TW200809825A - Optical pick-up unit for use in a multi-disc optical player - Google Patents

Abstract

An optical pick-unit unit for scanning a record carrier having at least one information layer, wherein the record carrier is first type of record carrier and/or at least a second type of record carrier, the optical pick-up unit comprising: at least one radiation source; at least one objective lens; at least one first optical element changeable between a first state and at least a second state; at least one second optical element with at least one structured surface for providing a wavefront aberration compensation comprising a polarization sensitive material, the structured surface having annular zones, each annular zones having a width, the annular zones forming a first stepped profile having a pattern of steps, wherein each step comprises additionally to the width of the width of the annular zone forming the step, a height. The structured surface comprises at least a second stepped profile with a number of steps forming the pattern of steps, wherein the first stepped profile and the at least second stepped profile are separated by an annular zone and the number of steps forming the pattern of steps of the first stepped profile and the number of steps forming the pattern of steps of the second stepped profile are equal in order to form at least one repetitive pattern of steps.

Description

200809825 IX. Description of the Invention: [Technical Field] The present invention relates to an optical pickup unit having at least a record carrier of an information layer, wherein the record carrier has one according to the request i A first type of record carrier of the first format and/or at least one second type of record carrier having a second format. The invention further relates to an optical disk drive having such an optical pickup unit. The invention further relates to an optical component having a structured surface. The invention further relates to a method of compensating for wavefront aberrations when scanning a first type of record carrier and a second type of record carrier. [Prior Art] This optical pickup unit is known from WO 03/049095 A2. There is a need in the art to provide an optical scanning device, an optical storage device of the so-called optical pickup unit (OPU), for scanning various types of optical record carriers, particularly for record carriers having a south information density, such as Blu-ray Disc (BD format), diversified digital disc (dvd-format), high-density diversified digital disc (HD-DVD-format) and optical disc (CD-format). Each of the aforementioned 4 has a different entity setting of the record carrier in order to achieve a different information storage density', in particular a different information layer depth. Scanning an information layer means reading information from the information layer and/or writing information on the information layer and/or erasing information from the information layer of the record carrier. Information density refers to the amount of information stored in each unit area of the information layer. A record carrier comprises a substrate with a reflective layer, at least one information layer 118305.doc 200809825 and a cover layer as generally described, which is generally a transparent layer made of a polymer, in particular polycarbonate (pc) ). The λ layer depth refers to the distance of the information layer from the surface of the record carrier into which a radiation beam is incident. Different types of record carriers have overlays of different thicknesses. For example, the HD DVD has a cover layer d = 〇 · 6 mm, wherein the record carrier has a cover layer cH ΐ · ΐ mm. Therefore, the depth of the information layer is different because the record carrier has different coverage thicknesses, especially HD_DVD and BD. The record carrier having more than one information layer image is a double layer BD, and the information layer of different information layer depths is included according to one interval between the layers of the poor layer. First, the information density can be increased by using a two- or three-layer record carrier, for example, the two-layer BD. Secondly, the information density can be increased by reducing the size of the radiation spot, which is called the scanning point, by scanning information from the information layer or from the information layer. The size of the scanning point depends on the wavelength λ of the radiation beam forming the scanning point and the numerical aperture NA. The size of the scan point can be reduced by increasing the numerical aperture NA&/or decreasing the wavelength λ. In an optical scanning device for scanning these types of record carriers, 'two types of blue lasers of wavelength λι = 780 nm, human 2 = 650 nm and human 3 = 405 nm are used. The minimum wavelength λ3 = 405 nm is used to scan the high-density information storage record carrier, such as HD-DVD, dual-layer BD and BD record carrier. The broom device for brooming HD-DVD operates on a numerical aperture ΝΑ-〇·65 and 3 record carrier having a cover layer thickness of 6 nm. 0 118305.doc 200809825 However, the scan BD record carrier The scanning device operates under a numerical aperture ΝΑ = 0.85 and a record carrier having a blanket thickness d = 0.1 nm. The optical pickup unit generally includes at least one radiation source that radiates at least one radiation beam, at least one beam splitter, and at least one objective lens that forms a scan spot by at least one radiation beam, and directs the scan spot to the δίΐ Floor. The light beam propagates along the optical axis of the optical component through the optical axis disposed along the optical axis of the optical pickup unit, and the scanning spot is scanned into the information layer or from the information The layer sweeps the seedlings for this information. The lightning spot is reflected by the reflective layer, propagates along the optical axis, and is guided by the optical splitter to a detecting component to detect the reflected scanning spot. In general, after a grating element is disposed in the radiation source, the radiation beam is split into two radiation beams to perform a focus error correction and a tracking error correction. It should be understood that the three radiation beams are correspondingly propagated through the optical pickup unit and are also measured by the detection element. The focus and tracking error correction can be performed using the measured signal transformed into an electrical signal. Depending on the numerical aperture of the objective lens and the thickness d of the cover layer of the different types of record carriers, a different amount of wavefront aberration, particularly the spherical aberration, occurs at the scanning spot. In order to perform one of the wavefront aberrations, different solutions have been proposed. An optical scanner # is proposed in WO 03/060892 A2, US 2005/0063282 A1, US 2005/0163015 A1 & us 2〇〇5/〇122883 Ai for scanning different information densities, in particular having 118305.doc 200809825 The record carrier with the depth of the information layer. SUMMARY OF THE INVENTION The disclosed optical scanning device includes a radiation source for emitting three radiation beams, at least one objective lens system for directing the scanning spot to the individual information layers. The record carriers to be scanned have different information layer depths. An optical component included has a diffractive structure called a phase structure with a non-zoneic class profile. The optical component includes a birefringent material that is sensitive to the different polarizations of the radiation beam. The level profile of the surface of the optical element is designed to extract the wavefront modification to the individual radiation beams, wherein the amount of the wavefront modification is different for each of the radiation beams having different wavelengths. WO 03/049095 A2 discloses an optical scanning device for scanning two different types of record carriers, in particular using a double layer Bd with a wavelength of λ = 405 nm and a BD record carrier. The optical scanning device disclosed includes a single radiation source that emits a radiation beam having a wavelength of 405 nm and an optical device comprising one of a birefringent material having a diffraction structure. a surface for compensating for the wavefront of the spot of the sweeping field in order to scan the double-layer BD record carrier for the fact that the objective lens is optimized to the depth of the information layer of the single-layer BD Aberration. This solution is not suitable for the compensation of the aberrations caused by the chopping during the scanning of a BD and an HD-DVD, because the information layer ice of the BD and HD-DVD record carriers is compared to the double layer BD and the BD. The fact that the information layer of the record carrier is very one and seven. Therefore, in the case of the BD and the HD-DVD record carrier H8305.doc 200809825, the wavefront aberration to be compensated for is very high. Accordingly, it is an object of the present invention to provide an optical pickup unit of the type mentioned at the outset which is capable of compensating for recording carriers that scan such carriers, such as BD, HD_DVD, CD and two; Pre-aberration.

One of the objects of the present invention is an optical disc cartridge capable of scanning different types of record carriers such as 2〇 and HD_DVD, DVD, and the like. A further object of the present invention is to provide a method for wavefront aberration compensation in an optical pickup unit that scans different types of optical carriers. According to one aspect of the invention, the object is achieved with reference to the light-forwarding unit mentioned at the outset, since the structured surface comprises at least a second-order shape with a second-order class of a formation-class pattern, Wherein the Pth white level profile and at least the second class profile are separated by an endless belt, and the number of classes of the first class profile is equal to the number of classes of the second class profile to form at least one Repeated class pattern.

