JPH06259783A - Light spot inspecting device - Google Patents

Abstract

PURPOSE:To accurately and rapidly detect an optical axis by detecting a strongest position of light intensity in comparing a central picture element with eight picture elements surrounding this element address as an assumed base point in light intensity. CONSTITUTION:A spot image is fetched into a frame memory 11 via a microscope 7 and a camera controller 8 by a command from a computer 13, and this raw picture is displayed on a TV monitor 12. The spot image fetched into the memory is subjected to arithmetic processing by a command. The base point is set at an approximately center of the spot image on the memory 11, and this light intensity is compared with the eight surrounding picture elements in turn. When there is no light intensity larger than the base point, the base point at this time is regarded as a peak position. When there are some picture elements having larger light intensity, the base point is moved to the largest light intensity, and this processing is repeated, and when a difference in intensity is eliminated, the movement is stopped, so that the base point exists always in a peak position of a light intensity distribution, and finally a point of the max. value of the light intensity is obtained, and hence this point is regarded as the optical axis. Thus, the optical axis can accurately be detected almost in a moment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical spot inspection device used for adjusting an inclination of an objective lens actuator in an optical pickup assembling process, and particularly, in the spot inspection process, an optical axis serving as a reference position is swift and high. The present invention relates to an optical spot inspection device that enables detection with high accuracy, reduces the burden on the operator, and enables quick and accurate spot inspection.

[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. A cover glass 6 having the same thickness as that of the optical disc 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. The microscope 7 has a built-in camera (not shown), 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 5 incorporated in the actuator 3 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.

The applicant of the present invention is concerned with a pickup inspection apparatus which solves such an inconvenience and enables the spot inspection process to be automatically performed to reduce the burden on the operator and prevent the quality from varying. , Already proposed (for example, Japanese Patent Application No. 4-214628, Japanese Patent Application No. 4)
-234230). By the way, in the inspection of such an optical pickup, particularly in the inspection of the light spot, first, the optical axis is detected, and the quality of the spot is judged by the distribution state of the light intensity of the cross section passing through the optical axis. There is.

Here, the optical axis means a point where the light intensity is the strongest, and in this case, the center of gravity of the light distribution is detected as the optical axis. That is, in the conventional inspection, when the optical axis is detected, the center of gravity is calculated for all the pixels of the camera, so that the calculation time becomes long. For example, in the case of 1,024 vertical pixels and 2,048 horizontal pixels, the total number of pixels is 2,097,152, and if 1 microsecond is required for calculation per pixel, it takes about 21 seconds. I need.

As described above, when inspecting the light spot, it is necessary to detect the optical axis for setting the reference position, and it takes time to detect the optical axis. If the optical axis detection process is time-consuming, the problem remains that the inspection time of the light spot is delayed.

[0013]

SUMMARY OF THE INVENTION According to the present invention, such inconvenience occurs in the conventional spot inspection of the optical pickup, and in the optical spot inspection device for the optical pickup filed previously, the detection of the optical axis serving as the reference position is detected. It solves the problem that it takes time to process, accurately and quickly,
An object of the present invention is to provide an optical spot inspection device capable of detecting an optical axis, reducing the burden on an operator at the time of spot inspection, and enabling highly accurate inspection.

[0014]

According to the present invention, firstly,
In the light spot inspection device that forms the light emitted from the lens on the image pickup element and performs the arithmetic processing using the intensity I (x, y) at the point (i, j) on the element, the intensity I
As a processing means for detecting the peak position of (x, y), the central point P of the light intensity distribution composed of pixels (m, n)
(I, j) is i = int (m / 2), j = int (n /
2), the intensity I (i, j) at the central point P
And the intensity difference dIn (i, j) at eight points in the vicinity of
Here, n = 1 to 8, dI1 = I (i + 1, j) -I (i, j) dI2 = I (i-1, j) -I (i, j) dI3 = I (i, j + 1) -I (i, j) dI4 = I (i, j-1) -I (i, j) dI5 = I (i + 1, j + 1) -I (i, j) dI6 = I (i + 1, j-1)- I (i, j) dI7 = I (i-1, j + 1) -I (i, j) dI8 = I (i-1, j-1) -I (i, j) and the neighborhood 8 Means for obtaining a point where the values of the intensity differences dI1 to dI8 at the points become maximum values;
The point at which the values of the intensity differences dI1 to dI8 are maximum values is newly set as a point P, and the intensity differences dIn at eight points in the vicinity thereof
Means for obtaining (i, j) by the above equations dI1 to dI8, and by sequentially repeating the process for obtaining the point where the value of the intensity difference dI1 to dI8 becomes maximum, the light intensity I ( The peak position of (x, y) is obtained.

Secondly, in the above-mentioned first inspection apparatus, a point which is moved a certain distance from the obtained peak position is used as a base point P.
1, detecting the intensity differences dI1 to dI8, and detecting the point whose value is closest to "0" as a new point P (i, j), and the repeating operation of the detecting means. The isointensity line up to the base point P1 that is sequentially obtained is obtained by the following, and ig and jg are expressed by the following formulas for the light intensity distribution I (i, j) in the range surrounded by the closed curve.

[Equation 5] And a center of gravity position calculating means for calculating the center of gravity according to the above, and calculating the coordinates as the peak position.

Thirdly, in the above-mentioned first inspection apparatus, for the light intensity distribution I (i, j) in the range of the radius R centered on the obtained peak position, ig and jg are expressed by the following equations:

[Equation 6] The center of gravity position calculating means for calculating the center of gravity and calculating the coordinates as the peak position is provided.

