KR100570859B1 - Spherical aberration regulation method in assembly process of optical pickup - Google Patents

Abstract

The present invention relates to a method for adjusting spherical aberration in an assembling process of an optical pickup apparatus. In particular, in assembling an optical pickup apparatus, a spherical aberration amount is detected indirectly from a cross section of a spot by using a two-dimensional spot profile. A method of adjusting spherical aberration in an assembling process of an optical pickup apparatus for assembling an optical pickup apparatus while moving a lens to be minimized.

According to the present invention, there is also provided a method for detecting spherical aberration from a spot profile of a manual skew adjusting device; A second step of detecting an optimum value of spherical aberration while moving the collimating lens of the optical pickup device; And a third step of fixing the collimating lens according to the optimum value detected in the second step.

Information storage recording media, optical pickup apparatus, spherical aberration, assembly process

Description

Spherical aberration regulation method in assembly process of optical pickup             

1 is a view showing an embodiment of a manual optical pickup skew adjusting apparatus according to the prior art.

2 is a view for explaining an optical beam having spherical aberration.

3 is a structural diagram of an objective lens system to which the present invention is applied.

4 is a graph showing spherical aberration values according to the positions of the collimating lens and the zoom lens and the voltage value of the liquid crystal device.

5 shows a two-dimensional spot file obtained from a CCD.

6 is a flowchart illustrating a method of adjusting spherical aberration in an assembly process of an optical pickup according to an exemplary embodiment of the present invention.

FIG. 7A is a two-dimensional spot file obtained from a CCD, and FIG. 7B is a graph showing the intensity distribution along the cross section of the spot file.

8 is a flowchart of a spherical aberration adjustment method according to another embodiment of the present invention.

Fig. 9 is an enlarged view of a portion of the graph showing the intensity along the cross section of the spot pile obtained by the CCD.

10 is a flowchart of a spherical aberration adjustment method according to another embodiment of the present invention.

FIG. 11A is a diagram showing a change amount of the ratio of the area of the main lobe to the side lobe according to the change of the spherical aberration, and FIG. 11C is a view showing the amount of change in intensity at the zero cross point according to the change in the amount of spherical aberration.

<Explanation of symbols for the main parts of the drawings>

301: blue light laser diode 302: beam splitter

303: collimating lens 304: zoom lens

305: liquid crystal element 306: objective lens

307: focusing / cylindrical lens 308: photodetector

310: manual skew adjustment unit 311: cover glass

312: Recollimating Lens 313: Beam Splitter

314: focus lens 315: cylinder lens

316: CCD 317: personal computer

The present invention relates to a method for adjusting spherical aberration in an assembling process of an optical pickup apparatus. In particular, in assembling an optical pickup apparatus, a spherical aberration amount is detected indirectly from a cross section of a spot by using a two-dimensional spot profile. A method of adjusting spherical aberration in an assembling process of an optical pickup apparatus for assembling an optical pickup apparatus while moving a lens to be minimized.

Currently, a phase change recording medium and a magneto-optical recording medium have been put into practical use as a large capacity information recording medium capable of high density recording of information.

Examples of the phase change recording medium include a read-only optical disc, a recordable optical disc capable of additionally recording information, and an updateable optical disc capable of erasing and rewriting information. In addition, the magneto-optical recording medium can basically erase and rewrite information.

Since the recorded information is read from either of the phase change recording medium and the magneto-optical recording medium, the optical pickup apparatus is used to record the information.

As is well known, the optical pickup device is composed of a laser light source, an objective lens, a detector such as a PD (Photo Detector), an actuator for driving the objective lens, and the like, and focuses the laser light emitted from the laser light source onto the objective lens. It irradiates the recording surface of the recording medium and detects the reflected light from the information recording medium with a detector and is incorporated in the information recording and reproducing apparatus.

The information recording and reproducing apparatus includes a tracking servo control system for controlling the laser light emitted from the optical pickup to accurately follow a predetermined track of the information recording medium based on the detection signal output from the detector of the optical pickup apparatus, A focus servo control system for controlling the spot of the laser light to be arranged on the recording surface irrespective of the curved state or the like is provided.