In accordance with the present invention, in order to understand the function of a structured surface, the principle of operation of the optical pickup unit (OPU) is briefly described below. The optical pickup unit is adapted to scan a first type of record carrier and/or at least a second type of record carrier, wherein the first type of record carrier, in particular a BD, has a first format, and the second A type of record carrier, in particular a HD-DVD has a second format. The first type of record carrier and the second type of record carrier have overlay layers of different thicknesses resulting in a different depth of the layer. The numerical aperture NA of the OPU is also different: BD 118305.doc -9- 200809825 is ΝΑΒΟ=0·85 and HD-DVD is NAHD_DVD=〇.65. The information layer of each record carrier may include a groove and a land between adjacent grooves, and the distance between adjacent grooves in # differs depending on the type of record carrier. The radiation beam in the diffracted radiation beam is focused on the first or the first optical pickup unit comprising at least one radiation source, preferably a semiconductor laser 'radiation-having-better wave=405 nm a light source, wherein the radiation beam propagates along an optical path. The optical pickup unit further includes a grating element for receiving the radiation beam to generate an η s = diffracted radiation beam and at least a first and a first order diffracted radiation beam, referred to as an auxiliary radiation beam, when the radiation When the beam passes through the grating element, where 1 and 1 are not equal to η. The n-th order diffracted radiation beam and the -f signal layer i' of the mth and third order record carriers are formed to form a broom spot of the first-order diffracted beam. The nth order diffracts the light spot of the light beam to focus on the land or groove from which the broom information is viewed. The claw and the first! The sequential diffracted radiation beam can be focused on the adjacent groove or lands, or the trowel can be focused on the transition from the lands to the grooves, depending on the type of record carrier that sweeps the cat. The broom spot (4) the information is on the information layer of the record carrier, or the information layer of the record carrier is scanned for the information, wherein the third and the _ Perform this focus error with vertical and/or radial misalignment. The mark or recess in the groove, the radiation beam of the root is adjusted during the reading due to the lands of the information layer or according to the information on the record carrier, the reflection H8305.doc -10- 200809825 changes. The reflected radiation beam and the reflected auxiliary beam pass through a further optical component, for example, a quarter-wave plate and a collimating lens, before being directed to a detecting element. The detecting component includes detecting component components for detecting the primary radiation beam and the auxiliary radiation beam. Herein, the detecting element component is converted into a light-restricting element component of the electric signal by the (four) measured n-beam. The electrical signal is supplied to a focus error preamble 4 which produces a focus error signal and a whip error signal. If the sweep spot is not in the desired position, the error signals are used to adjust the optical components within the optical pickup unit. Preferably, the detecting element comprises at least three light quadrant detecting element parts. Each light image limiting element part has a photosensitive surface for detecting the incident radiation beam. The beam is focused by the cover layer of thickness d on the 5th layer of the record carrier. The radiation beam is formed by the radiation beam, which is called the objective lens of the sweeping field to compensate for the spherical aberration caused by the cover layer, because the broom spot in the information layer is generally Department) Aberration. The optical pickup unit includes a first optical element that is changeable between a first evil and at least a second state. In order to perform compensation for the wavefront aberration occurring at the sweeping point due to the difference between the first and the second type of record carrier and the second type of recorder U layer/woodness, ': two polarization sensitive material And having a - structured surface - the second optical element is included in the radiation path of the radiation beam (four). Preferably, the optical component with the structured surface is included in the optically separated component: 118305.doc 200809825 is another polarization beam splitter, and at least the objective lens. The structured surface includes an angular region having a width in which a class profile having a class pattern is formed, wherein the width of each class is formed by the corresponding angular region. Each adjacent class has a height; the class combination to a class external shape forms the height of the class shape. According to the invention, the structured surface comprises at least two class profiles having a plurality of classes forming a class pattern, wherein the first class profile and at least the second class profile are separated by an endless belt and form the The number of classes in the class pattern of a white, 'and outer scorpion' is equal to the number of classes that form the class pattern of the second class. By this, it is helpful to have a repeating class pattern formed by the two class shapes. Therefore, the repeating class pattern forms a periodic diffraction structure. Herein, the boundary of the class outline is arranged in a radius configuration in which the aberration function is equal to an integral multiple λ. Because of the polarization sensitive material of the second optical component, whether the diffractive structure of the second optical component affects the radiation beam is dependent on the polarization of the radiation beam. In the optical path of the laser beam, a different wavefront aberration is added to each optical component to the radiation spot. The pattern of the level of the level, also known as the phase, can be made effective for one polarization direction, and is obliquely ineffective for the other orthogonal polarization direction because it is observed for the polarization and the orthogonal polarization. The refractive index..., according to the class shape of the present invention, a: by a preferred embodiment,

118305.doc embodiment, at least providing a class pattern of further class shape and a class pattern of the second class shape -12-200809825: the number of levels forming at least one of the class classes having at least the same number of classes with repetitions The class shape of the structured surface. »Xuanguang to 7L pieces t At least one structured table Φ contains three class shapes with the same number of classes of the class pattern. The at least-structured surface of the optical element relating to the pupil of the objective lens can then be divided into a plurality of regions 'per-region consisting of a class profile, which means that the class profile contains the same number of classes, each class Has a height. The amount of wavefront aberration introduced into the radiation beam by the number of the class in the optical element, and the height and width of the selected class are different in the scanning spot. The wavefront aberrations that are introduced will be briefly explained later: One of the radiation beams propagating along an optical path has a wavefront W with a predetermined shape, which is provided by the following equation: W = soil λ 2π where ' λ The wavelength of the radiation beam, and φ is the phase of the radiation beam. In each optical component through which the radiation beam passes, a wavefront aberration Wabb is introduced because in practice the optical component is imperfect. The wavefront aberration for a circular aperture can be described by a so-called Zernike P〇lynomial, which represents a complete set of surface deformations, by which an arbitrary wave aberration can be expanded into a discrete shape of a fixed size. This makes it possible to classify the wavefront image and to quantify the surface deformation. The nickname 118305.doc -13 - 200809825 is based on the exit of the optical component. The output of the optical component is 0 4 卞心出口九目 and the polar coordinate containing a radius term R(r) m , ^ K and a term dependent on the azimuth φ, by: Ζ:(^φ) = Κ- sin(m^) f〇r m>〇cos(m^) f〇r /72 < 〇 1 for m = 〇5 where the aperture is normalized, so (d)...i, and the azimuth φ is measured counterclockwise in the X-axis. x=r.c〇s +, ynh is small. These indices nh represent individual radial orientation sequences. These indices are due to the conventions used and are confused with the η and m of the diffracted light beam of the first reading. For example, the first-order wavefront aberration is a wavefront tilt or distortion, the second sequential wavefront aberration field and (4), the aberration and curvature, and the third-order wavefront aberration is a spherical aberration. The spherical aberration is the wavefront aberration of the fourth order. The defocus and spherical aberrations are circularly symmetrical, and because of the point on the optical axis, the symmetrical object points occur, which indicates that they are dependent in any direction perpendicular to the plane of the optical axis. - the introduction of an optical element having an optical axis within the optical path of the radiation beam causes an additional wavefront aberration &' and thereby causing a wavefront modification within the radiation beam to modify ΔΙ. From the depth of the information layer—the deviation of the design value—the specific information layer=degree of the broom spot on the information layer of the record carrier will be (4) surface aberration. For example, f' can be compensated for by introducing a phasefront aberration with the opposite spherical sign of the radiation beam (4) towards the depth of the information layer. The wavefront modifies the crocodile's shape and may be modified by one of the shapes of the first, second, or second order, or a continuous phase change in the radiant beam may be introduced. A fixed phase change means that the resulting wavefront is fixed after modifying the coefficient 2π of the AW before the wave is taken. The phase change ΔΦ of the radiation beam is provided by the following equation: · The optical component compensates for the amount of wavefront aberration introduced by the objective lens, especially the spherical aberration'. This aberration is for the BD record carrier and the HD-DVD record. In terms of the carrier, the information layers of different types of record carriers on the spot of the sweeping seed are different in depth. The difference in the spherical aberration is obtained from 2 31 μηη=1 16 λ rms. The corresponding peak value of the aberration function is estimated to be 3 · 9 in. The difference between the compensated spherical aberration amounts is between two levels of a double-layer BD, about 10 Γηλ/μιη·25 μιη=0_25 λ rms, which causes one of the aberration functions of about 〇·84 λ to correspond. The peak of the peak. A suitable diffraction structure-aperiodic structure with a sharp peak aberration less than λ is produced. For example, the order of the class height of the annular band is not a repeating sequence. This non-periodic diffraction structure is described in WO 03/G49G95 Α2. In order to correct the difference λ between the two spherical aberrations between the two types of record carriers, a non-periodic phase structure is not preferred, especially when the broom of the first and second types of record carriers The wavelengths are approximately the same, for example, on broom BD and HD_DVD. Thus the second optical element performing the compensation of the wavefront aberration needs to comprise a different structure, in particular a periodically structured surface. For the sweeping coffee and HD_DVD, the aforementioned periodic structuring 118305.doc -15-200809825 surface has a repeating at least two-stage shape that is helpful. Polarization sensitive materials, such as birefringent materials, affect the material of the laser beam as it passes. - An optical component made of a polarizing material that has a different effect on the beam. For example, the polarization-sensitive material used for the optical element may be a material that polymerizes and/or crystallizes, or a liquid crystal polymer. The polarization describes the plane of polarization for the electric field vector E of the direction of the propagation of the radiation beam, which is the optical axis. Polarization describes the light beam having an electric field vector relative to the direction of propagation of the light beam, which is generally the optical axis. a first-polarization system with respect to a first-oriented radiation beam of the electric field vector and a second polarization system having a first-order radiation beam, wherein the first orientation is generally orthogonal to The first direction. The polarization of a beam of light can be modified by an electro-optic element: whether the polarization changes, depending on the state of the electro-optic element. The radiation beam that excites the electro-optic element in the first state has a dipole-polarization relative to the light beam that excites the optoelectronic component in the second state - it has - unlike the first polarization Second polarization. According to a preferred embodiment of the invention, the pattern of the class comprises at least three classes 'where the class profile has a first height. These archaeological rates n are obtained from the equation: Φ

