Objective lens and optical head and optical disk device using the same
A technology for optical heads and optical discs, which is applied in the directions of recording/reproducing by optical methods, optical recording heads, beam guiding devices, etc., and can solve the problems of reduced power and difficulty in reproducing information.
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Embodiment 1
[0053] figure 1 A first embodiment of the optical head of the present invention is shown.
[0054] exist figure 1 Among them, the emitted light with a wavelength of about 650nm emitted by a semiconductor laser device 1 is converged by a converging lens 2 and converted into a substantially parallel beam 3 . The light beam 3 is p-polarized light, which enters and passes through the polarizing beam splitter 4 .
[0055] The light beam 3 passing through the polarizing beam splitter 4 is converted from linearly polarized light to substantially circularly polarized light by a 1 / 4 wave plate 5 , reflected by a mirror 6 , passes through an aperture control section 7 , and is incident on an objective lens 8 .
[0056] Such as Figure 2A As shown, the objective lens 8 includes a central portion A1, and a peripheral portion A2 surrounding the central portion A1. The numerical aperture (NA) of the central portion A1 is about 0.37, and the numerical aperture of the peripheral portion...
Embodiment 2
[0081] Figure 5 A second embodiment of the optical head of the present invention is shown.
[0082] exist Figure 5 Among them, the emission light with a wavelength of about 650nm emitted by the semiconductor laser device 21 is converged by a converging lens 22 and converted into a substantially parallel beam 23 . Light beam 23 is p-polarized light, incident and transmitted through polarizing beam splitter 24 . The light beam 23 transmitted through the polarization beam splitter 24 is reflected by a mirror 25 and is incident on a polarization hologram 26 .
[0083] Such as Image 6 As shown, the polarization hologram 26 is a hologram on a LiNb substrate with birefringence properties, and is configured to diffract ordinary light and transmit extraordinary light. Alternatively, the hologram can also be formed by subjecting a LiNb substrate to proton exchange.
[0084] Almost all components of the light beam 23 are extraordinary light, which enters and passes through the po...
Embodiment 3
[0097] Figure 8 A third embodiment of the optical head of the present invention is shown.
[0098] exist Figure 8 Among them, the emitted light with a wavelength of about 650nm emitted by a first semiconductor laser device 41 is p-polarized light, passes through a first polarization beam splitter 42, and then enters an optical path combining / decomposing device 43 . The light path combination / decomposition device 43 is configured to transmit light beams with a wavelength of about 650 nm and reflect light beams with a wavelength of about 780 nm. In this way, the emission light with a wavelength of about 650nm emitted by the first semiconductor laser device 41 passes through the optical path combining / decomposing device 43 and is then converged by the converging lens 46 to be converted into a substantially circularly polarized light beam 47 .
[0099] The light beam 47 passes through a 1 / 4 wave plate 49 that converts linearly polarized light into substantially circularly pola...
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Abstract
Description
Claims
Application Information
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