When reading the information recorded on the information recording medium, the information recorded on the information recording medium is detected by these control systems by detecting the reflected light which can be obtained in the state where the spot of the laser light accurately follows the track on the recording surface of the information recording medium. Is read and reproduced by the information reproducing system.

In addition, in the case of recording information on the information recording medium, the laser beam is applied at a higher intensity than the reading from the information recording system in a state in which the spot where the spot of the laser light is to be formed accurately follows the track on the recording surface of the information recording medium. The information is recorded on the information recording medium by emitting or stopping.

As the storage capacity of an information recording medium increases in recent years, the quality of a reproduction signal is more sensitive to the reproduction conditions. As the wavelength is shortened and the numerical aperture (NA) of the objective lens is increased in the information recording medium by blue laser light (Blu-ray), the storage capacity increases, but the tolerance of the optical pickup device required during reproduction becomes smaller. Therefore, in order to maintain the quality of the reproduction signal at a constant level in the information recording and reproducing apparatus, an optical aberration detection means is required from the assembling stage of the optical pickup apparatus.

Tolerance here refers to the amount allowed to vary the reference of a component or component from a target value. In the design of the optical pickup device, not only the optical design in the basic layout, but also the tolerance analysis to ensure that the desired performance is achieved when all the optical components are manufactured and assembled.

Therefore, in the design of the optical pickup device, not only the performance of the optical system, but also the effect of manufacturing and its tolerances on price and delivery time should be explained. Tolerance analysis is not only useful when constructing the system of the basic design, but also when you want to understand the key specifications that affect the performance of the main system, and when you want to determine the overall design precision of the tool / jig for the fabrication / assembly of optical components. In order to solve a defect, it is mainly used at the time of review of a design.

On the other hand, the aberration required to be detected in the assembling step is very sensitive to the influence of spherical aberration in the optical system considering the dual lens. The document "High density optical disk system using a new two-element lens and a thin substrate disk" by F. Maeda et al, published in the proceeding of ISOM96 P.342-344 is directed to an optical recorder having such a dual lens objective system. It is started.

Spherical aberration due to variation in thickness of the transparent layer is corrected by changing the position of the axis of the lens of the objective lens system. This lens system uses this value to determine the spherical aberration of the beam reflected from the recording medium and to position the lens. This document proposes two methods for determining the amount of spherical aberration of a reflected beam.

In the first method, the envelope magnitude of the information signal read out from the information recording medium is measured, and has the maximum value when the spherical aberration is the minimum value. In the second method, the shape of the focus error signal is analyzed by the action of the focus error, and the position of the lens is optimized to obtain the desired shape.

The first method requires the presence of an information signal, and therefore has the disadvantage that the method is not suitable for recording on an unrecorded recording medium.

The second method has the disadvantage that the shape of the focus error signal is analyzed and requires wobbling the objective system through the best focus.

1 is a view showing an embodiment of a manual optical pickup skew adjusting apparatus according to the prior art.

Referring to the drawings, the manual optical pickup skew adjusting apparatus according to the prior art includes a cover glass 102, a recollimating lens 103, a beam splitter 104, a focus lens 105a and 105b, a cylinder lens 106, CCDs 108a and 108b and a personal computer 109 are included.

Light emitted from the actuator 101 passes through the recollimating lens 103 and the focus lens 105b and is received by the CCD 108b. The operator then visually observes the monitor of the personal computer 109 to determine the degree of focus error and to perform skew adjustment during assembly.

Using such a manual skew adjustment apparatus of the objective lens according to the prior art, coma aberration and astigmatism can be determined from the spots detected by the CCDs 108a and 108b. That is, coma aberration can be known from the size of the skew and the direction of the skew according to the presence, position, and size of the primary ring of the spot, and the astigmatism can be known from the ellipticity of the spot.

However, in detecting spherical aberration, there is a problem that spot size is different and primary ring is large, so that spherical aberration cannot be quantified by using a manual skew adjusting device of an objective lens according to the prior art.

