JPH06180857A - Spot measuring method for optical pickup - Google Patents

Abstract

PURPOSE:To enhance detective sensitivity and to eliminate the individual variation in judges by automatically judging the quality of a spot from the intensity distribution of a first ring. CONSTITUTION:The primary ring 42 occurs around a main robe 41. Then, the spot is distorted due to the influence of the distortion of the optical parts of a lens and a prism, etc., constituting a pickup in the case of a defect spot. Then, the main robe 41 is deformed to a rice ball shape, and further the primery ring 42 appears in the state that the ring is interrupted at three positions. Then, a primary dark band exists between the main robe 41 and the primary ring 42 and a secondary dark band 45 exists around the primary ring 42 similarly. At this time, the primary ring 43 exists between the primary dark band 44 and the secondary dark band 45. Then, in the normal spot, two positions of the primary rings 42 with high intensity appear. The primary ring 42 with high intensity can appear to the entire periphere of the circumference of the main robe 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot measuring method of an optical pickup used for adjusting an inclination of an objective lens actuator in an assembling process of the optical pickup, and in particular, it is possible to judge the quality of the spot of a primary ring of the spot. Thus, the present invention relates to a spot measuring method for an optical pickup, which enables automatic determination with high detection sensitivity to reduce the burden on the operator and prevent variation in quality and erroneous detection.

[0002]

2. Description of the Related Art In the process of assembling an optical pickup, it is necessary to adjust the inclination of an objective lens actuator. Conventionally, as a method of adjusting the tilt of the objective lens actuator, a microscope, a camera, and a monitor are used, and instead of an optical disc, a cover glass having the same thickness is installed in parallel with the reference plane, and the spot of the objective lens is adjusted. An optical head adjusting method of enlarging and observing with a microscope is used (Japanese Patent Laid-Open No. 63-253538).

FIG. 19 is a diagram showing an example of the main configuration of an adjusting device for performing a conventional optical head adjusting process. In the figure, 1 is a housing of an optical pickup, 2
Is a deflection prism, 3 is an actuator, 4 is a screw, 5 is an objective lens, 6 is a cover glass, 7 is a microscope, 8 is a camera controller, 9 is a TV monitor, and LB is a laser beam.

As shown in FIG. 19, a deflection prism 2 is provided in a housing 1 of an optical pickup. Further, an actuator 3 is provided above the housing 1, and an objective lens 5 is provided therein.

The actuator 3 is fixed to the housing 1 with a screw 4, but the inclination of the actuator 3 can be adjusted by adjusting the tightening method of the screw 4. Also, the same thickness as the optical disc (t = 1.2 m
A cover glass 6 having m) is installed above the actuator 3 in parallel with the housing 1 of the optical pickup.

The conventional process of adjusting the tilt of the objective lens actuator is performed as follows. The laser beam LB is incident on the deflection prism 2, and the spot formed by the objective lens 5 is observed by the microscope 7. A camera (not shown) is connected to the microscope 7, and spots are displayed on the screen of the TV monitor 9 through the camera controller 8.

The operator adjusts the inclination of the actuator 3 while observing the display of the spot so that the primary side lobes are symmetrical. The tilt of the objective lens actuator is adjusted by the steps described above.

This adjusting step is performed for the purpose of improving the spot shape by adjusting the inclination of the objective lens incorporated in the actuator in parallel with the optical disc. Therefore, as described with reference to FIG. 19, it is performed while observing the spot image on the TV monitor. In this step, the spot shape is improved and at the same time, the spot having an abnormal shape is removed (in other words, In many cases, it also serves as the step of inspecting the spot shape).

This spot inspection process is usually performed visually by an operator using an empirical allowable limit sample. Therefore, not only is the burden on the operator heavy, but the subjectivity is likely to occur, which causes a problem in that the quality varies.

As one method for solving such inconvenience, the inventor of the present invention first captures a spot image from the camera controller 8 into a frame memory and then performs arithmetic processing on this image to obtain a spot image. We proposed a method for measuring the diameter, measuring the astigmatism (astigmatic difference), and further measuring the spot of the optical pickup so that the quality of the spot can be judged (the title of the invention "the spot measuring method of the optical pickup", December 1992). 14th application).

The spot measuring method of the optical pickup according to the present invention is a further improvement of the previously proposed spot measuring method of the optical pickup so that the quality of the spot can be determined with higher sensitivity. First, a spot measuring method of the optical pickup according to the invention of the prior application will be described.