The λ degree h and the influence of the class, and the material on the corresponding phase: Depending on the polarization of the radiation beam incident on the optical element, η may be HB305.doc -16- 200809825 "Material of the optical component Anomalous refractive index) or n (the normal refractive index), where η is different from ~. This causes two different corresponding phases for the anomaly and the normal mode: Φ = ^ ' he ------- R And φ = ' D h . 〇------ )

R expresses different amounts of wavefront aberrations of the spotted spot on the individual information layers of the individual record carrier. The ratio of the % of the phase to the scale of the enthalpy is expressed as: ^ = n〇 - 1 φβ , which in practice depends on the material used, which is quite close to 〇·75, which represents 3:4. This implies the use of a class number. For Ν 3, the normal mode can be used to scan the bd record carrier and to detect the abnormal pattern of the HD-DVD record carrier. With the dice, 丨, 2 The heights of the shapes formed by the sum of the heights of the three single classes are derived from: hj-j· η. - 1 whereby the phases for the BD record carrier are integer multiples, And the record carriers for the HD-DVD are a multiple of 8·π/3. This means that the 3 positive $杈 corresponds to the second diffraction order of the class profile of the optical element' and the abnormal mode corresponds to The m-two-1st diffraction order of the class profile of the optical element. The diffraction efficiency for H]>dvd is close to 118305.doc 200809825 27/4·π2==68% 〇 the minimum angular region The corresponding width is approximately η·4 μm. According to a preferred embodiment of the advancement, the pattern of the class contains at least four classes which result in a second height of the class profile. The four classes within the class shape correspond to Han. =4 and 』=〇, 丨, 2, 3, and: 5 one height, so for this BD The phases of the record carrier are integer multiples of 2π, and are used for multiples of the phase system 3π/2 of the HD-DVD. This indicates that the abnormal mode corresponds to the m=〇 diffraction order, and the normal mode corresponds to In the m=l diffraction order, for the HD-DVD, the diffraction is then very close to 8/π2=81% efficiently. The positive aberration function and the height profile of the diffraction structure are drawn. Shown in Figure 4. The aberration function (measured in radius) is derived from: Φ-6 l-224xr2-32.375xr4-9.459xr6-1.209xr8 5 where the radius of the pupil coordinate system is provided in mm. The objective lens has a diameter of 3.0 mm for scanning a BD# record carrier. The effective aperture diameter for scanning an HD-DVD record carrier is then obtained from: 〇·65/〇 ·85·3·0 mm=2.29 mm 因为This is because the aperture diameter of the HD-DVD record carrier is adjusted according to the numerical aperture NA, and the HD-DVD record carrier system is ΝΑ=0·65, And for the BD record carrier system 〇 = 〇 85. The minimum area is the outer area, and has a width of 8 · 5 microns, the preferred class height system 〇 · 5 226 microns, and the maximum class height is 118305.doc -18- 200809825 1_57 microns (for a material with n〇=1 575 and ne=1 775). It can be known that each class shape has a four-class class shape. This results in a higher efficiency than the class with three classes. Compared to a class shape with three classes, the width to be used is small. According to a further preferred embodiment of the invention, the class pattern comprises Classes with different widths. The width of the class affects the overall width of the class's shape. Classes with different widths are useful for joining a width that uses a fixed class number of class shapes. According to a further preferred embodiment of the invention, the wavefront aberration compensation comprises spherical aberration. The spherical aberration occurs especially if the objective lens of the optical recording player focuses the scanning spot on an information layer having an information layer depth different from the depth of the information layer corrected by the objective lens. This occurs in an optical pickup unit that is designed to scan a first type of record carrier having a first format, wherein the first format includes a first information layer depth and is used for scanning one A second type of record carrier having a second information layer depth. Spherical aberrations can be corrected by the addition of additional spherical aberration introduced by the optical element, which comprises a sensitive material and a structured material having a class appearance. A quantity of spherical aberration is adapted to compensate for the wavefront aberration introduced into a radiation beam that has passed through the optical element having a structured surface having a class shape having a class of repetitions. According to a further preferred embodiment of the present invention, the material of the optical element is a birefringent material having a refractive index ne, for the radiation beam having a polarization parallel to the optical axis, And at least a second refractive index η. And for the radiation beam having a second polarization perpendicular to the first polarization, the first refractive index 〜 and the second refractive index η. The difference is caused by the introduction of different amounts of aberrations to the radiation beam, wherein the introduction of the radiation beam with the first polarization is different from the radiation beam with the second polarization. Depending on the polarization of the radiation beam, when passing through an optical component of a birefringent material, birefringence causes the beam of the (four) beam to be split into two rays, an example of the normal ray and the anomalous ray ◊ birefringent material. Calcite crystal, cellophane or liquid crystal. The double birefringence is determined by: Δη, Quantification, wherein if ~ is used for the refractive index of the different ray, n 〇 is used for the refractive index of the normal ray. Both normal and abnormal rays are refracted. It is considered here only in special cases, that is, a class shape. For example, each class represents a phase, which is a multiple of a polarization state 2π, when the optical element is in this first polarization. The second optical device does not have an effect on the beam, but has an absolute influence on the beam when it is in the second orthogonal polarization state. After the polarization beam splitter is configured, the polarization itself is relatively affected by the aforementioned optical element. Therefore, the right-angle polarization is selected, and the additional spherical aberration is introduced into the radiation beam having the second polarization state by the class profile of the optical element. The polarization of the radiation beam having this first polarization state is not affected, which means that no additional spherical aberration is introduced into the radiation beam. Then, an optical component that performs the wavefront aberration, in particular, the spherical aberration is compensated for H8305.doc -20-200809825. According to a further act: bauxite 1> compared to the body embodiment, the first fold second refractive index η. According to one of the seven 仫 仫 & ^ 耵 drought \ and the ^ ^ M #: 〇. 65. (ne „ 1) < (n 〇 _1) < 〇 85 (ne_i) 〇 & And the normal refractive index - having birefringence characteristics for an optical pickup system: calcite, quartz, mechanically stretched polymer film. According to a further preferred embodiment, the birefringent polymer. The liquid crystal polymer phase structure can be pressed into the film by replicating the monomer phase onto the substrate with the mold, and then the structure is fixed by polymerization, such as, for example, ultraviolet light. The illumination can be achieved. The difference in refractive index An = ne-n () is substantially in the range between 〇. 丨 and 〇 3. According to a further embodiment, for the second polarized radiation beam, The amount of spherical aberration is substantially zero. Advantageously, the second optical element is designed to be introduced into the radiation beam passing through the optical element by an amount of spherical aberration of zero. According to a further embodiment, For the first polarized radiation beam, the amount of spherical aberration is substantially zero. A spherical aberration is introduced using a radiation beam with the inverted polarization. Advantageously, the second optical element is designed such that a value of one spherical aberration is introduced into the radiation passing through the optical element. According to a further embodiment of the invention, the optical component is disposed in the optical pickup unit for receiving the first radiant light 118305.doc -21 - 200809825 in a collimated state. The reason for collimating the beam is that the position is preferably fixed relative to the objective lens in order to avoid coma aberration when the (transverse) position of the element is changed relative to the objective lens by, for example, a misalignment. The beam of the objective lens is preferably collimated in order to avoid the change of the magnification for the disc or record = body, which may occur when the axis position of the objective lens is changed to maintain the focus of the scanning spot. According to a further preferred embodiment of the present invention, the optical pickup unit comprises a collimating lens, wherein the second optical element is disposed between the collimating lens and at least the objective lens. A simple method of aiming the radiation beam in front of the optical element with a collimating lens. According to a further preferred embodiment of the present invention, the first objective lens of the optical pickup unit 匕a is configured to form a scanning spot. An information layer of the third type of record carrier for obtaining an optical pickup unit for scanning at least three different types of record carriers having different formats. When using one having a first wavelength λι=4〇5 nm When the radiation beam is scanned by BE^HD-DVD, the scanning of the DVD and/or CD is performed using a first wavelength, especially for people 2=780 nm for CD and/or λ3 = 650 nm. In order to know the different types of record carriers, for example, 5, an optical pickup unit comprises three radiation wavelengths λι, ^ and Xin Xingtian source. In order to optimize the formation of the steed light spot on the information layer of a CD and/or DVD, a second objective lens system is preferably disposed in the optical pickup unit. This is due to the fact that the wavelengths of the CD and the DVD, the numerical aperture and the depth of the information layer of 118305.doc -22-200809825 are different from the BD and the HD_DVD, and therefore an objective lens is required to correct the different amounts. Spherical aberration. In accordance with a further preferred embodiment of the present invention, the at least one objective lens can be loaded within the actuator to mechanically change the position of the objective lens relative to the depth of the information layer of the record carrier. When the record carrier is broomed, the focus error correction detects the focus of the sweeping cat spot by using the debt test, and adjusts the position of the objective lens to perform the operation. The adjustment of the position of the objective lens relative to the depth of the information layer of the record carrier is substantially mechanically performed by an actuator. A standard part inside. The radiation beam on the optical pickup unit includes the actuator as the optical pickup unit. According to a further preferred embodiment of the present invention, u 3 is used to introduce a further optical component of the information layer directed to the record carrier. .