Accordingly, the present invention has been made to solve the above problems, and indirectly changes the spherical aberration from the two-dimensional spot profile to provide a method for correcting the spherical aberration using the skew adjusting device of the objective lens. It is an object of the present invention to provide a method for adjusting the spherical aberration in the assembly process of the optical pickup device to minimize the spherical aberration.

The present invention for achieving the above object is a first step of detecting the spherical aberration from the spot profile of the manual skew adjustment device; A second step of detecting an optimum value of spherical aberration while moving the collimating lens of the optical pickup device; And a third step of fixing the collimating lens according to the optimum value detected in the second step.

In addition, the present invention preferably comprises a fifth step of detecting an optimal value of spherical aberration while moving the zoom lens of the optical pickup apparatus; And a sixth step of fixing the collimating lens according to the optimum value detected in the fifth step.

In addition, the present invention preferably comprises a seventh step of detecting an optimum value of spherical aberration while changing the voltage of the liquid crystal element of the optical pickup device; And an eighth step of fixing the collimating lens according to the optimum value detected in the seventh step.

2 is a view for explaining an optical beam having spherical aberration.

2, the wavefront of the beam is indicated by line 201. If this beam does not have spherical aberration, this wavefront will be spherical surface 202 centered on axis 203. The difference between wavefront 201 and wavefront 202 in FIG. 2 is the lowest spherical aberration in the Seidel representation.

Wavefronts 201 and 202 have the same curve near axis 203. The beam of the beam is perpendicular to the wavefront. A paraxial ray, ie, a ray close to an axis such as rays 204 and 205, reaches the focal point 206 on this axis, the so-called paraxial focus. Rays further away from the axes of rays 207, 208, and the like, reach focal point 209 in the figure located to the left of focal point 206.

Ambient light, i.e. light rays near the edge of the beam, such as light beams 210, 211, reaches focal 212, so-called ambient light, in the figure located on the left side of focus 209. If the spherical aberration of the beam has a sign opposite that of the line drawn in the figure, the focus 209 will be to the right of the focus 206 and the focus 212 will be to the right of the focus 209.

A focus detector that is disposed in the optical beam and mainly captures the paraxial rays of the beam will detect a focal position close to or equal to the paraxial focal point 206. Another focus detector that is placed in the same beam and mainly captures ambient light will detect a focus position that is close to or equal to the position of the peripheral focus 212. The difference between these two detected foci is a measure of the sine and magnitude of the spherical aberration. If the optical beam does not have spherical aberration, paraxial and peripheral focus will coincide, and the focus detector will detect the same focal position.

3 is a structural diagram of an objective lens system to which the present invention is applied.

Referring to FIG. 3, the objective lens system to which the present invention is applied includes a blue light laser diode 301, a beam splitter 302, a collimating lens 303, a zoom lens 304, a liquid crystal element 305, and an objective lens 306. , A focusing / cylindrical lens 307, a photodetector 308, and a manual skew adjusting unit 310.

Wherein the blue light laser diode 301 is configured to generate a laser beam having a wavelength of 410 nm, the beam splitter 302 reflects one diffused laser beam emitted from the blue light laser diode 301, The reflected light reflected from the recording surface of the information recording medium D is transmitted.

In addition, the collimating lens (collimating lens) 303 converts one diffused laser beam to the beam splitter 302 to be converted into parallel light when irradiated.

The zoom lens 304 includes a first lens 304a having concave surfaces on both sides, and a second lens 304b having a flat surface on one surface thereof and a concave second lens 304b on the other surface. The zoom lens 304 enlarges and transmits parallel light incident from the collimating lens 303.

The spherical aberration correction liquid crystal element 305 performs a function of correcting spherical aberration of parallel light incident on both surfaces as a flat plate.

An objective lens 306 focuses a laser beam of parallel light converted by the collimating lens 303 and irradiates the information recording medium D. FIG.

On the other hand, the focusing / cylindrical lens 307 converts the laser beam reflected from the information recording medium D by astigmatism to perform a focus servo.

The photodetector 308 is configured to detect a reproduction signal and an error signal (focusing error and tracking error) to perform focusing servo and tracking servo.

