JPH06187660A - Optical pickup spot inspection device - Google Patents

Abstract

(57) [Summary] [Purpose] The process of detecting asbestos present in abnormal spots is automated to enable rapid and accurate detection of asbestos and reduce the burden on workers, and also to improve quality. Prevent. [Structure] The number of pixels in the area surrounded by a circle whose diameter is the minor axis of the elliptical spot and the number of pixels in the area outside the circle and inside the elliptical spot are measured to determine the minor axis. When the number of pixels in the area outside of the circle is equal to or larger than a predetermined value, it is determined that the spot has astigmatism. [Effect] Since the area determination is performed on the number of pixels of the spot, the determination accuracy is improved compared to the conventional method of determining by measuring the long axis and the short axis of the spot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot inspection device used in an optical pickup assembly process,
In particular, by automating the process of detecting astigmatism (astigmatism) present in abnormal spots, it is possible to quickly and accurately detect asbestos.
The present invention relates to a spot inspection device for an optical pickup that can reduce the burden on the operator and prevent the quality from varying.

[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. 14 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. 14, 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. 14, while observing the spot image on the TV monitor, this step improves the spot shape and at the same time removes the spot having an abnormal shape (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. Here, a general spot intensity distribution will be described.

FIG. 15 is a diagram showing an example of the intensity distribution of the spot when the tilt of the objective lens is adjusted well and there is no distortion. In the figure, x and y are x-axis coordinates and y-axis coordinates, I is the intensity of the spot, P is the point where the intensity peaks, Is is the predetermined intensity of the spot, 21 is the intensity distribution curve of the spot, and 22 is a straight line. , 23 indicates a plane perpendicular to the xy plane, 24 indicates a plane parallel to the xy plane, and θ1 indicates an angle between the x axis and the straight line 22.

As shown in FIG. 15, when the inclination of the objective lens is well adjusted and there is no distortion, the spot has a bell-shaped shape 21. As shown in FIG. 15, the intensity distribution 21 of a general spot has a primary ring symmetrical with respect to the central axis with respect to the main lobe (central portion), and sandwiches the peak of the primary ring, There is a bottom of the primary dark zone and a bottom of the secondary dark zone.

Note that, in FIG. 15, the point P and the coordinate origin are shown coincident with each other for easy understanding.
Here, the x-axis and the y-axis are set on the plane 24 on the assumption that the surface of the spot of the intensity distribution 21 is formed.

However, if the inclination of the objective lens is not good, the spot formed on the xy plane or the plane 24 will be
It becomes asymmetric with respect to the central axis and an abnormal spot occurs. Then, such abnormal spots include spots having astigmatism (astigmatism).

The cause of such astigmatism is that the position of the light emitting point of the laser diode is deviated in the parallel direction and the vertical direction with respect to the active layer. That is,
The astigmatism is caused by the deviation of the image forming points in two directions within a plane orthogonal to the optical axis, such as the xy plane in FIG.

By the way, since the spot is almost a perfect circle in the middle of both image forming points, the asspot cannot be detected only by looking at the in-focus position. The reason is that in the spot inspection device, the focus position is an operation for detecting the position where the spot becomes a perfect circle, and in the spot with astigmatism,
This is because the midpoint between these two image formation points is detected as the in-focus position (see FIG. 2 below).

[0016]

SUMMARY OF THE INVENTION The present invention solves such inconvenience that occurs during the spot inspection of the conventional optical pickup, and automates the step of detecting astigmatism (astigmatic difference) existing in an abnormal spot. An object of the present invention is to provide a spot inspection device for an optical pickup, which enables quick and accurate detection of astigmatism and reduction of the burden on an operator, and which prevents variation in quality.

[0017]

According to the present invention, firstly,
In the spot inspection device of the optical pickup device, which is a processing unit, the light emitted from the lens is imaged on the image pickup element and the calculation is performed using the intensity I (x, y) at the point (x, y) on the element. , Means for obtaining a point P (p, q) at which the intensity I (x, y) reaches a peak, and a plurality of straight lines Li on the image sensor passing through the point P (p, q) at the peak
A means for obtaining an intensity distribution Ii (x, y) on (i = 1 to n), and a second intensity Is at which the intensity of each intensity distribution Ii (x, y) decreases from the peak intensity by a predetermined ratio. When a spot defocused by a predetermined value from the in-focus position of the optical pickup device is imaged, a length ri corresponding to the radius of the spot in a certain direction is determined. , Ri = √ {(xi-p) ² +
(Yi-q) ² } and the length ri,
The smallest value is the radius rmin, and the strength I is outside the range surrounded by the circle of radius rmin from the point P (p, q).
When N is the number of pixels in a portion where (x, y) is larger than the second intensity Is, N is a means for comparing the magnitude of the predetermined value K1.

