CN1118798C - Optical head, recording and/or reproducing method, and method for detecting the thickness - Google Patents

Optical head, recording and/or reproducing method, and method for detecting the thickness Download PDF

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CN1118798C
CN1118798C CN 99102974 CN99102974A CN1118798C CN 1118798 C CN1118798 C CN 1118798C CN 99102974 CN99102974 CN 99102974 CN 99102974 A CN99102974 A CN 99102974A CN 1118798 C CN1118798 C CN 1118798C
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light
optical
recording
layer
thickness
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CN1229231A (en
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植田充纪
久保毅
铃木润一
坂本敏
川村洋
日根野哲
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索尼公司
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Abstract

用来在光盘上记录/复制信息信号的一种光头,在光盘的记录层上具有-个光透视层,在光头中包括一个用于准直透镜的驱动器。 On the optical disc for recording / reproducing optical head of the information signal, on the recording layer having a disc - a layer rays, in the optical head includes a driver for the collimator lens. 用准直透镜的驱动器在能够消除由于光透视层的厚度误差造成的球面象差的方向上移动设在光源和物镜之间的一个准直透镜。 A collimator lens actuator can be eliminated in a collimator lens disposed between the light source and moving the objective lens in the thickness direction since the upper layer error rays caused spherical aberration. 借助于这种结构,即使是为了提高光盘的记录容量而增大了装载在光头上的物镜的数值孔径NA,仍然可以减少球面象差的发生量。 With this structure, even in order to improve the recording capacity of the optical disc loaded on the optical head increases the numerical aperture NA of the objective lens, can still occur to reduce the amount of the spherical aberration.

Description

光头,记录和/或复制方法, 以及用来检测厚度的方法 An optical head, a recording and / or reproducing method, and a method for detecting the thickness of the

本发明涉及到用来记录和/或复制诸如光盘等信息记录媒体的一种光头,以及装有这种光头的一种记录和/或复制装置。 The present invention relates to a recording and / or reproducing apparatus for recording and / or reproducing information on the disc like recording medium such as an optical head and an optical head incorporating such. 本发明还涉及到诸如光盘等信息记录媒体的一种记录和/或复制方法,并且涉及到用来检测在记录媒体上面具有一个光透射层的信息记录媒体的光透射层厚度的一种方法。 The present invention further relates to a recording such as an information recording medium such as an optical disc and / or reproducing method, a recording method and relates to a light transmission layer thickness of the medium having an information layer on a light transmitting recording medium used above to detect.

诸如只读光盘,相变型光盘,磁光盘或是光记录卡等等信息记录媒体是专门用来存储诸如视频或是音频信息或者计算机数据等等数据的。 Such as read only optical disk, a phase change type optical disk, a magneto-optical disk or an optical recording card like information recording medium is designed to store information such as video or audio data or the computer data and the like. 近年以来,对这种信息记录媒体的高记录密度和大记录容量的需求变得越来越迫切。 In recent years, demand for high recording density and a large recording capacity of such information recording medium becomes more and more urgent.

为了提高信息记录媒体的记录密度,有一种有效的方法是增大装载在光头上的一个物镜的数值孔径NA,并且缩短光的波长,这样就能缩小由物镜形成的激光点的尺寸。 In order to increase the recording density of the information recording medium, there is an effective method is to increase a numerical aperture NA of the objective lens is mounted on the optical head, and to shorten the wavelength of light, so that we can reduce the size of the laser spot formed by the objective lens.

对于早期出现的数字光盘等小型光盘(CD)来说,物镜的数值孔径NA是0.45,所用的光的波长是780nm。 For early stage of the optical disk digital compact disc (CD), the numerical aperture NA of the objective lens is 0.45, the wavelength of light used is 780nm. 另一方面,对于记录密度和记录容量都比小型光盘更高的一种数字光盘DVD来说,物镜的数值孔径NA是0.6,所用的光的波长是650nm。 On the other hand, the recording density higher than the recording capacity of the compact disk and a digital disc (DVD), the numerical aperture NA of the objective lens is 0.6, the wavelength of light used is 650nm.

同时,在诸如光盘等信息记录媒体上记录有信息信号的记录层上有一个光透射层。 Meanwhile, recording information on a recording medium such as an optical disk has a light transmissive layer on the recording layer information signal. 在记录或是复制时用一个载有信息信号的记录层通过光透射层来照射这一记录层。 When copying or recording with a recording layer containing an information signal recording layer is irradiated by the light transmission layer. 如果光透射层的厚度存在误差,其厚度就会偏离预定的值,这种误差会产生球面象差。 If the light transmitting layer thickness errors, which will deviate from the thickness of a predetermined value, such an error is generated spherical aberration. 例如可以用以下的公式(1)来表示三阶球面象差:W40={Δt(n2-1)/(8n3)}NA4...(1)其中的Δt是光透射层的厚度误差,n是光透射层的折射率,NA是一个物镜的数值孔径。 For example, by the following equation (1) represents the third-order spherical aberration: W40 = {Δt (n2-1) / (8n3)} NA4 ... (1) where [Delta] t is the thickness error of the light transmission layer, n is is the refractive index of the light transmitting layer, NA is the numerical aperture of an objective lens.

从公式(1)中可见,由光透射层的厚度误差造成的球面象差与数值孔径NA的四次方成正比地增大。 Visible, caused by the thickness error of the light transmission layer spherical aberration and numerical aperture NA is increased in proportion to the fourth power from equation (1). 因此,增大数值孔径对于抑制球面象差的发生具有决定性的作用。 Thus, the numerical aperture is increased for suppressing the occurrence of spherical aberration has a decisive role.

从公式(1)中还可以看出,为了有效地抑制地址信号的球面象差,还可以缩小光透射层的厚度公差,从而减少其厚度误差。 From equation (1) it can also be seen that in order to effectively suppress the spherical aberration address signal difference, may reduce the light transmission layer thickness tolerance, thereby reducing the thickness error. 例如在DVD中,光透射层的厚度公差是±0.03mm。 For example, in a DVD, the light transmission layer thickness tolerance is ± 0.03mm. 如果要想将由于光透射层的厚度误差造成的球面象差抑制在相当于DVD等级的数值,在数值孔径NA为0.6的情况下,只要光透射层的厚度误差Δt处在公式(2)的范围之内就足够了:-0.00388/NA4≤Δt≤+0.00388/NA4...(2)从上述公式(2)中可以看出,在扩大数值孔径NA的情况下,就可以找到所需的公差值,以便将球面象差抑制在基本上相当于DVD的等级。 If it is a spherical aberration due to the thickness of the light transmitting layer corresponding to suppress errors caused DVD level value, in the case where the numerical aperture NA of 0.6, as long as the light transmission layer thickness error Δt in equation (2) within the scope suffice: -0.00388 / NA4≤Δt≤ + 0.00388 / NA4 ... (2) from the above equation (2) can be seen, in the case where the numerical aperture NA expansion, can find the tolerance value in order to suppress the spherical aberration of DVD level substantially equivalent. 从公式(2)中可见,如果数值孔径NA=0,7或是NA=0.85,只要Δt分别是-0.016mm≤Δt≤+0.016mm或者-0.0074mm≤Δt≤+0.0074mm就足够了。 From equation (2) it can be seen, if the numerical aperture NA = 0,7 or NA = 0.85, respectively, as long as Δt -0.016mm≤Δt≤ + 0.016mm or -0.0074mm≤Δt≤ + 0.0074mm sufficient.

然而,要缩小光透射层的厚度公差是极为困难的。 However, to reduce the light transmission layer thickness tolerance is extremely difficult. 尽管对于大规模生产系统并不需要明显地改变工艺,要提高光透射层厚度的精度仍然是极为困难的,这是因为此类误差主要取决于信息记录媒体的制造方法。 Although not required significantly alter the process for large scale production system, to improve the accuracy of the light transmitting layer thickness is still extremely difficult, because such errors are mainly dependent on the information recording medium manufacturing method. 如果能够实现光透射层厚度误差的精度,就需要彻底改变工艺,这样就会明显地增加制造成本。 If the accuracy of the thickness can be achieved error light transmission layer, it is necessary to completely change the process, which would significantly increase manufacturing costs. 因此,通过缩小光透射层厚度误差来抑制球面象差的方法是不可取的。 Thus, by reducing the thickness error of the light transmission layer to suppress the spherical aberration it is usually undesirable.

本发明的目的是提供一种光头和一种记录和/或复制方法,以及一种装置,即使在增大数值孔径时仍可以抑制球面象差。 Object of the present invention is to provide an optical head and a recording and / or reproducing method, and an apparatus, it can still be suppressed even when a spherical aberration to increase the numerical aperture difference.

本发明的另一个目的是提供一种记录和/或复制方法,即使在增大数值孔径时仍可以抑制球面象差。 Another object of the present invention is to provide a recording and / or reproducing method, still possible to suppress the spherical aberration even when the numerical aperture is increased.

本发明的再一目的是提供一种厚度检测方法,以便于检测设在一个信息记录媒体的记录层上面的一个光透射层的厚度。 A further object of the present invention is to provide a method of detecting thickness, provided in order to detect a thickness of the light transmitting layer is above the information recording medium a recording layer.

从一方面来看,本发明提供了一种用于信息记录媒体的光头,在信息记录媒体上用来记录信息信号的记录层上面具有一个光透射层,这种光头包括一个用来发光的光源,一个物镜,用来通过光透射层将来自光源的光会聚到记录层上,设置在光源和物镜之间的一个具有预定折射率的光学元件,以及根据光透射层的厚度来移动光学元件的一个移动装置。 Viewed from one aspect, the present invention provides an optical head for an information recording medium for the recording layer having an information signal recorded thereon a light transmitting layer on the information recording medium, the optical head comprising a light source for emitting light , an objective lens for passing the light transmission layer to converge light from the light source on the recording layer, an optical element having a predetermined refractive index is disposed between the light source and the objective lens, and move according to thickness of the light transmitting layer of the optical element a mobile device.

上述光头中的光学元件最好是一个准直透镜,如果光透射层处在规定的值,准直透镜就让光源发出的光基本上对准地落在物镜上。 Said optical head in the optical element is preferably a collimating lens, the light if the light transmission layer in the predetermined value, the collimator lens is substantially aligned with light emitted let fall on the objective lens.

在上述的光头中,如果物镜的数值孔径NA不小于0.65,信息记录媒体的光透射层的薄膜厚度就应该不小于0.47mm。 In the optical head, if the numerical aperture NA of the objective lens is not smaller than 0.65, the film thickness of the light transmittance of the information recording medium layer should not be less than 0.47mm.

移动装置中优选包括一个与从光源射向光学元件的光的光轴基本上平行的参考轴,用来支撑光学元件并且能够沿着参考轴移动的一个光学元件支撑装置,一个电机,以及一个传动装置,用来将电机的转动转换成平行于光轴的平移运动,并且将这种平移运动传递给光学元件支撑装置。 The mobile device preferably includes a shaft and a reference optical axis of light from the light source toward the optical element is substantially parallel, for supporting the optical element and the optical element is movable along a reference axis of the support means, a motor, and a drive means for converting rotation of the motor into a translational movement parallel to the optical axis, and transmits this translational movement of the support means to the optical element. 传动装置将电机的转动转换成平行于光轴的平移运动,用来移动光学元件支撑装置,进而使光学元件发生移动,从而根据光透射层的厚度来消除球面象差。 The transmission device converts rotation of the motor into a translational movement parallel to the optical axis, support means for moving the optical element, the optical element is moved further, thereby eliminating spherical aberration according to the thickness of the light transmitting layer.

利用这种光头可以通过移动装置来移动设在光源和物镜之间的一个具有预定折射率的光学元件,以便根据光透射层的厚度来消除球面象差。 With this movement of the optical head can be provided between the light source and the objective lens by means of a moving optical element having a predetermined refractive index, so as to eliminate spherical aberration according to the thickness of the light transmitting layer. 因此,尽管在光透射层中存在厚度误差,也能够抑制由于厚度误差造成的球面象差。 Thus, despite the thickness error of the light transmission layer can be suppressed due to the thickness error caused by spherical aberration.

在另一方面,本发明提供了一种记录和/或复制装置,用来在一种信息记录媒体的一个记录层上记录和/或复制信息信号,在这种记录媒体上还有一个光透射层,该装置包括用来检测光透射层厚度的厚度检测装置,以及一个用于信息记录媒体的光头,在信息记录媒体上用来记录信息信号的记录层上面具有一个光透射层。 In another aspect, the present invention provides a recording and / or reproducing apparatus for recording and / or reproducing information signals on a recording layer of an information recording medium in which the recording medium and a light transmission layer, the apparatus includes means for detecting a thickness of the light transmission layer thickness detecting means, and an optical head for information recording medium, the recording medium on the information recording layer for recording signal information above having a light transmitting layer. 这种光头包括一个用来发光的光源,一个物镜,用来通过光透射层将来自光源的光会聚到记录层上,设置在光源和物镜之间的一个具有预定折射率的光学元件,以及根据厚度检测装置检测到的光透射层的厚度来移动光学元件的移动装置。 This optical head comprises a light source for emitting light, an objective lens for passing the light transmission layer to converge the light from the light source on the recording layer, the optical element is provided having a predetermined refractive index between the light source and the objective lens, and in accordance with thickness detecting means for detecting the thickness of the light transmission layer to the mobile device to move the optical element.

上述光头中的光学元件最好是一个准直透镜,如果光透射层处在规定的值,准直透镜就让光源发出的光基本上对准地落在物镜上。 Said optical head in the optical element is preferably a collimating lens, the light if the light transmission layer in the predetermined value, the collimator lens is substantially aligned with light emitted let fall on the objective lens.

在上述的光头中,如果物镜的数值孔径NA不小于0.65,信息记录媒体的光透射层的薄膜厚度就应该不小于0.47mm。 In the optical head, if the numerical aperture NA of the objective lens is not smaller than 0.65, the film thickness of the light transmittance of the information recording medium layer should not be less than 0.47mm.

在上述的记录和/或复制装置中,移动装置包括一个与从光源发出并且落在光学元件上的光的光轴基本上平行的参考轴,用来支撑光学元件并且能够沿着参考轴移动的一个光学元件支撑装置,一个电机,以及一个传动装置,用来将电机的转动转换成平行于光轴的平移运动,并且将这种平移运动传递给光学元件支撑装置。 In the recording and / or reproducing apparatus, the mobile device comprises issuing a reference axis and the optical axis of light falling on the optical element from the light source substantially in parallel, for supporting the optical element and movable along the reference axis an optical element support means, a motor, and a drive means for converting rotation of the motor into a translational movement parallel to the optical axis, and transmits this translational movement of the support means to the optical element. 传动装置将电机的转动转换成平行于光轴的平移运动,用来移动光学元件支撑装置,进而使光学元件发生移动,从而根据光透射层的厚度来消除球面象差。 The transmission device converts rotation of the motor into a translational movement parallel to the optical axis, support means for moving the optical element, the optical element is moved further, thereby eliminating spherical aberration according to the thickness of the light transmitting layer.

利用这种记录和/或复制装置,可以通过移动装置来移动设在光源和物镜之间的一个具有预定折射率的光学元件,以便根据光透射层的厚度来消除球面象差。 With such a recording and / or reproducing apparatus, it can be moved by moving means disposed between the light source and the objective lens having a predetermined refractive index of the optical element, so as to eliminate spherical aberration according to the thickness of the light transmitting layer. 因此,尽管在光透射层中存在厚度误差,也能够抑制由于厚度误差造成的球面象差。 Thus, despite the thickness error of the light transmission layer can be suppressed due to the thickness error caused by spherical aberration.

在另一方面,本发明提供了一种记录和/或复制方法,用来在一种信息记录媒体的记录层上记录和/或复制信息信号,在这种记录媒体上还有一个光透射层,该方法包括采用一个具有发光光源的光头,一个物镜,用来通过光透射层将来自光源的光会聚到记录层上,以及设置在光源和物镜之间的一个具有预定折射率的光学元件,并且检测光透射层的厚度,根据检测的结果来移动光学元件,从而消除球面象差。 In another aspect, the present invention provides a recording and / or reproducing method for recording on a recording layer of an information recording medium and / or reproducing information signals on a recording medium in which there is a light transmitting layer the method uses a light source comprising an optical head having an objective lens for passing the light transmission layer to converge light from the light source on the recording layer, and an optical element having a predetermined refractive index is disposed between the light source and the objective lens, and detecting the thickness of the light transmissive layer, in accordance with the result of detection by moving an optical element, thereby eliminating spherical aberration.

上述光头中的光学元件最好是一个准直透镜,如果光透射层处在规定的值,准直透镜就让光源发出的光基本上对准地落在物镜上。 Said optical head in the optical element is preferably a collimating lens, the light if the light transmission layer in the predetermined value, the collimator lens is substantially aligned with light emitted let fall on the objective lens.

在上述的光头中,如果物镜的数值孔径NA不小于0.65,信息记录媒体的光透射层的薄膜厚度就应该不小于0.47mm。 In the optical head, if the numerical aperture NA of the objective lens is not smaller than 0.65, the film thickness of the light transmittance of the information recording medium layer should not be less than 0.47mm.

利用这种记录和/或复制装置,可以通过移动装置来移动设在光源和物镜之间的具有预定折射率的光学元件,以便根据光透射层的厚度来消除球面象差。 With such a recording and / or reproducing apparatus, the optical element may be moved with a predetermined refractive index disposed between the light source and the objective lens by the moving means, so as to eliminate spherical aberration according to the thickness of the light transmitting layer. 因此,尽管在光透射层中存在厚度误差,也能够抑制由于厚度误差造成的球面象差。 Thus, despite the thickness error of the light transmission layer can be suppressed due to the thickness error caused by spherical aberration.