Fourthly, in the above-mentioned first inspection apparatus, with respect to the obtained peak position P0 (i, j), coordinates (i-
R, j-R), (i-R, j + R), (i + R, j-
R), (i + R, j + R) inside the square having the vertices, ig and jg are given by

[Equation 7] The center of gravity position calculating means for calculating the center of gravity and calculating the coordinates as the peak position is provided.

Fifthly, in the second inspection apparatus, the maximum and minimum values of the X coordinate and the Y coordinate in the pixel coordinate group of the obtained isointensity line are respectively defined as Xmax, Xmin, Ymax,
Let Ymin be the following four points, (Xmin, Ymin),
(Xmax, Ymin), (Xmin, Ymax), (Xmax,
Ig and j for the interior of the rectangle with Ymax) as the vertex
g is the following formula,

[Equation 8] The center of gravity position calculating means for calculating the center of gravity and calculating the coordinates as the peak position is provided.

[0019]

According to the present invention, when inspecting a light spot, a temporary center of the optical axis is set in order to quickly and accurately detect the position where the light intensity reaches a peak, that is, the optical axis serving as the reference position. Compared sequentially with the light intensity of 8 pixels around it,
If there is a pixel having an intensity higher than the tentative center, the tentative center is moved in that direction and similarly compared with the light intensities of the eight pixels around it. Then, by repeating such operations in sequence, the pixel having the highest light intensity is detected and the center of the optical axis (the position serving as the reference for spot inspection) is determined (the invention of claim 1).

Further, similarly, the point moved from the position where the light intensity determined in this way has a peak is moved by a fixed distance as a base point (for example, P1) and similarly compared with the light intensities of the eight pixels around it. If there is a pixel whose light intensity is closest to “0”, that point is set as a new base point (P1) and sequentially compared with the light intensity of the eight pixels around it. By repeating this operation in sequence, an isointensity line based on a plurality of base points (P1) is obtained, and the light intensity distribution in the range surrounded by this closed curve is calculated according to the following equations (1) and (2). Find the center of gravity,
The coordinates are detected as the peak position (optical axis) (the invention of claim 2).

[0021]

[Equation 9]

Thirdly, regarding the light intensity distribution within a certain radius (for example, R) centering on the peak position detected by the invention of claim 1, the formula (1) explained in the invention of claim 2 and
The position of the center of gravity is obtained according to (2), and the coordinates are set as the peak (the invention of claim 3). Fourthly, similarly, with respect to the peak position detected by the invention of claim 1, the inside of the square within a predetermined value (eg, R) before and after the peak position is expressed by the formula (1) described in the invention of claim 2. The position of the center of gravity is obtained according to (2) and (2), and the coordinates are detected as the peak position (the invention of claim 4).

Fifth, in the pixel coordinate group of the isointensity lines obtained by the invention of claim 2, the inside of a rectangle having the maximum and minimum values of X and Y coordinates as vertices is described. The position of the center of gravity is obtained by performing calculations according to the equations (1) and (2) described in the invention, and the coordinates are detected as the peak position (optical axis) (the invention of claim 5). As described above, the optical spot inspection device for an optical pickup of the present invention detects the optical axis (the point where the light intensity is the strongest) necessary for the inspection of the optical spot, so that the optical axis can be detected accurately and quickly. become.

[0024]

First Embodiment As described above, the present invention aims at speeding up the optical axis detection processing in the pickup inspection apparatus previously applied, and the optical axis detection processing in the present invention is previously described. It is assumed that the applied pickup inspection device is used for inspection of a light spot. Therefore, the optical spot inspection apparatus of the present invention has the same hardware configuration as the pickup inspection apparatus previously applied.

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of the optical spot inspection device of the present invention. Reference numerals in the figure are the same as those in FIG. 19, and
Reference numeral 11 is a frame memory, 12 is a TV monitor similar to 9, a computer is 13, and a display is 14.

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 optical spot 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.

In this case, in the inspection of the light spot, a command is given from the computer 13 to the spot image once taken in the frame memory 11, and the command is given.
The calculation processing according to claim 5 is performed, and the result is displayed on the display 14. In this way, since the spot image on the image sensor of the camera is projected on the frame memory 11, it is possible to handle the assumed x, y coordinates on the image sensor as the x, y coordinates of the frame memory.

Regarding the optical axis detection processing, the intensity I (x, y) of each spot portion can be processed as a function I (x, y) of the coordinates (x, y) of the frame memory 11. . Next, the intensity distribution of the spot when the inclination of the objective lens 5 incorporated in the actuator 3 is properly adjusted will be described.

FIG. 2 is a diagram showing an example of the intensity distribution of the spot when the inclination of the objective lens is adjusted well and there is no distortion. In the figure, x and y are the x and y axes,
I is the intensity of the spot, P is the point where the intensity peaks, 21
Indicates a spot intensity distribution curve, and 22 indicates a straight line.

As shown in FIG. 2, 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 surface 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 surface.

The intensity of the spot at the point (x, y) on the image sensor is I (x, y), and the point at which the intensity peaks is P (xp, yp). Note that, in FIG. 2, the point P and the coordinate origin are shown as being coincident with each other for easy understanding. Next, considering the intensity distribution of the spot on the straight line 22 that passes through the point P and makes an angle θ1 with the x-axis, the result is shown in FIG. 3 below.