Secondly, in the first spot inspection apparatus, as a processing means, the radius rmin from the point P (p, q) is used.
Let N1 be the number of pixels within the range surrounded by and the radius rmin
The intensity I (x, y) is outside the range surrounded by
When the number of pixels in a portion larger than the intensity Is of N2 is N2, N2 / N1 and a predetermined value K2, or N2 / (N2 +
N1) and means for comparing the magnitude of the predetermined value K2 '.

Thirdly, in the first spot inspection apparatus, as the processing means, the maximum value of the radius ri is rma.
x, and the intensity I (x, y) within the range surrounded by the circle of radius rmax from the point P (p, q) is the second intensity Is.
When the number of pixels of the smaller portion is N ', a means for comparing the magnitude of N'and a predetermined value K3 is provided.

Fourthly, in the third spot inspection apparatus, as the processing means, the number of pixels in the portion where the intensity I (x, y) is larger than the second intensity Is is N3, and the intensity I
(X, y) is smaller than the second intensity Is and the point P
When N4 is the number of pixels inside the range surrounded by a circle having a radius rmax centered at (p, q), N4 / N3 and a predetermined value K3, or N4 / (N3 + N4) and a predetermined value K
3'is a configuration provided with a means for comparing the magnitude with that of 3 '.

Fifthly, in the first to fourth spot inspection apparatuses, as processing means, when counting the number of pixels, only the pixels on a plurality of straight lines passing through the point P (p, q) are counted. It is the structure provided with.

[0022]

According to the present invention, the spot image from the camera controller is once stored in the frame memory and the arithmetic processing is performed on this image so that the presence or absence of spot astigmatism 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, and the intensity I of each part of the spot is , Can be processed as a function I (x, y) of the coordinates (x, y) of the frame memory.

Conventionally, when the presence or absence of spot astigmatism is detected, the intensity distribution of the spot shown in FIG.
With respect to a cross section cut parallel to the plane, the diameter of the spot is measured in the longest and shortest directions, and the ratio of the two is obtained to determine the presence or absence of ashes. However, in practice, since it is easy to cause an error in the measurement of the diameter, in the present invention, in order to realize accurate detection of the ass with a small error, instead of the conventional determination by the detection of the major axis and the minor axis, The area is detected (two-dimensionally) for determination.

FIG. 2 is an example of the spot intensity distribution of the spot shown in FIG. 15 in which the light amount in the cross section cut parallel to the xy plane is reduced by a predetermined ratio from the intensity peak. In the figure, (1) shows no asbestos and (2) shows ashes. In the figure, So is a spot without asbestos,
Sa indicates a spot with asbestos.

In this case, an appropriate value can be selected as the predetermined ratio. For example, half value, 1 / e ² ,
Any other value may be used. The cross-sectional views shown in Figs. 2 (1) and 2 (2) are so-called spot shapes. As shown in Fig. 2 (1), the spots without spots are almost in focus and defocus. It becomes circular.

On the other hand, the spot with astigmatism becomes a circle at the time of focusing as shown in FIG. 2B, but when defocused, it becomes an elliptical spot of the vertical axis or the horizontal axis. . In this case, the ellipticity (ratio of major axis and minor axis) is
Since the spot itself deteriorates due to defocusing while changing with an increase in defocusing amount, defocusing may be performed by an appropriate distance from the in-focus point in order to determine the presence or absence of astigmatism.

Generally, the defocus amount is ± 2 μm.
At about a certain degree, the ovalization due to ashes appears remarkably. The detection of the ass is performed by detecting this ellipse,
In the conventional general detection method, it is performed by detecting the major axis and the minor axis of the ellipse.

The present invention is characterized in that, in order to accurately detect astigmatism with a small error, instead of detecting the major axis and the minor axis, the area is detected (two-dimensionally). The principle of the presence / absence determination by the spot inspection apparatus of the present invention will be described with reference to FIG.