在又一方面,本发明提供了一种用来检测设在信息记录媒体的一个记录层上的光透射层厚度的检测方法,在这种记录层上适合记录信息信号,该方法包括从一个光源发光,用一个物镜将光源发出的光会聚到信息记录媒体上,用一个用来检测聚焦误差信号的光电检测器来接收由物镜会聚到信息记录媒体并且从信息记录媒体上反射的反射光,并且根据光电检测器反射的反射光和光透射层的表面反射的反射光产生的聚焦误差信号中的信号部分检测出光透射层的厚度。 In yet another aspect, the present invention provides a method for detecting a recording layer provided on the information recording medium of the light transmission layer thickness is detected on such a recording layer for recording information signals, the method comprising a light source from light, an objective lens with a light source are converged onto the information recording medium, a focus error signal for detecting a photodetector to receive converged by the objective lens to the information recording medium and light reflected from the information recording medium, and thickness of the light transmitting layer is detected based on the focus error signal portion reflected signal light and the reflective surface of the light transmission layer is reflected by the photodetector in the light produced.

在本发明的厚度检测方法中,光透射层的厚度是根据聚焦误差信号来检测的,不需要专用的检测装置就能检测出光透射层厚度。 In the thickness detection method of the present invention, the light transmission layer has a thickness according to the focus error signal is detected, no special detection means can be detected light transmission layer thickness.

按照本发明,即使是增大了物镜的数值孔径NA,仍然可以抑制由于光透射层的厚度误差造成的球面象差。 According to the present invention, even when the numerical aperture NA of the objective lens is increased, the error can still be suppressed due to the thickness of the light transmission layer caused spherical aberration. 这样就能提高信息记录媒体的记录密度和记录容量,不需要提高信息记录媒体的制造成本,同时将光透射层厚度误差的公差保持在一个较大的值。 This would increase the recording density and the recording capacity of the information recording medium, need not increase the manufacturing cost of the information recording medium, while the tolerance error of the light transmission layer thickness is maintained at a large value.

图1表示了用来体现本发明的一个光头;图2表示用来体现本发明的一个记录和/或复制装置;图3表示象散象差;图4表示在象散象差方法中使用的一个光电检测器的光接收装置;图5表示在象散象差方法中使用的另一种光电检测器的光接收装置;图6表示在象散象差方法中使用的又一种光电检测器的光接收装置;图7表示出现在聚焦误差信号中的一种S-形曲线;图8表示在沿着指向光盘的方向上的光轴移动物镜时输出的一个聚焦误差信号;图9表示用来体现本发明的光头的另一个实施例; 1 shows an optical head used to embody the present invention; FIG. 2 shows a recording of the present invention to reflect and / or reproducing apparatus; FIG. 3 shows the astigmatic aberration; FIG. 4 shows the astigmatic aberration method used light receiving means of a photodetector; FIG. 5 shows another optical receiving apparatus of the photodetector astigmatic aberration used in the method; Figure 6 shows still another photodetector astigmatic aberration method for use in a light receiving means; FIG. 7 shows one kind now focus error signal S- shaped curve; FIG. 8 shows a focus error signal when the objective lens is moved along the optical axis in the direction toward the output disc; Figure 9 shows a another optical head according to the present invention be embodied in an embodiment;

图10是一个平面图,用来表示在图8的光头中使用的一个双轴驱动器的实施例;图11是一个侧视图,用来表示在图8的光头中使用的一个双轴驱动器的实施例;图12是一个透视图,用来表示透镜驱动装置的示意性结构;图13是图12中所示的透镜驱动装置的平面图;图14示意性地表示了第一实施例的光学系统;图15表示光透射层的厚度误差,波前象差,以及第一实施例中的一个准直透镜的位移量之间的关系;图16示意性地表示了第二实施例的光学系统;图17表示光透射层的厚度误差,波前象差,以及第一实施例中的一个准直透镜的位移量之间的关系。 FIG 10 is a plan view for showing one embodiment of a biaxial actuator used in the optical head of FIG. 8; FIG. 11 is a side view for showing one embodiment of a biaxial actuator used in the optical head of FIG. 8 ; FIG. 12 is a perspective view for showing a schematic structure of a lens driving device; FIG. 13 is a plan view of the lens driving device shown in FIG. 12; FIG. 14 schematically shows an embodiment of an optical system of the first embodiment; FIG. 15 indicates the thickness error of the light transmission layer, the wave front aberration, and the relationship between the amount of displacement of a collimator lens according to the first embodiment; FIG. 16 schematically showing an optical system of the second embodiment; FIG. 17 It indicates the thickness error of the light transmission layer, the wave front aberration, and the relationship between the amount of displacement of a collimator lens according to the first embodiment.

以下要参照附图详细地说明本发明的最佳实施例。 The following preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

图1表示了用来体现本发明的一个光头1。 1 shows an optical head for embodying an invention. 光头1是用来记录/复制一种相变光盘2的一种光头。 1 is an optical head for recording / reproducing a phase change optical disc 2. The optical head. 尽管本文中是以用来记录/复制相变光盘2的光头1为例的,本发明还可以广泛地适用于在用来记录信息信号的记录层上面有一个光透射层的那种信息记录媒体所使用的光头。 Although described herein is the recording / reproducing optical head for a phase-change optical disc 1, an example 2 of the present invention can be widely applicable to the above recording layer for recording the information signal, a kind of information recording medium of the light transmission layer the use of the head. 用来记录和/或复制的信息记录媒体可以是只读光盘,磁光盘或是一种光记录卡。 For recording and / or reproducing the information recording medium may be a read-only optical disk, a magneto-optical disk or an optical recording card.

用光头1来记录/复制光盘2,在光盘的基片3上具有一个通过相变来记录信息信号的记录层,基片的厚度d大约是1.2mm或是0.6mm,在记录层上还有一个光透射层4,其厚度t大约是0.1mm。 1 with the optical head for recording / reproducing the optical disc 2, having on the optical disc substrate 3 by a phase change recording layer of an information signal, the substrate thickness d of about 1.2mm or 0.6mm, on the recording layer as well as a light transmitting layer 4 having a thickness t of about 0.1mm. 光透射层4的作用是用来保护记录层的一个保护层。 The role of the light transmitting layer 4 is a protective layer for protecting the recording layer. 可以通过从光透射层4的一侧而不是基片3的一侧照射的光在光盘2上记录/复制信息信号,光透射层的薄膜厚度比基片3薄得多。 Can, the film thickness of the light transmitting layer 3 is much thinner than the substrate 2 by the light in the optical disc recording / reproducing information signals from the light transmitting layer 4 side rather than the side of the substrate 3 irradiated.

如果让光厚度较小的侧面落到记录层上,就可以抑制象差,从而获得比普通的CD或是DVD更高的记录密度和记录容量。 If we allow a small thickness of the light falls on the recording layer side surface, aberrations can be suppressed, thereby obtaining a recording density and recording capacity higher than ordinary CD or the DVD. 然而,本发明也可以用于利用从基片一侧入射的光来记录和/或复制信息信号的那种信息记录媒体。 However, the present invention can also be used with light incident from the substrate side to the recording and / or reproducing the information signal that the information recording medium.

参见图1,光头1包括一个光源10,衍射点阵11,偏振射束分离器12,准直透镜13,用于准直透镜14的驱动器,四分之一波片15,物镜16,物镜的双轴驱动器17,多镜头组件18,以及一个光电检测器19。 Referring to Figure 1, an optical head comprises a light source 10, a diffraction lattice 11, polarization beam splitter 12, a collimator lens 13, for driving the collimator lens 14, quarter wave plate 15, an objective lens 16, the lens biaxial actuator 17, a multi-lens assembly 18, and a photodetector 19.

在记录/复制过程中,光源10向着光盘2发射光束,构成光源的半导体激光器适合发射波长λ为650nm的线性偏振激光。 In the recording / reproducing process, the light source 10 emits a light beam toward the optical disc 2, constituting the semiconductor laser light source for emitting linearly polarized laser wavelength λ of 650nm. 为了从光盘2上复制信息信号,光源10发射一个具有恒定输出的激光束。 To copy an information signal from the optical disc 2, the light source 10 emits a laser beam having a constant output. 为了在光盘2上记录信息信号,光源10需要根据记录的信号来调制输出激光束的强度。 To record an information signal on the optical disc 2, the light source 10 is necessary to modulate the output intensity of the laser beam in accordance with recording signals.

本发明对光源10发射的激光的波长λ并没有限制。 The present invention is the wavelength λ of laser light emitted from the light source 10 is not limited. 例如,如果半导体激光器发射的激光波长比650nm短,为了获得高记录密度和高记录容量,就适合使用短波长的激光器。 For example, if the laser beam emitted from the semiconductor laser wavelength is shorter than 650nm, in order to obtain high recording density and high-recording capacity, it is suitable for short wavelength lasers.

从光源10发射的激光首先入射到衍射点阵11上并且受到衍射。 Laser light emitted from the light source 10 is first incident on the diffraction lattice 11 and is diffracted. 衍射点阵11的作用是将激光分离成至少三个部分,用于所谓的三点式规则伺服控制。 Action of the diffractive lattice laser 11 is separated into at least three parts, a so-called three-point rule for servo control.

被衍射点阵11衍射的零级光和一级光(统称为入射激光)通过偏振射束分离器12落在由两个球面透镜13a,13b共同构成的准直透镜13上。 11 is diffracted zero-order diffracted light and a dot of light (referred to as the incident laser light) through the polarizing beam splitter 12 falls by two spherical lenses 13a, 13b on the collimator lens 13 together constitute.

如果光盘2的光透射层4的厚度t处在预定的值,准直透镜13就能将入射到准直透镜13上的激光对准。 If the thickness of the optical disc 2 of the light transmitting layer 4 at a predetermined value t, the collimator lens 13 can be incident on the collimator lens 13 in the laser alignment. 换句话说,准直透镜13是一种具有预定折射率的光学器件,如果光盘2的光透射层4的厚度t处在预定的值,准直透镜13就能使入射的激光对准。 In other words, the collimator lens 13 is an optical device having a predetermined refractive index, if the thickness of the optical disc 2 of the light transmitting layer 4 at a predetermined value t, the collimator lens 13 can be aligned with the laser light is incident.

同时,准直透镜13被装载在准直透镜14的驱动器上,以便沿着入射激光的光轴纵向移动。 Meanwhile, the collimator lens 13 is loaded on the drive 14 of the collimator lens, so that the longitudinal direction along the optical axis of the incident laser. 如果光盘2的光透射层4的厚度脱离了预定值,就用准直透镜14的驱动器移动准直透镜13,校正由于光透射层4的厚度误差造成的球面象差。 If the thickness of the optical disc 2 of the light transmission layer 4 departs from the predetermined value, the collimator lens driver 14 moves the collimator lens 13, since the thickness of correcting errors caused by the light transmitting layer 4 of the spherical aberration. 也就是说,如果光盘2的光透射层4的厚度脱离了预定值,准直透镜13就会将入射激光转换成散射光或是会聚光,从而校正由于光透射层4的厚度误差造成的球面象差。 That is, if the thickness of the optical disc 2 of the light transmission layer 4 departs from the predetermined value, the collimator lens 13 converts the incident laser light will be scattered light or convergent light, thereby correcting the spherical since the thickness of the light transmitting layer 4 of the errors caused by aberration.

从准直透镜13发出的入射激光通过四分之一波片15落在物镜上。 From the incident laser beam emitted from the collimator lens 13 on the quarter wave plate 15 through objective lens falls. 在光线通过四分之一波片15时,入射的激光被转换成圆偏振光束之后落在物镜16上。 After the light 15, incident laser light is converted into a circularly polarized beam by the quarter wave plate 16 to fall on the objective lens.

物镜16被用来将光会聚到光盘2的记录层上。 The objective lens 16 is used to converge the light onto the recording layer of the optical disc 2. 转换成圆偏振光束的入射激光被物镜16会聚之后通过光盘2的光透射层4落到光盘2的记录层上。 After converted into circularly polarized incident laser beam is converged by the objective lens 16 through the light transmission layer of the optical disc 2 falls on the recording layer 4 of the optical disc 2.

尽管物镜16可以是单一的透镜,也可以按图1所示由连接到一起的两个透镜16a,16b构成。 Although the objective lens 16 may be a single lens, it may be configured in Figure 1 by the connection to the two lenses together 16a, 16b. 如果物镜16是由两个透镜16a,16b构成的,即使是扩大数值孔径NA,仍然很容易装配透镜,而不需要对各个透镜表面的曲面采用极为严格的公差。 If the objective lens 16 is composed of two lenses 16a, 16b, and notwithstanding that the numerical aperture NA is enlarged, the lens still easily assembled, without the need for extremely tight tolerances and each lens curved surface. 也就是说,如果能用两个透镜16a,16b构成透镜16,就能够比较容量扩大数值孔径NA,获得较高的记录密度和较高的记录容量。 That is, if the use of two lenses 16a, 16b constituting the lens 16, it is possible to expand the capacity of the numerical aperture NA comparison, to obtain a higher recording density and higher recording capacity.

也可以用三个以上的透镜构成物镜16。 It may be used three or more objective lenses 16. 如果用三个以上的透镜构成物镜16,就能够缓和各个透镜表面的曲率。 If the configuration of the objective lens 16 with three or more lenses, it is possible to alleviate the curvature of each lens surface. 然而,如果透镜的数量过多,就难以组合成高精度的透镜。 However, if too much number of lenses, it is difficult to combine into a high-precision lens. 因而需要用两个透镜来构成物镜。 Thus the objective lens needs to be configured with two lenses.

被物镜16会聚后落在光盘2的记录层上的入射激光受到记录层的反射而变成返回光束。 After the objective lens 16 is condensed the incident laser light falls on the recording layer of the optical disc 2 is reflected by the recording layer becomes the return beam. 这一返回光束通过物镜16落到四分之一波片15上。 This return beam falls on the quarter wave plate 15 through objective lens 16. 返回光束首先遵循原先的路径通过物镜16,并且通过四分之一波片15被转换成线性偏振光束,相对于入射光的偏振方向旋转了90°。 First return beam to follow the original path through the objective lens 16, and is converted into linearly polarized light beam by quarter wave plate 15, the polarization direction of the incident light with respect to the rotation of 90 °. 由准直透镜13对准后的返回光被入射到偏振光束分离器12上并且受到它的反射。 Returned by the alignment of the collimating lens 13 the light is incident on the polarization beam splitter 12 and is reflected by it.

由偏振光束分离器12反射的返回光通过多镜头组件18入射到光电检测器19上,由光电检测器进行检测。 12 by the polarization beam splitter 19 is reflected on the return, is detected by the photodetector by a multi-lens optical assembly 18 is incident on the photodetector. 多镜头组件18具有一个柱面光入射面和一个凹面光输出面。 Multi cylindrical lens assembly 18 having a concave light incident surface and a light output face. 多镜头组件18按照返回光的球面象差进行操作,通过所谓的球面象差方法执行聚焦伺服控制。 Multiple lens assembly 18 to operate in accordance with the spherical aberration of the returning light, focus servo control by the so-called spherical aberration method.

用来检测球面象差已经过多镜头组件18调和之后的返回光的光电检测器19可以包括六个光电检测器。 After returning light for detecting the spherical aberration of the lens assembly 18 has excessive harmonic photodetector 19 may include six photodetector. 光电检测器19输出的电信号与落在各个光电检测器上的返回光的光强度成正比,并且对这种电信号执行预定的计算,从中产生和输出诸如聚焦伺服信号或者跟踪伺服信号等等伺服信号。 Electrical signal output from the photodetector 19 is proportional to the light intensity of the return light falls on each photodetector, and performs predetermined calculations on this electrical signal, and generating therefrom an output signal such as a focus servo or a tracking servo signal and the like servo signals.

具体地说,用光电检测器19来检测球面象差已经过多镜头组件18调和之后的返回光根据所谓的球面象差方法产生和输出聚焦伺服信号。 Specifically, the photoelectric detector 19 to detect light generated in accordance with a so-called spherical aberration method and focus servo signal output after returning excessive spherical aberration of the lens assembly 18 has been reconciled. 光头1根据这些聚焦伺服信号来驱动载有物镜16的物镜17的双轴驱动器,从而执行聚焦伺服控制。 The optical head 1 according to the focus servo signal to drive the biaxial actuator carrying the objective lens 17 of the objective lens 16, thereby performing the focus servo control.

光电检测器19还要检测受到衍射点阵11衍射的0级光和±1级光的返回光束,按照所谓的三束方法产生跟踪伺服信号,并且输出所得的跟踪伺服信号。 The photodetector 19 also detects diffracted by the diffraction lattice 11 0 ± 1st light returned light beam, a tracking servo signal according to the so-called three-beam method, and outputs the resultant signal to the tracking servo. 光头1根据这些跟踪伺服信号来驱动载有物镜16的物镜17的双轴驱动器,从而执行跟踪伺服控制。 The optical head 1 according to the tracking servo signal for driving the biaxial actuator carrying the objective lens 17 of the objective lens 16, thereby performing tracking servo control.