FIG. 3 is a diagram showing an example of the intensity distribution of spots on a straight line 22 passing through the point P and forming an angle θ1 with the x-axis in FIG. In the figure, 23 is the intensity distribution curve of the spot,
24 is the primary ring, 25 and 26 are the peaks of the primary ring, and 27 is the main lobe.

The intensity distribution curve 21 of the spot shown in FIG.
Then, the intensity distribution of the spot on the straight line 22 which passes through the point P and makes an angle θ1 with the x-axis becomes a curve as shown by 23 in FIG. That is, the primary rings 24 having their peaks 25 and 26 are formed on both sides of the main lobe 27. Further, the raw image of the spot of FIG. 2 is displayed on the screen of the TV monitor 12 as shown in FIG.

FIG. 4 is a diagram showing an example of a raw image of a spot displayed on the screen of the TV monitor 12. Reference numerals in the figure are the same as those in FIG. 3, and 28 to 30 indicate certain straight lines.

The raw image of the spot on the screen of the TV monitor 12 shown in FIG. 4 is an image example when FIG. 2 is viewed from the positive direction of the I axis. As shown in FIG. 4, the spot (normal spot) in the case where the inclination of the objective lens is well adjusted and there is no distortion is that the primary ring 24 is aligned with a certain axis (x axis in this FIG. 4). The shape is almost symmetrical to that.

Therefore, the intensity distribution on the straight line 28 indicated by the chain double-dashed line is similar to that shown in FIG.
The peak of always appears in pairs. On the other hand, the intensity distribution on the straight line 29 shown by another two-dot chain line is as shown in FIG.

FIG. 5 shows a straight line 29 indicated by a two-dot chain line in FIG.
It is a figure which shows the example about the intensity distribution above. The horizontal axis of the figure is the straight line 29 of FIG. 4, and the vertical axis shows the intensity of the spot.

As shown in FIG. 5, no peak of the primary ring appears on the straight line 29 shown by the chain double-dashed line in FIG. In addition, depending on how to select the two-dot chain line,
This may be different from FIG. 5, for example, the straight line 30 in FIG.
In the case of, only one peak appears.

The intensity distribution of the straight line 30 shown in FIG. 4 is as shown in FIG. FIG. 6 is a diagram showing an example of the intensity distribution on the straight line 30 shown by the chain double-dashed line in FIG. The horizontal axis of the figure is the straight line 30 of FIG. 4, and the vertical axis shows the intensity I1 of the spot.

In the optical spot inspection apparatus on which the present invention is based, a plurality of straight lines (L) passing through the point P as shown in FIG.
1, L2, ..., Ln) Assuming the peak of the primary ring appearing in the intensity distribution on each straight line. According to the result of this consideration, in the case of a normal spot, the straight line 30 in FIG.
On a straight line other than the straight line that passes through the ring end, such as
It can be seen that the peaks of the primary ring always appear in pairs or not at all.

On the other hand, in the spot (abnormal spot) where the tilt adjustment is insufficient or the distortion is generated, an asymmetric or irregularly shaped primary ring occurs. FIG. 7 is an example of an abnormal spot and shows a case where the primary ring is asymmetric. Reference numerals in FIG.
And 31 and 32 are primary rings, and 33 and 34 are straight lines, respectively.

FIG. 8 is a diagram showing an example of a similarly abnormal spot, showing a case where the primary ring is irregular. The reference numerals in the figure are the same as those in FIG. 7, 35 to 37 are primary rings, and 38 to 39 are straight lines.

In the case of FIG. 7, considering the intensity distribution on the straight line as shown by 34, it becomes as shown in FIG. 9 below. FIG. 9 is a diagram showing an example of the intensity distribution on the straight line 34 shown by the chain double-dashed line in FIG. The horizontal axis of the figure is the straight line 34 of FIG. 7, and the vertical axis shows the intensity I2 of the spot.

As shown in FIG. 9, in the intensity distribution on the straight line 34 in FIG. 7, only one peak of the primary ring exists. That is, if the case of the straight line 33 in FIG. 7 is excluded, a spot having a straight line (cross section of the intensity distribution) in which only one peak of the primary ring exists has a high probability of being abnormal. be able to.

This point also applies to the straight lines 38 and 39 in FIG. In the light spot inspection device of the prior application, such normal / abnormal judgment of the light spot is performed by the arithmetic processing. In the optical spot inspection apparatus of the present invention, in the inspection of the optical spot, the optical axis (pixel at which the light intensity has a peak) that is the first required reference position can be detected quickly and accurately.

As described above, the spot image data, that is, the light intensity data is stored in the frame memory 11 of FIG. In this invention, the position where the light intensity reaches a peak is calculated for the data of this spot image.

FIG. 10 is a diagram showing addresses on the memory for explaining the operation of detecting the optical axis in the optical spot inspection apparatus of the present invention. In the figure, each of the nine matrices corresponds to a pixel address on the frame memory 11, and (i, j) indicates the central address.

In FIG. 10, nine matrixes at the center of the frame memory 11 are representatively shown. The optical axis detection procedure is as follows. Usually, when measuring the spot, the optical axis is set in the approximate center of the screen, so it is optimal to set the base point of peak detection at the screen center. Therefore, in FIG.
The base point P is set to the central pixel address (i, j).