An increase in defocusing to the aberration function 'the minimum size feature size of the sweeping cat spot' is achievable. By this, the maximum value of one of the slopes of the aberration function can be reduced to increase the width of the strip. And this mouth-minimum 裱5 加入 join the defocus increase HD-DVD freedom, Xuan & the spherical aberration of the Jing, and the simultaneous free running distance, ❹ 5, about 14 microns extra φ = 102 55" 杬The aberration function is: 2-r'28-1 18-4-9.368.r6-i.633.r8, 118305.doc -23 - 200809825 where the aberration function is not (4) previously mentioned mainly as the first _ _ name, which is a function of the defocus name. The optimal defocus spherical aberration ratio A2A is derived from the following aberration function: w-A40(6p4-6p2+l)+A20(2pM) ,

Among them, the amount of Zernike-type spherical aberration a4〇 is fixed, and the amount of the Nick type defocusing is variable. In the normal body of the W system, the radial variable P is defined as the ratio between the radial variable r and the pupil half control, so the value is: 0 < ρ < This goal is to minimize the slope value in the range 〇<p<1 to use the absolute value. According to the ratio of 〇8〇/八四〇, this maximum value is found when the edge of the pupil is p=l, or 疋 is at the local extreme of the law. Next, the following relationship is obtained: dw = 24A4〇p3 + (4A2〇 ^ 12A4〇)p and d2W ... 2 = +4 are ❶12. . By this, the local extremum is tied to:

P Τβ

-3A4Q" is supplied to: dW 8 该 The slope value at ρ = 1 is: dW φ ^ 12A- Ά 1 + 3A4 〇 J. The absolute values of the two slopes are equal if: 118305.doc -24- 200809825 8 3/2 "7? - 1 - 20 L 3Α4〇_ =12 1 -f L 3A40 It is for this answer if: △20 One by one 3 A4〇2 〇 By this, the aberration function is derived from:

W = A 40 6p4 — 9p2 + at: and the maximum absolute value of the slope is

dW

6A 40 degrees, with a class shape of N classes and a radius of a followed by a maximum width of the minimum diffraction ring from:

a 〇 A better design of the class shape is a = 115 mm, n = 4, and eight 40-^/5 parent 1.16 = 2.59 and ~_ = 18.4 microns. As discussed earlier, this can be helpful by adding a defocusing implementation. In a further preferred embodiment, the optical pickup unit comprises at least a second radiation source radiating a radiation beam having a second wavelength λ2 for recording at least a third type having a third format Carrier. The optical pickup unit is suitable for scanning CD, DVD, BD and HD-DVD record carriers. The optical element comprising a birefringent material is designed to push the periodic operating gap from the BD to the HD-DVD. In order to scan the record carrier of one of the record carriers of the type 118305.doc -25- 200809825, in particular a cd, possess one of the quality qualities of the scanning spot, when the same objective lens is used for two At the wavelength, the class shape of the structured surface of the optical element will negatively illuminate the quality of the spot. Therefore, the optical pickup unit that can bounce the four types of record carriers includes a light beam having a wavelength suitable for scanning a CD, and a second objective lens is coupled to the second type. The depth of the information layer of the record carrier, that is, the disc. Therefore, one of the optical pickup units capable of scanning the aforementioned four types of record carriers includes a radiation source having a wavelength suitable for scanning a CD, and a second objective lens coupled to the record carrier, that is, the CD. The depth of the information layer of the three types. According to a further preferred embodiment, the individual objective lens can be loaded into an actuator to mechanically change the position of the objective lens relative to the depth of the information layer of the record carrier. In each of the standard optical pickup units, the objective lens is loaded in the actuator for performing the focus error correction and/or the vertical error correction. According to a further preferred embodiment of the invention, the optical element is coupled to the first objective lens. This is helpful because it is somewhat less tolerant for a suitable ring, which is achievable with respect to the objective of the objective. In this paper, the resistance can be evaluated as follows. Regarding the objective lens, one of the optical elements can be added to the ring to add an additional wavefront aberration, that is, the coma aberration expressed by the relationship Α3ΐ = 8χΔχΑ40, Wherein, the lanthanum is the amount of displacement measured in units of the pupil radius. According to 118305.doc -26- 200809825 These RMS aberrations: A, = X 8Δ XA: = x A: Ο For Α3, Μ3<30 πιλ requires a 2RMS aberration, and the appropriate ring must satisfy this relationship: Α <〇·〇〇41, which involves an accuracy of about 4·7 μm for the diameter of a BD for a BD. This accuracy requires high precision fabrication of the optical component and the relative position of the optical component to the objective lens. In accordance with a further preferred embodiment of the present invention, the first and second objective lenses are loaded within the actuator. A further advantage of the relative position of the first objective lens and the second objective lens is that the two objective lenses are movable by the actuator, which reduces the cost of production. The object of the present invention is solved by an optical disk drive comprising the optical pickup unit of the foregoing specific embodiment. The optical drive is suitable for scanning these different types of record carriers, namely CD, DVD, BD and HD_DVD. The use of an optical component that performs the complement of the spherical aberration is due to the difference between bd&hd_dvd.