在从光盘2上复制信息信号时,光电检测器19也要按照预定的算法来处理与入射到各个光电检测器上的返回光的强度相对应的电信号,以便从光盘2上产生和输出重放信号。 When copying the information signal from the optical disc 2, and 19 have the strength to handle the return light incident on the respective photoelectric detector according to a predetermined algorithm photodetector corresponding electrical signal from the optical disc 2 so as to generate and output weight put signal.

在本发明的光头1上,物镜16被装载在物镜17的双轴驱动器上,用来实现跟踪伺服和聚焦伺服控制。 In the optical head 1 according to the present invention, the objective lens 16 is loaded on the biaxial actuator 17 of the objective lens, used to implement the tracking servo and focus servo control. 或者是将通过驱动器移动物镜的伺服控制仅仅用于聚焦伺服控制,同时通过移动整个光头来执行跟踪伺服控制。 Or through the servo control actuator for moving the objective lens is only the focus servo control, tracking servo control is performed simultaneously by moving the entire optical head.

在通过光头1将光聚焦在光盘2的光记录层上时,由于光盘2的光透射层4的厚度误差造成的象差主要是由于散焦或是球面象差而产生的。 When a light is focused on the optical recording layer of optical disk by the optical head 2, the aberration due to the thickness error of the light transmitting layer 4 of the optical disc 2 is caused mainly due to defocusing or spherical aberration generated.

用聚焦伺服控制可以校正散焦。 Focus servo control can be corrected defocus. 也就是说,用物镜17的双轴驱动器沿着物镜16的光轴在前后方向上移动物镜16,从而校正散焦,并且聚焦在记录层上。 That is, the biaxial actuator 17 by the objective lens along the optical axis of the objective lens 16 is moved in the longitudinal direction of the objective lens 16, thereby correcting defocusing, and is focused on the recording layer. 在普通的光头上也可以对散焦执行这种校正。 This correction can be performed in defocus on a common optical head.

另一方面,沿着光轴在前后方向上移动物镜并不能校正球面象差。 On the other hand, in the longitudinal direction along the optical axis and moving the objective lens can not correct spherical aberration. 如果能根据光透射层4的厚度t来更换物镜16或是改变物镜16的光学介质的折射率,就能够校正这种球面象差。 T can be replaced if the objective lens 16 depending on the thickness of the light transmitting layer 4, or changing the refractive index of the objective lens 16 of the optical medium, it is possible to correct such a spherical aberration. 然而,这些方案都是不现实的。 However, these schemes are not realistic.

按照本发明的光头1,可以用准直透镜14的驱动器在沿着光轴的前后方向上移动准直透镜13,用来校正光透射层4的厚度造成的球面象差。 An optical head according to the invention can be used to drive the collimator lens 14 of the collimator lens 13 moves in the front-rear direction along the optical axis for correcting the thickness of the light transmitting layer 4 caused by spherical aberration. 也就是说,采用本发明的光头1,准直透镜14的驱动器可以被用来移动准直透镜13,以便消除光盘2的光透射层4的厚度t造成的球面象差。 That is, the optical head 1 according to the present invention, the collimator lens driver 14 may be used to move the collimator lens 13, the optical disc 2 so as to eliminate the thickness of light transmitting layer 4 of the spherical aberration caused by t.

以下要详细地说明由于光透射层4的厚度误差而产生的球面象差以及用来校正这种象差的方法。 The spherical aberration due to the thickness error of the light transmitting layer 4 is produced and this method for correcting the aberrations to be described in detail.

如果光透射层4具有一定的厚度误差,就会产生可以用公式(1)表示的三次球面象差W40:W40={Δt(n2-1)/(8n3)}NA4...(1)如上所述,其中的Δt是光透射层的厚度误差,n是光透射层的折射率NA是一个物镜的数值孔径。 If the light transmitting layer 4 having a certain thickness error, it will have three times the sphere can be represented by the formula (1) aberration W40: W40 = {Δt (n2-1) / (8n3)} NA4 ... (1) above the, wherein the thickness error Δt is the light transmission layer, n is the refractive index of the numerical aperture NA of the light transmission layer is a objective lens.

公式(1)是用物镜的数值孔径NA根据总象差量的Taylor展开获得的,并且将其转换成波前象差。 Equation (1) using the numerical aperture NA of the objective lens is expanded in accordance with the total obtained aberration amount of Taylor, and converts it into a wave front aberration. 也就是说,如果用正弦函数来表示数值孔径NA并且将其展开,就可以获得以下的公式(3):sin(θ)=x-x3/6+x6/120-x7/5040+ρ(x)8...(3)从公式(3)右侧的第二项可以看出,波前象差是由上述公式(1)代表的三次球面象差。 That is, if the sinusoidal function represented by the numerical aperture NA and to expand it, can be obtained the following equation (3): sin (θ) = x-x3 / 6 + x6 / 120-x7 / 5040 + ρ (x ) ... 8 (3) from equation (3) to the right of the second term can be seen, the wavefront aberration by the above formula (1) represented by the three spherical aberration.

然而,从公式(3)中可以看出,实际的象差次数会更高。 However, it can be seen from equation (3), the actual frequency difference as will be higher. 从公式(3)右侧的第三项看到的波前象差是一个由以下的公式(4)代表的五度球面象差W50:W50={Δt(n3-1)(n2+3)/48n5}NA6...(4)由于光透射层4的厚度误差ti产生的三次球面象差W50和五次球面象差W60之和就是公式(1)和(4)的总和,可以表示成公式(5):W≈W40{[1+{(n2+3)/6n2}NA2} ...(5)通过用数值孔径NA对公式(5)微分就可以获得总的象差,并且用公式(6)来表示:δS={Δt(n2-1)/2n3}NA3[1+(n3+3)/4n2}NA2] ...(6)由上述公式(1)表示的三次球面象差W40可以用各个光学平面上产生的象差之和来表示。 From equation (3) the third term on the right side of the saw is a wave front aberration by the following Equation (4) represents the fifth spherical aberration is W50: W50 = {Δt (n3-1) (n2 + 3) /48n5}NA6...(4) due to the thickness error of three spherical light transmitting layer 4 is produced as ti aberration W60 is the sum of equations) and five times the sum of the difference between the spherical W50 (a and (4) may be expressed as equation (5): W≈W40 {[1 + {(n2 + 3) / 6n2} NA2} ... (5) by using the numerical aperture NA of the formula (5) can be obtained differentiating the total aberration, and treated with equation (6) represents: δS = {Δt (n2-1) / 2n3} NA3 [1+ (n3 + 3) / 4n2} NA2] ... (6) (1) represented by the above formula cubic spherical aberration W40 difference can be generated in the individual optical aberrations plane represented by the sum. 也就是说,如果只有三次球面象差W40,就可以通过在光源10和光透射层4之间的某一点上布置一个能够产生符号相反的球面象差的光学元件来进行校正。 That is, if only three of W40 spherical aberration, can be by the light source 10 and the light transmission layer is disposed between a point 4 capable of generating a sign opposite to the optical element of the spherical aberration to be corrected. 然而,从上述的公式(5)中可见,光透射层4的折射率n越小,并且物镜16的数值孔径NA越大,五次球面象差W60在光透射层4的厚度误差Δt产生的球面象差中所起的作用就越大,因此,仅仅校正三次球面象差W40是不够的。 However, from the above equation (5) can be seen, the smaller light transmission layer refractive index n 4, and the larger the numerical aperture of the objective lens NA 16, the fifth spherical aberration W60 Δt thickness error is generated in the light transmitting layer 4 spherical aberration in the role of the greater, therefore, only three times the correction of spherical aberration W40 is not enough.

值得注意的是,三次球面象差W40对3(=1.732)的光透射层4的折射率n来说是最大的,并且在光透射层4的折射率n小于上述值时急剧下降。 Notably, three of the spherical aberration of the refractive index n W40 3 (= 1.732) of the light transmitting layer 4 is the largest, and the light transmission layer refractive index n 4 is less than the above value drops sharply. 光透射层4的折射率n通常处在1.5左右。 The light transmission layer refractive index n 4 is usually about 1.5 in. 因此,如果五次球面象差W60的作用随着光透射层4的折射率n变小而增大,这一五次球面象差W60的作用就被总象差量的整体下降掩盖了,不会产生严重的问题。 Thus, if five of the spherical aberration W60 action as the refractive index n of the light transmitting layer 4 is increased becomes smaller, the fifth spherical aberration W60 effect was an overall decrease in the total amount of aberration masked, not It will have serious problems.

另一方面,如果物镜16的数值孔径NA按照上述方式增大,五次球面象差W60的作用就会增大。 On the other hand, if the numerical aperture NA of the objective lens 16 is increased as described above, the fifth spherical aberration W60 effects will increase. 五次球面象差W60的这种增大不会被掩盖。 Five W60 spherical aberration of this increase will not be covered. 如果增大了数值孔径NA,五次球面象差W60在整个球面象差中所占的比例就会变成最大,同时,五次球面象差W60在总体球面象差中大约占40%。 If the numerical aperture NA is increased, the spherical aberration W60 fifth spherical aberration throughout the proportion becomes maximum, while five spherical aberration W60 approximately spherical aberration in the overall 40%. 因此,在数值孔径NA比较大的系统中,需要对五次球面象差W60的作用给予足够的重视。 Thus, the numerical aperture NA larger systems, it is necessary to pay enough attention to five spherical aberration W60 role.

具体地说,假设数值孔径NA=0.6,并且光透射层4的折射率n=1.5,厚度误差Δt造成的总象差就是30μm。 Specifically, assuming that a numerical aperture NA = 0.6, and the refractive index of the light transmitting layer 4 of n = 1.5, the total thickness error Δt caused by aberrations is 30μm. 如果在考虑到五次球面象差W60的公式(6)中找出厚度误差Δt造成的总象差,它就是1.452μm。 If the thickness error in consideration identify five spherical aberration W60 formula (6) in the total aberration caused by Δt, it is 1.452μm. 另一方面,如果假设数值孔径NA=0.85,并且光透射层4的折射率n=1.5,厚度误差Δt就是30μm。 On the other hand, if it is assumed numerical aperture NA = 0.85, and the refractive index of the light transmitting layer 4 of n = 1.5, the thickness error Δt is 30μm. 从公式(6)中找出的厚度误差Δt造成的总象差大约是4.850μm。 From equation (6) identified in the total aberration caused by a thickness error Δt is approximately 4.850μm. 也就是说,如果光透射层4的厚度公差是±0.03mm,数值孔径NA是0.6,光透射层4的厚度误差Δt造成的总象差就不会超过1.452μm。 That is, if the light transmitting layer 4 thickness tolerance is ± 0.03mm, the numerical aperture NA is 0.6, a total light transmission layer 4 of the aberration thickness error Δt would cause no more than 1.452μm. 然而,如果数值孔径NA是0.85,五次球面象差W60就会增大,使总的象差行高可以达到4.850μm。 However, if the numerical aperture NA is 0.85, the spherical aberration W60 five will increase, so that the total aberration row height can reach 4.850μm.

为了校正上述的球面象差,如果能产生一个与公式(6)表示的球面象差量值相同且符号相反的象差就足够了。 In order to correct the spherical aberration, if possible to generate a formula (6) represent the same magnitude of the spherical aberration and the aberration of the opposite sign is sufficient. 最简单的方法就是在光源10和用于校正的准直透镜13之间插入一个平行的平板。 The easiest way is to insert a plate between the parallel light source 10 and the collimator lens 13 for correction. 在这种情况下,如果能满足公式(7)和(8):{(n12+3)/n12}NA12={(n02+3)/n02}NA02...(7){(n13-3)/n13}NA14={(n02-1)/n03}NA04...(8)就能够对五次球面象差W60进行校正。 In this case, if satisfy equation (7) and (8): {(n12 + 3) / n12} NA12 = {(n02 + 3) / n02} NA02 ... (7) {(n13-3 ) / n13} NA14 = {(n02-1) / n03} NA04 ... (8) it is possible to five spherical aberration W60 is corrected. 在这些公式中,NA0,n1和NA1是准直透镜13在入射光一侧的折射率,光透射层4的折射率,以及物镜16的数值孔径。 In these formulas, NA0, n1 is NA1, and the refractive index of the collimator lens 13 on the light incident side of the refractive index of the light transmitting layer 4, and the numerical aperture of the objective lens 16.

为了满足公式(7)和(8),考虑到折射率的实际容许值,物镜16的NA1和准直透镜13在入射光一侧的NA0需要保持同等的量值。 In order to satisfy the formula (7) and (8), taking into account the actual allowable value of the refractive index, NA1 of the objective lens and the collimator lens 16 on the light incident side 13 NA0 need to maintain the same magnitude. 具体地说,至少需要满足NA1/NA0≤2的关系。 Specifically, at least satisfy the relationship NA1 / NA0≤2 of. 但是,实际上不可能在增大物镜16的NA1的同时增大准直透镜13入射光一侧的NA0值。 Actually, however, impossible to increase the collimator lens 13 incident side NA0 value while increasing the NA1 of the objective lens 16. 因此,采用在光源10和准直透镜13之间插入平行平板的方法不可能完全校正这种球面象差。 Therefore, this is impossible to completely correct the spherical aberration in the light source 10 and the parallel plate is inserted between the collimator lens 13 method.

另外,如果采用不是平行平板的光学元件,如果仅仅将光学元件布置在光轴上,就难以完全地校正整个球面象差。 Further, if the optical element is not parallel plate, if only the optical element disposed on the optical axis, it is difficult to completely correct the spherical aberration of the whole. 从公式(1)和(4)中可见,三次球面象差W40和五次球面象差W60对数值孔径NA的数值是不同的。 From equations (1) and (4) can be seen, the three spherical aberration W40 and W60 for spherical aberration five numerical aperture NA values ​​are different. 因此需要用一种完全平衡的方法来执行校正,考虑到光透射层4的厚度公差,这种象差应该完全处在公差范围之内。 Thus the need for a fully balanced way to perform a correction, taking into account the tolerance of the thickness of the light transmission layer 4, which aberration should be well within the range of tolerance.

因此,如果采用本发明的光头1就可以实现完全平衡的校正,用准直透镜14的驱动器使三维的准直透镜13沿着光轴移动。 Thus, if the optical head 1 according to the present invention can achieve complete balance correction allows driving the collimator lens 14 of the three-dimensional collimator lens 13 is moved along the optical axis. 当准直透镜13在前后方向上移动时,就可以改变物镜16在入射光一侧的数值孔径NA,从而使球面象差得到校正。 When the collimator lens 13 is moved in the front-rear direction, you can change the numerical aperture NA of the objective lens 16 on the light incident side, so that the spherical aberration is corrected.

同时,在本发明的光头1中,准直透镜13的出射光瞳的直径应该比物镜16的入射光瞳的直径大得多。 Meanwhile, in the optical head 1 according to the present invention, the collimator lens diameter of the exit pupil diameter of the objective lens should be larger than the entrance pupil of 16 13. 在这种情况下,即使是改变物镜16的数值孔径NA,在物镜16光出射一侧的数值孔径NA也基本上保持不变,这样就能完成稳定的记录/复制。 In this case, even when the numerical aperture NA of the objective lens is changed to 16, the objective lens 16 at the light exit side numerical aperture NA remains substantially constant, so that stable recording can be done / replication.

在这种光头中,准直透镜13在入射光一侧的数值孔径NA主要是根据提高从光源发出的入射激光的耦合效率来设定的。 In this optical head, the collimator lens 13 on the light incident side numerical aperture NA is mainly based on improving the incident laser light emitted from the light source to set the coupling efficiency. 具体地说,数值孔径NA应该设定在大约0.3以下。 Specifically, the numerical aperture NA is set to be about 0.3 or less. 另一方面,为了缩小会聚在记录层上的光的直径,物镜16的数值孔径NA应该选择较大的值。 On the other hand, in order to reduce the diameter of the light focused on the recording layer, the objective lens numerical aperture NA 16 should be selected to a larger value. 如果需要使用比DVD更高的记录密度和记录容量,这一数值孔径NA就应该设定在不小于0.65。 If you need to use the recording capacity and recording density higher than the DVD, the numerical aperture NA is set to be not less than 0.65.

也就是说,按照本发明的光头1,准直透镜13在入射光一侧的数值孔径NA应该设定在这样的值,它明显地小于物镜16在出射光一侧的数值孔径NA。 That is, an optical head according to the invention, the collimator lens 13 on the light incident side numerical aperture NA should be set at such a value, it is significantly smaller than the numerical aperture NA of the objective lens 16 in the outgoing light side. 按照这种设定方式,由于准直透镜13沿着光轴移动而产生的球面象差主要是三次球面象差W40。 In this setting mode, since the spherical aberration of the collimator lens 13 along the optical axis is generated mainly three spherical aberration W40. 因此,通过移动准直透镜13不可能完全消除由于光透射层4的厚度误差Δt造成的全部球面象差。 Thus, by moving the collimator lens 13 can not completely eliminate the light transmitting layer 4 of the thickness error Δt caused all spherical aberration.

因此,在移动准直透镜13的过程中需要设定准直透镜13的移动目标位置,让象差的均方值变成最小。 Thus, during movement of the collimator lens 13 is required to set the movement target position of the collimator lens 13, so that the mean square value of the aberration becomes minimum. 具体地说,主光束和环境光束的光程差是通过光跟踪方法来计算的,并且在准直透镜的位置上获得光路径差也就是预先计算出的波前象差的最小均方值。 More specifically, the optical path difference between the main beam and the environment through the light beam tracking method is calculated, and the obtained optical path difference is a minimum mean square value previously calculated wavefront aberration at the position of the collimator lens. 在对光盘2进行记录/复制时,需要检测光透射层4的厚度t,并且通过准直透镜14的驱动器将准直透镜13移动到根据误差Δt预先计算出的位置上。 When the optical disc 2 for recording / reproducing is necessary to detect the light transmission layer thickness t 4, and by the collimator lens actuator 14 moves the collimator lens 13 according to the previously calculated error Δt position.