[0012]

Prior invention: In the prior invention, a spot image from a camera controller is once taken into a frame memory and arithmetic processing is performed on this image so that the quality of the spot can be automatically determined. Specifically, since the spot image on the image sensor is projected on the frame memory, the assumed x, y coordinates on the image sensor can be treated as the x, y coordinates of the frame memory.
The intensity I of each part of the spot can be treated as a function I (x, y) of the coordinates (x, y) of the frame memory.

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of a pickup inspection apparatus used in the prior invention. Reference numerals in the figure are the same as those in FIG. 19, 11 is a frame memory, and 12 is a T similar to 9.
V monitor, 13 is a computer, 14 is a display.

In FIG. 1, the configuration and operation from the housing 1 of the optical pickup to the camera controller 8 are the same as in FIG. In the pickup inspection apparatus shown in FIG. 1, a spot image is taken into a frame memory 11 through a microscope 7 and a camera controller 8 by a command from a computer 13, and a raw image thereof is displayed on a TV.
It is displayed on the screen of the monitor 12.

That is, the laser light LB is deflected by the deflection prism 2
The spot formed by the objective lens 5 is magnified by the microscope 7, and the signal of the spot image is stored in the frame memory 11 through the camera controller 8. The spot image stored in the frame memory 11 is displayed on the TV.
It is displayed as a raw image on the screen of the monitor 12.

On the other hand, the signal of the spot image is transferred from the frame memory 11 to the computer 13, various kinds of processing and calculation are performed, and the result is displayed on the screen of the display 14. The above is the outline of the pickup inspection device used in the prior invention, and in common with the present invention in that it inspects the spot, the specific measurement method is
Each is different.

Therefore, the previously proposed pickup inspection apparatus is an apparatus for which the spot measuring method of the present invention is intended to be used, and is closely related to the present invention.
It is not a known prior art. Therefore, first, the pickup inspection device of the invention of the prior application will be described.

[0018]

In the present invention, the pickup inspection device of the prior invention is used to measure the spot diameter and the astigmatism (astigmatic difference) without being affected by the rotation of the spot. Further, a spot measuring method is provided, which can judge the quality of the spot. Therefore, as the prior art, the first is the measurement of the spot diameter, the second is the measurement of ass (astigmatic difference), and the third is the determination of the quality of the spot. Below, in this order,
First, the rotation of the spot will be described.

FIG. 2 is a diagram showing an example of a spot formation state by the laser light LB incident on the objective lens 5.
The reference numerals in the figure are the same as those in FIG. 1, 21 is a spot,
x, y, and z respectively indicate coordinate axes.

In FIG. 2, a spot on the xz plane is shown, and the spot 21 has a very small half-value diameter (diameter when the spot intensity is half the maximum value) of about 1 μm. Is. The spot formed on the xy plane has a shape as shown in FIG.

FIG. 3 is a diagram showing an example of a state in which the spot of the laser beam LB incident on the objective lens 5 is formed on the xy plane. In the figure, 22 is a main lobe and 23 is a primary ring.

As shown in FIG. 3, the spot on the xy plane has a primary ring 23 around the main lobe 22. By the way, since the emitted light (FFP) from the laser diode has different sizes in the vertical direction and the horizontal direction, the spot is generally elliptical.

FIG. 4 is a diagram showing an example of the intensity distribution of the spot shown in FIG. 3, where (1) is the intensity distribution on the x-axis and (2) is y.
The intensity distribution on the axis is shown. In the figure, Wx and Wy represent the half-value diameters of the spots in the x and y directions, respectively.

As is apparent from FIGS. 4 (1) and 4 (2) and FIG. 3 described above, the spots have different sizes in the x direction and the y direction. In the case of FIG. The half-value diameter Wx of the spot is larger than the half-value diameter Wy of the spot in the y direction. Half-value diameters Wx, W of spots in x and y directions
Although there is such a relationship between y, if the optical components that make up the optical pickup are distorted, the spot is deformed,
The playback signal level drops.

FIG. 5 is a diagram showing an example of an abnormal spot. In the figure, 24 is a main lobe and 25 is a primary ring.