Light intensity I at central point P (i, j)
The light intensities of the eight pixels around (i, j) are compared. In FIG. 10, the upper left address (i-1, j-1)
To the lower right address (i + 1, j + 1), the respective light intensities I (i-1, j-1) to I (i +
1, j + 1) and the light intensity I (i, j) of the point P (i, j)
And are sequentially compared.

As a result of the comparison of the light intensities, the point P is moved in the direction (address) having the largest value. When there is no difference in intensity, the point P is not moved.

By repeating and executing the above process, the point P always exists at the peak position of the light intensity distribution. Therefore, finally, the light intensity I
A point P (i, j) having the maximum value of (i, j) is obtained.

The point P where this light intensity I (i, j) is maximum
Let (i, j) be P0. Through the above procedure, the point P0 at which the light intensity I (i, j) has the maximum value is obtained, and this point P0 is set as the optical axis. Next, the operation of the first embodiment will be shown by a flow.

FIG. 11 is a flow chart showing the main processing flow at the time of detecting the optical axis according to the first embodiment in the optical spot inspection apparatus of the present invention. In the figure, # 1
~ # 7 indicate steps.

In step # 1, the frame memory 1 of FIG.
The base point P is set at approximately the center of the spot image on 1 (see FIG. 10). In the next step # 2, the base point P (i,
The light intensity I (i, j) of the pixel j) is sequentially compared with the light intensity of the eight pixels around it.

At step # 3, the base point P is set to the eight surrounding pixels.
It is determined whether or not there is a pixel having a light intensity higher than that of the pixel. As a result of the determination in step # 3, if there is no pixel having an intensity higher than that of the pixel of the base point P (when the light intensity does not differ from the light intensity I of the pixel of the base point P), the process proceeds to step # 7. The point P at the time point is set to P0, and the flow of FIG. 11 is ended.

On the other hand, if there is a pixel having an intensity higher than that of the pixel at the base point P, the process proceeds to step # 4. In step # 4, the point P is moved in the direction in which the value of the light intensity is the highest among the eight surrounding pixels.

Next, in step # 5, the light intensity of the new point P is compared with the light intensity of the eight pixels around it. In step # 6, it is determined whether or not the surrounding 8 pixels include a pixel having a light intensity higher than that of the pixel at the base point P.

If there is a pixel having an intensity higher than that of the pixel at the base point P, the process returns to step # 4 again, and the same processing is repeated. Then, when it is detected in step # 6 that there is no pixel whose light intensity is larger than the pixel of the point P, the process proceeds to step # 7, and the point P at that time is set to P
The flow of FIG. 11 is ended with 0.

By the above processing of steps # 1 to # 7, the pixel at the position where the light intensity distribution has a peak is detected,
That position is the optical axis. As described above, in the light spot inspection apparatus of the present invention, the temporary base point P is set in the center of the screen, the difference from the light intensity of the eight pixels around it is obtained, and the base point is set to the position of the pixel where the light intensity is maximum. While moving P, the position (P0) of the pixel having the maximum light intensity is obtained to determine the optical axis.

In the optical spot inspection apparatus of the present invention, the light intensities are sequentially compared from the pixel at the center of the frame memory 11 where the optical axis is likely to exist. Therefore, compared with the conventional optical axis detection method,
The optical axis can be detected accurately at a high speed of millisecond.

[0061]

Second Embodiment Next, a second embodiment will be described. This embodiment corresponds to the invention of claim 2, but also relates to the invention of claim 1. The second embodiment is characterized in that the center of gravity of the light intensity can be calculated quickly and accurately, and the optical axis position is detected at a high speed.

In the first embodiment described above, the light intensity I (i, i,) of the pixel at the temporarily set central point P (i, j) is set.
The case where the optical axis is determined by detecting the position point P0 at which the light intensity reaches a peak while repeating the comparison between j) and the light intensity of eight surrounding pixels has been described. However, for example, when the light intensity distribution I (i, j) has asymmetry or when the data has noise, the optical axis
It may not match the position point P0 where the light intensity has a peak.

That is, the position where the light intensity peaks is not always the optical axis. In such a case, conventionally, a method of obtaining the center of gravity of the light intensity and determining the position as the optical axis has been adopted.

However, also in the case of this method, conventionally, for all pixels (pixels on the entire surface of the memory 11 shown in FIG. 1),
The center of gravity of the light intensity was calculated. Therefore, when the number of pixels is large, the number of times of calculation increases, so that the intensity calculation time becomes long and the peak position detection (optical axis detection) becomes slow.

In the second embodiment, the center of gravity of the light intensity is calculated so that the optical axis position can be detected at a higher speed than in the conventional method. Specifically, the center of gravity of the light intensity distribution is obtained with reference to the point P0 which is the peak position obtained in the first embodiment.

FIG. 12 is a diagram showing addresses on a memory for explaining the operation of optical axis detection according to the second embodiment in the optical spot inspection apparatus of the present invention. In the figure, each matrix corresponds to a pixel address on the frame memory 11, a diagonal matrix indicates pixels forming a contour line or a circle, P0 is a point (pixel) at a peak position, and P1 is a peak value. A point (pixel) having a lower predetermined value A is shown.

In FIG. 12, a plurality of matrices including the point P1 of the predetermined value A centered on the point (pixel) P0 at the peak position on the frame memory 11 are representatively shown, but in reality, For example, 1,024 vertical pixels and 2,0 horizontal pixels.
Like 48 pixels, the spot image is composed of many matrices. The procedure for detecting the optical axis by the center of gravity is as follows.