在这种光头1中,准直透镜13的移动距离应该比准直透镜13的焦距小得多,因此,由准直透镜13的移动而产生的波前象差Wrms就会比准直透镜13的聚焦小得多。 In this optical head 1, a moving distance of the collimator lens 13 should be smaller than the focal length of the collimator lens 13, therefore, by the wave movement of the collimator lens 13 is generated will be higher than the front aberration Wrms collimator lens 13 the focus is much smaller. 在这种情况下,准直透镜13的移动量与移动准直透镜13时产生的球面象差的量值成正比,这样就简化了准直透镜14的驱动器的结构及其驱动方式。 In this case, the amount of movement of the collimator lens 13 and the collimator lens is proportional to the movement of the spherical aberration generated when the magnitude of 13, thus simplifying the structure of the collimator lens actuator 14 and a driving manner. 换句话说,如果准直透镜13的移动距离远远小于准直透镜13的聚焦,对伺服机构的结构是非常有利的。 In other words, if the moving distance of the collimator lens 13 is much smaller than the focus of the collimator lens 13, the structure of the servo mechanism is very advantageous.

在上述的光头1中,由于光透射层4的厚度误差Δt造成的球面象差是通过移动准直透镜13而得到校正的。 In the aforementioned optical head 1, the spherical aberration due to the thickness error of the light transmission layer 4 of the resulting Δt is corrected by moving the collimator lens 13. 然而,由于光透射层4的厚度误差Δt造成的球面象差也可以用除准直透镜13之外的其他任何适当的光学设备来校正。 However, the spherical aberration due to the thickness error of the light transmission layer 4 of Δt may also be caused by any other suitable calibration of optical apparatus other than a collimator lens 13.

按照本发明,只要将用来校正由于光透射层4的厚度误差Δt造成的球面象差的光学元件布置在光源10和物镜16之间就足够了。 According to the present invention, as long as the optical element for correcting a light transmitting layer 4 of the thickness error Δt caused spherical aberration is disposed between the light source 10 and the objective lens 16 is sufficient. 例如,设在光源10和准直透镜13之间的一个透镜可以沿着光轴在前后方向上移动。 For example, one lens disposed between the light source 10 and the collimator lens 13 may be moved along the optical axis in the longitudinal direction. 或者是省掉准直透镜13,让光源10发出的光以发散光的状态落到物镜16上。 Or dispense a collimator lens 13, so that the light emitted from the light source 10 in a divergent state to fall on the objective lens 16. 在这种情况下,只要将透镜设在入射到物镜16上的发散光的光程上,并且沿着光轴在前后方向上移动就足够了。 In this case, the lens provided on the divergent light incident on the optical path of the objective lens 16, and along the optical axis in the longitudinal direction is sufficient.

然而,如果需要用上述光头1中的准直透镜13来校正球面象差,并且光透射层4的厚度处在预定的值,物镜16上的入射激光就是准直的光,因此,物镜16就能象一个便于操作的平行系统透镜那样工作。 However, if the optical head 1 in the above-described collimator lens 13 to correct the spherical aberration, and the light transmitting layer 4 has a thickness in the predetermined value, the laser beam incident on objective lens 16 that collimate light, and therefore, the objective lens 16 on the lens as a parallel system can operate as easy to work. 因此,在实际情况下,可以象光头1那样用准直透镜13作为校正球面象差的光学器件。 Thus, in practice, it can be used as the optical device 13 as correction of the spherical aberration of the collimator lens 1 as the optical head.

尽管上述的说明是针对光透射层4的厚度误差Δt造成的球面象差的校正来解释的,还可以让用于象差校正的光学元件移动,用来检测环境的变化,例如温度的变化,光盘2在径向方向上的倾斜,光透射层4的折射率n的变化,或者是构成光头1的光学元件的错位等等,并且用来校正由这些因素造成的象差。 While the above description is directed to the correction of the spherical aberration caused by a thickness error Δt 4 is a light transmission layer of explanation, the optical element can also allow for movement of aberration correction, to detect changes in the environment, such as temperature changes, the optical disc 2 is inclined in the radial direction, the refractive index change of the light transmission layer 4 of n, or offset optical head 1 constituting the optical element, etc., and the like for correcting the difference caused by these factors.

同时还希望这种光头1能够将物镜16的数值孔径NA扩大到满足DVD的要求,以便进一步提高记录密度。 It is also desirable that the optical head 1 16 can be a numerical aperture NA of the objective lens extended to meet the requirements of DVD, in order to further improve the recording density. 如上文所述,数值孔径NA应该设定在不小于0.65。 As described above, the numerical aperture NA is set to be not less than 0.65.

然而,如果增大了物镜16的数值孔径NA,除了上述的球面象差之外还会出现彗形象差增大的问题。 However, if increasing the numerical aperture NA of the objective lens 16, in addition to the above-described spherical aberration is coma aberration also increases the problem. 彗形象差是由于光盘2的径向倾斜而产生的,并且随着物镜16的数值孔径NA的三次方正比增大。 Coma aberration due to the optical disc 2 is inclined radially generated, and as the three numerical aperture NA of the objective lens 16 Founder ratio increases. 因此,随着数值孔径NA的增大,抑制彗形象差的问题就变得更重要了。 Thus, as the numerical aperture NA, the problem of suppressing coma aberration becomes more important.

为了抑制彗形象差,减少光透射层4的厚度t是一种有效的方法。 In order to suppress the coma, reducing the thickness t of the light transmitting layer 4 is an effective method. 例如在DVD中,径向倾斜的倾斜角是±0.4°,为了维持必要的公差值,光透射层4的厚度t应该满足以下的公式(9):t≤0.1296/NA3...(9)举例来说,如果NA≥0.65,满足公式(9)的t≤0.47mm。 For example, in DVD, the radially inclined angle is ± 0.4 °, in order to maintain the necessary tolerance value, the light transmission layer thickness t 4 should satisfy the following equation (9): t≤0.1296 / NA3 ... (9 ) for example, if NA≥0.65, satisfy equation (9) t≤0.47mm. 因此,如果光头1中的物镜16的数值孔径NA不小于0.65,就应该将光透射层4的厚度t设定在0.47mm以下。 Thus, if the numerical aperture NA of the objective lens 16 in the optical head 1 is not smaller than 0.65, it should be light transmitting layer 4 has a thickness t is set at 0.47mm or less. 因此,为了获得高记录密度,如果将物镜16的数值孔径NA设定在不小于0.65,就能将光透射层4的厚度t的公差维持在满足普通DVD的值。 Thus, to obtain high recording density, if the numerical aperture NA of the objective lens 16 is set at not less than 0.65, the light transmission layer can be thickness t 4 of the tolerance is maintained at a value that satisfies the general DVD.

从上述的公式(9)中可以看出,如果再增大物镜16的数值孔径NA,让NA≥0.7,就应该t≤0.37mm。 As can be seen from the above equation (9), if the numerical aperture NA of the objective lens 16 is increased, so that NA≥0.7, it should t≤0.37mm. 如果进一步增大物镜16的数值孔径NA,让NA≥0.85,就应该t≤0.21mm。 If further increasing the numerical aperture NA of the objective lens 16, so that NA≥0.85, it should t≤0.21mm.

一般来说,要获得狭窄的径向倾斜公差是有困难的。 In general, to obtain a narrow tolerance of the radial tilt is difficult. 如果需要,其费用将会明显地增加。 If needed, the cost will be significantly increased. 然而,如果能随着物镜16的数值孔径NA充分地减少光透射层4的厚度t,以便通过增大物镜16的数值孔径NA而达到增加记录密度的目的,径向倾斜公差就可以保持在普通DVD所要求的值。 However, if the light transmission as the numerical aperture NA of the objective lens 16 is sufficiently reduced thickness t 4 so as to achieve the purpose of increasing the recording density by increasing the numerical aperture NA of the objective lens 16, a radial tilt can be maintained at normal tolerance DVD desired value. 因此,如果随着物镜16的数值孔径NA的增大而减少光透射层4的厚度t,就能获得较高的记录密度,不会由于径向倾斜公差过小而使费用明显地上升。 Thus, if with increasing numerical aperture NA of the objective lens 16 and reduce the thickness t of the light transmitting layer 4, a high recording density can be obtained, the cost will not be increased significantly due to the radial inclination is too small tolerances.

作为本发明的记录和/或复制装置的一个实施例,在图2中表示了一种记录/复制装置30,它具有一个如上文所述的用来记录/复制光盘2的光头1。 The present invention is a recording and / or reproducing apparatus according to an embodiment showing a recording / reproducing apparatus 30 in FIG. 2, having a as described above for recording / reproducing head 2 of the optical disc 1.

尽管在下文中是参照用来记录/复制相变型光盘2的记录/复制装置来说明的,本发明还可以用于具有光头的各种类型的记录和/或复制装置。 Although in the following with reference to the recording / reproducing recording / reproducing apparatus 2 phase-change optical disk will be described, the present invention can also be used for various types of recording and / or reproducing apparatus having an optical head. 用来记录和/或复制的信息记录媒体可以是一种只读光盘,磁光盘,或者是一种光记录卡。 For recording and / or reproducing the information recording medium may be a read-only optical disk, a magneto-optical disk, or an optical recording card.

记录/复制装置30包括一个用来旋转驱动光盘2的主轴电机31,用来记录/复制信息信号的光头1,用来移动光头1的进给电机32,用来执行调制/解调工作的一个调制解调电路33,用于光头1的伺服控制的一个伺服控制电路34,以及用来控制整个系统的一个系统控制器35。 The recording / reproducing apparatus 30 includes a spindle motor for rotationally driving the optical disc 2 is 31, for recording / reproducing an information signal head for moving the head a feed motor 32 for performing modulation / demodulation of a work modulation and demodulation circuit 33, a servo for servo control of an optical head control circuit 34, and a system controller for controlling the entire system 35.

主轴电机31在伺服控制电路34的控制下被驱动,并且按照预定的rpm转动。 The spindle motor 31 is driven under the control of the servo control circuit 34, and is rotated in the predetermined rpm. 也就是说,用主轴电机31来卡住需要记录或是复制的光盘2,并且用伺服控制电路34驱动主轴电机31按照预定的rpm转动。 That is, the spindle motor 31 needs to be jammed recording or reproduction optical disk 2, and the servo control circuit 34 drives the spindle motor 31 is rotated in a predetermined rpm.

在记录/复制信息信号时,光头1将激光照射在光盘2上,随着光盘2的转动而检测返回的光。 When recording / reproducing information signals, the optical head 1 irradiates a laser beam on the optical disc 2, the rotation of the optical disc 2 and detect the return light. 在记录信息信号时,由外部电路36传送并且用调制电路33按照预定方式进行调制的信号被传送到光头1,然后用按照光强度进行调制的激光束照射在光盘2上。 Laser beam transmitted signal when recording the information signal, and is modulated in a predetermined manner from the external circuit 36 ​​transmits the modulating circuit 33 is supplied to the optical head 1, and then modulated in accordance with the light intensity on the optical disc 2. 在复制信息信号时,光头1将一个恒定输出的激光束照射在转动的光盘2上,并且根据返回光产生重放信号,将重放信号提供给调制解调电路33。 When reproducing information signals, an optical head irradiating a laser beam to a constant rotational output on the optical disc 2, and the return light signal generated in accordance with the reproduction, the reproduced signal is supplied to the modulation and demodulation circuit 33.

光头1还被连接到伺服控制电路34。 The optical head 1 is also connected to the servo control circuit 34. 在记录/复制信息信号的过程中,光头1按照上述的方式根据从转动的光盘2上反射的返回光产生聚焦伺服信号和跟踪伺服信号,将伺服信号提供给伺服控制电路34。 In the recording / reproducing process of the information signal, the optical head 1 according to the above manner to generate light focus servo signal and a tracking servo signal according to the rotation of the returned light reflected from the optical disc 2, provides a servo signal to the servo control circuit 34.

调制解调电路33被连接到系统控制器35和外部电路36。 Modulation and demodulation circuit 33 are connected to the system controller 35 and an external circuit 36. 在光盘2上记录信息信号时,调制解调电路33在系统控制器35的控制下从外部电路36接收需要记录在光盘2上的信号,并且对接收的信号进行调制。 When the information signal recorded on the optical disc 2, the modulation and demodulation circuit 33 receives a signal to be recorded on the optical disc 2 from the external circuit 36 ​​under the control of system controller 35, and the received signal is modulated. 经过调制解调电路33调制后的信号被传送到光头1。 Signal after modulation the modulation and demodulation circuit 33 is transmitted to the head 1. 在从光盘2上复制信息信号时,调制解调电路33在系统控制器35的控制下接收由光盘2产生的信号,对重放信号进行调制。 When copying the information signal from the optical disc 2, the modulation and demodulation circuit 33 receives the signal generated by the optical disc 2 under the control of system controller 35, the reproduced signal is modulated. 被调制解调电路33解调的信号从调制解调电路33输出到外部电路36。 The demodulation circuit 33 demodulates the modulation signal 33 outputted from the modem circuit 36 ​​to an external circuit.

进给电机32被用来沿着光盘2的径向将光头1输送到预定的位置,它是由来自伺服控制电路34的控制信号驱动的。 Feed motor 32 is used to transport an optical head along the radial direction of the optical disc 2 to a predetermined position, which is controlled by a drive signal from the servo circuit 34. 也就是说,将进给电机32连接到伺服控制电路34并且受到它的控制。 That is, the feed motor 32 is connected to the servo control circuit 34 and controlled by it.

伺服控制电路34在系统控制器35的控制下控制进给电机32,这样就能将光头1输送到面对光盘2的预定位置。 Servo control circuit 34 controls the feed motor 32 under the control of system controller 35, so that the optical head can be conveyed to a predetermined position facing the optical disc 2. 伺服控制电路34同时还连接到主轴电机31,用来在系统控制器35的控制下控制主轴电机31的操作。 The servo control circuit 34 and is also coupled to the spindle motor 31, for controlling operation of a spindle motor 31 under the control of the system controller 35. 也就是说,用伺服控制电路34控制主轴电机31,在记录/复制信息信号的过程中按照预定的rpm旋转驱动光盘2。 That is, the servo control circuit 34 controls the spindle motor 31, recording / reproducing information signals according to a predetermined rpm during the optical disc 2 rotationally driven. 伺服控制电路34还被连接到光头1上,并且在记录/复制信息信号的过程中从光头1上接收伺服信号,按照这种伺服信号用装载在光头1上的物镜17的双轴驱动器来实现聚焦伺服控制和跟踪伺服控制。 The servo control circuit 34 is also connected to the optical head 1 and recording / reproducing information signals during servo signal received from the optical head 1, in such a servo signal loaded on the optical head 1 of the objective lens 17 of the biaxial actuator is achieved focus servo control and tracking servo control.

另外,在体现本发明的记录/复制装置30中,伺服控制电路34还可以作为检测装置来操作,根据聚焦伺服信号检测出光盘2的光透射层4的厚度t。 Further, the present invention is embodied in a recording / reproducing apparatus 30, the servo control circuit 34 may also operate as a detecting means for detecting the light transmission layer thickness t 2 of the optical disk 4 according to the focus servo signal. 以下要说明用伺服控制电路34检测光透射层4的厚度的方法。 The method to be described below the thickness of the light transmitting layer 4 of the detection circuit 34 of the servo control.

在光电检测器1的光电检测器19发出的聚焦伺服信号当中包括聚焦推进信号和聚焦误差信号。 In the focus servo signal photodetector 19 of the photodetector 1 is sent including a focus error signal and a focus signal propulsion. 用聚焦推进信号表示光盘2反射的全部返回光的光量,并且用来将物镜16移动到聚焦位置附近。 A focus signal representing the amount of light to promote all of the optical disc 2 to return the light reflected by, and serves to focus the objective lens 16 is moved to the vicinity of the position. 在根据聚焦推进信号将物镜1移动到聚焦位置附近之后,用聚焦误差信号将物镜16保持在刚好聚焦的位置上。 After the objective lens based on a focus signal propulsion 1 is moved to the vicinity of the focus position, the focus error signal with the lens holder 16 in a position just focused on.

记录/复制装置30按照球面象差方法获得聚焦误差信号。 The recording / reproducing apparatus 30 according to the focus error signal to obtain a spherical aberration method. 在球面象差方法中,将玻璃板制成的一个平行平板式的光学元件布置在返回光的光学会聚路径中,用来故意产生一个很大的球面象差,在最小模糊圈的前面和后面检测出光束的形状,从中获得聚焦误差信号。 In the spherical aberration method, a flatbed optical element made of a glass plate is arranged parallel to the return light converging optical paths for intentionally generating a large spherical aberration, the front and back of the circle of least confusion detecting the shape of the beam, a focus error signal is obtained therefrom.

以下如图3所示以一个平行平板20为例来解释球面象差方法。 As shown in FIG. 3 or less parallel plate 20 a spherical aberration as an example to explain the method. 尽管图1中所示的光头1采用了多镜头组件18作为产生球面象差的光学元件,但是在此处为了简化而使用了平行平板20作为产生球面象差的光学元件。 Although the optical head shown in FIG. 11 uses a multi-lens assembly 18 to produce an optical element as a spherical aberration, but is used here in order to simplify the parallel plate optical element 20 produced as spherical aberration.