Comparing the spot shown in FIG. 5 with the spot shown in FIG. 3 above, in the case of an abnormal spot,
The shape of the main lobe 24 is not a clean ellipse but is distorted, and the primary ring 25 is also interrupted, and occurs at, for example, three points. In the prior invention and the conventionally known measuring method, the spot as shown in FIG. 5 was visually inspected.

That is, since the judgment is made on the basis of, for example, an ideal shape as shown in FIG. 3 or an allowable limit sample in a state where the shape is slightly collapsed, the judgment accuracy is poor and individual differences occur. There was a problem. In the spot measurement method of the optical pickup filed previously, the inspection of an abnormal spot is performed as follows (third embodiment of the invention of the prior application).

FIG. 6 is a diagram showing an example of the shape of the spot in the case of inspecting the spot in the spot measuring method of the invention of the prior application. (1) shows an abnormal spot and (2) shows a normal spot. In the figure, 31 is the main lobe of the abnormal spot, 32 is the intensity peak position of the main lobe, 33 is the circumference, 34 is the main lobe of the normal spot, r is the radius, and ψ is the azimuth angle.

As shown by the solid line in FIG. 6 (1), when the main lobe 31 of the abnormal spot is detected, the radius r as indicated by the broken line 33 is centered on the intensity peak position 32 of the main lobe 31. Assume the circumference of. Then, consider the intensity distribution of the spot.

For the spot shown in FIG. 6A, the intensity distribution I (ψ) on the circumference 33 is extracted. That is, the intensity I (ψ) on the circumference 33 is extracted while sequentially moving the position of the straight line by the angle ψ. In this case, the azimuth angle ψ and the intensity distribution I (ψ) have a relationship as shown in FIG.

FIG. 7 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ). The horizontal axis of the figure is the azimuth (ψ),
The vertical axis represents the intensity I (ψ), 35 is the intensity distribution of the abnormal spot, 35a to 35c are the maximum points, and 35d to 35d.
35f is the minimum point and 36 is the intensity distribution of the normal spot.
6a to 36c show the maximum points, and 36d and 36e show the minimum points.

Regarding the main lobe 31 of the abnormal spot shown in FIG. 6 (1), the x-axis direction is used as a reference (azimuth angle ψ = 0.
If the intensity I (ψ) is plotted as
A characteristic curve as shown by the solid line 35 is drawn. And
In this intensity distribution I (ψ), the maximum points are 35a, 35
It occurs at three points b and 35c, and the minimum points are also 35d and 35c.
e, 35f at three locations.

On the other hand, in the case of the main lobe 34 of the normal spot shown in FIG. 6B, the characteristic curve as shown by the broken line 36 in FIG. 7 is obtained. The intensity distribution I shown by the broken line 36
In (ψ), the maximum points are 36a and 36b (36c is 36
same as a), and the minimum point is also 36d.
And 36e.

In the invention of the prior application, regarding the characteristic curve of FIG.
Paying attention to the maximum and minimum points of the spot, the normality / abnormality of the spot is determined by the number of maximum and minimum points. Therefore, in the prior invention, the processing is performed according to the flow shown in FIG.

FIG. 8 is a flow chart showing the flow of a basic process at the time of determining whether the spot is normal or abnormal in the third embodiment of the invention of the prior application. In the figure, # 1 to #
7 shows a step.

In step # 1, the frame memory 1 of FIG.
Capture the spot image on 1. In the next step # 2,
A point P (xp, yp) at which the intensity I (x, y) reaches a peak is obtained.

In step # 3, the intensity distribution I (ψ) on the circumference centered on the point P (xp, yp) is extracted. In the next step # 4, the maximum of the intensity distribution I (ψ) is obtained, and the number n thereof is counted.

In step # 5, it is checked whether the count number n is greater than 3. If the number n is not larger than 3, the process proceeds to step # 6 and it is determined that the spot is normal.

On the other hand, if the number n is greater than 3, then
The process proceeds to step # 7, and it is determined that the spot is abnormal. By the above steps # 1 to # 7, the spot normality /
Abnormality is determined.

As described above, in the invention of the prior application, the abnormal spot is determined from the number N of the maximum values of the intensity distribution on the circumference of the circle having the predetermined radius with the spot having the maximum intensity as the center. ing. Therefore, it becomes possible to quantitatively judge the quality of the spot, and the judgment criterion is clear.
As compared with the conventional visual determination, stable quality determination can be performed.