A value obtained by multiplying the light intensity value at the point P 0 at the peak position by a predetermined ratio (for example, 0.9) is obtained,
Let that value be A (in this case, A = 0.9 × light intensity value of point P0). The light intensity of the point P0 and the light intensity of the eight pixels around it are sequentially compared.

As a result of comparing the light intensities in the above, the point having the smallest value is set as the point P. If the intensity of the point P is larger than the above value A, the light intensity of the point P is further compared with the light intensities of the eight pixels around it.

If the intensity of the point P is smaller than the previous value A, this process is stopped. When the pixel having the light intensity value A (light intensity of 0.9 of the light intensity value of the point P0) is detected by the processing from the above, the point is set as P1.

The light intensities of eight pixels around the point P1 are sequentially compared, and the point P1 is moved to the pixel whose difference is closest to “0”. The above process is repeated to detect the point P1.

For the pixels in the range surrounded by the lines (contour lines) of equal intensity where the light intensity thus obtained has a value of A (A = 0.9) with respect to the peak value,
The center of gravity of the light intensity distribution is calculated by (1) and (2).

[0073]

[Equation 10]

By the processings 1 to 3, the optical axis obtained from the center of gravity of the light intensity distribution is detected. Next, the operation of the second embodiment will be shown by a flow.

FIGS. 13 and 14 are flowcharts showing the main processing flow at the time of detecting the optical axis according to the second embodiment of the present invention. In the figure, # 11 to # 27 indicate steps, and ~ indicate connection points.

In step # 11, the processing of the flow of FIG. 11 is performed, and the point P at which the intensity distribution I (i, j) reaches a peak is obtained.
Detect 0. In step # 12, a value obtained by multiplying the value of the light intensity at the point P0 by a predetermined ratio (for example, 0.9) is calculated,
Let that value be A (A is a value obtained by multiplying the value of the light intensity at the point P0 by 0.9).

In step # 13, the light intensity I (i, j) of the pixel at the point P0 is sequentially compared with the light intensity of eight surrounding pixels. In step # 14, the base point P0 is set to the eight surrounding pixels.
It is determined whether or not there is a pixel having a light intensity smaller than that of the pixel.

As a result of the judgment in step # 14, the base point P0
If there is no pixel whose intensity is smaller than that of the pixel (when the light intensity is higher than the light intensity of the pixel of the base point P0), the process proceeds to step # 15, an error is displayed, and the flow of FIG. 13 is terminated. . The reason is that the pixel at the base point P0 is at the position where the light intensity is at the peak, and there should be no pixel having a light intensity higher than this.

On the other hand, if there is a pixel whose intensity is smaller than that of the base point P0, the process proceeds to step # 16. In step # 16, the point P is set to the pixel having the smallest light intensity value among the eight surrounding pixels.

In the next step # 17, the light intensity of the pixel at the point P is compared with a predetermined value A (for example, a peak light intensity of 0.9). If the light intensity at point P is a predetermined value A
If not equal to, the process proceeds to the next step # 18, and the light intensity of the pixel newly set as the point P is sequentially compared with the light intensity of the eight pixels around it.

At step # 19, the point P is moved to the pixel having the smallest light intensity value among the eight surrounding pixels. In step # 20, the light intensity of the pixel at the point P is compared with the predetermined value A.

If the light intensity at the point P is not equal to the predetermined value A, the process returns to the previous step # 18 and the same process is repeated. Then, in step # 20, when a pixel (point P) having a light intensity of value A is detected, step #
In step 21, the pixel is set as the point P1, and the information on the position is held in the memory.

In step # 22, the light intensity of the point P1 is compared with the light intensity of the eight pixels around it. Next step #
At 23, of the eight surrounding pixels, the pixel having the closest difference in light intensity to "0" is set as a new point P1, and the information of the position is held in the memory.

In step # 24, the pixel is set as a new point P1 and its light intensity is compared with the light intensity of eight surrounding pixels. In step # 25, of the eight surrounding pixels, the pixel having the closest difference in light intensity to "0" is set as the n-th point P1, and
The information on the position is held in the memory.

At step # 26, the difference in light intensity is "0".
It is determined whether or not the point P1 of the pixel close to "has a closed curve as shown in FIG. 12. If it is not a closed curve, the process returns to the previous step # 24 and the same processing is repeated.

Then, in step # 24, when it is detected that the points P1 sequentially detected become a closed curve, the process proceeds to step # 27. At step # 27, the center of gravity of the light intensity distribution is obtained by the above equations (1) and (2) for the area surrounded by the point P1.

The area surrounded by the points P1 sequentially detected by such processing, that is, the points P1 having the light intensity of the value A obtained by multiplying the peak value of the light intensity by a predetermined ratio (for example, 0.9). Is calculated by the above equations (1) and (2) to find the center of gravity of the light intensity distribution. Through the above processing of steps # 11 to # 27, the center of gravity of the distribution of the light intensity within the range surrounded by the pixel (contour line) of the point P1 as shown by the hatching in FIG. 12 is obtained.

That is, the coordinate position indicated by ig in the above equation (1) and jg in the above equation (2) becomes the optical axis. In this way, by detecting the optical axis by calculating the center of gravity of the distribution of light intensity, the optical axis can be detected stably even if the spot shape is distorted or noise is present. Is significantly shortened as compared with the conventional method.

