Abstract

We quantify the effects of disk tilt and objective lens tilt on the push–pull tracking error signal of an optical disk data storage system. For a grooved disk, such as a recordable compact disk that operates at a laser wavelength of λ, it is found that disk tilt produces a tracking offset of 0.05λ per degree of tilt, whereas objective lens tilt produces an offset of 0.012λ per degree of tilt. The amplitude of the tracking error signal decreases by 2.5% at the disk tilt angle of 0.3° and by 5% at the objective lens tilt of 0.3°. We achieved these simulations with the computer program diffract, which performs a combination of diffraction and ray–tracing calculations through the entire optical path, from the light source to the detectors.

© 1997 Optical Society of America

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References

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  1. L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
    [CrossRef]
  2. M. Mansuripur, The Physical Principles of Magneto-optical Recording (Cambridge U. Press, Cambridge, UK, 1995), pp. 29–32.
  3. Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
    [CrossRef]
  4. M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
    [CrossRef]
  5. C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
    [CrossRef]
  6. P. Kuttner, “Design and testing of lenses for optical disk technology,” Opt. Eng. 22, 473–478 (1983).
    [CrossRef]
  7. The computer program diffract is commercially available from MM Research, Inc., Tucson, Arizona 85718. The theoretical basis of this program is described in the following papers by M. Mansuripur: “Certain computational aspects of vector diffraction problems,” J. Opt. Soc. Am. A 6, 786–805 (1989); “Analysis of multilayer thin-film structures containing magneto-optic and anisotropic media at oblique incidence using 2 × 2 matrices,” J. Appl. Phys. 67, 6466–6475 (1990).
  8. A. B. Marchant, Optical Recording (Addison-Wesley, Reading, Mass., 1990), p. 312.
  9. T. A. Olson, “Digital optical storage media guidelines,” in Optical Data Storage, D. Chen, ed., Proc. SPIE382, 164–171 (1983).
    [CrossRef]

1987

Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
[CrossRef]

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

1983

P. Kuttner, “Design and testing of lenses for optical disk technology,” Opt. Eng. 22, 473–478 (1983).
[CrossRef]

Azuma, K.

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Chung, C. S.

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

Gong, M.

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

Kuttner, P.

P. Kuttner, “Design and testing of lenses for optical disk technology,” Opt. Eng. 22, 473–478 (1983).
[CrossRef]

Lee, C. W.

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

Mansuripur, M.

M. Mansuripur, The Physical Principles of Magneto-optical Recording (Cambridge U. Press, Cambridge, UK, 1995), pp. 29–32.

Marchant, A. B.

A. B. Marchant, Optical Recording (Addison-Wesley, Reading, Mass., 1990), p. 312.

Nagaoka, Y.

Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
[CrossRef]

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Olson, T. A.

T. A. Olson, “Digital optical storage media guidelines,” in Optical Data Storage, D. Chen, ed., Proc. SPIE382, 164–171 (1983).
[CrossRef]

Pan, L.

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

Pei, J.

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

Rim, K.-H.

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

Seong, P. Y.

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

Shin, D. H.

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

Sunohara, M.

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Tanaka, Y.

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
[CrossRef]

Ueda, M.

Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
[CrossRef]

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Xu, D.

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

Yuan, H.

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

IEEE Trans. Consumer Electron.

M. Sunohara, Y. Tanaka, Y. Nagaoka, M. Ueda, K. Azuma, “Single lens CD player pickup system using a bi-aspheric molded glass lens,” IEEE Trans. Consumer Electron. CE-33, 520–530 (1987).
[CrossRef]

Jpn. J. of Appl. Phys.

Y. Tanaka, Y. Nagaoka, M. Ueda, “Lensand optics for optical disk system,” Jpn. J. of Appl. Phys. 26, 121–126 (1987).
[CrossRef]

Opt. Eng.

P. Kuttner, “Design and testing of lenses for optical disk technology,” Opt. Eng. 22, 473–478 (1983).
[CrossRef]

Other

The computer program diffract is commercially available from MM Research, Inc., Tucson, Arizona 85718. The theoretical basis of this program is described in the following papers by M. Mansuripur: “Certain computational aspects of vector diffraction problems,” J. Opt. Soc. Am. A 6, 786–805 (1989); “Analysis of multilayer thin-film structures containing magneto-optic and anisotropic media at oblique incidence using 2 × 2 matrices,” J. Appl. Phys. 67, 6466–6475 (1990).