However, in the prior invention, the shape of the main lobe of the spot is determined when the quality of the spot is judged. Therefore, there is a problem that the detection sensitivity is not so high.

[0042]

SUMMARY OF THE INVENTION According to the present invention, such inconvenience that occurs during the spot inspection of the conventional optical pickup and the spot measuring method of the invention of the prior application is solved, and the quality of the spot can be determined with high detection sensitivity. An object of the present invention is to provide a spot measuring method for an optical pickup, which can be automatically performed to reduce the burden on the operator, prevent variations in quality and erroneous detection. Specifically, it is an object of the present invention to provide a spot measurement method for an optical pickup that enables determination with high detection sensitivity by extracting the primary ring of the spot and determining the quality of the spot.

[0043]

According to the present invention, firstly,
The spot narrowed down by the objective lens is enlarged with a microscope,
In the determination method for determining the quality of the spot of the optical pickup by capturing the intensity distribution of the spot in the memory of the computer by the image pickup tube, the means for extracting the primary ring of the spot as the processing means, and ψ as the azimuth angle. In doing so, means for obtaining the intensity distribution I (ψ) of the primary ring, means for obtaining the maximum value of the intensity distribution I (ψ), and means for obtaining the number N of azimuth angles ψ possessed by the maximum value. Equipped with
A spot measuring method of an optical pickup which extracts a primary ring of a spot, obtains an intensity distribution I (ψ) of the primary ring, obtains a maximum value thereof, and obtains the number N of azimuth angles ψ having the maximum value. is there.

Secondly, in the first spot measuring method, the intensity distribution I (ψ) of the primary ring is used as a processing means.
Means for determining the maximum value Imax and the minimum value Imin of the
Means for obtaining the contrast R of the intensity distribution I (ψ) of the next ring by R = (Imin) / (Imax), and when the contrast R is larger than a predetermined value, it is determined as a normal spot, When it is smaller than the predetermined value, the spot measurement method of the optical pickup is to judge the quality of the spot from the number of maximum values of the intensity distribution I (ψ).

Thirdly, the spot narrowed down by the objective lens is magnified by a microscope, the intensity distribution of the spot is taken into the memory in the computer by the image pickup tube, and the judgment method for judging the quality of the spot of the optical pickup is processed. As means, means for extracting the primary ring of the spot, and intensity distribution I of the primary ring when ψ is an azimuth angle
(Ψ), a means for obtaining the maximum value of the intensity distribution I (ψ), a maximum value of the maximum values is I1 (ψ1), the next largest maximum value is I2 (ψ2), and the difference is And a means for obtaining Δψ = ψ1−ψ2, where Δψ is deviated from approximately 180 °, the spot measurement method is an optical pickup that determines the spot as a defective spot.

[0046]

In the prior invention, since the shape of the main lobe of the spot is determined, the detection sensitivity is not so high, and the spot measuring method of the optical pickup of the present invention uses the conventional main lobe. Instead of the determination, the quality of the spot is determined by the shape of the primary ring in which the distortion appears more significantly (the invention of claim 1).
Therefore, it becomes possible to judge the quality of the spot with higher detection sensitivity.

Further, in the quality judgment of the spot according to claim 1, there is a possibility that a normal spot is erroneously detected as a defective spot in the case of a primary ring having a low contrast. Therefore, when the contrast is larger than a predetermined value, Even if the primary ring appears over the entire circumference, it is possible to accurately determine the quality of the spot by determining that the spot is a normal spot and when the value is less than that, the spot quality determination according to claim 1 is performed. Thus, the false detection is further reduced (the invention of claim 2).

Further, in the intensity distribution of the primary ring of the spot, in the case of a normal spot, the interval between the maximum points is about 18
Paying attention to the point that it becomes 0 °, the maximum value of the intensity distribution,
By judging whether the spot is good or bad depending on whether the angle between the next largest value is about 180 °,
The erroneous detection is further reduced (the invention of claim 3).

[0049]

[Embodiment 1] Next, a spot measuring method for a pickup according to the present invention will be described in detail with reference to the drawings. This embodiment is mainly related to the invention of claim 1, but is also related to the invention of claim 2.
As described above, in the present invention, the primary ring is used instead of the determination by the main lobe of the prior invention. First, the shape of the spot will be described.

FIG. 9 is a diagram showing an example of the shape of a defective spot. In the figure, 41 is a main lobe and 42 is 1.
Next ring, 43 is primary ring band, 44 is primary dark band, 45
Indicates a secondary dark zone.

