Abstract

Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk.

© 2002 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
    [CrossRef]
  2. G. J. Sprokel, “Reflectivity, rotation, and ellipticity of magnetooptic film structures,” Appl. Opt. 23, 3983–3989 (1984).
    [CrossRef] [PubMed]
  3. Diffract is a product of MM Research, Inc., Tucson, Arizona.
  4. J. E. Greivenkamp, J. H. Bruning, “Phase shifting interferometers,” in Optical Shop Testing, 2nd ed., D. Malacara ed. (Wiley, New York, 1992), pp. 501–598.
  5. P. Hariharan, B. F. Oreb, T. Eiju, “Digital phase-shifting interferometry: a simple error-compensating phase calculation algorithm,” Appl. Opt. 26, 2504–2506 (1992).
    [CrossRef]
  6. N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
    [CrossRef]
  7. R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
    [CrossRef]
  8. R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).
  9. S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
    [CrossRef]
  10. M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
    [CrossRef]
  11. T. McDaniel, Handbook of Magneto-Optical Data Recording: Materials, Subsystems, Techniques (Noyes Data Corporation/Noyes Publications, N.J., 1997).

1996 (1)

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

1993 (1)

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

1992 (1)

1991 (1)

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

1987 (1)

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

1984 (1)

1971 (1)

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Akahira, N.

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

Aso, K.

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

Bruning, J. H.

J. E. Greivenkamp, J. H. Bruning, “Phase shifting interferometers,” in Optical Shop Testing, 2nd ed., D. Malacara ed. (Wiley, New York, 1992), pp. 501–598.

DeNeufville, J.

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Eiju, T.

Feinleib, J.

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Greivenkamp, J. E.

J. E. Greivenkamp, J. H. Bruning, “Phase shifting interferometers,” in Optical Shop Testing, 2nd ed., D. Malacara ed. (Wiley, New York, 1992), pp. 501–598.

Hariharan, P.

Hashimoto, S.

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

Hashimoto, S.-I.

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

Ichimura, I.

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

Imanaka, R.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Kaneko, M.

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

Kawamura, I.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Kojima, R.

R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).

Kouzaki, T.

R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).

Matsunaga, T.

R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).

McDaniel, T.

T. McDaniel, Handbook of Magneto-Optical Data Recording: Materials, Subsystems, Techniques (Noyes Data Corporation/Noyes Publications, N.J., 1997).

Moss, S. C.

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Nishino, S.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Nishiuchi, K.

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

Ochiai, Y.

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

Ohno, E.

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

Ohta, T.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Okazaki, Y.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Oreb, B. F.

Ovshinsky, S. R.

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Sabi, Y.

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

Saimi, T.

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Sprokel, G. J.

Takao, M.

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

Watanabe, K.

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

Yamada, N.

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).

Appl. Opt. (2)

Appl. Phys. Lett. (1)

J. Feinleib, J. DeNeufville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

IEEE Trans. Magn. (2)

S. Hashimoto, Y. Ochiai, M. Kaneko, K. Aso, K. Watanabe, “Magnetic properties and influence of nitrogen in sputtered TbFeCo films,” IEEE Trans. Magn. 23, 2278–2280 (1987).
[CrossRef]

M. Kaneko, Y. Sabi, I. Ichimura, S.-I. Hashimoto, “Magneto-optical recording on Pt/Co and GdFeCo/TbFeCo disks using a green laser,” IEEE Trans. Magn. 29, 3766–3771 (1993).
[CrossRef]

J. Appl. Phys. (1)

N. Yamada, E. Ohno, K. Nishiuchi, N. Akahira, M. Takao, “Rapid-phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. Appl. Phys. 69, 2849–2856 (1991).
[CrossRef]

Jpn. J. Appl. Phys. (1)

R. Imanaka, Y. Okazaki, T. Saimi, I. Kawamura, T. Ohta, S. Nishino, “‘PD’ (powerful optical disk system) for multimedia,” Jpn. J. Appl. Phys. 35, 490–494 (1996).
[CrossRef]

Other (4)

R. Kojima, T. Kouzaki, T. Matsunaga, N. Yamada, “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks,” in Optical Data Storage, S. R. Kubota, T. J. Milster, P. J. Wehrenberg, eds., Proc. SPIE3401, 14–23 (1998).

Diffract is a product of MM Research, Inc., Tucson, Arizona.

J. E. Greivenkamp, J. H. Bruning, “Phase shifting interferometers,” in Optical Shop Testing, 2nd ed., D. Malacara ed. (Wiley, New York, 1992), pp. 501–598.

T. McDaniel, Handbook of Magneto-Optical Data Recording: Materials, Subsystems, Techniques (Noyes Data Corporation/Noyes Publications, N.J., 1997).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (20)

Fig. 1
Fig. 1

Simulation results pertaining to the exit pupil phase pattern when the laser beam is focused at one of three positions on a CD-ROM pit. Each phase distribution is plotted in gray scale, with black representing the minimum and white the maximum value. In (a) and (c), where the focused spot is on a pit edge, Φmin = -58.21° and Φmax = +67.29°. In (b), where the focused spot is at the pit center, Φmin = 0° and Φmax = +102.43°.

Fig. 2
Fig. 2

Regular array of CD pits used in computer simulations. The pits have a length of 1.6 µm, a width of 0.52 µm, and a depth of λ/4; the track pitch (i.e., the distance between adjacent tracks, which in this example run along 45° diagonal lines) is 1.6 µm.