[0089]

Third Embodiment Next, a third embodiment will be described. This embodiment corresponds to the invention of claim 3, but is also related to the inventions of claim 1 and claim 2. In the second embodiment described above, the case where the calculation range of the center of gravity of the light intensity distribution is obtained by the contour line of 0.9 (= A) of the peak intensity has been described.

However, since the cross-sectional intensity of the light spot (see FIG. 7) usually has a Gaussian distribution, the contour line has a shape close to a circle. In this third embodiment, focusing on this point,
The peak position (point P0) and a predetermined ratio (for example, 0.
9) multiplied by a value A (in this case, A = 0.9 × point P0
This is characterized in that the optical axis can be more easily obtained by obtaining the center of gravity of the light intensity inside the circle having the radius of the distance from the pixel having the light intensity value of (1).

Therefore, also in the third embodiment, the center of gravity of the light intensity distribution is obtained for the spot pixels similar to those in FIG. 12 described in the second embodiment. The procedure of the optical axis detection according to the third embodiment is as follows, but the processes up to are the same as those of the second embodiment.

A value obtained by multiplying the light intensity value at the point P0 at the peak position by a predetermined ratio (for example, 0.9) is obtained,
Let that value be A (in this case, A = 0.9 × light intensity value of point P0). The light intensity of the point P0 and the light intensity of the eight pixels around it are sequentially compared.

As a result of comparing the light intensities, the point having the smallest value is set as the point P. If the intensity of the point P is larger than the above value A, the light intensity of the point P is further compared with the light intensities of the eight pixels around it.

If the intensity of the point P is smaller than the previous value A, this process is stopped. The light intensity value is A (A
= 0.9), the point is set to P1.

The straight line distance between this point P1 and the peak position P0 is calculated, and the value is set as the radius R, and a circle centered on the peak position P0 is calculated. For the part surrounded by this circle, the above equations (1) and (2)
The center of gravity of the light intensity distribution is calculated by. The optical axis obtained from the center of gravity is detected by the processes of to. Next, the operation of the third embodiment will be shown by a flow.

FIG. 15 is a flow chart showing the main processing flow at the time of detecting the optical axis according to the third embodiment of the present invention. In the figure, # 31 to # 35 indicate steps.

At step # 31, the process of step # 11 in FIG. 13 is performed to obtain the point P0. In the next step # 32, the processes of steps # 12 to # 21 of FIGS. 13 and 14 are performed to obtain the point P1.

At the next step # 33, the straight line distance R between the points P0 and P1 is obtained. In step # 34, a circle centered on the point P0 and having a radius R is obtained. Proceeding to step # 35, the center of gravity of the distribution of the light intensity is obtained by the above equations (1) and (2) for the area surrounded by the circle of radius R.

As a result of the above processing of steps # 31 to # 35, the light within the range surrounded by the pixels (contour lines) of the circle having the radius R centered at the point P0 is shown as shown by the hatching in FIG. The center of gravity of the intensity distribution is required. In the third embodiment, since only one point P1 needs to be detected in the contour line detection processing, the optical axis can be obtained at a higher speed than in the second embodiment.

[0100]

Fourth Embodiment Next, a fourth embodiment will be described. This embodiment corresponds to the invention of claim 4, but is also related to the inventions of claim 1 and claim 2. In the third embodiment described above, the case where the calculation range of the center of gravity of the light intensity distribution is inside the radius R has been described.

However, the calculation of the center of gravity is
It is easier to make a square. Moreover, as described in the third embodiment, since the contour lines are close to circles, there is an advantage that an error does not occur even if the calculation range of the center of gravity is a square.

FIG. 16 is a diagram showing the address relationship on the memory for explaining the operation of the optical axis detection according to the fourth embodiment in the optical spot inspection apparatus of the present invention. The reference numerals in the figure are the same as those in FIG. 12, and the diagonal lines indicate the pixels in the square or rectangular centroid calculation range.

In FIG. 16, a plurality of matrices are representatively shown with the point (pixel) P0 at the peak position on the frame memory 11 as the center. However, as described with reference to FIG. Displays a number of matrices. Next, the procedure will be described, but in this embodiment, the procedures up to are the same as those in the second and third embodiments described above, and therefore detailed description will be omitted.

The pixel position of the peak point P0 is (i0, j
0), and the pixel position of the point P1 is (i1, j1),
The distance between the points P0 and P1 is calculated, and the value is set as R. Center of gravity calculation range in X-axis direction (i0-R, i0 + R)
And the inside of a square in the Y-axis direction (j0-R, j0 + R).

By such processing, the center of gravity of the light intensity is obtained for the pixels in the range surrounded by the diagonal lines in FIG. 16, and the optical axis is detected. Next, the operation of the fourth embodiment will be shown by a flow.

FIG. 17 is a flow chart showing the main processing flow at the time of detecting the optical axis according to the fourth embodiment of the present invention. In the figure, # 41 to # 45 indicate steps.

At step # 41, the process of step # 11 in FIG. 13 is performed to obtain the point P0. In the next step # 42, the processes of steps # 12 to # 21 of FIGS. 13 and 14 are performed to obtain the point P1.

At the next step # 43, the pixel position of the point P0 is set to (i0, j0), and the pixel position of the point P1 is set to (i1, j).
As 1), the distance between the point P0 and the point P1 is obtained, and the value is set as R. In step # 44, the calculation range of the center of gravity is set in the X axis direction (i0-R, i0 + R) and the Y axis direction (j0-R,
j0 + R) is set as a square area.