In the spot image, a primary ring 42 is formed around the main lobe 41. In the case of a defective spot, as shown in FIG. 9, the spot is generally distorted due to the influence of distortion of optical components such as a lens and a prism that form the pickup.

In the case of FIG. 9, the main lobe 41
Is transformed into a rice ball shape, and the primary ring 42 is
It appears in three places with a break. Then, a primary dark band 44 as shown by a broken line exists between the main lobe 41 and the primary ring 42, and a secondary dark band 45 also shown by a broken line exists around the primary ring 42. . In addition,
The middle of the primary dark zone 44 and the secondary dark zone 45 is the primary ring zone 4.
It is 3.

FIG. 10 is a diagram showing an example of the shape of a normal spot. Reference numerals in the figure are the same as those in FIG.

In the normal spot, as shown in FIG. 10, two primary rings 42 having high strength appear around the main lobe 41. Further, in the case of a normal spot, the primary ring 42 having high strength may appear on the entire circumference of the main lobe 41.

FIG. 11 is a diagram showing another example of the shape of a normal spot. In the figure, 46 is a main lobe,
47 indicates a primary ring.

The spot shown in FIG. 11 is also an example of a normal spot shape. The difference in the shape of the spot between FIG. 11 and the previous FIG. 10 is due to the difference in the laser diode mounted in the optical pickup and the parameter of the beam shaping, and the objective lens 5 that narrows down the spot.
If the intensity distribution of the beam LB incident on is more uniform, a spot as shown in FIG. 11 is formed, and if it is not uniform, the FFP of the laser diode reflects the situation of the incident angle θ. A spot like 10 is formed.

Also in the spot measuring method of the present invention, the spot inspection image is taken into the frame memory 11 by using the pickup inspection apparatus shown in FIG. Then, the primary ring of this spot is extracted as follows.

FIG. 12 is a diagram for explaining a method of extracting the primary ring of the spot. Reference numerals in the drawing are the same as those in FIG. 9, and reference numeral 48 denotes a secondary ring.

As shown in FIG. 12, the primary dark band 44 and the secondary dark band 45 are detected in the sectional shape of the spot image. And, the primary ring zone 4 which is an intermediate region
For 3, the intensity distribution is extracted.

Although not shown in FIGS. 9 and 10, similarly, the secondary dark band 45 and the tertiary dark band are detected, and the intensity distribution of the secondary ring band which is an intermediate region between them is extracted. Then, a secondary ring as indicated by 48 in FIG. 12 is detected. Then, with respect to the primary ring band 43 of FIGS. 9 and 10, the intensity of the spot light is extracted for each predetermined azimuth angle ψ.

FIG. 13 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ). The horizontal axis of the figure shows the azimuth (ψ), the vertical axis shows the intensity I (ψ), 51 is the intensity distribution of the abnormal spot, and 51a to 51c are the maximum points thereof.
51d to 51f are local minimum points, 52 is the intensity distribution of a normal spot, 52a and 52c are local maximum points, and 52c to 52e are local minimum points.

In FIG. 13, the solid line intensity distribution 51 is a characteristic curve in which the intensity distribution I (φ) of the primary ring of the distorted spot shown in FIG. 9 is plotted. In the intensity distribution 51 indicated by the solid line, there are three local maximum points, as indicated by 51a to 51c.

On the other hand, the intensity distribution 52 shown by the broken line in FIG. 13 is a characteristic curve in which the intensity distribution I (ψ) of the primary ring of the normal spot shown in FIG. 10 is plotted. In the intensity distribution 52 indicated by the broken line, there are only two maximum points, as indicated by 52a and 52b.

As is clear from FIG. 9, distortion corresponding to the distortion of the optical components is also generated in the main lobe 41 of the spot, but the distortion generated in the primary ring 42 is larger, so its intensity distribution I The unevenness in (ψ) also becomes large. In this embodiment, as shown in FIG. 13, attention is paid to the number N of maximum points of the intensity distribution I (ψ) of the primary ring, and N ≧
When it is 3, it is determined as a defective spot.

FIG. 14 is a flow chart showing the flow of basic processing when determining the quality of a spot in the spot measuring method of the present invention. In the figure, # 11- #
18 shows a step.

