) feedback with the pico-motor driven mirror, and (c) improved feedback system using the piezomotor driven mirror. The laser energy is normalized to its average level.

Fig. 11
Fig. 11

Ion beam profile measured at the furthest laser wire measurement station (250 meters away from the laser). (a) Horizontal and (b) vertical profiles. Dots are measured data and lines are the automatic Gaussian fitting curves.

Tables (2)

Tables Icon

Table 1 Individual camera axis spatial and angular resolution.

Tables Icon

Table 2 Laser wire feedback system standard deviations, reduction ratios, and angular stability with the feedback on for a gain factor of 1.

Equations (5)

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y ( t ) = x ( t ) + V ( t ) / V p p ,
V ( t ) = V ( t t d ) + γ δ ( t t d ) ,
δ ( t ) = V p p [ S P y ( t ) ] .
T ( ω ) = Y ( ω ) X ( ω ) = 1 exp ( i ω t d ) 1 + ( γ 1 ) exp ( i ω t d ) .
g ( f ) = | Y ( f ) X ( f ) | = 1 1 γ + ( γ / 2 sin ( π f t d ) ) 2 .

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