Optimal control of force microscope cantilevers. II. Magnetic coupling implementation
J. Appl. Phys. 80, 1959 (1996); doi:10.1063/1.363086
Issue Date: 15 August 1996
You are not logged in to this journal. Log in
We describe the implementation of optimal controllers for damping the motion of cantilevers used in magnetic resonance force microscopy. We demonstrate that optimal control is achievable and that torsional magnetic coupling provides an effective actuation method. Cantilever Brownian vibrational amplitude was reduced from 2 to 0.16 Å and resonant quality was reduced from 2000 to 5. Applied control fields were sufficiently small that they would not affect magnetic resonance phenomena. ©1996 American Institute of Physics.
| History: | Received 21 November 1995; accepted 13 May 1996 |
| Permalink: |
http://link.aip.org/link/?JAPIAU/80/1959/1 |
KEYWORDS and PACS
MAGNETIC FORCE MICROSCOPY,
OPTIMAL CONTROL,
RESONANCE,
COUPLING,
MECHANICAL VIBRATIONS,
SIGNAL,
TO,
NOISE RATIO,
FEEDBACK
- 07.79.Pk
Instruments, apparatus, components, and techniques common to several branches of physics and astronomy Scanning probe microscopes, components, and techniques Magnetic force microscopes - YEAR: 1996
PUBLICATION DATA
0021-8979 (print)
1089-7550 (online)
REFERENCES (20)
For access to fully linked references, you need to log in.
For access to fully linked references, you need to Log in.
- D. Rugar, C. S. Yannoni, and J. A. Sidles,
Nature 360, 563 (1992 ). - O. Züger and D. Rugar, Appl. Phys. Lett. 63, 2496 (1993).
- O. Züger and D. Rugar, J. Appl. Phys. 75, 6211 (1994).
- D. Rugar, O. Züger, S. Hoen, C. S. Yannoni, H.-M. Vieth, and R. D. Kendrick,
Science 264, 1560 (1994 ). - K. J. Bruland, J. Krzystek, J. L. Garbini, and J. A. Sidles, Rev. Sci. Instrum. 66, 2853 (1995).
- For analytic expressions we adopt the convention of two sided power spectrum S
(
) with a transform pair defined as S(
) = ![[integral]](http://scitation.aip.org/stockgif3/int.gif)
Rx(
)ej
d
, Rx(
) = (1/2
)![[integral]](http://scitation.aip.org/stockgif3/int.gif)
S
(
)ej
d
, where Rx(
) = E[x(t)x(t+
)]. Numerical values are presented as one sided spectra S(
) = 2S(
) that are read from standard laboratory instruments. - J. A. Sidles and D. Rugar, Phys. Rev. Lett. 70, 3506 (1993).
- J. A. Sidles, J. L. Garbini, and G. P. Drobny, Rev. Sci. Instrum. 63, 3881 (1992).
- J. Mertz, O. Marti, and J. Mlynek, Appl. Phys. Lett. 62, 2344 (1993).
- J. A. Sidles, J. L. Garbini, K. J. Bruland, D. Rugar, O. Züger, S. Hoen, and C. S. Yannoni, Rev. Mod. Phys. 67, 249 (1995).
- J. L. Garbini, K. J. Bruland, W. M. Dougherty, and J. A. Sidles, J. Appl. Phys. 80, 1951 (1996).
- MQP-B powder from Magnequench, Anderson, IN.
- Microlevers from Park Scientific Instruments, Sunnyvale, CA.
- J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993).
- Here optimal control parameters are computed for one controller from previously given experimental parameters, as well as some additional data. Quoted equation numbers refer to Part I of this article (Ref. 11). The desired response amplitude xmax = 0.2 Å and actuation force amplitude umax = 1013 N determine that X = 4×1022 m2 and U = 1026 N2, therefore
= 4.76×102 according to Eq. (16). The measured optical noise floor determines V = S/2 = 2.88×1026 m2/Hz, and Rcant = 7.95×1014 photons/s according to Eq. (45) where Nfib = 1.4591 and R = 1.65×1015 photons/s from the 420 µW optical power. From these data, R
= 2.30×1039 N2/Hz and R
= 1.26×1029 N2/Hz, thus, W = 1.26×1029 N2/Hz, according to Eqs. (42) and (43). From W, V, and Eq. (25),
= 0.1995. The optimal controller parameters can then be determined according to Eqs. (31), (32), and (33): K
= 4.16 N/m; Z
= 2.74×105 rad/s; 
= 3.45×104 rad/s; and Q
= 4.10. - P. Horowitz and W. Hill, The Art of Electronics (Cambridge University, 1989), p. 276.
- D. Rugar, H. J. Mamin, R. Erlandsson, J. E. Stern, and B. D. Terris, Rev. Sci. Instrum. 59, 2337 (1988).
- D. Rugar, H. J. Mamin, and P. Guethner, Appl. Phys. Lett. 55, 2588 (1989).
- The laser (single-mode FC connectorized Mitsubishi ML40116R) and photodiodes (FC connectorized Mitsubishi PD-2101) are available from Seastar Optics, Sidney, B.C. Canada.
- S. Hoen, O. Züger, C. S. Yannoni, H. J. Mamin, K. Wago, and D. Rugar, in Technical Digest of the 1994 Solid State Sensor and Actuator Workshop, Hilton Head, SC, (Transducers Research Foundation, Catalog No. 94TRF-0001, 1994), p. 209.







