JPH06268261A - Light emitting point detection method of light emitting device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a light emitting position detecting method of a light emitting element capable of simultaneously detecting a reference point and a light emitting point with high accuracy by using one imaging device. In a method for detecting a light emitting position of a light emitting element placed on a support 7, an imaging device 5 is arranged in a direction perpendicular to a light emitting surface of the light emitting element, and light from the light emitting surface is imaged.
The image picked up by the image pickup device 5 is subjected to image processing to detect the light emitting position of the light emitting element 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting position detecting method for a light emitting element, and more particularly to a light emitting position detecting method for aligning the position of the light emitting point of a laser diode with a predetermined position from a reference point of its support. It is about.

[0002]

2. Description of the Related Art Laser diodes are widely used as light sources for optical head devices such as compact discs and magneto-optical discs.

FIG. 8 is a sectional view of a laser diode having a double hetero structure formed on an n-GaAs substrate 41. The active layer 43 is a semiconductor having a small band gap, and the n-clad layer 42, P- and
The cladding layer 44 and the 2ndP-cladding layer 46 are made of a semiconductor having a large band gap.

When a positive voltage is applied to the P-electrode 48 and a negative voltage is applied to the n-electrode 49, electrons flow from the n-clad layer 42 and holes flow from the P-clad layer 44 into the active layer 43. These are confined in the active layer 43 by an energy barrier resulting from the band gap difference at the heterojunction. This confinement of carriers promotes efficient recombination of electrons and holes and generates spontaneous emission light. The spontaneous emission light promotes the recombination of the next electron and hole. On the other hand, since the end face of the active layer 43 functions as a reflecting mirror of the optical resonator, stimulated emission and optical amplification proceed while light reciprocates in the resonator.

Further, since the double hetero coupling is used, the refractive index of the active layer 43 is larger than the refractive indexes of the n-clad layer 42 and the P-clad layer 44, so that the active layer 43 functions as an optical waveguide. Are confined in the active layer 43, and light loss is reduced.

Here, when the injection current is increased to some extent, laser oscillation occurs, the output intensity of light emission suddenly increases, and laser light having directivity and a narrow spectrum width is emitted.

The n-GaAs layer 45 is a layer for confining a current, and the cap layer 47 is for reducing the electric resistance with the P-electrode 48.

The above-mentioned laser diode is supported on a photodiode serving as a support table having electrodes and the like. FIG. 9 is a perspective view showing a laser diode supported on a photodiode. As shown in FIG. 9, the laser diode 1 is supported on the photodiode 7. At this time, the center of the light emitting region of the active layer 43 of the laser diode 1 (hereinafter referred to as the light emitting point) is the reference point of the photodiode 7. Is supported at a predetermined position. This is because when the laser diode 1 is packaged and the position of its light emitting point is displaced, when the laser diode 1 is used as a light source of an optical head device, for example, an error occurs in the servo system of the optical head device. is there.

Therefore, the position of the light emitting point of the laser diode 1 is detected, the positional relationship between the light emitting point and the reference point is obtained, and the laser diode 1 is fixed / supported to the photodiode 7 in accordance with the reference point.

However, since the light emitting surface of the laser diode 1 is usually distorted, the reference point is rarely found on the light emitting surface. For example, the reference point is often found on other than the light emitting surface such as the electrode 3. Conventionally, one CCD camera is attached in parallel to the light emitting surface of the laser diode 1, the light emitted from the laser diode 1 is imaged by this CCD camera, and the imaged image is subjected to binary image processing to detect the position of the light emitting point. I do. The reference point of the electrode 3 or the like is imaged by another CCD camera, and the positions of the reference points are detected by pattern comparison of the captured images. The two CCs mentioned above
The part that the D cameras commonly image is determined as the common origin of the two CCD cameras (hereinafter referred to as the origin alignment of the two CCD cameras), and the position of the light emitting point from the reference point is determined by the two CCD cameras. I was seeking through the origin.

[0011]

As described above, conventionally, the origins of two CCD cameras are aligned and one C camera is used.
The position of the light emitting point from the origin is obtained by the CD camera, the position of the reference point from the origin is obtained by the other CCD camera, and the position of the light emitting point from the reference point is obtained. One CCD camera is required, the apparatus is complicated, and the origin alignment between the CCD cameras is required, which makes adjustment difficult. Further, since the position of the light emitting point was detected by binary image processing, it cannot be said that the detection accuracy is sufficient.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a light emitting position detecting method for a light emitting element which can simultaneously detect a reference point and a light emitting point with high accuracy by using one image pickup device.

[0013]

According to the present invention, there is provided a method for detecting a light emitting position of a light emitting element placed on a support, wherein an image pickup device is arranged in a direction perpendicular to a light emitting surface of the light emitting element. Then, the light from the light emitting surface is picked up, and the image picked up by the image pickup device is image-processed to detect the light emitting position of the light emitting element.