FIG. 3 is a diagram for explaining the shape of the spot to be detected and the judging method at the time of detecting astigmatism in the spot inspection apparatus of the present invention. In the figure, P is the center position of the intensity distribution of the spot, rmin is the radius in the minor axis direction, S1 is the area of the circle with radius rmin, and S2 is the area excluding the area of circle S1 from the total area.

In FIG. 3, the state of the cross section cut parallel to the xy plane at the intensity (light amount) level Is of the spot shown in FIG. 15 is lowered by a predetermined ratio from the peak value of the intensity, that is, , The shape of the spot defocused by a predetermined value on the imaging element is shown. As shown in FIG. 3, an area S1 surrounded by a circle whose diameter is the minor axis of the elliptical spot and an area S2 outside the circle and inside the elliptical spot are measured, and the minor axis is defined as the diameter. When the area S2 outside the circle to be circled is equal to or larger than a predetermined value, it is determined that the spot has astigmatism (the invention of claim 1).

Further, the area of the elliptical spot changes depending on the shape of the spot, and even if the ellipticity is the same, if the spot area becomes large, it is outside the circle S1 having the minor axis of FIG. The area S2 in the spot also becomes larger. Therefore, in order to further improve the determination accuracy, the ratio of the outer area S2, specifically, the ratio of the two (S2 / S
1) or when the ratio of the outer area S2 to the total area (S1 + S2) {S2 / (S1 + S2)} is greater than or equal to a predetermined value, it is determined that the spot has astigmatism (the invention of claim 2).

Further, the area (S3) of the elliptical spot,
The area enclosed by a circle having the major axis of the elliptical spot as the diameter and the area between the elliptical spot (S3) inside the circle (S4 in the shaded area) was measured, and the area between the major axis and the elliptical spot was measured. When the area (S4) is equal to or larger than the predetermined value, it is determined that the spot has astigmatism (the invention of claim 3).

Also in this case, the ratio of both (S4 / S
3) or ratio to total area (S3 + S4) {S
If 4 / (S3 + S4)} is greater than or equal to a predetermined value, it is similarly determined that the spot has astigmatism, whereby the determination accuracy can be further improved (the invention of claim 4). In the above judgment, the area of the ellipse is calculated and judged.
In order to simplify the calculation, the number of pixels on a plurality of straight lines passing through the intensity peak point P is counted, and instead of the determination by the total area, when the number of pixels is a predetermined value or more, the spot has an astigmatism. It is determined that there is (invention of claim 5).

[0034]

[Embodiment 1] Next, a spot inspection apparatus of 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 the basic principle of the hardware configuration and the determination of the presence / absence of asbestos are also related to the inventions of claims 2 to 5.

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of the spot inspection apparatus of the present invention. The reference numerals in the figure are the same as those in FIG.
1 is a frame memory, 12 is a TV monitor similar to 9,
Reference numeral 13 denotes a computer, and 14 denotes 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 those in FIG. In the spot inspection apparatus of the present invention 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 the raw image is displayed on a screen of a TV monitor 12. indicate.

On the other hand, after transmitting the command, the computer 13 applies the processes of claims 1 to 5 to the image stored in the frame memory 11 and displays the result on the display 14. The inspection apparatus shown in FIG. 1 is intended to detect spot astigmatism (astigmatism).

In FIG. 3 described above, in order to explain the principle of spot detection of astigmatism in the present invention, a method of determining the presence or absence of astigmatism based on the areas S1 and S2 of the elliptical spot has been described. However, in the actual processing, the number of pixels existing in each region (areas S1 and S2) of the elliptical spot is counted, and the determination is performed based on the number of pixels in each region.

As already described in detail with reference to FIG. 15 above, when the inclination of the objective lens is well adjusted and there is no distortion, the intensity distribution of the spot has a bell-shaped shape 21. Here, assuming the xy plane of the image sensor (generally, the image sensor is planar) on which the image of this spot is formed, the x axis and the y axis are set on this plane.

The intensity of the spot at the point (x, y) on the image pickup device is I (x, y), and the point at which the intensity peaks is P (p, q). Next, consider the intensity distribution of the spot on the straight line 22 that passes through the point P and forms an angle θ1 with the x-axis. In FIG. 15 above, a straight line Li on the image sensor passing through the point P
Can be generally expressed by Li = (x−p) × tan θ1 + q.

