Abstract

One can control the aberrations of an optical readout system by varying the width of a strip of antireflection coatings deposited upon plastic objective lenses. It is found that one can control the magnitude of the third-order astigmatism of the system by changing the coating width. This process has the advantage that it does not significantly cause other kinds of aberration such as coma and spherical aberrations to deteriorate. When these nonrotational symmetrically (NRS) coated lenses are used for off-axis operations such as tracking movements in optical drives, the change in the magnitude of the astigmatism (ΔAS) that is generated can be made smaller than those of symmetrically coated or noncoated lenses. As much as a 73% decrease in ΔAS was observed experimentally with a NRS-coated lens. Including the birefringence of the plastic material in the analysis yields a low and constant level of astigmatism generated by shifting of the objective lens.

© 2000 Optical Society of America

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References

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  1. H. Kawai, M. Suzuki, A. Yoshida, “Birefringence-free acrylic resin for precision plastic optics,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, F. W. Frank, ed., Proc. SPIE3135, 42–51 (1997).
    [CrossRef]
  2. H. Yamazaki, T. Matsumaru, “Device for recording or reproducing information on an optical recording medium having an objective lens with an astigmatism producing off optical axis minimum total astigmatism position to correct tracking astigmatism,” U.S. patent5,754,504 (19May1998).
  3. K. M. Hung, “Effects of asymmetrically molded plastic objective lens on the push–pull tracking error signal in an optical disk drive,” Appl. Opt. 39, 1309–1314 (2000).
    [CrossRef]
  4. G. H. Meeten, Optical Properties of Polymers (Elsevier, Barking, UK, 1986).

2000 (1)

Hung, K. M.

Kawai, H.

H. Kawai, M. Suzuki, A. Yoshida, “Birefringence-free acrylic resin for precision plastic optics,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, F. W. Frank, ed., Proc. SPIE3135, 42–51 (1997).
[CrossRef]

Matsumaru, T.

H. Yamazaki, T. Matsumaru, “Device for recording or reproducing information on an optical recording medium having an objective lens with an astigmatism producing off optical axis minimum total astigmatism position to correct tracking astigmatism,” U.S. patent5,754,504 (19May1998).

Meeten, G. H.

G. H. Meeten, Optical Properties of Polymers (Elsevier, Barking, UK, 1986).

Suzuki, M.

H. Kawai, M. Suzuki, A. Yoshida, “Birefringence-free acrylic resin for precision plastic optics,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, F. W. Frank, ed., Proc. SPIE3135, 42–51 (1997).
[CrossRef]

Yamazaki, H.

H. Yamazaki, T. Matsumaru, “Device for recording or reproducing information on an optical recording medium having an objective lens with an astigmatism producing off optical axis minimum total astigmatism position to correct tracking astigmatism,” U.S. patent5,754,504 (19May1998).

Yoshida, A.

H. Kawai, M. Suzuki, A. Yoshida, “Birefringence-free acrylic resin for precision plastic optics,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, F. W. Frank, ed., Proc. SPIE3135, 42–51 (1997).
[CrossRef]

Appl. Opt. (1)

Other (3)

H. Kawai, M. Suzuki, A. Yoshida, “Birefringence-free acrylic resin for precision plastic optics,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, F. W. Frank, ed., Proc. SPIE3135, 42–51 (1997).
[CrossRef]

H. Yamazaki, T. Matsumaru, “Device for recording or reproducing information on an optical recording medium having an objective lens with an astigmatism producing off optical axis minimum total astigmatism position to correct tracking astigmatism,” U.S. patent5,754,504 (19May1998).

G. H. Meeten, Optical Properties of Polymers (Elsevier, Barking, UK, 1986).

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Figures (20)

Fig. 1
Fig. 1

Geometry of the coating on a plastic objective lens.

Fig. 2
Fig. 2

Astigmatism contour of an asymmetrically coated objective lens as the lens is rotated. The cross indicates the astigmatism value of a noncoated lens.

Fig. 3
Fig. 3

Variation in the magnitude of astigmatism generated by various coating widths.

Fig. 4
Fig. 4

Variation in spherical aberration of the system by rotation of the objective with a 2-mm-wide coating. The cross indicates the value of a noncoated lens.

Fig. 5
Fig. 5

Spot diagrams of the image point: (a) noncoated lens, (b) lens coated with a 2-mm strip at α = 60°.

Fig. 6
Fig. 6

Amount of off-axis astigmatism generated by shifting of the objective lens with a 2-mm-wide coating. The dashed curve shows the result for a noncoated lens.

Fig. 7
Fig. 7

Astigmatism contour when the 2-mm-coated lens is shifted along its coated strip (solid curve) and perpendicular to its coated strip (dashed curve).

Fig. 8
Fig. 8

(a) Off-axis astigmatism generated by shifting of the 2-mm-coated lens. (b) Geometry defining shift angle θ.

Fig. 9
Fig. 9

Dependence of ΔAS on shift angle θ for the 2-mm-coated lens.

Fig. 10
Fig. 10

Off-axis astigmatism generated by shifting of the 2.4-mm-coated lens.

Fig. 11
Fig. 11

Coated lens observed under a microscope. The coating strip can be seen clearly.

Fig. 12
Fig. 12

Optical setup for measuring the transmission wave-front quality of an objective lens: I/O, input–output.

Fig. 13
Fig. 13

Experimental astigmatism data for an unmasked PMMA lens. The angular separation between two adjacent filled circles is 15° ± 2°. The dashed circle is the fitted result.

Fig. 14
Fig. 14

Two-dimensional wave-front phase plots of masked lenses with coating widths (a) 0.5 ± 0.2 mm; (b) 1.0 ± 0.2 mm; (c) 1.5 ± 0.2 mm; (d) 2.0 ± 0.2 mm; (e) 3.0 ± 0.2 mm.

Fig. 15
Fig. 15

Experimental astigmatism data for a 2-mm-coated PMMA lens. The angular separation between two adjacent filled circles is 15 ± 2°. The dashed circle is the simulation result.

Fig. 16
Fig. 16

Experimental data for the magnitude of astigmatism generated by several coating widths. The dashed curve is the simulation result.

Fig. 17
Fig. 17

Magnitude of off-axis generated by shifting of an unmasked objective lens. The dashed curve is the simulation result.

Fig. 18
Fig. 18

Magnitude of off-axis astigmatism generated by shifting of a 2-mm-coated PMMA lens.

Fig. 19
Fig. 19

Experimental astigmatism data for a 2-mm-coated Zeonex lens. The angular separation between two adjacent filled circles is 15° ± 2°. The dotted circle is the fitted result.

Fig. 20
Fig. 20

Magnitude of off-axis astigmatism generated by shifting of a 2-mm-coated Zeonex lens.

Tables (1)

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Table 1 Aspheric Components of 4th, 6th, 8th, and 10th Orders for Surfaces of the Lens

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