The asset layer ice allows for an optimized high density record carrier and hd-DVD scan. The use of at least one second source of radiation and a second objective lens additionally allow for the broom of the CD and DVD. The terminology is as described above, further solved by an optical component for providing compensation for wavefront aberrations in an optical pickup unit, wherein the optical component comprises a sensitive material and has a structure 118305 having at least one repeating class profile. Doc -27- 200809825 The surface of the class has a class pattern, and each class has a height and width. In general, the aforementioned optical component can support an optical pickup unit. The optical element herein has all of the characteristics of the features of the optical pickup unit discussed above. With four features, the optical component can introduce a wavefront aberration to the scanning spot of the information layer of the record carrier. The object is also solved by a method for an optical pickup unit of an optical disc drive to perform wavefront aberration compensation when scanning a record carrier, according to a method mentioned at the outset, because of the modification One of the optical features of the at least one optical component of the optical pickup unit is further stepped to compensate for the wavefront aberration in a scan spot by using a wavefront aberration to the scan spot greater than λ, The wavefront aberration is due to the fact that the first information layer depth of the first type of record carrier is different from the second information layer depth of the second type of record carrier. — This is helpful because the spherical aberration introduced into the scanning spot causes a bad broom performance. This is corrected by using the aforementioned method. According to a further preferred aspect of the method, the compensation is based on the polarization of the light beam incident on the optical-to-optical unit, and the spherical image is introduced by a quantity. Poor to: Light point execution. ^ The features to be understood, the features described and the features that should be explained below are not only applicable to the combination of the mentioned persons, but also for other combinations or single use without exceeding the present invention. The scope. 118305.doc -28- 200809825 [Embodiment] Now, the present invention will be described below with reference to additional figures of the drawings in accordance with the specific embodiments. For the convenience of (4), the information storage medium is called a record carrier. The broom information may include writing information to, reading and/or erasing information of one of the record carriers. , Figure! — — 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 光学 概要 光学 概要 光学 概要 概要 概要 概要 光学 概要 概要14 on. According to the present invention, the (four) pickup unit 1G is adapted to scan the i-record on the record carrier 12, which has a high recording density and - a large valley 1 for the recorded information, preferably HD_DVDs (high density diversity) Digital Video Disc) and BD (Blu-ray Disc) A preferred embodiment of the present invention is capable of scanning four types of record carriers: CD, DVD, BD and HD-DVD. The record carrier 12 includes a substrate 24 and a transparent layer. At least one information layer 4 is disposed between them. In the case of a double-layer record carrier, for example, a double-layer BD, two information layers are disposed on the transparent layer, also referred to as a cover layer 18, The record carrier 12 has a different depth and is separated by about a micron. A further transparent layer is not shown here to separate the two information layers. The individual transparent layer, that is, the cover layer, has a different type of record carrier 12 The transparent layer, also referred to as the cover layer 18, has the function of protecting the upper layer of the layer 14 of the upper layer, although the substrate 24 provides the mechanical support 0 118305.doc 29- 200809825 information can be optically detectable Format, save In the information layer 14 of the record carrier 12, the indicia configuration is substantially in the form of parallel, concentric or spiral 'not shown in Figure 1. The indicia can be in any optically readable mode', for example The format of the groove or region with reflection coefficients is either different from the surrounding magnetization direction, or a combination of one of these formats. The different types of record carriers 12 can be distinguished by a different structure of the record carrier 12, That is, the difference in thickness 16 of the cover layer 18 is disposed on the surface 20 of the record carrier on which the radiation beam 21 is incident. The record carrier 12 further includes a reflective layer 22 disposed on the information layer 14 of the record carrier. Between the substrate 24, the first type of record carrier, that is, the HD-DVD typically has a thickness d = 0.6 mm of the cover layer 18, however, the BD record carrier typically has a thickness d of the cover layer. = 0.1 mm. For a further type of record carrier, that is, the double-layer BD record carrier, wherein a second information layer 14 not shown herein is disposed, an additional spacer layer is not shown herein. Separating the two information layers. The distance between the surface 20 of the record carrier 12 and the information layer 14 is called the information layer depth 25. Therefore, the first type of record carrier includes a first information layer depth of 25, And the second type of record carrier comprises a second information layer depth of 25 M. The radiation beam 21 is emitted by a radiation source 26, preferably a semiconductor laser. The radiation beam typically has a wavelength λ = 4〇5纳米0 H8305.doc -30- 200809825 Even in the specific embodiment shown in Fig. 1a and discussed herein, only one source 26 is shown and discussed, according to the present invention, the 〇pu A second and/or third light source may be included which emits a second and/or third radiation beam having a wavelength of =2=78〇N and/or λ3=650 nm for scanning one Different types of record carriers in the optical pickup unit. According to the invention, the radiation source 26 emits the radiation beam 2 1 having a wavelength of 1 == 4 〇 5 nm suitable for scanning HD-DVD and BD record carriers.