The photodetector 308 is typically provided with a focusing / cylindrical lens 307 which focuses light and focuses only one of the vertical and horizontal directions orthogonal to the optical axis of the focused light beam and transmits it in the other direction as it is.

Referring to the operation of the optical system, first, when a diffused laser beam is generated and emitted from the blue light laser diode 301 is incident to the beam splitter 302, reflected by the beam splitter 302, reflected by the beam splitter 302 The diffuse laser beam is incident on the collimating lens 303 and is converted into parallel light in the collimating lens 303.

The zoom lens 304 enlarges and transmits parallel light incident from the collimating lens 303, and the liquid crystal element 305 corrects spherical aberration.

Then, the laser beam changed into collimated light from the collimating lens 303 is incident on the objective lens 306, and the objective lens 306 focuses the laser beam on the recording surface of the information recording medium D, that is, the pits. Investigate.

Further, the laser beam irradiated and reflected on the recording surface of the information recording medium D sequentially passes through the objective lens 306, the collimating lens 303, the beam splitter 302, and the focusing / cylindrical lens 307. The photodetector 308 is received by the photodetector 308 which performs focusing servo and tracking servo by the push-pull method and the astigmatism method by the received laser beam, and simultaneously converts the laser beam into an electrical signal to convert the information recording medium. The data recorded in (D) is read.

On the other hand, in the optical pickup corresponding to the blue laser light using the zoom lens 304, spherical aberration changes when the collimating lens 303 and the zoom lens 304 are moved in the optical axis direction. Even when the liquid crystal element 305 for correcting spherical aberration is included, changing the voltage applied to the liquid crystal element 305 changes the spherical aberration.

Meanwhile, the manual skew adjusting unit 310 may include a cover glass 311, a recollimating lens 312, a beam splitter 313, a focus lens 314a and 314b, a cylinder lens 315, a CCD 316a and 316b, A personal computer 317.

Light emitted from the objective lens 306 passes through the recollimating lens 312 and the focus lens 314b and is received by the CCD 316b.

4 is a graph showing spherical aberration values according to the positions of the collimating lens and the zoom lens and the voltage value of the liquid crystal device.

In FIG. 4, the X-axis is the displacement on the optical axis of the collimating lens 303 and the zoom lens 304 or the voltage change of the liquid crystal element 305, and the spherical aberration is the minimum at the point where the Y value is maximum.

As can be seen from FIG. 4, there is a point where the spherical aberration is minimized when the collimating lens 303 and the zoom lens 304 are displaced on the optical axis or the voltage of the liquid crystal element 305 is changed.

However, since the spherical aberration cannot be directly obtained by the conventional method, the change due to the spherical aberration must be indirectly considered from the two-dimensional spot profile obtained in the CCD. The absolute value is the same but the sign is different depending on whether the point of spherical aberration is in front of or behind the image plane. In FIG. 4, when the position on the optical axis of the collimating lens and the zoom lens or the voltage of the liquid crystal element is adjusted, the spherical aberration has the same left and right centers around the point where the spherical aberration is zero, thereby determining whether the spherical aberration is left or right. .

However, in the upper light path of FIG. 3, a cylinder lens 315 is included, which causes astigmatism when the focal point is changed. Before focusing, the astigmatism method, which is one of the optical pickup servers, can determine not only the defocus amount but also the sign of spherical aberration.

This is because by comparing the long axis and short axis positions of the ellipse generated by the astigmatism, it is possible to know whether the point where the focal point is located is in front of or behind the image plane, and the sign of the spherical aberration can be determined. After the sign is determined, the spherical aberration is calculated, and the data is corrected by considering the sign in the calculated spherical aberration.

5 shows a two-dimensional spot file obtained from a CCD.

In FIG. 5, as the spherical aberration increases, the area of the side lobe increases, and thus, the indirect spherical aberration change can be inferred by obtaining the ratio of the side lobe area to the main lobe area.

That is, in FIG. 5, when the spherical aberration is the smallest, the main lobe area is relatively small and the side lobe area is the largest, so that the area of the main lobe divided by the side lobe area is the smallest value.

However, the disadvantage of using this method is that since the area of the side lobe is considerably smaller than that of the main lobe, an expensive CCD and a frame grabber are required.