如果将平行平板20作为产生球面象差的光学元件,从以下的公式(10)就能得到球面象差量δy:δy={(n2-1)sin2θ×t}/(n2-sin2θ)3/2 ...(10)其中的θ,n和t分别代表返回光开口的角度,布置在有限光路径上的平行平板20的折射率及其厚度。 If the parallel plate optical element 20 produced as spherical aberration, (10) can be obtained from the spherical aberration amount Ay following formula: δy = / (n2-sin2θ) {(n2-1) sin2θ × t} 3 / 2 ... (10) where θ, n and t represent the return opening angle of the light, the refractive index and thickness of the parallel plate in the optical path 20 a limited arrangement.

为了用球面象差方法检测出聚焦误差信号,用一个光电检测器来检测具有球面象差的光束。 Order spherical aberration detection method of the focus error signal by a photo detector to detect a light beam having a spherical aberration. 图4到6表示了适合使用球面象差方法检测聚焦误差信号的一个光电检测器的光接收部21。 4 to 6 shows a method for detecting a spherical aberration of the light receiving portion of the focus error signal of a photodetector 21. 这一光接收部21具有矩形的形状,并且用两条垂直分割线将其分割成四段。 The light receiving portion 21 has a rectangular shape, and with two perpendicular division lines dividing it into four sections. 当激光在光盘的记录层上刚好处在聚焦状态时,如果将光电检测器设定在让光接收部21上的光束点22变成最小模糊圈,光接收部21上的光束点22在非聚焦状态下就会变成椭圆形的点。 When the laser light on the recording layer of the optical disc in the just focus state, if the photodetector is set so that the beam spot 21 on the light-receiving portion 22 becomes the minimum circle of confusion, the beam spot 21 on the light receiving portion 22 in a non- it becomes oval focusing point state. 如果用A,B,C和D来表示光接收部21的各个段,通过一个电流-电压转换放大器对光接收部21接收到的光量所执行的放大计算,所获得的聚焦误差信号FE就是电压信号FE=(A+C)-(B+D)。 If A, B, C, and D to indicate sections of a light receiving portion 21 by a current - the focus error signal voltage conversion amplifier light receiving unit amplifies the calculation amount of received light 21 performed, the obtained FE is the voltage signal FE = (A + C) - (B + D).

如果激光束被聚焦在光盘的记录层上,引入区21上的光束点22就是椭圆形的,如图4所示。 If the laser beam is focused on the recording layer of optical disk 22 is introduced into an elliptical beam spot on the region 21, as shown in FIG. 在光接收部21的各个段中的光量是(A+C)=(B+D),因此,FE=0。 In each section of the light amount of the light receiving portion 21 is (A + C) = (B + D), therefore, FE = 0.

如果光盘的记录层更加靠近激光的聚焦点,光接收部21上的光束点22就是椭圆形的,如图5所示。 If the recording layer of the optical disc is closer to the focal point of the laser, the beam spot on the light receiving portion 2122 is elliptical, as shown in FIG. 在光后续部21的各个段中的光量是(A+C)<(B+D),因此,FE<0。 In each section of the light amount of light portion 21 is follow-up (A + C) <(B + D), therefore, FE <0.

如果光盘的记录层远离激光的聚焦点,光接收部21上的光束点22就是椭圆形的,如图6所示。 If the recording layer of the optical disc shown in FIG away from the focal point of the laser beam, the beam spot on the light receiving portion 2122 is elliptical, as shown in FIG 6. 在光后续部21的各个段中的光量是(A+C)>(B+D),因此,FE>0。 In each section of the light amount of light portion 21 is follow-up (A + C)> (B + D), therefore, FE> 0.

如图7所示,如果将聚焦偏差绘制在横轴上,将聚焦误差信号的输出绘制在纵轴上,由此获得的聚焦误差信号就可以用一条S形曲线来表示。 As shown in FIG 7, if the output of the focus offset plotted on the horizontal axis, the focus error signal is plotted on the vertical axis, whereby a focus error signal can be obtained with an S-shaped curve. S形曲线中心的零点代表刚好聚焦的点。 Zero represents S-shaped curve centered just focus point. 同时,从S形曲线的一个峰值Pa到另一侧的峰值Pb的范围Wa通常被称为聚焦推进范围。 Meanwhile, a range from the peak Pa S-shaped curve to the other side of the peak Pb is commonly referred to as Wa focused propulsion range.

为了在光头1中实现聚焦伺服控制,在检测到聚焦推进信号时需要驱动物镜17的双轴驱动器,以便使物镜16沿着光轴在前后方向上移动。 In order to realize the focus servo control in the optical head 1, upon detection of the biaxial actuator needs to be driven when the focus of the objective lens 17 advance signal, so that the objective lens 16 is moved along the optical axis in the longitudinal direction. 根据聚焦推进信号使物镜的焦点定位在记录层的附近。 The focus of the objective lens focal advance signal is positioned in the vicinity of the recording layer. 当物镜16的焦点被定位在记录层的附近,并且物镜16处在聚焦推进范围之内时,就利用物镜17的双轴驱动器让物镜16沿着光轴在前后方向上逐渐移动,自始至终地保持刚好聚焦的位置,让聚焦误差信号始终处在零点。 When the focus of the objective lens 16 is positioned in the vicinity of the recording layer, and the objective lens 16 in the focusing range to promote, on the use of the biaxial actuator of the objective lens 17 gradually moves the objective lens 16 along the optical axis in the longitudinal direction, maintained throughout just focus position, so that the focus error signal is always at zero. 这样就能相对于记录层始终设定在聚焦状态。 This will always be set with respect to the recording layer in the focus state.

以上说明了聚焦伺服控制的原理。 The principle described above focus servo control. 在惯用的记录/复制装置中,从记录层反射的返回光获得的聚焦误差信号FE被用来实现聚焦伺服控制。 In the conventional recording / reproducing apparatus, the recording layer returns from the reflected light obtained focus error signal FE is used to implement the focus servo control. 然而,入射的激光不仅受到记录层的反射,或多或少地还会受到光盘2上处在光透射层4表面上的表面反射。 However, not only the incident laser beam is reflected by the recording layer, but also by the more or less on the surface of the reflective surface of the light transmitting layer 4 in the optical disc 2. 由于光透射层4的表面反射的返回光而形成图7所示的S形曲线。 Since the return light reflected from the surface of the light transmitting layer 4 is formed S-shaped curve shown in FIG. 7. 在以下的说明中,由于光透射层4的表面反射的返回光而出现聚焦误差信号的S形曲线被称为第一S形曲线,而由于光盘1的记录层表面反射的返回光造成的聚焦误差信号被称为第二S形曲线。 In the following description, since the return light reflected from the surface light transmitting layer 4 of the S-curve appears in the focus error signal is referred to as a first S-shaped curve, and because the surface of the optical disc 1 recording layer returns caused by focused light reflected It is referred to as a second error signal S-curve.

按照本发明的记录/复制装置30响应上述的第一和第二S形曲线,根据聚焦误差信号来检测光透射层4的厚度t。 According to the present invention, a recording / reproducing apparatus 30 responsive to said first and second S-shaped curve, to detect the thickness t of the light transmitting layer 4 of the focus error signal. 也就是说,在本发明的记录/复制装置30中,在记录/复制操作开始之前用物镜17的双轴驱动器使物镜16沿着光轴前后移动,直到物镜的焦点位置从光透射层4的表面移到记录层上。 That is, in the present invention, a recording / reproducing device 30, the recording / reproducing operation is started before the objective lens 17 with a biaxial driver enable the objective lens 16 is moved back and forth along the optical axis until the focal position of the objective lens from the light transmitting layer 4 move to the surface of the recording layer. 根据物镜16的移动速度和对应着第一和第二S形曲线的聚焦误差信号来检测光透射层4的厚度t。 The moving speed of the objective lens 16 and the corresponding first and second focus error signal S-curve to detect the thickness t of the light transmitting layer 4.

以下要参照图8给予说明。 The following explanation is given in relation to figure 8. 在图8中表示了当物镜16在接近光盘2的方向上沿着光轴移动时输出的聚焦误差信号,图中的横轴和纵轴分别代表时间和输出的聚焦误差信号。 Shows a focus error signal when the objective lens 16 along the optical axis in a direction approaching the optical disc 2 is outputted in FIG. 8, the horizontal and vertical axes represent time and the focus error signal output.

在图8中,W1是物镜16跨过第一S形曲线的聚焦推进范围所需要的时间。 In FIG. 8, W1 is the objective lens 16 across the range of time to promote the focus of the first S-shaped curve required. 也就是说,W1代表聚焦误差信号随着物镜16的移动从最大值变到最小值所需要的时间,而P1代表了光盘2的光透射层4表面上的一个聚焦点,也就是相对于光透射层4的表面刚好聚焦的点。 That is, the representative W1 of the focus error signal with the movement of the objective lens 16 is changed from the maximum value to the minimum time required, and P1 represents a focal point on the surface of the optical disc 2 of the light transmitting layer 4, i.e. with respect to light 4-point transmission layer surface just focus.

在图8中,W2是物镜16跨过第二S形曲线的聚焦推进范围所需要的时间。 In FIG. 8, W2 is the objective lens 16 across the time range of the second focus advancing S-shaped curve required. 也就是说,W2代表聚焦误差信号随着物镜16的移动从第二S形曲线上的最大值变到最小值所需要的时间,而P2代表了光盘2的光透射层4表面上的一个聚焦点,也就是相对于记录层刚好聚焦的点。 That is, W2 with the movement of the focus error signal representative of the objective lens 16 from the maximum value of the second S-shaped curve is changed to the minimum time required, and P2 represents a focus on the surface of the optical disc 2 of the light transmitting layer 4 point, i.e. the point with respect to the recording layer just focusing.

另外,图8中的W3代表从聚焦在光盘2的光透射层4表面上的一点P1直到聚焦在光盘2的记录层上的一点P2所经历的时间。 Further, W3 in FIG. 8 representatives from the optical disc 2 focused on the surface of the light transmitting layer 4 of the point P1 at time point P2 until the focus on the recording layer of the optical disc 2 experienced.

在这种情况下,如果聚焦推进范围的长度是A,用以下的公式(11)就可以获得光透射层4的厚度t:t=W3×{(A/W1)2+(A/W3)2}1/2...(11)同时,在目前常用的光头中,聚焦推进范围的长度A被设定在20μm左右。 In this case, if the focal length is advancing range A, (11) can be obtained by the following equation light transmitting layer thickness is t 4: t = W3 × {(A / W1) 2+ (A / W3) ... 2} 1/2 (11) simultaneously, in the commonly used optical head, advancing the focus range is set at a length a of about 20μm.

在按照本发明的记录/复制装置30中,伺服控制电路34根据公式(11)获得光透射层4的厚度t。 In accordance with the present invention, a recording / reproducing apparatus 30, the servo control circuit 34 (11) to obtain the thickness t of the light transmitting layer 4 according to the formula. 因此,记录/复制装置30的伺服控制电路34可以作为一种厚度检测装置,用来检测光透射层4的厚度。 Thus, the recording / reproducing device 30 of the servo control circuit 34 can be used as a thickness detection means for detecting the thickness of the light transmission layer 4.

尽管可以对光透射层4的厚度t仅仅检测一次,最好的方式还是通过多次检测而获得一个平均值。 Although light transmission layer thickness t 4 only tested once, the best way is detected by a plurality of times to obtain a mean value. 也就是说,在检测光透射层4厚度t的过程中,按照例如100到200Hz的预定频率反复地前后移动物镜17的双轴驱动器,反复获得光透射层4的厚度t,从中找到一个平均值。 That is, during the detection light transmitting layer 4 in the thickness t of, for example, according to a predetermined frequency 200Hz 100 repeatedly moves back and forth in the biaxial actuator of the objective lens 17 is repeated to obtain the thickness t of the light transmitting layer 4, to find a mean value . 这样就能更加精确地检测出光透射层4的厚度t。 This will more accurately detect the light transmitting layer thickness is t 4.

按照上述方式检测到光透射层4的厚度t的伺服控制电路34向光盘2发出一个控制信号,利用准直透镜14的驱动器来移动准直透镜13,根据这一控制信号将光透射层4的厚度误差可能造成的球面象差减少到最小。 According to the above embodiment detects the servo light transmitting layer thickness T 4 of the control circuit 34 issues a control signal, the drive collimating lens 14 to move the collimator lens 13, in accordance with this control signal, the light transmitting layer 4 to the optical disc 2 spherical aberration caused by a thickness error may be minimized. 在对光透射层4的厚度误差造成的球面象差进行校正之后,记录/复制装置30就象普通的记录/复制装置一样执行记录/复制操作。 After the light transmitting layer 4 of the thickness error caused by spherical aberration is corrected, the recording / recording apparatus 30 as an ordinary copying / reproducing apparatus performs the same recording / reproducing operations.

在本发明的记录/复制装置30中,光透射层4的厚度t是在记录/复制操作之前进行测量的,以便能校正厚度误差造成的球面象差。 In the present invention, a recording / reproducing apparatus 30, the light transmission layer thickness t 4 is the recording / reproducing operation prior to measurement in order to correct errors due to the thickness of the spherical aberration. 因此,即使是光透射层4的厚度t存在厚度误差,仍然能够抑制球面象差的发生,从而在最佳状态下执行记录/复制操作。 Thus, even if the light transmitting layer 4 has a thickness t of the thickness error is present, the spherical aberration is still possible to suppress the occurrence of the difference, so as to perform recording / reproducing operations in the best condition.

采用本发明的光头,只要移动具有预定折射率的光学元件就足以消除取决于光透射层厚度的球面象差,因此,这种光头并不仅限于图1所示的结构。 Using the optical head according to the present invention, as long as the movement of the optical element having a predetermined refractive index is sufficient to eliminate the layer thickness depends on the light transmissive spherical aberration, and therefore, this optical head is not limited to the configuration shown in FIG. 以下要参照图9到11详细说明本发明的光头的各种变更形式。 The following detailed description of various alternative forms of the optical head of the present invention with reference to FIGS. 9-11.

图9所示的光头100是一种用于记录/复制相变型光盘101的光头。 An optical head 100 shown in FIG. 9 is a recording / reproducing phase change optical disk 101 for the optical head. 适合用这种光头100记录/复制的光盘101具有一个基片102,设在基片上的一个记录层,可以通过相位变化来记录信息信号,以及设在记录层上面的一个光透射层103。 In this optical head 100 for recording / reproducing an optical disc 101 having a substrate 102, provided on the substrate a recording layer, information signals can be recorded, and a recording layer disposed above the light transmission layer 103 through the phase change. 用入射到光透射层103一侧的光对光盘101进行记录或是复制。 Recording or copying of the optical disc 101 with a light incident side of the light transmission layer 103.

光头100包括用来检测光盘101的光透射层103厚度的第一光学系统104以及一个第二光学系统105。 The optical head 100 includes a light transmission layer for detecting a first optical system of the optical disc 101 104 103 thickness 105 and a second optical system. 为了在光盘101上记录/复制信息信号,第二光学系统105需要根据第一光学系统104检测到的光盘101的光透射层103的厚度对光盘101的光透射层103的厚度误差造成的球面象差进行校正。 To 101 on the optical disc recording / reproducing information signals, the second optical system 105 needs the thickness of the light transmission layer 101 of the optical disc 103 detected by the thickness error of the light transmission layer 101 of the optical disc 103 causes a first optical system 104 according to the spherical aberration differential correction.

第一光学系统104包括一个光源106,偏振射束分离器107,准直透镜108,一个物镜109,以及一个光电检测器110。 A first optical system 104 includes a light source 106, a polarization beam splitter 107, a collimator lens 108, a lens 109, and a photodetector 110.

光源106向着光盘101发光。 Emitting light source 106 toward the optical disc 101. 光源106可以采用一个发射波长为635到650nm短波长激光的半导体激光器。 A light source 106 may be used for the emission wavelength of the semiconductor laser 635 to 650nm short wavelength laser. 光源106发出的激光受到偏振射束分离器107的反射之后落到准直透镜108上。 Fall on the collimator lens 108 after emitted from the laser light source 106 is reflected by the polarizing beam splitter 107.

用粘结到一起的两个球面透镜108a,108b构成的准直透镜108将入射到准直透镜108上的激光对准。 Bonded together with two spherical lenses 108a, 108b composed of the collimator lens 108 on the laser light incident to the collimator lens 108 is aligned. 被准直透镜108对准的激光落在物镜109上。 Aligned laser collimating lens 108 falls on the objective lens 109.

入射到物镜109上的激光被物镜109会聚之后通过光透射层103落到光盘101的记录层上。 Laser light incident on the objective lens 109 is converged by the objective lens 109 after the light transmission layer 103 falls on the recording layer of the optical disc 101. 物镜109被装载在一个双轴驱动器111上,可以在沿着光轴的方向和与其垂直的方向上移动。 The objective lens 109 is loaded on a biaxial actuator 111 can move in a direction along the optical axis and a direction perpendicular thereto.

经过物镜109的会聚之后落在光盘101的记录层上的激光受到记录层的反射后变成了返回光束。 After the objective lens 109 converges the laser beam on the recording layer of the optical disc 101 is reflected falls on the recording layer becomes a return beam. 这种返回光沿着跨过偏振射束分离器107的原来的光程减退,最后入射到光电检测器110上。 Such return light loss across the polarizing beam splitter along the original optical path 107, and is incident onto the photo detector 110.