The xenon radiation beam 21 enters a diffraction grating element 28, hereinafter referred to as a grating element 28, which converts the radiation beam 21 into a primary radiation beam and at least two auxiliary radiation beams, each auxiliary radiation beam being adjacent to the primary radiation beam. The primary radiation beam and the auxiliary radiation beams are not separately shown here. The primary radiation beam and the two auxiliary radiation beams are used to perform the tracking error correction and/or the focus error correction in the optical pickup unit 10, which will be described later. The diffracted light beam is assigned the reference number 3 以下 below. The n-diffracted radiation beam 30 includes a (fourth) light beam that is diffracted in the ηth order, which is preferably a light-emitting beam that is diffracted in a zero order and a mth and a first order radiation beam, which is preferably a _± - The (four) beam that is sequentially diffracted. It is also possible to select other diffraction sequences of the auxiliary radiation beam for the purpose of implementing the diffracted radiation beam 30. The path == shot + the Han beam 3G propagates along the optical path of the optical pickup unit (four) and passes through the beam splitting element 34. The beam splitter 34 is preferably a cubic polarizing beam splitter 34. The division, and the knife precursor can also be a plate polarizing beam splitter. (4) The transmitted beam 36 is substantially parallel to the incident flat polarization) 118305.doc &gt;31-200809825, and the reflected beam is predominantly perpendicular to the plane of incidence (s-polarization) polarization. The radiation beam 36 that has passed through the beam splitter 34 is guided by an aiming element 38, for example a collimating lens, and directed by an objective element 42 by a reflective element, such as a mirror 40. The crucible pu comprising two objective lenses is also part of the invention. The at least one objective lens 42 focuses the radiation beam 36 onto the information layer 14 of the record carrier 12. Herein, a radiation spot is formed, referred to as a scanning spot 44. The radiation spot 44 is reflected from the reflective layer of the record carrier 12 and propagates along the optical path back to the radiation beam 45, after passing through a cylindrical lens 48, 'reflecting and colliding by the beam splitter 34 The cylindrical lens 48 focuses the returning radiation beam 45 onto the detecting element 46 on an intrusive element 46. The return radiation beam 45 includes the primary radiation beam and the auxiliary radiation beams. The detecting element 46 includes radiation receiving detecting element components 50, 52 and 54, wherein each detecting element component 50, 52 and 54 is provided with at least a radiation sensitive area which converts the incident radiation beam into an electrical signal. A preferred embodiment of the detection element 46 is shown in detail in Figure lb. The detection element 46 generally comprises three types of radiation detecting element components 5, 52 and 54, which are generally quadrant sensing element components having four separate radiation-sensitive surfaces. For example, the four radiation-sensitive surfaces A1 to A4 for the four sensing component parts 50 are shown in FIG. 1b for detecting the four radiation-sensitive surfaces C1 to C4 of the component component 52, and for detecting The four radiation-sensitive surfaces B 1 to B4 of the component component 54 are measured. It is also possible to use a pick-up component part that has only two light-emitting 118305.doc -32-200809825 damage zones or a pick-up component component having more than four light-sensitive areas. On each of the radiation sensitive areas A1 to C4, the electrical signal from which the radiation beam is incident can be used to perform the radial tracking error correction and/or focus error correction. According to the present invention, the optical pickup unit 10 further includes a first optical element 56 that is changeable between a first state and at least a second state, wherein in the first state, the first optical component 56 is A method different from the first optical element 56 in the second state affects the polarization of the first radiation beam 36. For example, the first optical element 56 is an electro-optical element comprising liquid crystal molecules interposed between two transparent planar plates, the transparent planar plates having a conductive transparent layer formed on an inner surface thereof, which forms such An electrode for the liquid crystal, and an electrode having the first optical element 56. The first optical element 56 rotates the polarization of the incident radiation beam by 90 in a first state and does not affect the polarization of the incident radiation in a second state. The first optical element 56 is, in particular, a planar crystal comprising a liquid crystal layer interposed between two transparent planar sheets having a conductive transparent layer formed on an inner surface thereof which forms an electrode of the electro-optic element. Applying a voltage to the electrode allows the electro-optic element to transition from a first state to a second state, and vice versa. The application of this voltage results in the alignment of a liquid crystal single molecule, generally parallel to the optical axis of the objective lens 42. In the second state, the off state is referred to as having no applied voltage, and when passing through the liquid crystal single molecule, the polarization of the incident radiation beam is rotated by 9 。. . In the on state, the liquid crystal single molecule 56 has no effect on the polarization of the radiation beam 118305.doc -33 - 200809825 through the liquid crystal single molecule. Preferably, the liquid crystal layer is relatively thin, typically 4-6 micrometers. Next, the first optical element 56 is capable of transforming the polarization of the radiation beam by the electrodes of the first optical element 56. Piece control, which is not shown here, is preferred in the first embodiment, which has a relative amount of wavefront aberration input signal. Applying an external voltage to the external voltage of the polarization and the second polarization is performed by one of the optical elements in the scanning spot 44. The replacement method is a half-wave plate, which can be mechanically constructed. Rotating around - parallel to the axis of the wire - the angle of greatness. The polarization of the incident radiation beam is unaffected at: 疋 upward, and in this second orientation, the polarization of the incident beam is rotated more than 9 degrees. A further optical component, including a second optical component of the polarization sensitive material, is included in the optical path in front of the objective lens 42. The second optical element 6A comprises, in particular, a birefringent material, such as a liquid crystal polymer component, which aligns its own single molecule along one of the materials of the second optical element. The material of the first optical element 60 has a refractive index: the abnormal refractive index ne and the normal refractive index η. . The refractive index of the birefringent optical element is η due to an incident radiation beam having a polarization perpendicular to the optical axis of the material. And is ne because of an incident radiation beam having a polarization parallel to its optical axis. Then, depending on the polarization of the light beam, the Korean beam is achievable with different optical effects. The optical effect is achieved by the second optical element 60 and includes at least one structured surface having a class profile comprising a ring of a specific width H8305.doc-34-200809825. When the first polarization system is perpendicular to the optical axis, the radiation beam % of a first polarization incident on the optical element 60 has a refractive index n. The diffraction&apos; and the refractive index ne are diffracted when the first polarization is parallel to the optical axis. Then, based on the different information layer depths of a second type of record carrier compared to a first type of record carrier, the wavefront aberration can introduce the radiation beam, such as a spherical aberration, to compensate for the occurring wavefront aberration. . Herein, the distance of the objective lens 42 has been optimized to the information layer depth 25 of the first type of record carrier, the record carrier requiring further introduction of spherical aberration to perform the scanning of the scan of the second type of record carrier beam. Further, a change element 62 is preferred, which is in particular a quarter-wave damper plate. The changing element 62 is interposed between the optical element 6A and the objective lens 42. Here, within the polarization beam splitter 34, the reflection is within a polarization 90 of the incident radiation beam. Rotate. Conclusion The optical pickup unit 1 〇 according to the invention comprises a radiation source 26 ′ radiating a radiation beam, in particular a wavelength of 4 〇 5 nm, an electro-optical element 56 and an optical element 60, wherein the electro-optical element 56 selectively alters the polarization of the 3 s S beam, and the optical element 6 〇 introduces a spherical aberration to the blast beam. The optical pickup unit 10 includes the objective lens 42 mounted within an activator. The actuator mechanically changes relative to a position of the distance to the information layer of the record carrier. Preferably, in a specific embodiment suitable for brooming four different types of record carriers, a second objective lens, not shown, is included in the figure. Figures 2a and 2b schematically illustrate the optical pickup unit. The output of 1〇118305.doc -35- 200809825     only the record carrier, the objective lens 42 and the optical element 60. The reason is not as shown in Figure 2a is about having a numerical aperture να = 〇 · 85 And a BD record carrier having a cover layer thickness of dU mm, and the case in FIG. 2b is for the scan having a numerical aperture ΝΑ=0·65 and a cover layer thickness d=0.6 mm of the hd-DVD record This is the case with the carrier. It is clear that the formation of the broom spot 44 on the information layer 14 of the record carrier 12 is performed by the objective lens 42 and the cover layer 18 having the thickness 16. This is because of the cover layer. 1 8 is a transparent material, for example, a polycarbonate acts as an optical component. Therefore, a distance between an open surface of the objective lens 42 and the information layer 14 is such that it has an information layer depth.