6 is a flowchart illustrating a method of adjusting spherical aberration in an assembly process of an optical pickup according to an exemplary embodiment of the present invention.

Referring to the drawings, the spherical aberration adjustment method in the assembly process of the optical pickup according to an embodiment of the present invention, first calculates the area of the main lobe and the area of the side lobe to calculate the ratio of the main lobe area and the side lobe area (Step S101).

Thereafter, while moving the collimating lens forward (step S102), the area of the main lobe is obtained and the area of the side lobe is obtained to calculate the ratio of the main lobe area and the side lobe area (step S103).

Next, it is judged whether the above calculated value is small compared with the value already stored (step S104), and if it is small, it is repeated from the step S102, and if it is large, the area of the main lobe after the backward movement of the collimating lens (step S105). The method is repeated from step S103 for calculating the ratio between the main lobe area and the side lobe area by obtaining the area of the side lobe.

At this time, if the calculated value and the stored value are the same or within the error range, after fixing the collimating lens (step S106), while moving the zoom lens forward (step S107), the area of the main lobe is obtained and the area of the side lobe is obtained. The ratio of the area and the side lobe area is calculated (step S108).

Next, it is determined whether or not the above calculated value is small by comparing with the already stored value, and if it is small, the process is repeated from step S107, and if it is large, after the backward movement of the zoom lens (step S110), the area of the main lobe is obtained and The process is repeated from step S108 where the area is calculated to calculate the ratio between the main lobe area and the side lobe area.

At this time, if the calculated value and the stored value are the same or within the error range, after fixing the zoom lens (step S111), the voltage of the liquid crystal element is increased (step S112), the area of the main lobe is obtained, and the area of the side lobe is obtained. The ratio of the area and the side lobe area is calculated (step S113).

Next, it is determined whether or not the above calculated value is small by comparing with the already stored value, and if it is small, it is repeated from the step S112, and if it is large, the area of the main lobe is obtained while reducing the voltage of the liquid crystal element (step S115) and the side lobe is obtained. It is repeated from step S113 to calculate the ratio between the main lobe area and the side lobe area by obtaining the area of?.

At this time, if the calculated value and the stored value are the same or within the error range, the voltage value of the liquid crystal element is fixed (step S116).

FIG. 7A is a two-dimensional spot file obtained from a CCD, and FIG. 7B is a graph showing the intensity distribution along the cross section of the spot file.

Referring to FIG. 7A, as the spherical aberration increases, the area of the side lobe increases, so that the side lobe area increases and the main lobe area decreases.

Accordingly, as shown in FIG. 7B, when the integral amount of the inner circumference and the intensity of the outer circumference are obtained based on a constant radius R ₁ , the relative change in the spherical aberration can be seen. The radius R ₁ is such that when the spherical aberration is zero, the ratio between the inner and outer circumferences is 1.

This method is quite insensitive to noise because it uses the ratio of the integral of the intensity when correctly focused. However, it is difficult to distinguish the change caused by spherical aberration and defocusing.

8 is a flowchart of a spherical aberration adjustment method according to another embodiment of the present invention.

Referring to the drawings, in the spherical aberration adjustment method according to another embodiment of the present invention, first, the inner intensity integration amount within the radius R ₁ and the outer intensity integration amount are calculated to calculate the ratio of the inner intensity integration amount and the outer intensity integration amount. (Step S201).

Subsequently, while moving the collimating lens forward (step S202), the inner intensity integration amount within the radius R ₁ is obtained and the outer intensity integration amount is calculated to calculate the ratio of the inner intensity integration amount and the outer intensity integration amount (step S203). .

Next, judging whether the above calculated value is small compared with the already stored value, if it is small, repeats from the above step S202, and if it is large, after calculating the inner intensity intensity within the radius R ₁ after the backward movement of the collimating lens, It is repeated from step S203 in which the intensity integration amount is calculated to calculate the ratio of the inner circumference intensity integration amount and the outer circumference intensity integration amount within the radius R ₁ .