第一光学系统104根据光盘101的光透射层103和记录层表面上的聚焦误差信号来检测光盘101的光透射层103的厚度。 A first optical system 104 according to the focus error signal on the recording layer 103 and the surface 101 of the optical disc to detect the light transmission layer thickness of the light transmission layer 101 of the optical disc 103.

第二光学系统105包括一个光源112,一个柱面透镜113,偏振射束分离器114,准直透镜115,衍射点阵116,光程提升反射镜117,四分之一波片118,一组两个物镜119,以及一个光电检测器120。 The second optical system 105 includes a light source 112, a cylindrical lens 113, the polarizing beam splitter 114, collimator lens 115, a diffraction lattice 116, the optical path to enhance the reflection mirror 117, the quarter-wave plate 118, a set of two objective lenses 119, 120 and a photo detector.

由发射波长为400到650nm短波长激光的半导体激光器构成的光源112朝着光盘101发射激光。 A semiconductor laser light source emitting a wavelength of 400 to 650nm of the short wavelength laser 112 emits laser light toward the configuration of the optical disc 101. 从光源112发出的激光落在柱面透镜113上。 Laser light emitted from the light source 112 falls on the cylindrical lens 113.

从柱面透镜113入射到准直透镜115上的激光是射束的形状,并且通过偏振射束分离器114落在准直透镜115上。 Cylindrical lens 113 is incident from the laser to the collimator lens 115 is a beam shape, and by polarization beam splitter 114 to fall on the collimator lens 115.

如果光盘101的光透射层103的厚度处在预定的值,激光就会入射到由粘结到一起的两个球面透镜构成的准直透镜11上并且被对准。 If the thickness of the optical disc 101 of the light transmission layer 103 at a predetermined value, the laser will be incident on the collimator lens by the bonding together of two spherical lenses 11 and aligned. 准直透镜115被装载在准直透镜121的一个驱动器上,并且可以沿着入射激光的光轴前后移动。 The collimator lens 115 is loaded on a drive collimator lens 121, and is movable back and forth along the optical axis of the incident laser light.

如果光盘101的光透射层103的厚度t脱离了预定值,就用准直透镜115来对准准直透镜115,以便校正由于光透射层103的厚度误差造成的球面象差。 If the thickness of the optical disc 101 t of the light transmission layer 103 from the predetermined value, the alignment of the collimator lens 115 to the collimator lens 115, so as to correct an error since the thickness of the light transmission layer 103 caused by spherical aberration. 也就是说,如果光盘101的光透射层103的厚度t脱离了预定值,就用准直透镜115将入射激光转变成发散光或是会聚光,以便校正由于光透射层103的厚度误差造成的球面象差。 That is, the optical disc 101 if the light transmission layer thickness t of 103 out of a predetermined value, the collimator lens 115 into laser light incident divergent light or convergent light, since the thickness of 103 to correct the errors due to the light transmission layer spherical aberration. 从准直透镜115发出的激光落在衍射点阵116上。 Laser beam emitted from the collimator lens 115 falls on the diffraction lattice 116.

入射到衍射点阵116上的激光受到衍射点阵116的衍射后变成一个三束激光。 Laser light incident on the diffraction lattice 116 is diffracted into a lattice three beams diffracted laser light 116. 衍射点阵116被用来将激光分解成至少三个光束,以便用所谓的三点式方法执行跟踪伺服控制。 To the diffraction lattice 116 is decomposed into at least three laser beams, so as to perform tracking servo control by the so-called three-point method. 从衍射点阵116射出的激光在其前进方向上被光程提升反射镜117转向,落在四分之一波片118上。 Emitted from the laser diffraction lattice 116 in its forward direction to enhance the optical path steering mirror 117, a quarter wave plate 118 to fall.

入射到四分之一波片118上的激光从线性偏振状态被变成圆极化状态。 Laser light 118 incident on the quarter wave plate circularly polarized state is changed into the linearly polarized state. 从四分之一波片118输出的激光落在一组两个物镜119上。 Laser light output from the quarter wave plate 118 to fall on the objective lens 119 a set of two.

入射到一组两个物镜119上的激光被会聚之后通过光透射层103落到光盘101的记录层上。 A set of two incident on the objective lens 119 by the laser beam 103 falls on the light transmission layer recording layer of the optical disc 101 after being converged. 由两个物镜119a,119b构成的这一组两个物镜119被装载在双轴驱动器111上,并且可以在沿着光轴的方向和与其垂直的方向上移动。 The two lens groups 119 consisting of two lens 119a, 119b is loaded on the biaxial actuator 111, and can be moved in a direction along the optical axis and a direction perpendicular thereto. 被一组两个物镜119会聚之后落到光盘101的记录层上的入射激光受到记录层的反射之后变成了返回光束,然后沿着前进的光程逆行通过一组两个物镜119,并且会聚到准直透镜115上。 Laser beam is incident on the recording layer 119 a set of two objective optical disc 101 falls after the return beam into a converging, in the forward and reverse optical path of the objective lens 119 through a set of two, and then condensing the recording layer is reflected to the collimator lens 115. 产生的会聚光受到偏振射束分离器114的反射后入射到光电检测器120上,用光电检测器进行检测。 Converging light generated by the polarizing beam splitter 114 incident on the back reflector to the photo detector 120, detected by the photodetector.

参见图9,第二光学系统105包括一个会聚透镜122,用来会聚被偏振射束分离器114反射的激光,和一个用来接收由会聚透镜122会聚的激光的输出调节光电检测器123,以便根据接收到的光量自动调节从光源112发出的激光的输出。 Referring to Figure 9, a second optical system 105 comprises a converging lens 122 for converging the laser polarization is reflected by the beam splitter 114, and for receiving a laser beam condensed by the condenser lens 122 and output the adjusted photodetector 123, so that automatically adjust the output of the laser light emitted from the light source 112 in accordance with an amount of received light.

在本实施例的光头100上,将第一光学系统104的物镜109和第二光学系统105的一组两个透镜装载在双轴驱动器111上,从而使其在双轴的方向上移动,用来实现对光盘101的跟踪控制和聚焦控制。 In the optical head 100 of the present embodiment, the objective lens 109 first optical system 104 and second optical system 105 is a set of two lenses mounted on the biaxial actuator 111, so that it moves in the biaxial direction, with to achieve tracking control and focusing control of the optical disc 101.

图10和11示意性地表示了一个双轴驱动器111的结构。 10 and FIG. 11 schematically shows the structure of a biaxial actuator 111. 这种双轴驱动器111包括一个用来装载物镜109和一组两个物镜119的鼓轮130,以及用来在两个垂直方向上移动鼓轮130的一个电磁驱动机构131。 This biaxial actuator 111 includes a lens 109 for loading a set of two of the objective lens 119 and the drum 130, and an electromagnetic drive mechanism for moving the drum 130 to 131 in two perpendicular directions.

参见图10和11,鼓轮130基本上是一个具有顶板的圆筒,并且用一个支撑轴132支撑在它的中心。 Referring to FIGS. 10 and 11, the drum 130 is basically a cylinder having a top plate, and is supported in its center by a support shaft 132. 鼓轮130被支撑着绕支撑轴132的轴线转动和滑动。 Drum 130 is supported rotatably about the axis of the support shaft 132 and the slide. 物镜109和一组两个物镜119被安装在鼓轮130上的支撑轴132两侧的对称点上,让彼此的光轴相互平行。 132 point symmetry on both sides of the support shaft 109 and a set of two objective lens 119 is mounted on the drum 130, so that the optical axes are parallel to each other.

参见图10和11,用来移动鼓轮130的电磁驱动机构131包括具有一个聚焦磁铁133的磁路,一对聚焦轭铁134,135,一个跟踪磁铁136,一对跟踪轭铁137,138,一个聚焦线圈139,以及一个跟踪线圈140。 Referring to FIGS. 10 and 11 for moving the drum 131 of the electromagnetic drive mechanism 130 comprises a focusing magnet having a magnetic circuit 133, a pair of focusing yokes 134, a tracking magnet 136, pair of tracking yokes 137, 138, a focusing coil 139, and a tracking coil 140.

如图11所示,在电磁驱动机构131的跟踪线圈141内侧固定安装着一个金属件141,用来设定鼓轮130的中性位置。 11, the electromagnetic coil 131 of the tracking drive mechanism 141 fixedly attached to a metal inner member 141 for setting the neutral position of the drum 130. 由于金属件141朝着被分成两个平面磁极的跟踪磁铁136的两个磁极的边界受到吸引,鼓轮130被设定在跟踪方向也就是第二方向的中性位置上,同时被设定在聚焦方向也就是第一方向的中性位置上。 Since the metal member 141 toward the plane is divided into two magnet poles tracking two pole boundary 136 is attracted, the drum 130 is set in the tracking direction is a second direction on the neutral position, is set at the same time focus direction is a first direction on the neutral position. 利用弹性橡胶等等构成的一个中性位置支撑机构将鼓轮130保持在装有支撑轴132的一个支撑基座142的中性位置上。 An elastic rubber and the like constituting a neutral position of the support mechanism of the drum 130 will be held in a neutral position with a supporting shaft 142 supported on the base 132.

保持在中性位置上的鼓轮130受到电磁驱动机构131的驱动,使其沿着支撑轴132的轴线滑动,并且绕着支撑轴132的轴线转动。 Held in a neutral position on the drum 130 by driving the electromagnetic drive mechanism 131, to slide along the axis of the support shaft 132, and rotates about the axis of the support shaft 132.

也就是说,电磁驱动机构131根据通过可弯曲基片143传送给聚焦线圈139的聚焦误差信号使鼓轮130沿着支撑轴132的轴线移动。 That is, the electromagnetic drive mechanism 131 along the axis 130 moves the support shaft 132 according to the focus error signal, the focusing coil 139 so that the drum 143 through the flexible substrate transfer. 通过鼓轮130沿着支撑轴132的轴线的滑动对一组两个物镜119执行相对于光盘101的聚焦控制。 Along the sliding axis of the support shaft 132 with respect to the focusing control of the optical disc 101 is a set of the objective lens 119 is performed by two drum 130.

另一方面,电磁驱动机构131根据通过可弯曲基片143传送给跟踪线圈140的跟踪误差信号使鼓轮130绕着支撑轴132的轴线转动。 On the other hand, the electromagnetic drive mechanism 131 of the coil 140 so that the tracking error signal 130 about the drum rotation axis of the support shaft 132 by passing under the flexible substrate 143 to the tracking. 通过鼓轮130绕着支撑轴132的轴线的转动对一组两个物镜119执行相对于光盘101的跟踪控制。 Tracking control with respect to the optical disc 101 on a set of the objective lens 119 is performed by two axis of rotation of the drum 130 about the support shaft 132.

在上述的光头100中对聚焦伺服控制和跟踪伺服控制方法分别采用了所谓的球面象差方法和三点式方法。 In the optical head 100 in the focus servo control and tracking servo control method were used a so-called spherical aberration method and three-point method. 由一个四段光电检测器用球面象差方法来检测从光盘上通过柱面透镜反射的激光,并且算出从各个段上获得的检测输出的和以及/或是差,将从中推导出聚焦误差信号作为激光相对于记录层的散焦分量。 A photo detector according to the four methods to detect the spherical aberration by the cylindrical lens laser light reflected from the optical disk, and calculates the detection output obtained from the respective segments and and / or the difference, derived from the focus error signal as laser defocus component of the recording layer.

三点式方法使用衍射点阵将来自光源的单束激光分离成一个主激光束(零级光束)和两个子光束(±一级光束),在照射在记录轨迹中心上的主激光束的前、后发出两个子光束。 Three-point method using a diffraction lattice from the single laser light source is separated into a main laser beam (zero order beam) and two sub beams (± first order light), before the main laser beam is irradiated on the center of the recording track, the issued two sub-beams. 用具有两个光接收部的光电检测器来检测在主激光束的前、后发出的子光束的反射光束,以便找出从光接收部获得的检测输出之间的差别,从中推导出跟踪误差信号,将其作为主光束相对于记录轨迹的偏差分量。 A photodetector having two light receiving portions of the sub-beams reflected light beam is detected before the main laser beam, after issuing the order to find the difference between the light receiving portion obtained from the detection output, a tracking error derived therefrom signal, which is a main component of the recording light beam with respect to the track deviation.

为了用这种光头100对光盘101进行复制,第一光学系统104根据光盘101的记录层和光透射层103表面上的聚焦误差信号来检测光盘101的光透射层103的厚度。 To this optical disc 101 the optical head 100 pairs of replication, a first optical system 104 to detect the thickness of the disc 101 of the light transmission layer 103 according to the focus error signal on the recording layer surface of the optical disc 101 and the light transmission layer 103. 也就是说,第一光学系统104的双轴驱动器111让物镜109在双轴驱动器111的驱动下沿着光轴前后移动,根据物镜109的移动速度和聚焦误差信号所提供的第一和第二S形曲线通过公式(11)检测出光透射层103的厚度。 That is, the biaxial actuator 104 of the first optical system 111 so that the objective lens 109 is moved back and forth along the optical axis in the biaxial actuator 111 is driven, the moving speed of the objective lens 109 and the focus error signal provided by the first and second S-shaped curve (11) detects the thickness of the light transmission layer 103 by the equation.

用第一光学系统104检测到的光透射层103的厚度是按照图中没有表示的控制电路所计算和预定的表和功能来确定的。 Thickness of the light transmission layer 103 is detected by the first optical system 104 is calculated according to the control circuit not illustrated and a predetermined function of the determined and tables. 在确定了光透射层103的厚度之后,由这种控制电路来决定其操作方式,用来校正由于光盘101的厚度误差造成的球面象差,并且将指示这种操作的控制信号发送给第二光学系统105。 After determining the thickness of the light transmission layer 103 by such a control circuit to determine its mode of operation, for correcting the optical disc 101 due to the thickness error caused by spherical aberration, and transmits a control signal indicative of such operations to the second The optical system 105. 第二光学系统105根据这些控制信号来控制准直透镜121的驱动器,从而使准直透镜115逐步移动,尽量减少由于光透射层103的厚度误差造成的球面象差。 A second optical system 105 in accordance with these control signals to control the drive of the collimator lens 121, a collimator lens 115 so that the stepwise movement, minimize the thickness of the light transmission layer 103 of an error caused by spherical aberration.

在对光透射层103的厚度误差造成的球面象差进行校正之后,第二光学系统105对光盘101执行尽量/复制操作。 After correction of the spherical aberration in the light transmission layer thickness error 103 caused by the second optical system 105 performs the optical disc 101 as possible / copy operation. 准直透镜115的驱动器按照这种方法将准直透镜115移动到其最佳位置,对光透射层103的厚度误差造成的球面象差进行校正,从而产生最佳的信号。 A collimator lens 115 in this drive method collimator lens 115 is moved to its optimal position, the spherical aberration of the light transmission layer thickness error correcting caused 103 to generate the best signal.

在第二光学系统105中复制光盘101时,第一光学系统104的作用是一个用来检测第二光学系统105中的工作距离的光学系统,也就是检测光盘101和一组两个物镜119之间的间隔。 When the second optical system 105 to copy the optical disc 101, the role of the first optical system 104 is an optical system for detecting the working distance of the second optical system 105, the optical disc 101 is detected and the objective lens 119 of a set of two interval between.

在第二光学系统105中通过沿着光轴移动一组两个物镜119来执行聚焦推进操作,由于一组两个物镜119的NA很大,聚焦推进范围是很窄的,光盘101和一组两个物镜119之间的工作距离不能大于0.5mm。 By the second optical system 105 along the optical axis of the objective lens 119 to a set of two propulsion perform focusing operation, a set of two due to the large NA of the objective lens 119, the focus range is very narrow advance, and a plurality of the optical disc 101 the working distance between the objective lens 119 is not greater than two 0.5mm. 因此,如果光盘101存在表面偏差,或者是光盘101的高度偏离了一个参考值,光盘101就可能会在聚焦推进操作期间碰到一组两个物镜119。 Thus, if the optical disc 101 surface aberrations present, the optical disc 101 or the height deviates from a reference value, the optical disc 101 may encounter a group of two advancing the objective lens 119 during focusing operation.

因此,在第二光学系统105执行聚焦推进操作期间,第一光学系统104可以作为一个辅助装置,用来防止光盘101碰到一组两个物镜119。 Thus, during the second focusing optical system 105 performs advancing operation, a first optical system 104 can be used as an auxiliary means for preventing the optical disc 101 of the objective lens 119 across a set of two.

也就是说,在第二光学系统105执行聚焦推进操作期间,从光源106发出的激光照射在光盘101上,并且用光电检测器110来接收和检测聚焦误差信号。 That is, during the second focusing optical system 105 performs advancing operation, the laser is irradiated from the light source 106 on the optical disc 101, and receives and detects a focus error signal by the photo detector 110. 根据这种聚焦误差信号就可以检测出装载在通常和物镜109一同使用的鼓轮上的一组两个物镜119的大致位置。 According to such a focus error signal can be detected is substantially a group of two positions of the objective lens 119 is mounted on the drum and the objective lens 109 is generally used together. 根据由第一光学系统104检测到的一组两个物镜119的位置信息,光头100驱动双轴驱动器111,防止光盘101碰到一组两个物镜119。 The position information of a set of two of the objective lens 119 is detected by the first optical system 104, the optical head 100 drives the biaxial actuator 111, the optical disc 101 to prevent the objective lens 119 across a set of two.