纪录6's record carrier optimization system is not suitable for one There is a second type of carrier having a second information layer depth, because the additional focusing of the overlay layer 18 is different. Since the difference of the thickness 16 of the overlay layer between a BD and an HD_DVD disc is about 500 micrometers, It is possible to obtain a scanning spot 44 on the information layer 14 of the second type of record carrier, but the quality of the scanning spot material is therefore different from the second type of record carrier, and in actual cases is insufficient to scan the A second type of record carrier. According to the invention, an additional wavefront aberration, in particular a spherical aberration, is introduced by the second optical element 60, with the radiation beam 36 passing first before being incident on the objective lens 42 A method of the optical element 6 is disposed in front of the objective lens 42. By the conventional -L - a &lt;Tian Tianbiandi first learning element 60, a spherical aberration is introduced into the Koda field beam 3 6 if The polarization of the beam of light beam 36 is the shape of the class, which is not depicted here, and can be explained in Figures 3 to 5, resulting in a diffraction of the radiation beam % a slight 118305.doc -36 - 200809825, resulting in the introduction of the spherical surface Aberration. According to the invention, the package The class outline of the annular band includes at least a repeating class pattern having a specific height 90 and a width associated with the width of the endless belt. Not shown here, but may be explained by principle, an optical may be used Element 60 is designed to have two structured surfaces 61 on opposite sides of the second optical element 60. Figure 3a illustrates the optical element 60 having a class profile 64, 66, 68 and 70, wherein one of the class profiles 64 has a radius The 72-series differs from the radius 94 of the class profile 66. The reference numeral 74 depicts the center of the optical element 6'''''''''''''''''''' In part, the four-class shapes 64, 66, 68, and 70 are shown. It can be understood that in the case of the class shape 64 to 68, each class shape contains the classes 76, 78, 8 and 82' and, in the case of the class profile, includes three classes 84, % and 88. . Each class contains a height, indicated by reference numeral 9〇, and a degree of visibility, indicated by reference numeral 92. The width 92 of a class is indicated by the type of the ring. The endless belt is about an annular region of a particular width 92. The A distance 72 also relates to the radius of the center 74 of the structured profile 64. The radius of the P white outline 66 is represented by the distance 94. The aforementioned distances 72 and 94 are the boundaries of the class profiles 64 and 66, and corresponding to a radius configuration, the mid-m erect positive aberration function is equal to an integer multiplied by the wavelength person. This will be explained with reference to Figures 3, 4 and 5. It can be understood that the class shape 64 '66 and 68 contains four classes, three of which have a turn to be ancient ^ will be Adu 90, and the fourth class has one of 118305.doc -37 - 200809825 one equals zero The height. Thus, the class profile 70 contains three classes: the two orders have a height of 90, and a third class has a height equal to zero. The sum of the 9 degrees south of the corpse-level appearance results in a total of 96'' of the class shape of 6 4, 6 6 and 6 8 and the sum of the heights 90 results in a total height of 96 of the class shape. . Thus, it can be appreciated that the height 96 of the class profile 70 is different from the individual heights of the class profiles 64, 66 and 68. The decision value for the relative phase of the anomaly and normal mode is the height of a single level of 9 〇 because the height 90 (hj) determines the pattern of the diffracted ray of the radiation beam, by virtue of the class pattern Class diffraction. In Fig. 4, an example of a structured surface 6 of the second optical element 60 having seven class shapes having three classes for each class profile can be viewed from a calculated aberration function 100. It can be seen that the class appearance 98 contains a class having a height of one of the individual classes. The same reference numerals are used for the shape of the class, since the class shape has the same white level and is therefore considered a repeating class shape. The widths 92 of the individual classes are different for the purpose of implementing the required distances between the boundaries of the profiles 98 and the center of the optical element 60, 1 , 2, 104, 106, 108, 1 10, 1 12, 1 14. Figure 5 illustrates a further embodiment of the structured surface 61 comprising a second optical element 6 of a seven-stage configuration having a total of six-stage shape ι 6 and a class profile 118. It will be appreciated that the class profile 116 contains four classes 'where the class pattern 118 contains three classes. Once calculated, the disparity function 120 is also not depicted in FIG. 5, wherein the disparity function 12 uses a structured surface η containing the 118305.doc -38-200809825 with the class outline 116 and the class shape ιι8, The second optical element 60 is obtained. The height % of the class profile 118 is less than the degree 96 of the class profile 116, wherein the high ranks of the classes are equal. Figure 6 contains a further embodiment of the structured surface of the second optical component 60, which further includes a class profile 124, wherein each class profile 124 has four classes. It will be appreciated that the profiles 124 The heights of each of these classes are 90 equal, resulting in an equal height 96 for one of the individual class profiles 124, and thus within one of the structured surfaces repeating the periodic structure. Figures 4 and 5 are shown. In 6, the material of the optical element with the structured surface comprises a polarization sensitive material, in particular a birefringent material, which is preferably a liquid crystal polymer. One example for a liquid crystal polymer has A normal refractive index of 11. 1,575 and an abnormal refractive index of =1 775 liquid crystal polymer, which results in a ratio of 0.75, that is, |, which means the use of a number Ν class, where Ν = 4 or Ν = 3. In general, the material of the optical element is selected in such a manner that the refractive index of the birefringent medium of the optical element 60 obeys the following equation: 0·65 &lt;(η^1)/(η^ΐ) &lt;〇·85. The correspondence The aberration function is also depicted in Figure 6 at the reference number 126. Figure 7 illustrates a portion of one embodiment of the optical pickup unit 10 that includes two objective lenses 42 and 128 that are adapted to broom four A different type of record carrier. The second optical element 60 is tightly loaded on the objective lens 42. A dichroic beam splitter 40 is included for reflecting the radiation beam having a person = 4 〇 5 nm, 118305.doc -39 - 200809825 is directed toward the objective lens 42 and transmits the radiation beam having χ==65〇N and/or λ==78〇N. The objective lens 42 is designed to have a wavelength λι = 4〇5奈One of the radiation beams 36 forms a scanning spot 44, not shown, and the second objective 128 is designed to form a scanning spot 44 of a different wavelength for execution of the third type of record carrier. Scanning, especially the CD or dvd. Next, in the case of using the optical path including the objective lens 128, in the case of scanning the and/or DVD, no additional spherical aberration is added. It is understood that two The objective lenses 42 and 128 are mounted on a common actuation component, depicted by a rectangle symbol 130 The objective lenses 42 and 128 can then be adjusted according to the tracking error correction or the focus error correction. The optical component 60 includes a structured surface 132 that includes one of the class shapes depicted in Figures 4, 5 or 6. Or a further class shape. According to the present invention, it is important that the class shapes are repeated in the structured surface forming a repeating class pattern. The optical element 60 can be assembled with the structured surface 132, the structured surface 132 Include a first repeating class pattern and a person or a second repeating class pattern and/or further repeating the class pattern. Here, the first repeating class pattern and the second repeating class pattern are different, in particular the first repeat The height of the pattern class and the class of the younger repeating pattern class are different. Each class shape may include a class of equal width and/or a class of different widths. The scope of the present invention also includes an optical disk drive capable of scanning at least two types of record carriers, wherein the two types of record carriers have different information layer depths and 118305.doc -40 - 200809825 / or different numerical apertures, including an optical Element 6〇, which performs the compensation of the wavefront aberrations that occur. The occurring wavefront aberration is compensated by a method for use in the optical pickup unit, comprising the step of modifying the optical feature of at least one optical component of the optical pickup unit for applying a wavefront aberration The fact that the depth of the first information layer of the first type of record carrier is different from the depth of the second information layer of the second type of record carrier is greater than the depth of the scanning field in the scanning spot. This wavefront aberration is produced. The method is achieved by applying an optical component in the optical pickup unit, wherein the optical component comprises at least a second class profile having a pattern class, wherein the first class profile and at least the second class profile are formed by a ring shape The strips are separated, and the pattern of the class of the first class profile is equal to the pattern of the class of the second class profile. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the present invention will become more apparent from the description and appended claims appended claims <RTIgt; A view, and a schematic view of one of the detecting elements of the optical pickup unit of FIG. 1b; FIG. 2 is a schematic view of the optical element having a structured surface, and FIG. 2b is a schematic view; 2a is a schematic view of one of the optical elements in plane AA, wherein only the right portion is shown; a schematic view of one of the optical elements is shown in Figure 3a, for - with a numerical aperture NA 〇.85 The optical lens of the record carrier and the record carrier of the scan 118305.doc -41 - 200809825, and a schematic view of the optical element is shown in Fig. 3b. The optical lens and the numerical aperture ΝΑ = = 〇β65 HD-DVD record carrier; Figure 4 is a schematic view of one of the aberration functions (upper curve), and a structured surface of one of the optical elements (first embodiment); Figure 5 The optical component a second embodiment of the structured surface of the curve) and the corresponding aberration curve (upper curve); FIG. 6 is a structuring of the optical element of a third embodiment (lower curve) A schematic view of the surface shape and the corresponding aberration function (upper curve); FIG. 7, which includes FIGS. 7a and 7bFig. 7, includes a schematic view of one of the optical pickup units of one of the two optical lenses. . [Main component symbol description] 12 Record carrier 14 Information layer 16 Thickness 18 Cover layer 20 Surface 21 Radiation beam 22 Reflecting layer 24 Substrate 25 Information layer depth 26 Radiation source 28 Diffraction grating element 118305.doc - 42 - 200809825 30 Radiation beam 32 Light path 34 Light splitting element 36 Light beam 38 Aiming element 40 Mirror 40f Dichroic beam splitter 42 Objective lens 44 Scanning spot 45 Returning radiation beam 46 Detecting element 48 Cylindrical lens 50 Radiation receiving detecting element part 52 Radiation receiving detecting element part 54 Radiation receiving detecting element component 56 Optical element 60 Second optical element 62 Changing element 128 Objective lens 130 Actuator 132 Structured surface 118305.doc -43