Fig. 3
Fig. 3

Distributions of left, intensity and right, phase at the exit pupil of the 0.6-N.A. objective lens. The objective focuses a collimated laser beam on the disk surface shown in Fig. 2. The three rows in this figure correspond to three locations of the focused spot relative to a pit.

Fig. 4
Fig. 4

Computed plots of (a), average intensity and (b), average phase at the exit pupil of the objective when the focused spot scans along one of the tracks depicted in Fig. 2. The averaging of intensity and phase is made by integration over the exit pupil at a fixed position of the disk.

Fig. 5
Fig. 5

Simplified diagram of a scanning optical microscope. The filtered and collimated laser beam is focused onto the disk through an objective lens. The reflected beam is separated from the incident beam at the beam splitter and then focused onto the detector(s) by the same (or another) lens. The Wollaston prism is needed for polarization signal measurements.

Fig. 6
Fig. 6

Experimental setup for measuring the phase distribution that appears at the objective’s exit pupil. The collimated laser beam is separated into two components with different polarization states (p and s). The s component is reflected at polarizing beam splitter PBS to the reference mirror; the p component is transmitted and focused onto the disk through the objective lens. The λ/4 plates in the test and reference arms are needed to rotate (through 90°) the polarization vectors of the returning beams. Regular beam splitter BS creates two beams in the return path; the beam is further split among four detectors by the two Wollaston prisms. The beam transmitted by the beam splitter goes through a λ/4 plate whose fast and slow axes are aligned with the polarization directions of the test and reference beams; this produces a 90° phase shift between the test and the reference beams in the horizontal arm of the detection module. The relative phases of the test and the reference beams arriving at detectors 1, 2, 3, and 4 are, therefore, 0°, 90°, 180°, and 270°, respectively.

Fig. 7
Fig. 7

Intensity images of a 10 µm × 10 µm section of a DVD- ROM taken at λ = 488 nm with linear polarization direction parallel to the tracks. (a), N.A., 0.8; (b), N.A., 0.6. The lower resolution of the latter lens produces blurred marks.

Fig. 8
Fig. 8

Intensity images of a 10 µm × 10 µm section of a DVD- ROM taken at λ = 690 nm. (a), N.A., 0.8; (b), N.A., 0.6. Compared with those in Fig. 7, the longer-wavelength laser produces images with lower resolution.

Fig. 9
Fig. 9

Intensity image of a 10 µm × 10 µm section from a PC disk taken at λ = 488 nm with a N.A. of 0.8, with the direction of linear polarization parallel to the tracks. The dark marks correspond to amorphous regions on a bright (crystalline) background.

Fig. 10
Fig. 10

Polarization images of several periodic mark sequences recorded on a MO disk. The mark sequences range in period from 3.864 to 0.774 µm, as indicated. Images were taken with a 0.8-N.A. objective at (a), λ = 488 nm and (b), λ = 690 nm. Sharper mark boundaries are observed in the 488-nm image.

Fig. 11
Fig. 11

(a), Intensity and (b), (c), polarization images of a small section from a CD-ROM. The polarization rotation at the disk surface is caused by a slight difference in the reflectivities of p- and s-polarized light from the pit boundaries. In a the signals from the two detectors (see Fig. 5) were added together; in b one of the two detector signals was simply subtracted from the other; in (c) the differential signal was normalized by the sum signal.

Fig. 12
Fig. 12

Scanned images of a small section from a metallized diffraction grating (period, 100 µm). (a), Intensity image; (b), phase image shown in gray scale; (c), phase image shown as a 3D plot.

Fig. 13
Fig. 13

Four interferograms, with relative phase shifts of 0°, 90°, 180°, and 270°, recorded from the detectors 1, 2, 3, 4, respectively, shown in Fig. 6. It is from these intermediate images that the phase images in Figs. 12(b) and 12(c) are obtained.

Fig. 14
Fig. 14

Same as Fig. 13 but the sample in this case is a CD-ROM disk.

Fig. 15
Fig. 15

Phase images obtained from a small section of a CD- ROM. The intermediate images (i.e., phase-shifted interferograms) that correspond to this image are shown in Fig. 14.

Fig. 16
Fig. 16

Same as Fig. 14 but the disk in this case is slightly tilted away from the focal plane of the objective.

Fig. 17
Fig. 17

Same as Fig. 15 but the disk in this case is slightly tilted away from the focal plane of the objective.

Fig. 18
Fig. 18

Phase images obtained from a small section of a DVD-ROM at λ = 633 nm; NA, 0.8.

Fig. 19
Fig. 19

Conventional image (obtained with a white-light microscope) of a PC sample upon which several parallel lines were recorded. The bright lines are crystalline on a dark amorphous background.

Fig. 20
Fig. 20

Scanned images of a small section of the PC sample shown in Fig. 19. (a), Intensity image; (b), phase image in gray scale; (c), cross-sectional plot of the phase image shown in (b) obtained by averaging of ten lines along the horizontal direction.

Tables (1)

Tables Icon

Table 1 Specifications of Optical Disks Used for Measurements Reported in This Paper

Equations (2)

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

ΔΦ=tan-1S4-S2/S1-S3.
ΔLmin=0.61λNA.

Metrics