同时,如果一组两个物镜119明显地偏离了第一光学系统104的聚焦推进范围,第一光学系统104可能就不能产生聚焦误差信号。 Meanwhile, if a set of two objective lenses 119 deviate significantly from the range of the first optical focusing propulsion system 104, a first optical system 104 might not generate a focus error signal. 来自光盘101的整个反射光是用第一光学系统104来检测的,并且根据检测到的等级在第一光学系统104的聚焦推进范围内推进一组两个物镜119。 Entire light reflected from the optical disc 101 with first optical system 104 is detected, and advances a set of two objective lenses 119 in the advancing range of the first focusing optical system 104 according to the detected level.

因此,在这种光头100中,第一光学系统104被用作一个负责聚焦推进的辅助光学系统,以便用第二光学系统105复制光盘101,无论光盘101有没有表面或是高度的偏差,都能实现正确的聚焦推进,不会让一组两个物镜119碰到光盘101。 Thus, in this optical head 100, a first optical system 104 is used as a charge of the secondary optical system focusing advance, a second optical system 105 to copy the optical disc 101, whether the optical disc 101 or there is no surface height variation, both to achieve correct focus forward, will not let a set of two objective lens 119 across the disc 101.

第一光学系统104用于聚焦推进的辅助功能或是工作距离检测方法也可以用除了球面象差方法以外的方法来实现,例如微分同心圆方法。 A first optical system 104 for focusing the propulsion or auxiliary functions working distance detection method can also be used a method other than the spherical aberration of the method to achieve such differential concentric circles method.

光头1使用准直透镜14的驱动器作为使准直透镜13在消除由光盘2的光透射层4的厚度而产生的球面象差的方向上移动的装置。 1 using the optical head driver 14 of the collimator lens as the collimator lens unit 13 moves in the direction to eliminate the thickness of the light transmitting layer 4 of the optical disc 2 is generated spherical aberration. 光头1还使用准直透镜121的驱动器作为移动装置,使准直透镜115在消除由光盘101的光透射层103的厚度而产生的球面象差的方向上移动。 An optical head using the collimator lens 121 also drives a mobile device, the collimator lens 115 is moved in the direction indicated by elimination of thickness of the light transmission layer 101 of the optical disc 103 is generated spherical aberration. 以下要参见图12和13说明这些移动装置(以下称为透镜驱动机构)的结构。 Referring to the 12 and 13 illustrate the structure of these mobile devices (hereinafter referred to as a lens driving mechanism) FIG.

图12和13所示的透镜驱动机构160使准直透镜在消除由信息记录媒体的光透射层的厚度而产生的球面象差的方向上移动。 And a lens driving mechanism 12 shown in FIG. 13 160 the collimator lens is moved in the direction indicated by eliminating the thickness of the light transmitting layer information recording medium is generated spherical aberration. 透镜驱动机构160包括一个与光轴平行布置的参考轴161,与光轴平行布置的一个副参考轴162,以及支撑在这些参考轴161,162上的一个准直透镜支架163。 Lens drive mechanism 160 comprises a shaft 161 with reference to the optical axis is arranged parallel to a reference axis parallel to the optical sub-arrangement 162, a collimating lens and supported on these shafts 161, 162 of the holder 163 reference.

参考轴161和副参考轴162被安装和固定在光头的一个静止部分上。 Reference axis 161 and the auxiliary reference axis 162 is mounted on and fixed to a stationary part of the optical head. 准直透镜支架163被支撑着并且沿着光轴相对于这些参考轴161,162做滑动运动。 The collimating lens holder 163 is supported relative to the reference axis 161, 162 make sliding movement along the optical axis. 通过移动来消除球面象差的准直透镜被装载在准直透镜支架163上。 By moving the collimating lens to eliminate a spherical aberration is loaded on the collimator lens holder 163. 通过沿着参考轴161,162往复移动准直透镜支架163,透镜驱动机构160使装载在准直透镜支架163上的准直透镜相对于光轴方向往复平移移动。 The collimator lens 160 mounted on the collimator lens holder 163 is reciprocated by 163, a lens holder driving mechanism of the collimator lens 161 along the reference axis relative to the optical axis direction reciprocating translation movement.

透镜驱动机构160还包括一个驱动机构,用来使准直透镜支架163沿着参考轴161和副参考轴162往复移动,作为用来移动准直透镜支架163的动力源的一个dc电机164,一个传动装置165,用来将dc电机164的旋转运动转换成沿着光轴的平移运动,并且将平移运动传递给准直透镜支架163。 Lens drive mechanism 160 further includes a drive mechanism for moving the collimator lens holder 163 to reciprocate along the reference axis 161 and the auxiliary reference axis 162, as a power source for moving the collimating lens holder 163 to a dc motor 164, a drive means 165 for converting the rotational motion of the dc motor 164 to translational movement along the optical axis, and transmitting a translational movement to the collimating lens holder 163. 利用传动装置165将准直透镜支架163的旋转运动转换成沿着光轴的平移运动,使准直透镜支架163发生移动,让准直透镜在消除由信息记录媒体的光透射层的厚度而产生的球面象差的方向上移动。 Transmission means 165 using the rotational motion of the collimator lens holder 163 into translational movement along the optical axis of the collimator lens holder 163 moves occurs, so that the collimator lens is produced by eliminating the thickness of the light transmitting layer information recording medium movement in the direction of spherical aberration.

传动装置165包括安装在准直透镜支架163上的一个齿条166,安装在dc电机164的旋转轴上的第一齿轮167,用来传递dc电机164的旋转动力,一个第二齿轮168,用来将dc电机164的旋转运动转换成沿着光轴的平移运动,以及一个第三齿轮169,用来将被第二齿轮168转换成沿着光轴的平移运动的驱动力传递到齿条166上。 It means 165 includes a rack gear mounted on the collimator lens holder 163 is 166, the first gear mounted on the rotary shaft 167 of dc motor 164 for transmitting rotational power of the dc motor 164, a second gear 168, with to convert the rotational motion of the dc motor 164 to 169, 168 to be converted to a translational movement along the optical axis, and a third gear of the second gear into a translational movement along the optical axis of the driving force is transmitted to the rack 166 on.

透镜驱动机构160包括一个安装在光头的静止部分上的基座170。 Lens drive mechanism 160 comprises a base 170 mounted on the stationary portion of the optical head. dc电机164,第二齿轮168以及第三齿轮169被安装在基座170上。 dc motor 164, the second gear 168 and the third gear 169 is mounted on the base 170. 驱动力从第三齿轮169传递到齿条166上,齿条166是由两个齿条166a,166b构成的双齿条结构,用来移动齿条166和第三齿轮169之间的轮齿。 The driving force is transmitted from the third gear 169 to the rack 166, the rack 166 is a double rack structure consisting of two racks 166a, 166b, for moving the rack between the teeth 166 and the third gear 169. 用一个弹簧171将齿条166a,166b连接到一起。 The rack 171 by a spring 166a, 166b are connected together.

如果需要用这一透镜驱动机构160来移动准直透镜,就转动dc电机164使第一齿轮167转动。 If needed the lens driving mechanism 160 to move the collimator lens, dc motor 164 rotates the first gear 167 rotates. 第一齿轮167的转动被传递到第二齿轮168,转换成沿着光轴的平移运动。 Rotation of the first gear 167 is transmitted to the second gear 168 is converted into a translational movement along the optical axis. 被第二齿轮168转换成沿着光轴的平移运动的驱动力通过第三齿轮169传递给齿条166。 A second gear 168 is converted into a translational movement along the optical axis of the driving force is transmitted to the rack 166 through the third gear 169.

齿条166被安装在准直透镜支架163上,支架被支撑着相对于参考轴161,162沿着光轴滑动。 The rack 166 is mounted on the collimator lens holder 163, the holder is supported with respect to the reference axis 161, 162 slide along the optical axis. 这样,准直透镜支架163就能在通过第三齿轮169传递到齿条166上的驱动力的作用下沿着光轴移动,从而使装载在准直透镜支架163上的准直透镜沿着光轴移动。 Thus, the collimating lens holder 163 can be transmitted through the action of the third gear 169 to the driving force of the rack 166 move along the optical axis, so that the collimator lens mounted on the collimator lens holder 163 along the optical axis.

利用上述的透镜驱动机构160可以使准直透镜准确地移动。 The collimator lens 160 can be accurately moved using the lens driving mechanism. 这样就能用这一透镜驱动机构160充分地消除由光透射层的厚度变化造成的球面象差。 This allows the lens driving mechanism 160 with substantially eliminate variations caused by the thickness of the light transmitting layer spherical aberration.

在上述的透镜驱动机构160中,dc电机164可以采用一个脉冲驱动式的步进电机,每一个脉冲的转动使准直透镜移动的距离是13.8μm。 In the lens driving mechanism 160 in the above, dc motor 164 can be driven using a pulse of the stepping motor, the rotation of each pulse so that the distance of the collimator lens is moved 13.8μm. 如果在以下的例子中的光学系统中使用这种电机,相对于光透射层的厚度变化而言,dc电机的每一个脉冲的转动对球面象差的校正量大于等于0.2μm。 If such a motor in an optical system in the following examples, with respect to the light transmitting layer thickness variation, the rotation of each pulse motor dc correction for spherical aberration is greater than or equal 0.2μm. 这样就足以校正由于光透射层的厚度变化而产生的球面象差。 This is sufficient to correct a variation in thickness of the light transmission layer is generated spherical aberration.

另外,上述的透镜驱动机构160结构比较简单,并且可以减少尺寸和成本。 Further, the configuration of the lens driving 160 mechanism is simple and can be reduced in size and cost.

以下要说明体现了本发明的光头的光学系统的一些最佳实施例。 Be described below reflects preferred embodiments of the optical system of the optical head according to the present invention.

在以下的说明中,包括透镜的光学系统的具体实施例是用来解释如何通过移动准直透镜来校正球面象差的。 In the following description, the specific embodiments of the embodiment includes a lens optical system is used to explain how to correct the spherical aberration by moving the collimator lens. 值得注意的是,准直透镜的移动距离或是精度仅仅取决于物镜的光出射一侧的数值孔径NA和设在光盘的距离层上面的光透射层的厚度,与物镜的结构无关。 Notably, a moving distance of the collimator lens or the accuracy depends only on the thickness of the objective lens of the light exit numerical aperture NA of the optical disc and disposed above the layer from the light transmitting layer side of the objective lens regardless of structure. 因此,在物镜的光出射一侧上的数值孔径NA的具体数值是给定的,但是省略了其他的透镜数据。 Thus, the specific value of the light exit side numerical aperture NA of the objective lens are given, but omits other lens data.

另外,在以下的说明中分别解释了使用粘接的球面透镜作为准直透镜的一个例子(例1)和使用表面相位式全息透镜作为准直透镜的一个例子(例2)。 Further, in the following description are explained using the adhesive of a spherical lens as a collimating lens of an example (Example 1) and a surface phase hologram using a lens as an example of the collimating lens (Example 2). 然而,也可以用一种非球面透镜或是Fresnel透镜作为准直透镜。 However, a non-spherical lens may be a Fresnel lens or a collimator lens. 此外也可以使用一种所谓的体积相位式全息透镜。 Also it may be used a so-called volume phase type hologram lens. 例1图14表示本实施例的一种光学系统。 Example 1 14 shows an optical system according to the present embodiment. 图示的光学系统表示用来记录/复制光盘50的光头的光学系统中的基本部分,在光盘的基片50a表面上设有一个记录层,在记录层上面还设有一个光透视层50b。 Illustration showing an optical system for recording / reproducing optical system of the optical head base portion 50 in the optical disc, a recording layer provided on the surface 50a of the optical disk substrate, the recording layer also has a top perspective view of the optical layer 50b. 在光源和物镜51之间布置着一个衍射点阵52,一个偏振射束分离器53,一个准直透镜54,以及一个孔径挡板55。 Between the light source and the objective lens 51 is arranged with a diffraction lattice 52, a polarization beam splitter 53, a collimator lens 54, and a shutter aperture 55. 准直透镜54是用无色的第一透镜54a和第二透镜54b构成的一个粘结的球面透镜。 The collimator lens 54 is a spherical lens with a colorless adhesive first lens 54a and second lens 54b thereof. 透镜54a,54b都是球面透镜。 Lens 54a, 54b are spherical lenses. 入射光一侧的数值孔径NA被设定在0.14。 The light incident side numerical aperture NA is set at 0.14.

在表1中表示了这种光学系统的透镜数据。 Shows lens data of such an optical system is shown in Table 1. 表1中所示的透镜数据包括一个物镜面OBJ,衍射点阵52的光入射面s1和光照射面s2,偏振射束分离器53的光入射面s3和光出射面s4,准直透镜54的第一透镜54a的光入射面s5,构成准直透镜54的第一和第二透镜54a,54b的粘结面s6,以及准直透镜54的第二透镜54b的光出射面S7。 The lens data shown in Table 1 includes an object lens OBJ, the light irradiated surface s2, the polarization beam splitter the light incident surface s3 53 of the diffraction lattice light incident surface 52 of the s1 and and the light exit surface s4, the collimator lens 54 s5 a light incident surface 54a of the lens, lens 54a constituting the first and second collimator lens 54, the light of the adhesive surface S6 54b, 54b and a second lens 54 is a collimator lens exit surface S7. 在表1中,s8是一个虚构的表面,而STO是与物镜51相联系的一个孔径挡板55。 In Table 1, s8 is an imaginary surface, and the STO is a baffle 55 associated with the aperture 51 of the objective lens.

表1 Table 1

假设光盘50的光透视层50b的厚度是0.1mm,物镜51的数值孔径NA是0.85,而采用的光的波长λ是635nm。 Assuming that the thickness of the layer 50b ray optical disc 50 is 0.1mm, numerical aperture NA of the objective lens 51 is 0.85, and the wavelength λ of light used is 635nm. 物体与光学系统的图象之间的比例系数是0.1891。 Proportionality coefficient between the image object and the optical system is 0.1891.

图15表示在上述光学系统中的光透视层50b的厚度误差与波前象差之间的关系。 15 shows the relationship between the thickness error in the optical layer 50b is a perspective view of the optical system in the wavefront aberration. 同时,在出射光瞳面上的标准偏差WFBrms在图15中是用波前象差来表示的,并且用λ来表示所采用的光的波长。 Meanwhile, the standard deviation of the exit pupil plane 15 in FIG WFBrms wavefront aberration is expressed, and with λ represents the wavelength of the light to be used. 另外,对于准直透镜54没有移动的情况,也就是在球面象差没有得到校正的情况下,在图15中用虚线A1和实线A2来表示光透视层50b的厚度误差与波前象差之间的关系,在移动准直透镜54的情况下,也就是根据光透视层50b的厚度误差对球面象差进行校正的情况下,用一条虚线A3来表示。 Further, in the case of the collimator lens 54 is not moved, i.e. in the case where the spherical aberration is not corrected, in FIG. 15 by a dotted line and a solid line A1 to A2 represent aberration error in the optical thickness of layer 50b is a perspective wavefront a case where the relationship between, in the case where the movement of the collimator lens 54, that is, according to the thickness error correcting rays layer 50b of spherical aberration by a dashed line denoted A3.

参见图15,如果光透视层50b没有厚度误差,这种光学系统中的波前象差大约是0.003λ。 Referring to FIG 15, if there is no layer 50b ray thickness error, such an optical system aberration wavefront is about 0.003λ. 从图15中可见,如果不移动准直透镜54,波前象差就会急剧增大。 Seen from FIG. 15, if the collimator lens 54 is not moved, the wavefront aberration increases abruptly. 然而,如果根据光透视层50b的厚度误差来移动准直透镜54,由光透视层50b的厚度误差产生的波前象差就能得到明显的抑制。 However, if the collimator lens is moved according to the thickness of the layer 50b error ray 54, generated by the wave aberration error in the optical thickness of the layer 50b is a perspective front can be significantly suppressed.

具体地说,通过移动准直透镜54可以使波前象差得到抑制,如以下的公式(12)所示:ΔL≈21Δt ...(12) Specifically, by moving the collimator lens 54 so that the wave front aberration can be suppressed, as in the following equation (12) shown: ΔL≈21Δt ... (12)

即使是光透视层50b的厚度发生变化,例如光透视层50b的厚度误差处在±10μm的量级,仍可以将波前象差抑制在不大于0.01λ。 Even 50b is a perspective layer thickness of the light changes, for example ray 50b of the layer thickness error in the order of ± 10μm, still can suppress the wavefront aberration is not larger than 0.01λ.

在上述的公式(12)中,ΔL是准直透镜54的移动量,其正方向是准直透镜远离光盘50的移动方向,而Δt是光透视层50b的厚度误差。 In the above equation (12), [Delta] L is the amount of movement of the collimator lens 54, the collimator lens is a positive direction away from the moving direction of the optical disc 50, and Δt is the layer thickness error ray 50b. 例2图16表示本实施例的一种光学系统。 Example 2 FIG. 16 shows an optical system according to the present embodiment. 图示的光学系统表示用来记录/复制光盘60的光头的光学系统中的基本部分,在光盘的基片60a表面上设有一个记录层,在记录层上面还设有一个光透视层60b。 Illustration showing an optical system for recording / reproducing optical system of the optical head base portion 60 in the optical disc, a recording layer provided on the surface 60a of the optical disk substrate, the recording layer also has a top perspective view of the optical layer 60b. 在光源和物镜61之间布置着一个由全息透镜构成的准直透镜54,以及一个孔径挡板63。 Between the light source and the objective lens 61 is arranged with a collimator lens 54 composed of the hologram lens, and a shutter aperture 63.