Then, the intensity distribution Ii on each straight line Li
(X, y) is obtained, and for each straight line Li, a point at which the intensity Ii decreases from the peak intensity by a predetermined ratio and becomes the second intensity Is is obtained. By such processing, as shown in FIG. 3, the frame memory (imaging element) 1
On 1, a spot defocused by a predetermined value is obtained.

FIG. 4 is a diagram showing an example of a state in which a spot defocused by a predetermined value from the intensity peak value is formed on the image pickup device. In the figure, N1 is the number of pixels in a region surrounded by a circle having a radius in the minor axis direction (○)
Pixels) and N2 indicate the number of pixels in the area outside the area surrounded by the circle having the number of pixels N1 (pixels indicated by ●).

In this FIG. 4, the radius rmi shown in FIG.
The number of pixels in the area S1 of the circle of n is shown by N1, and the number of pixels in the area S2 outside the circle and inside the elliptical spot is shown by N2. Then, when the number of pixels N2 (N in claim 1) in this case is larger than the predetermined value K1, it is determined that the spot has astigmatism.

FIG. 5 is a diagram showing another example of a state in which a spot defocused by a predetermined value from the intensity peak value is formed on the image pickup device. Reference numerals in the figure are the same as those in FIG.

In the case of an elliptical spot, its axial direction is generally different from the arrangement direction of the pixels on the image pickup device, as shown in FIG. However, in most cases, spots are formed on the image sensor in the state as shown in FIG.

However, the processing for spot astigmatism detection is the same whether the pixel arrangement direction is the state shown in FIG. 4 or the state shown in FIG. In this embodiment, the spot astigmatism detection operation is performed by the following flow of FIG.

FIG. 6 is a flow chart showing the basic processing flow when spot astigmatism is detected in the spot inspection apparatus of the present invention. In the figure, # 1 to # 9 indicate steps.

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

In step # 3, assuming a plurality of straight lines Li: y = tan θi × (x−p) + q passing through the point P (p, q), the intensity distribution Ii (x, y) on each straight line is assumed. Ask for. In step # 4, for each straight line Li, the intensity Ii
Is reduced from the peak intensity by a predetermined ratio to obtain points Si (xi, yi) that become the intensity Is, and ri = √ {(xi-p) ² + (yi-q) ² } from these points Si. Ask for.

Proceed to step # 5, and the minimum value rmin of ri
(= Minor axis radius) In step # 6, r = √
The number N of pixels with {(x−p) ² + (y−q) ² }> rmin and intensity I (x, y)> Is (N2 in FIGS. 4 and 5)
Ask for.

In the next step # 7, it is checked whether N> K1. If it is not N> K1, it is determined in step # 9 that there is no spot on the spot, and the flow of FIG. 6 is terminated.

If N> K1, it is determined in step # 8 that there is a spot on the spot, and the flow of FIG. 6 is terminated. As a result of the processing in steps # 1 to # 9 described above, FIG.
The presence / absence of astigmatism in the spots shown in FIG.

[0053]

Second Embodiment Next, a second embodiment will be described. This embodiment corresponds to the invention of claim 2. In the first embodiment described above, when the number N2 of pixels in the area outside the circle having the radius in the minor axis direction as the diameter of the spot is equal to or greater than a predetermined value, it is determined that the spot has astigmatism.

In the second embodiment, in order to further improve the determination accuracy, the ratio of the number of pixels N2 in the outer area to the number of pixels N1 in the area surrounded by the circle having the radius in the minor axis direction as the diameter. Specifically, the ratio of both (N2 / N1) or the ratio of the number of pixels (N1 + N2) {N2 / (N1 + N)
2)} is greater than or equal to a predetermined value, it is determined that the spot has astigmatism. Others are the same as those in the first embodiment.

FIG. 7 is a flow chart showing the basic processing flow at the time of spot astigmatism detection in the second embodiment of the present invention. In the figure, # 11 to # 19 indicate steps.

In step # 11, the spot image is captured on the frame memory 11 of FIG. Proceeding to step # 12, a point P (p, q) at which the intensity I (x, y) reaches a peak is obtained.

In the next step # 13, assuming a plurality of straight lines Li: y = tan θi × (x−p) + q passing through the point P (p, q), the intensity distribution Ii (x, y) is calculated. In step # 14, for each straight line Li,
A point Si (xi, yi) at which the intensity Ii is reduced from the peak intensity by a predetermined ratio to become the intensity Is is obtained, and ri = √ {(xi-p) ² + (yi-q) is obtained from these points Si.
² } is calculated.