Claims (1)

200809825 X. Patent application scope · An optical pickup unit for brooming a record carrier (12) having at least one information layer (14), wherein the record carrier (12) has a first format a first type of record carrier and/or at least one second type of record carrier having a second format, the optical pickup unit (1) comprising: _ at least one radiation source (26) radiating a first radiation beam (21) Having a first wavelength for scanning the first type of record carrier and/or the at least second type of record carrier; at least one objective lens (42) for using a first radiation beam ( 21) forming a first radiation spot (44) directed onto the information layer (14) of the first type of record carrier and/or the at least second type of record carrier; at least a first optical element (38) Between a first state and at least a second state, wherein one of the first radiation beams is polarized by the first optical element (38) in the first state and the first one in the second state The optical element (38) is affected in different ways, resulting in a first polarization of the first optical beam (21) of the first optical element (38), and a first pass of the first optical component (38) in the second state a second polarization of the radiation beam (21); - at least one second optical element (60) having at least one structured surface (61) for providing a wavefront aberration compensation, the at least one second optical component ( 60) comprising a polarization sensitive material, the at least one structured surface (61) having an annular band 'each of the annular bands having a width (92), the annular bands forming a younger class shape (64, 66, 68), which has a first number of classes forming a pattern of one of the classes (78, 80, 82), wherein each 118305.doc 200809825 one class (78, 80, 82) contains a ring that forms the class a height (90) outside the width (92) of the strip, characterized in that the at least one structured surface (61) comprises at least one second level profile (64, 66, 68) having a second number of classes Forming a pattern of the class, wherein the first class profile (64, 66, 68) and the at least second class are outside The shapes (66, 68) are separated by an endless belt, and the number of classes of the first class profile (64, 66, 68) is equal to the number of classes of the second class profile (64, 66, 68), In order to form at least one repeating pattern of the class. 2. An optical pickup unit according to claim 1, characterized in that at least one further class profile (64, 66, 68) is provided, wherein the number of classes of the pattern forming the class (78, 80, 82) of the further class profile is Equal to the number of classes of the pattern (78, 80, 82) forming the first and second class profiles (64, 66, 68), the class shapes (64, 66, 68) forming the at least one structuring Surface (61) having at least one repeating pattern of the class. 3. An optical pickup unit according to claim 1 or 2, characterized in that the pattern of the class comprises at least three classes (84, 86, 88) which result in a first height (96) of one of the class profiles (70). 4. An optical pickup unit according to claim 1 or 2, characterized in that the pattern of the class comprises at least four classes (76, 78, 80, 82) which result in a second height (96,) of one of the class shapes. 5. An optical pickup unit according to claim 1 or 2, characterized in that the pattern of the class comprises classes (76, 78, 80, 82, 84, 86, 88) having different widths (92). 118305.doc 200809825 6. The optical pickup unit of claim _, characterized in that the wavefront aberration complement 4 includes a compensation for spherical aberration. 7. An optical pickup unit according to item 1 or 2, characterized in that the material of the optical element ((9)) is a birefringent material having - for the radiation beam having a polarization parallel to the pupil axis a first refractive index 〜, and for: at least a second refractive index n of the radiation beam having a second polarization perpendicular to the first polarization. It causes the radiation beam (36) with the first polarization to be different from the spherical aberration of the light beam (4) with the second polarization. 8. The optical pickup unit of claim 6, characterized by the first refractive index ne and the second refractive index η. They are related to each other according to the following relationship: 〇.65(ne—ι)&lt;(η〇])&lt;〇 〜~”). An optical pickup unit according to item 7, wherein the birefringent material is a liquid crystal polymer. 10. The optical pickup unit of claim 6, wherein the amount of spherical aberration is substantially zero for the radiation beam (36) of the second polarization. An optical pickup unit according to claim 6, characterized in that the amount of the spherical aberration is substantially zero for the radiation beam (36) of the first polarization. 12. The optical pickup unit of claim 6, wherein the amount of spherical aberration is zero for the radiation beam (36) of the second polarization. 13. The optical pickup unit of claim 6, wherein the amount of spherical aberration is zero for the radiation beam (36) of the first polarization. 14. The optical pickup unit of claim 2 or 2, wherein the second optical component (60) is disposed in the optical pickup unit (1()) for receiving 118305.doc 200809825 in a The first radiation beam (36) in a straight state. The optical pickup unit of claim 2 or 2, wherein the optical pickup unit (10) comprises a collimating lens, wherein the second optical element (6〇) is disposed on the collimating lens and the at least one objective lens ( 42) Between. 16. The optical pickup unit of claim 2 or 2, wherein the optical pickup further comprises a second objective lens (128) configured to form a scan spot (44). The information layer (14) of the third type of record carrier (12) is for obtaining an optical pickup unit for scanning at least three different types of record carriers having different formats. 17. The optical pickup unit of claim 2 or 2, wherein the optical pickup (10) comprises a further optical component for performing the radiation beam directed onto the information layer (14) of the record carrier One is defocused. 18. The optical pickup unit of claim 2 or 2, wherein the optical pickup unit (10) comprises at least one dichroic beam that emits a radiation beam having a second wavelength λ2 for scanning at least A third type of record carrier having a third format. 19. The optical pickup unit of claim 1 or 2, wherein the individual objective lenses (42, 128) are loaded in an actuator (13) for relative to the 'record carrier (12) The depth of the information layer (14) mechanically changes the position of the first and second objective lenses (42, 128). 20. The optical pickup unit of claim 18, wherein the second optical element (60) is coupled to the first objective lens (42). An optical pickup unit according to claim 19, characterized in that the first (42) and the second objective lens (128) are movable by the actuator (1; 3〇). 118305.doc 200809825 22 - A disc player comprising an optical pickup unit (10) as claimed in claim 1 or 2. An optical element for providing wavefront aberration compensation in an optical pickup unit (10) as claimed in claim 1 or 2, the optical element comprising a polarization sensitive material and having a structure with at least one repeating class appearance The surface (61) has a pattern of one class, and each class (78, 80, 82, 86, 88) has a height (90) and a width (90). 24. A method for use in an optical pickup unit (1) of an optical disk drive of claim 22, for performing compensation of wavefront aberrations when scanning a record carrier (12), wherein The record carrier (12) is a first type of record carrier having a first format, wherein the first format includes a first information layer depth (25'), and/or a second format a second type of record carrier comprising a second information layer depth (25,), the method comprising the steps of: - sweeping the information layer (14) of the first type or the second type of record carrier; The following steps: modifying the optical characteristics of at least one optical component (6〇) of the far optical pickup unit (1〇) in order to compensate for a scan light by applying a wavefront aberration to the sweeping field point larger than λ The point (44) is due to the fact that the first information layer depth (25') of the first type of record carrier is different from the second layer of the second type of record carrier (25, j) A method of claim 24, characterized in that According to claim 21, in the optical pickup unit (1) of claim 1 or 2, the compensation is based on the polarization of the radiation spot (36) incident on the optical element (60) by introducing a spherical image The difference is performed to the scanning spot (14). 118305.doc