A. B. Marchant, Optical Recording (Addison-Wesley, Reading, Mass., 1990), p. 312.

T. A. Olson, “Digital optical storage media guidelines,” in Optical Data Storage, D. Chen, ed., Proc. SPIE382, 164–171 (1983).
[CrossRef]

C. S. Chung, C. W. Lee, P. Y. Seong, K.-H. Rim, D. H. Shin, “New stable servo method for optical disk systems,” in Optical Data Storage ’95, G. R. Knight, H. Ooki, Y. S. Tyan, eds., Proc. SPIE2514, 267–273 (1995).
[CrossRef]

L. Pan, D. Xu, M. Gong, H. Yuan, J. Pei, “Testing of optical disk axial run-out and tilt,” in Optical Storage: Third International Symposium, F. Gan, ed., Proc. SPIE2053, 160–163 (1993).
[CrossRef]

M. Mansuripur, The Physical Principles of Magneto-optical Recording (Cambridge U. Press, Cambridge, UK, 1995), pp. 29–32.

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Figures (10)

Fig. 1
Fig. 1

(a) Schematic diagram of the principle of TES generation; the difference between the signals of detector 1 and detector 2 produces the tracking error signal; (b) tracking error signal varies between positive values and negative values as the beam crosses from land to groove.

Fig. 2
Fig. 2

Schematic diagram of the optical path with (a) tilt of the disk and (b) tilt of the objective lens.

Fig. 3
Fig. 3

(a) Diagram of the planes at which wave fronts are converted to rays and vice versa; (b) calculated irradiance; and (c) calculated phase of the E-field distribution after rays are traced through the objective lens and the substrates and retraced away from focus. The substrate has 0.3° tilt, which is responsible for the observed coma on the wave front. There is approximately 0.3 waves of coma.

Fig. 4
Fig. 4

(a) Diagram of regime in which ray-tracing techniques are not valid and diffraction calculations must be used; (b) calculated irradiance; and (c) calculated phase of the E-field distribution after rays are reflected from the grooved surface of the disk with 0.3° of tilt. The irradiance distribution shows interference effects of the +1 and -1 orders, and the phase distribution indicates more than 4 waves of tilt in the wave front caused by the tilt of the disk. The abrupt changes between black and white indicate a 2π jump in the calculated wave front, but the wave front is continuous. (To enhance the visibility of the diffraction orders in this plot, we calculated the irradiance distribution with a groove depth of λ/8.)

Fig. 5
Fig. 5

(a) Diagram of the region of the reflected path in which ray tracing is applicable; (b) calculated irradiance; and (c) calculated phase of the E-field distribution after rays return through the substrate and the objective lens. The irradiance distribution shows the interference effects of the +1 and -1 orders. The phase distribution no longer shows significant coma. Because of reflection, the system is symmetric in double path and the odd aberrations are nearly compensated. (To enhance the visibility of the diffraction orders in this plot, we calculated the irradiance distribution with a groove depth of λ/8.)

Fig. 6
Fig. 6

Logarithmic plots of irradiance that show the focused beam at the plane of the disk: (a) the comatic spot caused by 0.3° disk tilt; note the rather large shift of the spot away from the center of the coordinate system, which is the point where the optical axis crosses the focal plane; (b) the comatic spot caused by 0.3° of objective lens tilt. In both cases, as the tilt angle increases, the beam continues to shift away from the center and its irradiance distribution becomes larger and more asymmetric.

Fig. 7
Fig. 7

A sketch of the land and groove at the disk surface, showing the movement of the point of peak irradiance that brings the TES to zero. In the absence of tilts, the TES equals zero when the point of peak irradiance is at A. When tilts are introduced into the system, the point of peak irradiance at which the TES equals zero shifts to B.

Fig. 8
Fig. 8

(a) Calculated TES versus the radial position r of the focused spot for several angles of disk tilt; the distance r is measured from the center of the track. (b) Close-up view of the boxed region in (a).

Fig. 9
Fig. 9

Peak shift away from the center of the groove, resulting from (a) disk tilt and (b) objective lens tilt when the TES is zero. We neglected the large shift of the beam (of the order of 5λ) by placing the groove of interest beneath the shifted beam. The dots represent computed data points, and the solid straight lines are best-fit linear curves. The slope of the fitted curve in (a) is 0.05λ per degree of disk tilt, and that in (b) is 0.012λ per degree of lens tilt. Fluctuations of the data are caused by numerical errors, as evidenced by the small peak shift that exists even when the tilt angles are zero. Although the pixel-to-pixel spacing at the focal plane of the lens is 0.08λ, the magnitude of error observed in these peak-shift calculations is quite small.

Fig. 10
Fig. 10

Computed amplitude of the TES versus tilt angle for disk tilt (solid curve) and objective lens tilt (dashed curve); the amplitudes are scaled with respect to the nominal tilt-free system.

Tables (1)

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Table 1 Parameters of Simulated Recordable Compact Disk Storage System

Equations (1)

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TES=S1-S2S1+S2.

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