The process proceeds to step # 15, and the minimum value rmi of ri
Find n (= minor axis radius). In step # 16, r = √
^{{(X-p) 2 +} (y-q) 2} The number of pixels of ≦ rmin N1
And r = √ {(xi-p) ² + (yi-q) ² }> rmi
The number N2 of pixels with n and intensity I (x, y)> Is is counted.

At the next step # 17, N2 / N1> K
2 or check if N2 / (N2 + N1)> K2 '. If N2 / N1> K2, or N
If 2 / (N2 + N1)> K2 ', step # 18
Then, it is determined that there is a spot on the spot, and the flow of FIG. 7 is ended.

N2 / N1> K2, or N2 / (N2
Unless + N1)> K2 ', it is determined in step # 19 that there is no astigmatism in the spot, and the flow of FIG. 7 is similarly ended. Through the above processing of steps # 11 to # 19, the size of the spot varies depending on the ratio between the number N1 of pixels in the area surrounded by a circle whose radius is the radius of the spot in the minor axis direction and the number N2 of pixels in the outer area. The presence or absence of ass is determined.

[0061]

Third Embodiment Next, a third embodiment will be described. This embodiment corresponds to the invention of claim 3. The first and second
In the example, the presence or absence of spot astigmatism was determined by the number of pixels using an area surrounded by a circle having a radius in the minor axis direction of the elliptical spot. In the third embodiment, the presence / absence of spot astigmatism is determined by the number of pixels using a region whose radius is the diameter of the elliptical spot in the major axis direction.

FIG. 8 is a diagram for explaining the shape of the spot to be detected and the judging method at the time of detecting astigmatism in the spot inspection apparatus of the present invention. In the figure, rmax is the radius in the major axis direction, S3 is the elliptical spot area, and S4 is the radius rma.
Indicates the area of the circle of x.

In this FIG. 8 as well, similar to FIG. 3 described above, the intensity (light intensity) level reduced from the peak value of intensity by a predetermined ratio, that is, the shape of the spot defocused by a predetermined value on the image pickup element is shown. Shows. In the third embodiment, a region S4 (diagonal line) between an ellipse spot region S3, a region surrounded by a circle having the major axis of the ellipse spot as a diameter, and an ellipse spot region S3 inside the circle. Section) and the area S4 inside the circle having the major axis as the diameter is equal to or larger than a predetermined value, it is determined that the spot has astigmatism.

FIG. 9 is a diagram showing an example of a state in which a spot defocused by a predetermined value from the intensity peak value is formed on the image sensor. In the figure, N3 is the number of pixels of the elliptical spot (pixels marked with ◯), N4 is the pixel of the area between the area surrounded by a circle having the radius of the major axis direction of the elliptical spot and the elliptical spot inside thereof. Number (Indicates the number of pixels marked with ●.

In FIG. 9, a region surrounded by a circle having N3 as the number of pixels in the region S3 of the elliptical spot shown in FIG. 8 and the major axis of the elliptical spot as a diameter, and an ellipse inside the circle. The number of pixels in a region S4 (hatched portion) between the spot region S3 and N4 is shown. Then, when the number of pixels N4 in this case (N 'in claim 3) is larger than the predetermined value K3, it is determined that the spot has astigmatism.

FIG. 10 is a diagram showing another example of a state in which a spot defocused by a predetermined value from the intensity peak value is formed on the image pickup device. Reference numerals in the figure are the same as those in FIG.

In the case of an elliptical spot, generally, as shown in FIG. 10, its axial direction is different from the arrangement direction of the pixels on the image pickup element, but the arrangement direction of the pixels is as shown in FIG. However, even in the state of FIG. 10, the spot astigmatism detection processing is the same. Next, a flow of the third embodiment will be shown.

FIG. 11 is a flow chart showing a basic processing flow at the time of spot astigmatism detection in the third embodiment of the present invention. In the figure, # 21 to # 29 indicate steps.

At step # 21, the spot image is captured in the frame memory 11 of FIG. Proceeding to step # 22, a point P (p, q) at which the intensity I (x, y) reaches a peak is obtained.