At step # 11, a spot image is captured on the frame memory 11 of FIG. Next Step # 12
Then, the primary ring is extracted.

In step # 13, the intensity distribution I (φ) of the primary ring is extracted. In the next step # 14, the maximum value of the intensity distribution I (ψ) is obtained.

At step # 15, the number N of maximum values is counted.

At step # 16, it is checked whether the count number N is larger than 3. If the number N is not larger than 3, the process proceeds to step # 17 and it is determined that the spot is normal.

On the other hand, if the number N is greater than 3, then
The process proceeds to step # 18 and it is determined that the spot is abnormal. The quality of the spot in the intensity distribution of the primary ring is determined by the above processing of steps # 11 to # 18.

As described above, in this embodiment, regarding the intensity distribution of the primary ring of the spot, the quality of the spot is judged from the number N of the maximum values. Therefore, it is possible to quantitatively determine the quality of the spot with respect to the intensity distribution of the primary ring in which the distortion is more prominent.
Since the criterion for determination is clear, it is possible to perform stable pass / fail determination as compared with conventional visual determination.

As a measure against noise, smoothing can be applied to the intensity distribution I (ψ) of such a primary ring. In this case, more stable determination is possible, and false detection can be further reduced.

[0073]

Second Embodiment Next, a second embodiment will be described. This embodiment corresponds to the invention of claim 2. In the above-mentioned first embodiment, the method of judging the quality of the spot is explained when the primary ring of the spot is divided into three parts and appears.

In the second embodiment, when the primary ring of a normal spot appears over almost the entire circumference of the main lobe as shown in FIG. 11, or when the primary ring has three rings.
Even if it appears in a spot, its strength is relatively large, and if the contrast between the maximum value and the minimum value is relatively low, the quality of the spot can be accurately judged. Similarly, the pickup inspection device of the prior invention shown in FIG. 1 is used. First, as shown in FIG. 11, 1
The intensity distribution of the primary ring will be described for the case where the secondary ring appears almost all around the main lobe.

FIG. 15 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ) when the primary ring appears over almost the entire circumference of the main lobe. In the figure, the horizontal axis represents the azimuth angle (ψ), the vertical axis represents the intensity I (ψ), and
61 is the intensity distribution of the first normal spot, which is 61a-61.
c is the maximum point, 61d and 61e are the minimum points, and 62 is the second point.
In the intensity distribution of the normal spot of, 62a and 62c have their maximum points, 62c to 62e have their minimum points, Imax has its maximum value,
Imin indicates the minimum value.

When the primary ring appears almost all around the main lobe, the intensity distribution I of the primary ring I
(Ψ) changes as shown by the solid line 61 in FIG. Comparing FIG. 15 with FIG. 13 above, the contrast of the intensity distribution is lower in FIG.

That is, in the intensity distribution of the abnormal spot indicated by the solid line 61, the maximum value Imax and the minimum value Imax of the maximum points thereof.
The difference between the two is small. Further, even when the primary ring appears at three places over the entire circumference of the main lobe, it is necessary to determine that the spot is normal.

FIG. 16 is a diagram showing another example of the shape of a normal spot. In the figure, 63 is a main lobe,
64-66 show primary rings.

As shown in FIG. 16, the main lobe 6
When there are three primary rings 64 to 66 around the circumference of 3, the primary rings indicated by 64 and 65 have a substantially symmetrical shape and are considered to be normal spots. The intensity distribution in this case is changed as shown by the broken line 62 in FIG.

In the case of the intensity distribution of the broken line 62, a small maximum value 62a is generated, but in the first embodiment described above, since three or more maximum points are detected, it is judged as a defective spot, False detection will occur. In the second embodiment, in order to prevent such erroneous detection, the maximum value Imax and the minimum value Imin of the primary ring are obtained, and the ratio (contrast R) between them, that is, R = (Imin ) /
When (Imax) is larger than a predetermined value, it is determined as a normal spot.

FIG. 17 is a flow chart showing the flow of basic processing for determining the quality of a spot in the second embodiment of the present invention. In the figure, # 21 to # 31
Indicates a step.

At step # 21, the spot image is captured in the frame memory 11 of FIG. Next step # 22
Then, the primary ring is extracted.

In step # 23, the intensity distribution I (φ) of the primary ring is extracted. In the next step # 24, the maximum value Imax and the minimum value Imin of the intensity distribution I (ψ) are obtained.