In this case, the calculated value and the stored value is equal to or errors if less than the range to obtain the inner strength measure of after fixing the collimating lens (step S206), (step S207) while forward movement of the zoom lens, within a radius R ₁ outer strength The amount is calculated to calculate the ratio between the inner circumference intensity integral and the outer circumference intensity integration amount (step S208).

Next, it is judged whether the above calculated value is small compared with the value already stored, and if it is small, it is repeated from the above step S207, and if it is large, the inner intensity integration amount within the radius R _{1 after} the backward movement of the zoom lens (step S210). It is repeated from step S208 to calculate the ratio of the inner circumference intensity integral and the outer circumference intensity integral within the radius R ₁ by obtaining the outer circumferential intensity integration amount.

At this time, if the calculated value and the stored value are the same or within the error range, after fixing the zoom lens (step S211), the voltage of the liquid crystal element is increased (step S212), and the inner intensity integration amount within the radius R ₁ is obtained and The amount is calculated to calculate the ratio between the inner circumferential intensity integral and the outer circumferential intensity integrated within the radius R ₁ (step S213).

Next, judging whether the above calculated value is small compared with the already stored value, if it is small, repeats from the step S212, and if it is large, the internal intensity integral within the radius R ₁ is obtained while reducing the voltage of the liquid crystal element, Repeating from step S213 for calculating the intensity integration amount to calculate the ratio between the inner circumference intensity integration amount and the outer circumference intensity integration amount.

At this time, if the calculated value and the stored value are the same or within the error range, the voltage value of the liquid crystal element is fixed (step S216).

Fig. 9 is an enlarged view of a portion of the graph showing the intensity along the cross section of the spot pile obtained by the CCD.

Referring to FIG. 9, at the points Z ₁ and Z ₂ where the intensity when the spherical aberration is zero passes the zero of the y-axis (here, the point is called a "zero crossing point"), the spherical aberration is As it increases, the value of the y-axis increases. That is, the change in the spherical aberration can be known by obtaining the value at the Z ₁ or Z ₂ point. In this method, since the difference between the y-axis values at the two points is almost similar to the difference in the spherical aberration, a relatively accurate spherical aberration amount can be obtained.

10 is a flowchart of a spherical aberration adjustment method according to another embodiment of the present invention.

Referring to the drawings, the spherical aberration adjusting method according to another embodiment of the present invention detects the spherical aberration by obtaining the intensity at the zero cross point (step S310).

Thereafter, while moving the collimating lens forward (step S311), the intensity is calculated at the zero cross point to calculate spherical aberration (step S312).

Next, it is determined whether or not the above calculated value is small by comparing with the already stored value, and if it is small, the process is repeated from the step S313, and if it is large, the intensity is obtained from the zero cross point after the backward movement of the collimating lens (step S314). It repeats from step S312 for calculating the aberration.

At this time, if the calculated value and the stored value are the same or within the error range, after fixing the collimating lens (step S315), while moving the zoom lens forward (step S316), the spherical aberration is detected by obtaining the intensity at the zero cross point (step S316). S317).

Next, it is judged whether or not the above calculated value is small compared with the value already stored (step S318). If it is small, the process is repeated from the above step S316, and if it is large, the intensity at zero cross point after the backward movement of the zoom lens (step S319). It is repeated from step S317 to find the spherical aberration.

At this time, if the calculated value and the stored value are the same or within the error range, after fixing the zoom lens (step S320), the voltage of the liquid crystal element is increased (step S321), and the intensity is obtained at the zero cross point to detect spherical aberration (step S322).

Next, it is determined whether or not the above calculated value is small by comparing with the already stored value (step S323). If the value is small, the process is repeated from step S321. If the value is large, the voltage of the liquid crystal element is reduced (step S324). The repetition is performed from step S322 in which the intensity is obtained and the spherical aberration is detected.

At this time, if the calculated value and the stored value are the same or within the error range, the voltage value of the liquid crystal element is fixed (step S325).

On the other hand, the patterns of diffraction were analyzed using the conditions (Table 1) of the effects of the proposed methods.

Numerical aperture (NA) 0.85 wavelength 408 nm

A Gaussian beam distribution with different waists along the axis is given by Equation 1

In the exit pupil, the complex amplitude including aberration is represented by the following (Equation 2).