在表2中表示了这种光学系统的透镜数据。 Shows lens data of such an optical system is shown in Table 2. 表2中所示的透镜数据包括一个物镜面OBJ,准直透镜62的光入射面s1和光照射面s2,以及一个虚构的表面s3。 Table 2 shows lens data of an object lens included in the OBJ, the light incident surface of the collimating lens and the light irradiation surface s1 s2 62 and an imaginary surface s3. 另外,STO是与物镜61相联系的一个孔径挡板63。 Further, STO is a baffle 63 associated with the aperture 61 of the objective lens.

表2 Table 2

假设光盘50的光透视层60b的厚度是0.1mm,物镜61的数值孔径NA是0.85,而采用的光的波长λ是635nm。 Assuming that the thickness layer 60b ray optical disc 50 is 0.1mm, numerical aperture NA of the objective lens 61 is 0.85, and the wavelength λ of light used is 635nm. 物体与光学系统的图象之间的比例系数是0.1891。 Proportionality coefficient between the image object and the optical system is 0.1891.

同时,准直透镜62是一种所谓的表面相位型全息透镜,适合按照入射光的相位差对入射光进行衍射,在透镜的入射光一侧的数值孔径NA等于0.16。 Meanwhile, the collimator lens 62 is a so-called phase hologram surface of the lens, for diffracting incident light in accordance with a phase difference of incident light, the numerical aperture NA of the lens at the light incident side is equal to 0.16.

对准直透镜62的透镜表面进行机加工,对入射光产生相位差。 Lens surface of the collimator lens 62 is machined to produce a phase difference to incident light. 也就是说,对准直透镜62的透镜表面进行机加工,对发射的光产生相位差,从而产生衍射的光。 That is, the lens surface of the collimator lens 62 is machined, produce light emission phase difference, thereby generating light diffraction. 在本实施例的光学系统中,通过准直透镜62上的衍射获得的第一级衍射光落在物镜61上。 In the optical system of the present embodiment, the first order diffraction by the diffraction obtained collimator lens 62 on the light falls on the objective lens 61.

准直透镜62最好是具有传播的形状,也就是一种锯齿形状。 The collimator lens 62 is preferably a shape having a spread, which is a kind zigzag shape. 如果采用锯齿形状的准直透镜62,几乎100%的入射光都会变成第一级衍射光,这样就能获得很高的光利用效率。 If the zigzag shape of the collimator lens 62, almost 100% of incident light will become a first-order diffracted light, so that we can get a high light use efficiency.

准直透镜62的特性可以用以下的相位差函数公式(13)来表示:m=C1R2+C2R4+C3R6+C4R8...(13)其中的m代表衍射参考波长下的光程差。 Characteristics of the collimator lens 62 may be a phase difference function expressed by the following equation (13): m = C1R2 + C2R4 + C3R6 + C4R8 ... (13) where m represents the diffraction optical path difference at a reference wavelength. 如果在制作准直透镜时假设两点光源是处在无穷远的位置,在上述公式(13)中就可以用基片上的极坐标多项式来表示用表面相位型全息透镜构成的准直透镜62的各个表面中的相位偏差。 If it is assumed in the production source is a collimator lens in the infinity two o'clock position in the above formula (13) can be used in the polar coordinate polynomial expressed on the substrate surface of the collimating lens with a phase hologram lenses 62 phase deviation of each surface. 本实施例中采用的准直透镜62是一种全息透镜,其中的相位差函数是一种轴对称的全息透镜。 A collimator lens 62 employed in the present embodiment is a holographic lens in which the phase difference function is a hologram lens symmetrical axis. 在上述的公式(13)中,R代表从光轴算起的距离。 In the above formula (13), R represents the distance from the optical axis. 在表2中,C1,C2,C3和C4代表相位差函数的系数,准直透镜62的衍射参考波长被设定在635nm。 In Table 2, C1, C2, C3 and C4 are coefficients representative of the phase difference function, the diffractive collimating lens 62 is set to a reference wavelength at 635nm.

在上述的光学系统中,光透视层60b的厚度误差与波前象差的关系如图17所示,与图16类似,在波前象差的出射光瞳面上的标准偏差WFErms是由用λ表示的光的波长来代表的。 In the optical system, the optical thickness error layer 60b is a perspective relationship with the wave front aberration shown in Figure 17, similar to FIG. 16, the wave front aberration of the standard deviation of the exit pupil plane is used WFErms λ represents a wavelength of light to represent. 在图17中,在根据光透视层60b的厚度误差移动准直透镜62的情况下,实线A4表示光透视层60b的厚度误差与波前象差之间的关系,用虚线A5表示对波前象差进行校正的情况。 In FIG 17, in a case where the thickness of layer 60b error ray collimator lens 62 is moved, as a solid line A4 shows the relationship between the thickness error in the optical layer 60b is a perspective wavefront difference of the wave represented by a broken line A5 front aberration correcting situation.

参见图17,如果光盘60的光透视层60b没有厚度误差,这一光学系统中的波前象差大约是0.003λ。 Referring to Figure 17, if the optical disc 60 is a perspective layer 60b has no thickness error, the aberration of the optical system of the wavefront is about 0.003λ. 从图17中可见,如果根据光透视层60b的厚度误差来移动准直透镜62,就能够明显地抑制由于光透视层60b的厚度误差而产生的波前象差。 Seen from FIG. 17, if the collimator lens 62 is moved according to the thickness error in the optical layer 60b is a perspective view, it is possible to significantly inhibit the wave aberration due to the thickness error in the optical layer 60b is a perspective front generated. 具体地说,如果按照公式(14)来移动准直透镜62,波前象差就能受到抑制:ΔL≈14Δt ...(14)与光透视层60b的厚度变化无关。 Specifically, according to the equation (14) to move the collimator lens 62, wavefront aberration can be suppressed: ΔL≈14Δt ... (14) independent of the layer thickness variation of ray 60b.

在以上的公式(14)中,ΔL是准直透镜62的移动量,其正方向是准直透镜的移动方向,而Δt是光透视层60b的厚度误差。 In the above formula (14), [Delta] L is the amount of movement of the collimator lens 62, which direction is the positive direction of movement of the collimator lens, and Δt is the layer thickness error ray 60b.

同时,如果按照例1或2的方式移动准直透镜,在透镜之间有可能产生偏差,或者是有可能在透镜表面上出现倾斜现象。 Meanwhile, if the movement of the collimator lens according to Example 1 or 2, the deviation between the lens may occur, or there may occur the phenomenon of inclination on the lens surface. 这种偏差或是倾斜会造成彗形象差或是球面象差。 This bias or tilt will cause coma or spherical aberration. 如果彗形象差或是球面象差急剧增大,系统就会发生故障。 If coma or spherical aberration increases rapidly, a system failure occurs. 由于在准直透镜上入射光一侧的数值孔径NA很小,例1或2的光学系统不容易在透镜之间造成偏差或是透镜表面的倾斜。 Since the numerical aperture NA of incident light on the small side collimator lens optical system of Example 1 or 2 is not likely to cause deviation or tilt between the lens surfaces of the lens. 具体地说,大约30μm的偏差或是0.1°左右的透镜表面倾斜在实际使用中不会给光学系统造成问题,因为此时的彗形象差或是球面象差是很小的。 Specifically, a deviation of approximately 30μm or the lens surface inclination of approximately 0.1 ° in practical use will not cause problems to the optical system, because the coma or the spherical aberration is small.

Claims (15)

1.用于信息记录媒体的一种光头,在信息记录媒体上用来记录信息信号的记录层上面具有一个光透射层,这种光头包括:一个用来发光的光源;一个物镜,用来通过上述光透射层将来自上述光源的光会聚到上述记录层上;设置在上述光源和物镜之间的一个具有预定折射率的光学元件;以及根据上述光透射层的厚度来移动上述光学元件的一个移动装置,该移动装置包括:一个与从光源射向光学元件的光的光轴基本上平行的参考轴;用来支撑上述光学元件并且能够沿着上述参考轴移动的光学元件支撑装置;一个电机;以及一个传动装置,用来将电机的转动转换成平行于上述光轴的平移运动,并且将这种平移运动传递给上述光学元件支撑装置;上述传动装置将电机的转动转换成平行于上述光轴的平移运动,用来移动上述光学元件支撑装置,进而使上述光 1. An optical head for information recording medium, the recording medium on the information recording layer for recording signal information above having a light transmitting layer, the optical head comprising: a light source for emitting light; an objective lens for passing light converging the light transmissive layer from the light source onto the recording layer; optical element is provided having a predetermined refractive index between the light source and the objective lens; and moving one of the optical element according to the thickness of the light transmission layer mobile device, the mobile device comprising: a reference axis with the optical axis of light from the light source toward the optical member substantially parallel; for supporting the optical element and said reference element is movable along the optical axis of the support means; a motor ; and a transmission means for converting rotation of the motor is parallel to the optical axis of translational movement, and transmits this translational movement of the support means to said optical element; and the actuator motor into rotation parallel to the light translational movement of the shaft for moving the optical element support means, thereby enabling the light 元件发生移动,从而根据上述光透射层的厚度来消除球面象差。 Element moves, thereby eliminating spherical aberration according to the thickness of the light transmission layer.
2.按照权利要求1的光头,其特征是上述光头中的光学元件是一个准直透镜。 2. The optical head as claimed in claim 1, characterized in that said optical head in the optical element is a collimator lens.
3.按照权利要求1的光头,其特征是上述光透射层的薄膜厚度不大于0.47mm,并且上述物镜的数值孔径NA不小于0.65。 3. The optical head as claimed in claim 1, wherein the film thickness of the light transmissive layer is not greater than 0.47mm, and the numerical aperture NA of the objective lens is not smaller than 0.65.
4.按照权利要求1的光头,其特征是上述光头进一步包括一个双轴驱动器,用来在沿着光轴的方向和与其垂直的方向上移动上述物镜。 4. The optical head as claimed in claim 1, wherein said optical head further includes a biaxial actuator used in a direction along the optical axis and a direction perpendicular thereto for moving the objective lens.
5.按照权利要求4的光头,其特征是上述双轴驱动器是一个鼓轮,它可以绕着与物镜的光轴平行的一个轴转动,并且可以沿着上述轴滑动,上述双轴驱动器可以用来支撑物镜。 5. The optical head as claimed in claim 4, wherein said biaxial actuator is a drum, which can be rotated about an axis parallel to the optical axis of the objective lens, and can slide along the shaft, the biaxial actuator can be used to support the objective lens.
6.按照权利要求1的光头,其特征是上述双轴驱动器使上述光学元件在沿着光轴的方向上朝着消除光透射层的厚度变化所产生的球面象差的方向移动。 6. The optical head as claimed in claim 1, wherein the biaxial driver causes the optical element in a direction along the optical axis direction towards the elimination of the light transmission layer thickness variation of the spherical aberration generated by the movement.
7.按照权利要求1的光头,其特征是输出激光的波长不大于650nm。 7. The optical head as claimed in claim 1, wherein the wavelength of the output laser beam is not greater than 650nm.
8.一种记录和/或复制装置,用来在一种信息记录媒体的记录层上记录和/或复制信息信号,在这种记录媒体上还有一个光透射层,该装置包括:用来检测上述光透射层厚度的厚度检测装置;以及一个用于信息记录媒体的光头,在信息记录媒体上用来记录信息信号的记录层上面具有一个光透射层,这种光头包括:一个用来发光的光源;一个物镜,用来通过上述光透射层将来自上述光源的光会聚到上述记录层上;设置在上述光源和物镜之间的一个具有预定折射率的光学元件;以及根据上述厚度检测装置检测到的上述光透射层的厚度来移动上述光学元件的移动装置,该移动装置包括:一个与从光源发出并且落到光学元件上的光的光轴基本上平行的参考轴;用来支撑上述光学元件并且能够沿着上述参考轴移动的光学元件支撑装置;一个电机;以及一个传动装 A recording and / or reproducing apparatus for recording on a recording layer of an information recording medium and / or reproducing information signals on a recording medium in which there is a light transmitting layer, the apparatus comprising: means for detecting the thickness of the light transmission layer thickness detection device; and an optical head for information recording medium, the recording medium on the information recording layer for recording signal information above having a light transmitting layer, the optical head comprising: a light emission for a light source; an objective lens for passing the light from the light transmitting layer converges the light source onto the recording layer; disposed between the light source and the objective optical element having a predetermined refractive index; and the above-described thickness detecting means detected thickness of the light transmitting layer of the optical device to movement of the mobile element, the mobile apparatus comprising: a light source emitted from the reference axis and the optical axis of light falls on the optical element is substantially parallel; for supporting the above-described the optical element and the optical element support means is movable along the reference axis; a motor; and a drive means 置,用来将电机的转动转换成平行于上述光轴的平移运动,并且将这种平移运动传递给上述光学元件支撑装置;上述传动装置将电机的转动转换成平行于上述光轴的平移运动,用来移动上述光学元件支撑装置,进而使上述光学元件发生移动,从而根据上述光透射层的厚度来消除球面象差。 Set, for converting rotation of the motor is parallel to the optical axis of translational movement, and transmits this translational movement of the support means to said optical element; the power transmission means converts the rotation of the motor is parallel to the optical axis of translational movement for moving the optical element support means further moved so that the optical element, thereby eliminating spherical aberration according to the thickness of the light transmission layer.
9.按照权利要求8的记录和/或复制装置,其特征是上述光学元件是一个准直透镜。 9. The recording and / or reproducing apparatus according to claim 8, wherein said optical element is a collimating lens.
10.按照权利要求8的记录和/或复制装置,其特征是上述光透射层的薄膜厚度不大于0.47mm,并且上述物镜的数值孔径NA不小于0.65。 10. The recording and / or reproducing apparatus according to claim 8, wherein the film thickness of the light transmissive layer is not greater than 0.47mm, and the numerical aperture NA of the objective lens is not smaller than 0.65.
11.按照权利要求8的记录和/或复制装置,其特征是上述光头进一步包括一个双轴驱动器,用来在沿着光轴的方向和与其垂直的方向上移动上述物镜。 11. The recording and / or reproducing apparatus according to claim 8, wherein said optical head further includes a biaxial actuator used in a direction along the optical axis and a direction perpendicular thereto for moving the objective lens.
12.按照权利要求11的记录和/或复制装置,其特征是上述双轴驱动器是一个鼓轮,它可以绕着与物镜的光轴平行的一个轴转动,并且可以沿着上述轴滑动,上述双轴驱动器可以用来支撑物镜。 12. The recording and / or reproducing apparatus according to claim 11, wherein said biaxial actuator is a drum, which can be rotated about an axis parallel to the optical axis of the objective lens, and can slide along the axis of the biaxial actuator may be used to support the objective lens.
13.按照权利要求8的记录和/或复制装置,其特征是上述双轴驱动器使上述光学元件在沿着光轴的方向上朝着消除光透视层的厚度变化所产生的球面象差的方向移动。 13. A recording and / or reproducing apparatus according to claim 8, characterized in that the direction of the driver causes the biaxial optical element in the direction along the optical axis towards the elimination of layer thickness variations rays generated by the spherical aberration mobile.
14.按照权利要求9的记录和/或复制装置,其特征是输出激光的波长不大于650nm。 14. A recording and / or reproducing apparatus according to claim 9, wherein the wavelength of the output laser beam is not greater than 650nm.
15.一种用来检测设在信息记录媒体的一个记录层上的光透射层厚度的检测方法,在上述记录层上适合记录信息信号,该方法包括:从一个光源发光;用一个物镜将上述光源发出的光会聚到上述信息记录媒体上;用一个用来检测聚焦误差信号的光电检测器来接收由上述物镜会聚到上述信息记录媒体上并且从上述信息记录媒体上反射的返回光,并且根据上述光电检测器反射的返回光和上述光透射层的表面反射的返回光产生的上述聚焦误差信号中的信号部分检测出上述光透射层的厚度。 15. A method for detecting a thickness of the light transmission layer provided on a recording layer of the information recording medium is detected, for recording an information signal on the recording layer, the method comprising: emitting from a light source; an objective lens with the above converging the light emitted from the light source to the information recording medium; detecting a focus error signal for a photodetector to receive converged by the objective lens to the information recording medium and the return light reflected from the information recording medium, and in accordance with above the photodetector reflected return light and the surface of the light transmitting layer signal portion returns to the focus error signal detected by the light generation of the light transmission layer thickness reflective.
CN 99102974 1998-01-09 1999-01-09 Optical head, recording and/or reproducing method, and method for detecting the thickness CN1118798C (en)

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Publication number Priority date Publication date Assignee Title
KR100657247B1 (en) 1999-11-30 2006-12-19 삼성전자주식회사 Objective lens for high density optical condensing and optical pickup apparatus employing it and optical disk
CN101221782B (en) 2002-02-26 2010-09-22 松下电器产业株式会社 Optical element and optical head device using the same
US7254107B2 (en) 2003-04-07 2007-08-07 Matsushita Electric Industrial Co., Ltd. Optical head and optical recording and reproducing apparatus
CN100401394C (en) 2004-12-06 2008-07-09 上海乐金广电电子有限公司 Optical picking system
KR100675863B1 (en) 2005-01-24 2007-02-02 삼성전기주식회사 Optical pick-up device
CN100545924C (en) 2005-04-21 2009-09-30 松下电器产业株式会社 Optical head and optical information recorder/reproducer
CN101401156B (en) 2006-03-29 2011-07-27 三菱电机株式会社 Lens driving device, optical pickup device and installation adjusting method

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