At step # 25, the ratio R = (Imin
) / (Imax) is greater than a predetermined value a. If the ratio R is greater than the predetermined value a, then
The process proceeds to step # 26 and it is determined that the spot is normal.

On the other hand, if the ratio R is not larger than the predetermined value a, the process proceeds to step # 27 to obtain the maximum value of the intensity distribution I (ψ).

At step # 28, the number N of maximum values is counted.

At step # 29, it is checked whether the count number N is larger than 3. If the number N is greater than 3, the process proceeds to step # 30 and it is determined that the spot is abnormal.

On the other hand, if the number N is not larger than 3, the process proceeds to step # 31 to determine that the spot is normal.
Since the determination based on the contrast R is performed by the processing in steps # 21 to # 31 described above, even if the primary ring is divided into three parts over almost the entire circumference of the main lobe, there is no error and the spot It becomes possible to judge pass / fail, and false detection is reduced.

[0089]

Third Embodiment Next, a third embodiment will be described. This embodiment corresponds to the invention of claim 3. First and second
In the embodiment described above, the method for judging the quality of the spot when the primary ring of the spot appears in three places is described.

In the third embodiment, instead of the number of primary rings of the spot, attention is paid to the angle at which the maximum value appears,
The feature is that the quality of the spot can be accurately determined. Due to the relationship between the azimuth angle ψ and the intensity I (ψ) shown in FIG. 13, the interval between the maximum points 52a and 52b is about 180 ° in the case of a normal spot.

On the other hand, in the case of an abnormal spot,
Since the maximum points exist at three places, the maximum points 51a to 51c
Is about 120 ° (= 360 ° / 3). Such a relationship also applies to FIG. 15.

Therefore, in this third embodiment, the azimuth angles ψ1, ψ2, (ψ3, ...) Which are the maximum points are obtained, and the maximum value I1 (ψ1) and the next maximum value are calculated in descending order of strength. Two local maximum values of the value I2 (ψ2) are obtained. The difference Δψ between the two, that is, the maximum value I1 (ψ1) of the maximum values
And the difference between the next largest maximum value I2 (ψ2) and Δψ = ψ1-
ψ2 is obtained, and when the difference Δψ is deviated from approximately 180 °, the spot is determined as a defective spot.

FIG. 18 is a flow chart showing the flow of basic processing for determining the quality of a spot in the third embodiment of the present invention. In the figure, # 41 to # 49
Indicates a step.

At step # 41, the spot image is loaded into the frame memory 11 of FIG. Next step # 42
Then, the primary ring is extracted.

In step # 43, the intensity distribution I (ψ) of the primary ring is extracted. In the next step # 44, the maximum value of the intensity distribution I (ψ) is obtained.

At step # 45, the maximum maximum value I1
Find (ψ1). At step # 46, the next largest maximum value I2 (ψ2) is obtained.

At step # 47, the difference Δφ = φ1−
Check if ψ2 is approximately 180 °. If the difference Δφ between the two is approximately 180 °, the process proceeds to step # 48 and it is determined that the spot is normal.

As a result of checking in step # 47, if the difference Δψ between them is not approximately 180 °, step # 49.
Go to and determine that the spot is defective. Step # 4 above
By the processing of 1 to # 49, in the intensity distribution of spots, it is determined that a spot in which the angular interval between the maximum value and the next largest maximum value is about 180 ° is normal, and a spot greatly deviated from 180 ° is detected. It is determined to be defective.

As described above, in the third embodiment, with respect to the maximum value in the intensity distribution of the primary ring of the spot,
The angle between the maximum value and the next largest value is about 180 °
Whether or not the spot is good or bad is determined. Therefore, it is possible to make a determination with less erroneous detection.

[0100]

According to the spot measuring method of the first aspect, the quality of the spot is automatically judged from the intensity distribution of the primary ring. Therefore, compared with the conventional method of determining from the intensity distribution of the main lobe, the detection sensitivity is higher and
Since the conventional visual judgment is replaced by the quantitative judgment, there is no individual difference among the judges.

According to the spot measuring method of claim 2, when the contrast (Imin) / (Imax) is a predetermined value or more, it is judged as a normal spot, and when it is less than the predetermined value, the spot measuring method of the preceding claim 1 is used. It is decided automatically. Therefore, it is possible to judge the quality of the spot where the primary ring is generated all around, without error, and the false detection is significantly reduced.