Here, W (x, y) means wavefront aberration, and since spherical aberration is detected, we need to know W (x, y) by spherical aberration. do.

Where W ₄₀ is the spherical aberration expressed in zernike polynomial. Based on the above equation, the simulation by diffraction is shown in Figs. 11A to 11C.

FIG. 11A is a diagram showing a change amount of the ratio of the area of the main lobe to the side lobe according to the change of the spherical aberration, and FIG. 11B is a ratio of the intensity integral and the outer intensity integral of the inner circumference according to the change of the spherical aberration. 11C is a view showing the amount of change in intensity at the zero cross point according to the change in the amount of spherical aberration.

As can be seen from the figure, it can be seen that the smallest change in the ratio between the intensity integral amount of the inner circumference and the outer intensity intensity amount is the smallest, and the greatest amount of change in intensity at the zero cross point.

When the spherical aberration changed from 0 to 0.1λ, the amount of change based on the maximum value is shown in Table 2 below.

Way Internal and external strength intensity ratio Area ratio between main lobe and side lobe Spot size change Intensity change at zero point Change  10%  20%  0  100%

From the above, it can be seen that the intensity change is the best at the zero point. However, the method has the disadvantage of requiring expensive equipment. In addition, the method using the area of the main lobe and the side lobe has a larger variation than the method using the inner and outer circumferences, but there is a problem that the side lobe is greatly changed because other aberrations may be included in addition to the spherical aberration. Therefore, it may be considered that the method of using the ratio of the inner and outer circumferential strength integration is most suitable.

According to the present invention as described above, there is an effect that it is possible to adjust the spherical aberration in the assembling process by detecting the spherical aberration at a lower cost than when using the interferometer.

In addition, according to the present invention, by adjusting the spherical aberration of the optical pickup device using the blue laser light in the assembly process, it is possible to realize the large-capacity information recording storage medium.

What has been described above is only one embodiment for performing the spherical aberration adjusting method in the assembling process of the optical pickup apparatus according to the present invention, the present invention is not limited to the above-described embodiment, it is claimed in the claims As will be apparent to those skilled in the art to which the present invention pertains without departing from the gist of the present invention, the technical spirit of the present invention will be described to the extent that various modifications can be made.

Claims (7)

A first step of detecting spherical aberration from the spot profile of the manual skew adjusting device; A second step of detecting an optimum value of the spherical aberration while changing the spherical aberration through the optical axis movement of the optical component in the optical pickup device; And And a third step of fixing the collimating lens according to the optimum value detected in the second step. The method of claim 1, In the first step, the detection of spherical aberration from the spot profile is characterized by determining the area of the main lobe and the area of the side lobe, and then calculating the ratio of the area of the main lobe to the area of the side lobe to detect the spherical aberration. Spherical aberration adjustment method in the assembly process of the optical pickup device. The method of claim 1, In the first step of detecting spherical aberration from the spot profile, the spherical aberration is detected by calculating the intensity integral of the inner circumference and calculating the intensity integral of the outer circumference, and then calculating the ratio of the intensity integration and the intensity integration of the outer circumference. Spherical aberration adjustment method in the assembling process of the optical pickup device, characterized in that. The method of claim 1, The detecting of the spherical aberration from the spot profile in the first step comprises detecting the spherical aberration by detecting the intensity at the zero cross point. The method according to any one of claims 1 to 4, A fourth step of detecting an optimum value of spherical aberration while moving the zoom lens of the optical pickup apparatus; And And a fifth step of fixing the collimating lens according to the optimum value detected in the fourth step. The method of claim 5, wherein A sixth step of detecting an optimum value of spherical aberration while changing the voltage of the liquid crystal element of the optical pickup device; And And a seventh step of fixing the collimating lens according to the optimum value detected in the sixth step. The method according to any one of claims 1 to 4, A fourth step of detecting an optimum value of spherical aberration while changing the voltage of the liquid crystal element of the optical pickup device; And And a fifth step of fixing the collimating lens according to the optimum value detected in the fourth step.

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