At the next step # 23, a plurality of straight lines Li: y = tan θi × (x−p) + q passing through the point P (p, q) are assumed, and the intensity distribution Ii (x, y) is calculated. In step # 24, for each straight line Li,
A point Si (xi, yi) at which the intensity Ii is reduced from the peak intensity by a predetermined ratio to become the intensity Is is obtained, and ri = √ {(xi-p) ² + (yi-q) is obtained from these points Si.
² } is calculated.

The process proceeds to step # 25 and the maximum value rma of ri
Find x (= major axis radius). In the next step # 26, r
= √ {(x−p) ² + (y−q) ² } ≦ rmax, and count the number N ′ of pixels with intensity I (x, y) <Is.

At the next step # 27, it is checked whether N '> K3. If N '> K3, in step # 28, it is determined that there is a spot, and the flow of FIG. 11 is terminated.

If N '> K3 is not satisfied, the process proceeds to step # 29 to determine that there is no spot on the spot, and similarly, the flow of FIG. 11 is ended. Steps # 21- # above
By the processing of No. 29, the number of pixels using an area whose radius is the diameter of the ellipse spot in the major axis direction, in particular, an area surrounded by a circle whose diameter is the major axis of the ellipse spot in FIG. And the size of the number N4 of pixels in the area S4 (hatched portion) between the area S3 of the elliptical spot and the area S3 of the elliptic spot are compared, and the presence or absence of spot astigmatism is determined.

[0074]

Fourth Embodiment Next, a fourth embodiment will be described. This embodiment corresponds to the invention of claim 4. In the third embodiment, the presence or absence of spot astigmatism was determined by the number of pixels (N4 in FIG. 9) using a region whose radius is the diameter of the elliptical spot in the long axis direction.

In this case also, the ratio of both (N4 / N
3), or if the ratio {N4 / (N3 + N4)} to the total number of pixels (N3 + N4) is equal to or more than a predetermined value, if the spot has an astigmatism, the determination is performed as in the second embodiment. The accuracy can be further improved.

FIG. 12 is a flow chart showing a basic processing flow at the time of spot astigmatism detection in the fourth embodiment of the present invention. In the figure, # 31 to # 39 indicate steps.

At step # 31, the spot image is captured in the frame memory 11 of FIG. Proceeding to step # 32, a point P (p, q) at which the intensity I (x, y) reaches a peak is obtained.

At the next step # 33, a plurality of straight lines Li: y = tan θi × (x−p) + q passing through the point P (p, q) are assumed, and the intensity distribution Ii (x, y) is calculated. In step # 34, for each straight line Li,
A point Si (xi, yi) at which the intensity Ii is reduced from the peak intensity by a predetermined ratio to become the intensity Is is obtained, and ri = √ {(xi-p) ² + (yi-q) is obtained from these points Si.
² } is calculated.

The process proceeds to step # 35, where the maximum value rma of ri
Find x (= major axis radius). In the next step # 36, the number of pixels N3 with intensity I (x, y) ≧ Is and r = √
The number of pixels N4 with {(x−p) ² + (y−q) ² } ≦ rmax and intensity I (x, y) <Is is counted.

At the next step # 37, N4 / N3> K
4 or N4 / (N3 + N4)> K4 '. If N4 / N3> K4 or N
If 4 / (N3 + N4)> K4 ', step # 38
Then, it is determined that there is a spot on the spot, and the flow of FIG. 12 is ended.

N4 / N3> K4 or N4 / (N3
+ N4)> K4 ', the process proceeds to step # 39,
It is determined that there is no ass in the spot, and similarly, as shown in FIG.
Ends the flow. By the above processing of steps # 31 to # 39, a region S4 (diagonal line) between a region surrounded by a circle having the major axis of the elliptical spot of FIG. 8 as a diameter and a region S3 of the elliptical spot inside the circle. Number of pixels in part) N4
And the number N3 of pixels in the elliptical spot area S3 are compared to determine whether or not there is spot astigmatism.

[0082]

Fifth Embodiment Next, a fifth embodiment will be described. This embodiment corresponds to the invention of claim 5. In the first to fourth embodiments described above, attention is paid to the area of a circle whose radius is the radius of the elliptical spot in the short axis direction or the long axis direction, and the number of pixels in each area (N1, N2 in FIG. 4, FIG. 9) is used. N3, N4)
The presence or absence of spot ashes was judged.