In the spot measuring method according to the third aspect of the present invention, a spot having a maximum point angular interval of about 180 ° is determined to be normal, and a spot greatly deviated from 180 ° is automatically determined to be defective. Therefore, erroneous detection is reduced, and the quality of the spot can be determined with high sensitivity.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of a pickup inspection device used in the prior invention.

FIG. 2 is a diagram showing an example of a spot formation state by a laser beam LB incident on an objective lens 5.

FIG. 3 is a diagram showing an example of a state in which a spot formed by a laser beam LB incident on an objective lens 5 is formed on an xy plane thereof.

FIG. 4 is a diagram showing an example of the intensity distribution of the spots shown in FIG.

FIG. 5 is a diagram showing an example of an abnormal spot.

FIG. 6 is a diagram showing an example of the shape of a spot when a spot inspection is performed in the spot measuring method of the invention of the prior application.

FIG. 7 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ).

FIG. 8 is a flowchart showing a basic processing flow when determining whether a spot is normal or abnormal in the third embodiment of the prior invention.

FIG. 9 is a diagram showing an example of the shape of a defective spot.

FIG. 10 is a diagram showing an example of a shape of a normal spot.

FIG. 11 is a diagram showing another example of a normal spot shape.

FIG. 12 is a diagram illustrating a method of extracting a primary ring of a spot.

FIG. 13 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ).

FIG. 14 is a flowchart showing a basic processing flow when determining the quality of a spot in the spot measuring method of the present invention.

FIG. 15 is a characteristic diagram showing an example of the relationship between the azimuth angle ψ and the intensity I (ψ) in the case where the primary ring appears over almost the entire circumference of the main lobe.

FIG. 16 is a diagram showing another example of the shape of a normal spot.

FIG. 17 is a flow chart showing a basic processing flow when determining whether a spot is good or bad in the second embodiment of the present invention.

FIG. 18 is a flowchart showing the flow of a basic process when determining the quality of a spot in the third embodiment of the present invention.

FIG. 19 is a diagram showing an example of a main part configuration of a conventional adjusting device that performs an optical head adjusting step.

[Explanation of symbols]

 1 Optical Pickup Housing 2 Deflection Prism 3 Actuator 4 Screw 5 Objective Lens 6 Cover Glass 7 Microscope 8 Camera Controller 9 TV Monitor 11 Frame Memory 12 TV Monitor 13 Computer 14 Display

Claims (3)

[Claims] 1. A determination method, wherein a spot narrowed down by an objective lens is magnified by a microscope, the intensity distribution of the spot is captured by an image pickup tube into a memory in a computer, and the quality of the spot of an optical pickup is determined. Means for extracting the primary ring of the spot, and intensity distribution I of the primary ring when ψ is an azimuth angle
A means for obtaining (ψ), a means for obtaining a maximum value of the intensity distribution I (ψ), and a means for obtaining the number N of azimuth angles ψ having the maximum value are provided, and the primary ring of the spot is extracted. , The intensity distribution I (ψ) of the primary ring is obtained, the maximum value thereof is obtained, and the number N of azimuth angles ψ possessed by the maximum value is obtained. 2. The spot measuring method according to claim 1, wherein as a processing means, a means for obtaining a maximum value Imax and a minimum value Imin of the intensity distribution I (ψ) of the primary ring, and the intensity distribution I of the primary ring. Means for obtaining the contrast R of (ψ) by R = (Imin) / (Imax), and when the contrast R is larger than a predetermined value, it is determined as a normal spot, and when it is smaller than a predetermined value. Is a spot measuring method for an optical pickup, characterized in that the quality of the spot is judged from the number of maximum values of the intensity distribution I (ψ). 3. A determination method, wherein a spot narrowed down by an objective lens is magnified by a microscope, the intensity distribution of the spot is taken into a memory in a computer by an image pickup tube, and the quality of the spot of an optical pickup is determined. Means for extracting the primary ring of the spot, and intensity distribution I of the primary ring when ψ is an azimuth angle
(Ψ), a means for obtaining the maximum value of the intensity distribution I (ψ), a maximum value of the maximum values is I1 (ψ1), the next largest maximum value is I2 (ψ2), and the difference is And a means for obtaining Δψ = ψ1−ψ2, where Δψ is deviated from about 180 °, the spot is determined to be a defective spot.