Optical head device, diffraction element, optical information device, computer, disc player, car navigation system, optical disc recorder, and vehicle
A technology of an optical head device and a diffractive element, which can be applied to optical recording heads, optical recording/reproducing, beam guiding devices, etc., and can solve the problems of tracking error signal amplitude drop
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Embodiment approach 1
[0156] figure 1 It is a diagram schematically showing the configuration of the optical head device according to Embodiment 1 of the present invention.
[0157] In order to make the light beam 14 emitted from the light source (such as a red light source) 12 form a sub-spot (subspot: subspot) on the optical disc 27, after passing through (a part of diffraction) a diffraction element 31 that diffracts a part of the light, use a beam splitter (beam splitter) 3000 Reflection, using the collimating lens 70 to convert the parallelism (for example, to convert into approximately parallel light), the objective lens 25 makes the light beam 14 pass through a transparent substrate of about 0.6mm and converge on the recording surface of optical discs 27 such as DVD-R and DVD-RAM . The light beam reflected by the recording surface of the optical disc 27 returns along the same optical path, passes through the beam splitter 3000, and is branched into a direction different from that of the li...
no. 2 Embodiment approach
[0167] Due to restrictions on the shape of the optical head device, etc., there are cases where it is necessary to replace figure 1 The diffractive element 31 is used for sub-beam generation with a diffractive element, such as image 3Like the 3100 of the 3100, it is installed close to the light source 12 and away from the collimator lens 70. In addition, with this arrangement, since the required effective diameter of the diffraction grating 3100 can be reduced and the external shape can also be miniaturized, there is an effect that the material cost of the diffraction element 3100 can be reduced.
[0168] However, in this case, if Figure 4A As shown, the area where the sub-beam is generated by the diffraction grating 3100 is different from the area where the main beam is generated, and the generation area 402 of the sub-beam 242 and the generation area 403 of the sub-beam 243 are offset in the Y direction relative to the transmission area 401 of the main beam 214 . The r...
no. 3 Embodiment approach
[0175] replace figure 1 The diffraction grating 3120 according to the third embodiment of the present invention is used as the diffraction element 31 . Such as Figure 6A As shown, the diffraction element 3120 further divides the central area 3129 between the first diffraction grating area 3121 with a phase of 0 degrees and the second diffraction grating area 3122 with a phase of 180 degrees by six dividing lines 3128 extending in the T direction into 7 areas, the third diffraction grating area 3123 with a phase of 60 degrees, the fourth diffraction grating area 3124 with a phase of 120 degrees, the fifth diffraction grating area 3125 with a phase of -120 degrees, and the sixth diffraction grating area with a phase of -60 degrees Diffraction grating region 3126 . According to this configuration, since the generation region 4320 of the sub-beam 3420 and any of the generation region 4220 of the sub-beam 3320 almost equally include the diffraction grating region in opposite ph...
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