At step # 45, the center of gravity of the distribution of light intensity is obtained by the above equations (1) and (2) for the area surrounded by the square. Through the processing of steps # 41 to # 45 described above, as shown by hatching in FIG. 16, the X-axis direction (i0-R, i0 + R) surrounding the point P0 and the Y-axis direction (j0-R, (j0 + R) The center of gravity of the light intensity distribution within the range surrounded by the square is obtained.

In the fourth embodiment, the calculation range of the position of the center of gravity is simplified as compared with the third embodiment. Therefore, it is possible to perform a higher-speed operation and obtain sufficient accuracy.

[0111]

Fifth Embodiment Next, a fifth embodiment will be described. This embodiment corresponds to the invention of claim 5, but is also related to the inventions of claims 1 to 4. 2nd to 4th mentioned above
The calculation processing method according to the embodiment, that is, the limitation of the calculation range of the center of gravity position by the contour line method is an extremely effective processing method in terms of calculation speed and accuracy when the spot is distorted or not a perfect circle. Is.

However, since the boundary of the calculation range is complicated, the calculation method also becomes complicated. The fifth embodiment is characterized in that the range of a rectangle circumscribing such a contour line is set as the calculation range, thereby making the calculation process simpler and faster.

Next, the procedure will be described. In FIG. 16 described in the fourth embodiment, from among the pixels P (i, j) forming the diagonally shaded contour lines,
The largest coordinate value (imax, jmax) and the smallest coordinate value (imin, jmin) are obtained.

As the calculation range of the center of gravity, the point P0 (imi
n, jmin), point P1 (imax, jmin), point P2 (i
min, jmax) and the point P3 (imax, jmax) determine the inner region of a rectangle that forms a vertex. The subsequent arithmetic processing is the same as in the case of the second embodiment.

By the above procedure, the rectangular calculation range is determined. Next, the operation of the fifth embodiment will be shown by a flow.

FIG. 18 is a flow chart showing the main processing flow for detecting the optical axis according to the fifth embodiment of the present invention. In the figure, # 51 to # 53 indicate steps.

At step # 51, the processing of steps # 41 and # 42 of FIG. 17 is performed to make a point P forming a contour line.
(Corresponding to the point P1 in the flow of FIG. 17) is calculated. In the next step # 52, the pixels P (i,
j), the largest and smallest coordinates in the X-axis direction and the largest and smallest coordinates in the Y-axis direction are obtained, and the points P0 (imin, jmin) and P1 (imax
, Jmin), point P2 (imin, jmax), point P3 (im
Set a total of 4 points (ax, jmax).

In step # 53, the center of gravity of the distribution of light intensity is obtained by the above equations (1) and (2) for the area surrounded by the rectangles forming the vertices at the four points of coordinates P0 to P3. By the processing of steps # 51 to # 53 described above, the center of gravity of the distribution of the light intensity within the range surrounded by the rectangle having the four points as vertices is obtained.

According to the fifth embodiment, since the calculation range of the center of gravity is a rectangle circumscribing the contour line, the optical axis position can be detected easily and at high speed. Therefore,
Even if the spot shape is distorted, quickly and accurately,
It is possible to find the position of the center of gravity.

[0120]

According to the optical spot inspection apparatus of the first aspect, as described with reference to FIG. 10, the pixel address (i, j) at the substantially center is set to the temporary base point P, and the eight pixels around it are set. The position P0 at which the light intensity reaches its peak is detected by sequentially comparing it with the light intensity of. Therefore, in a normal case, the position P0 where the light intensity peaks can be obtained by the calculation of about 100 pixels.

In this case, the number of calculations is about 800, and the calculation time is about 8 milliseconds, which is shortened to 1/1000 or less as compared with the conventional 21 seconds. Therefore, practically, the peak position can be detected almost instantly.

In the optical spot inspection apparatus of the second aspect, even if the shape of the spot is distorted or noise is present,
The optical axis can be detected stably. Moreover, the calculation time is remarkably shortened as compared with the conventional method.

In the optical spot inspection apparatus of the third aspect, the contour line is obtained by a circle, and the center of gravity of the light intensity distribution is calculated. Therefore, as compared with the optical spot inspection apparatus according to the second aspect of the present invention, it becomes possible to perform a higher speed calculation, and moreover, necessary and sufficient accuracy can be obtained in practical use.

In the optical spot inspection device of the fourth aspect, the calculation range of the position of the center of gravity is simplified as compared with the optical spot inspection device of the third aspect. Therefore, as compared with the optical spot inspection device according to the third aspect, it is possible to perform a higher-speed calculation and obtain sufficient accuracy.

According to the optical spot inspection apparatus of the fifth aspect, the position of the center of gravity can be quickly and accurately obtained even when the shape of the spot is distorted. Comparing the above effects of the optical spot inspection device according to claims 1 to 5 with respect to the calculation speed and the accuracy of the position of the center of gravity, the calculation speed is faster.
3, 5, and 2, and the accuracy of the position of the center of gravity is, on the contrary, in the order of claims 2, 5, 3, 4, and 1.

That is, on the average, the optical spot inspection device of claim 3 is excellent in terms of calculation speed and accuracy of the position of the center of gravity, but when the calculation speed is important, the light spot inspection device of claim 1 is used. When the spot inspection device attaches importance to the accuracy of the position of the center of gravity, the optical spot inspection device according to claim 2 is the most excellent. Therefore, it is clear that the most preferable result can be obtained by appropriately selecting according to the purpose of the optical spot inspection device, the required performance and the like.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of the intensity distribution of a spot when the tilt of the objective lens is adjusted well and there is no distortion.