In the fifth embodiment, instead of counting all the pixels in each area, the point P at which the intensity peaks is displayed.
Only the pixels on a plurality of straight lines passing through (p, q) are counted, and the presence or absence of spot astigmatism is determined by the same determination method as in the first to fourth embodiments. Therefore, according to the fifth embodiment, the time for counting the number of pixels can be shortened and the memory capacity can be saved.

FIG. 13 is a diagram for explaining the shape of the spot to be detected and the determination method at the time of detecting asbestos in the spot inspection apparatus of the present invention. (1) is a circle whose radius is the radius of the elliptical spot in the minor axis direction. In the case of counting the number of pixels by paying attention to the area of (2), (2) is a case of counting the number of pixels by paying attention to the area of a circle having a radius in the major axis direction. In the figure, Li is a straight line, n1 to n4 are N1 to N in FIG. 5 and FIG.
The number of pixels corresponding to 4 is shown.

As in the case of the first embodiment, when the number of pixels is counted by paying attention to the area of a circle whose radius is the radius of the elliptical spot in the minor axis direction, the line Li (shown in FIG. i =
1 to n) are set appropriately and only the number of pixels on each straight line Li is counted. Then, when the number of pixels n2 is equal to or larger than a predetermined value, it is determined that the spot has astigmatism.

Similarly, in the case of the second embodiment, the ratio of both pixels (n2 / n1) or the number of pixels (n1 + n2).
When the ratio {n2 / (n1 + n2)} with respect to is greater than or equal to a predetermined value, it is determined that the spot has astigmatism. In the case of the third embodiment, as shown in FIG. 13 (2), attention is paid to the area of a circle having the radius in the major axis direction of the elliptical spot as the number of pixels n4 (N 'in claim 3). ) Is larger than a predetermined value, it is determined that the spot has astigmatism.

The same applies to the case of the fourth embodiment, and when the ratio (n4 / n3) of both pixels or the ratio {n4 / (n3 + n4)} to the number of pixels (n3 + n4) is a predetermined value or more, the spot is It is determined to have. In the fifth embodiment, as described above, only the number of pixels on the plurality of straight lines Li is counted to determine the presence / absence of spot astigmatism.

[0088]

According to the spot inspection apparatus of the first aspect, a spot defocused from the in-focus position by a predetermined value is imaged on the image pickup device, and the spot is outside the minor axis of the spot.
In addition, the number of pixels inside the spot (N in FIG.
The presence / absence of asbestos is determined by whether or not 2) is larger than a predetermined value. Therefore, as compared with the conventional method of measuring and determining the long axis and the short axis of the spot, the area determination can be performed, and the determination accuracy is improved.

In the spot inspection apparatus according to the second aspect, the ratio of the number of pixels is used in order to further improve the determination accuracy. Since the area to be counted increases, the count time of the number of pixels (N1 in FIG. 4) becomes longer accordingly. Therefore, the determination accuracy is further improved as compared with the spot inspection apparatus according to claim 1.

In the spot inspection apparatus according to the third aspect of the present invention, it depends on whether or not the number of pixels (N4 in FIG. 9) of the portion inside the long axis of the spot and outside the spot is larger than a predetermined value. , The presence of asses is determined. Therefore, similarly to the spot inspection apparatus of claim 2, the determination accuracy is further improved.

In the spot inspection apparatus of the fourth aspect, the ratio of the number of pixels is used in order to improve the determination accuracy. It should be noted that since the count target area increases, the count time of the number of pixels (N3 in FIG. 9) becomes longer accordingly. Therefore, the determination accuracy is further improved as compared with the spot inspection apparatus according to the third aspect.

In the spot inspection apparatus according to the fifth aspect, the number of spot pixels is narrowed down to a plurality of lines passing through the point where the intensity reaches a peak. Therefore, the counting time of the number of pixels is shortened, and the amount of data is reduced accordingly, so that the memory capacity is also reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of a spot inspection device of the present invention.

2 is an intensity distribution of the spot shown in FIG.
It is a figure which shows each example of the spot shape of the surface in which the light quantity fell from the peak of intensity by the predetermined ratio in the cross section cut | disconnected parallel to a plane.

FIG. 3 is a diagram illustrating a shape of a detected spot and a determination method when an asth is detected in the spot inspection apparatus of the present invention.

FIG. 4 is a diagram showing an example of a state in which a spot defocused by a predetermined value from an intensity peak value is formed on an image sensor.