FIG. 3 is a diagram showing an example of intensity distribution of spots on a straight line 22 that passes through a point P and forms an angle θ1 with the x-axis in FIG.

FIG. 4 is a diagram showing an example of a raw image of a spot displayed on the screen of the TV monitor 12.

5 is a diagram showing an example of an intensity distribution on a straight line 29 indicated by a chain double-dashed line in FIG.

FIG. 6 is a diagram showing an example of an intensity distribution on a straight line 30 indicated by a chain double-dashed line in FIG.

FIG. 7 is a diagram showing an example of an abnormal spot, showing a case where the primary ring is asymmetric.

FIG. 8 is also a diagram showing an example of an abnormal spot, showing a case where the primary ring is irregular.

9 is a diagram showing an example of the intensity distribution on a straight line 34 indicated by a two-dot chain line in FIG.

FIG. 10 is a diagram showing addresses on a memory for explaining the operation of detecting the optical axis in the optical spot inspection device of the present invention.

FIG. 11 is a flowchart showing a main processing flow at the time of detecting the optical axis according to the first embodiment in the optical spot inspection apparatus of the present invention.

FIG. 12 is a diagram showing addresses on a memory for explaining the operation of optical axis detection according to the second embodiment in the optical spot inspection apparatus of the present invention.

FIG. 13 is a flowchart showing a main processing flow at the time of detecting an optical axis according to the second embodiment of the present invention.

FIG. 14 is a flowchart showing a main processing flow at the time of detecting an optical axis according to the third embodiment of the present invention.

FIG. 15 is a flowchart showing the main processing flow at the time of detecting the optical axis according to the third embodiment of the present invention.

FIG. 16 is a diagram showing an address relationship on a memory for explaining the operation of optical axis detection according to the fourth embodiment in the optical spot inspection apparatus of the present invention.

FIG. 17 is a flowchart showing a main processing flow at the time of detecting an optical axis according to the fourth embodiment of the present invention.

FIG. 18 is a flowchart showing the main processing flow at the time of optical axis detection according to the fifth 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 similar to 9 13 Computer 14 Display

Claims (5)

[Claims] 1. Light emitted from a lens is imaged on an image pickup device, and an intensity I (x, at a point (i, j) on the device is formed.
In a light spot inspection device that performs calculation processing using y), as a processing unit that detects the peak position of the intensity I (x, y), the central point P of the light intensity distribution composed of pixels (m, n) is used.
(I, j) is i = int (m / 2), j = int (n /
2), the intensity I (i, j) at the central point P
And the intensity difference dIn (i, j) at eight points in the vicinity
(Where n is an integer of 1 to 8) dI1 = I (i + 1, j) -I (i, j) dI2 = I (i-1, j) -I (i, j) dI3 = I (i, j + 1) -I (i, j) dI4 = I (i, j-1) -I (i, j) dI5 = I (i + 1, j + 1) -I (i, j) dI6 = I (i + 1 , J-1) -I (i, j) dI7 = I (i-1, j + 1) -I (i, j) dI8 = I (i-1, j-1) -I (i, j) Means and means for obtaining a point where the values of the intensity differences dI1 to dI8 at the eight neighboring points have a maximum value; Intensity difference at 8 nearby points dIn
Means for obtaining (i, j) by the above equations dI1 to dI8, and by sequentially repeating the process for obtaining the point where the value of the difference in intensity dI1 to dI8 becomes the maximum, the light intensity I ( x, y)
An optical spot inspection device characterized by determining the peak position of. 2. The inspection apparatus according to claim 1, wherein the intensity difference dI1 to dI8 is determined with a point moved by a certain distance from the determined peak position as a base point P1, and the value of the difference is closest to “0”. A detecting means for detecting a point as a new point P (i, j), and an isointensity line up to the base point P1 sequentially obtained by the repeating operation of the detecting means, and the range surrounded by the closed curve Ig and jg for the light intensity distribution I (i, j) of And a center of gravity position calculating means for calculating the center of gravity according to the above and calculating the coordinates as the peak position. 3. The inspection apparatus according to claim 1, wherein for the light intensity distribution I (i, j) within a radius R centered around the obtained peak position, ig and jg are expressed by the following equations: An optical spot inspection device comprising: a center of gravity position calculating means for calculating the center of gravity according to the above and calculating the coordinates as a peak position. 4. The inspection apparatus according to claim 1, wherein, with respect to the obtained peak position P0 (i, j), coordinates (i
-R, j-R), (i-R, j + R), (i + R, j-
R), (i + R, j + R) inside the square having vertices, ig and jg are expressed by the following equations: An optical spot inspection device comprising: a center of gravity position calculating means for calculating the center of gravity according to the above and calculating the coordinates as a peak position. 5. The inspection apparatus according to claim 2, wherein the maximum value and the minimum value of the X coordinate and the Y coordinate are respectively set to Xmax, Xmin and Ymax in the pixel coordinate group of the obtained isointensity lines.
, Ymin, the following four points (Xmin, Ymin
), (Xmax, Ymin), (Xmin, Ymax), (Xm
ax, Ymax) for the interior of a rectangle with vertices
g and jg are given by the following equations, and An optical spot inspection device comprising: a center of gravity position calculating means for calculating the center of gravity according to the above and calculating the coordinates as a peak position.