FIG. 5 is a diagram showing another example of a state in which a spot defocused from the intensity peak value by a predetermined value is formed on the image sensor.

FIG. 6 is a flowchart showing a basic processing flow when spot astigmatism is detected in the spot inspection apparatus of the present invention.

FIG. 7 is a flowchart showing a basic processing flow when spot astigmatism is detected in the second embodiment of the present invention.

FIG. 8 is a diagram illustrating a shape of a detected spot and a determination method when an asth is detected in the spot inspection apparatus of the present invention.

FIG. 9 is a diagram showing an example of a state in which a spot defocused by a predetermined value from an intensity peak value is formed on an image sensor.

FIG. 10 is a diagram showing another example of a state in which a spot defocused by a predetermined value from the intensity peak value is formed on the image sensor.

FIG. 11 is a flowchart showing a basic processing flow at the time of spot astigmatism detection in the third embodiment of the present invention.

FIG. 12 is a flowchart showing a basic processing flow when spot astigmatism is detected in the fourth embodiment of the present invention.

FIG. 13 is a diagram illustrating a shape of a detected spot and a determination method when an asth is detected in the spot inspection apparatus of the present invention.

FIG. 14 is a diagram showing an example of a main part configuration of a conventional adjusting device that performs an optical head adjusting step.

FIG. 15 shows that the tilt of the objective lens is well adjusted, and
It is a figure which shows an example of the intensity distribution of the spot when there is no distortion.

[Explanation of reference numerals] 1 housing of optical pickup 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 (5)

[Claims] 1. Intensity I (x, y) at a point (x, y) on the imaging device is formed by forming an image of light emitted from a lens on the imaging device.
In the spot inspection device of the optical pickup device for performing the calculation using y), as processing means, means for obtaining a point P (p, q) at which the intensity I (x, y) reaches a peak, and point at which the peak is reached Intensity distribution I on a plurality of straight lines Li (i = 1 to n) on the image sensor passing through P (p, q)
a means for obtaining i (x, y), and a position (x where the intensity of each intensity distribution Ii (x, y) becomes a second intensity Is which is reduced from the peak intensity by a predetermined ratio.
i, yi) and a spot defocused by a predetermined value from the in-focus position of the optical pickup device is imaged, the length ri corresponding to the radius of the spot in a certain direction is expressed as ri = √ {(xi-p) ² + (yi-q) ² } means, and the smallest value of the length ri is the radius rmin, which is surrounded by a circle of radius rmin from the point P (p, q) And N is the number of pixels in a portion outside the range where the intensity I (x, y) is greater than the second intensity Is, and means for comparing the magnitude of N with a predetermined value K1. A spot inspection device for an optical pickup. 2. The spot inspection apparatus according to claim 1, wherein as a processing means, the number of pixels within a range surrounded by a radius rmin from the point P (p, q) is set to N1, and the pixel is outside the range surrounded by the radius rmin. If the number of pixels in a portion where the intensity I (x, y) is larger than the second intensity Is is N2, N2 / N1 and a predetermined value K
2. A spot inspection apparatus for an optical pickup, characterized by comprising means for comparing the magnitude of 2 or N2 / (N2 + N1) with a predetermined value K2 '. 3. The spot inspection apparatus according to claim 1, wherein as a processing means, a maximum value of the radius ri is rmax, and a point P (p, q).
From N to the predetermined value K3, where N'is the number of pixels in the area surrounded by the circle of radius rmax and the intensity I (x, y) is smaller than the second intensity Is. This is a configuration provided with a means for comparing. 4. The spot inspection apparatus according to claim 3, wherein as a processing means, the number of pixels in a portion where the intensity I (x, y) is larger than the second intensity Is is N3, and the intensity I (x, y) is Second intensity Is
Is smaller than N4 and the number of pixels inside a range surrounded by a circle having a radius rmax centered on the point P (p, q) is N4, N4 / N3 and a predetermined value K3 or N4 /
A spot inspection device for an optical pickup, comprising means for comparing the magnitude of (N3 + N4) with a predetermined value K3 '. 5. The spot inspection apparatus according to any one of claims 1 to 4, wherein as processing means, when counting the number of pixels, means for counting only pixels on a plurality of straight lines passing through a point P (p, q) is provided. An optical pickup spot inspection device characterized by being provided.