Further, according to the present invention, in the light emitting position detecting method for a light emitting element, which is placed on a support base and has a first light emitting point and a second light emitting point on opposing light emitting surfaces, the above-mentioned light emitting is performed. An image pickup device is arranged in a direction perpendicular to a predetermined surface on the support table arranged in parallel to the light emitting surface of the element, light from the facing light emitting surface is picked up, and an image picked up by the image pickup device is displayed. Image processing to perform the first light emission point and the second light emission point.
The position of the light emitting point of the light emitting element is detected, and the displacement of the light emitting surface of the light emitting element from the predetermined surface of the support base is confirmed based on the detected positions of the first light emitting point and the second light emitting point. This is solved by the method for detecting the light emitting position of the light emitting element.

Further, according to the present invention, the above-mentioned problems can be solved by a method for detecting a light emitting position of a light emitting element, which is characterized in that the focus of the image pickup device is focused on the active layer of the light emitting element.

Further, according to the present invention, the above-mentioned subject is arranged such that the image pickup device is arranged so that the pattern on the support table which serves as a reference of the light emitting position of the light emitting element can be picked up, and the image is picked up. This is solved by a light emitting element light emitting position detecting method, characterized by detecting a reference point which is a reference of a light emitting position of the light emitting element by performing image processing on an image captured by the device.

According to the present invention, the above problem is solved by a method for detecting a light emitting position of a light emitting element, which is characterized in that an optical filter is used for adjusting the light amount so that the light amount of the light emitting element falls within the sensitivity range of the image pickup device. To be done.

According to the present invention, the above object is to obtain an intensity distribution waveform of light by converting an image obtained by the image pickup device into a digital image and arithmetically processing the digital image corresponding to a light emitting direction of the light emitting element. The light emitting position detection method of the light emitting element is characterized by detecting the light emitting position of the light emitting element.

[0019]

According to the present invention, as shown in FIG.
Are arranged in a direction perpendicular to the light emitting surface 8 of the light emitting element 1. The image pickup device 5 is focused on the active layer of the light emitting element 1, the light 2 from the light emitting element 1 is picked up, the picked-up image is converted into a digital image, and the light emitting direction of the light emitting element 1 is set to Y.
Direction, the intensity distribution of light can be obtained by arithmetically processing the image located on the same scanning line for each scanning line of the digital image corresponding to the Y direction. A point having a peak light intensity in this light intensity distribution corresponds to a light emitting point.

Further, since the image pickup device 5 picks up the pattern 3 serving as the reference of the light emitting position of the light emitting element 1 and converts the picked-up image into a digital image for image processing, the reference point of the pattern 3 is obtained and from this reference point. The light emitting position of the light emitting element 1 can be obtained.

Further, as shown in FIG. 5, the image pickup device 5 is arranged in a direction perpendicular to the surface 20 of the support base 7 arranged parallel to the light emitting surface 8a of the light emitting element 10. The image pickup device 5 allows the light 2a from the light emitting surfaces 8a and 8b which face each other.
And 2b are picked up, the picked-up image is converted into a digital image, and the same image processing as described above is performed, whereby the positions of the first light emitting point and the second light emitting point of the light emitting surfaces 8a and 8b are respectively changed. Is required. When the direction orthogonal to any of the normal direction of the surface 20 of the support base and the direction of the imaging device 5 is defined as the X direction, the values of the X direction coordinate of the first light emitting point and the second light emitting point are the same. Then, since the light emitting direction of the light emitting element 10 and the surface 20 of the support base 7 are orthogonal to each other, the light emitting direction of the light emitting element and the surface of the support base 7 are deviated from the X coordinate of the first light emitting point and the second light emitting point. The deviation from the orthogonality can be confirmed.

Further, the light emitting element 1 is formed by using the optical filter 4.
By adjusting the light amount so that the light amount is within the sensitivity range of the imaging device 5, the light emitting position of the light emitting device 1 can be detected without changing the emitted light amount of the light emitting device 1.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram for explaining a light emitting position detecting method of a laser diode according to a first embodiment of the present invention. As shown in FIG. 1, the device for detecting the light emitting position includes a laser diode 1 as a light emitting element.
Of the laser diode 1 perpendicular to the light emitting surface 8 of
A CCD camera 5 as an image pickup device for picking up an image of, for example, the electrode 3 is provided as a pattern serving as a reference of the light 2 from and the light emitting position of the light emitting point. Further, an optical filter 4 for keeping the amount of light from the laser diode 1 within the sensitivity range of the CCD camera and an image processing device 6 for image-processing the picked-up image output from the CCD camera 5 are respectively provided.

The light emitting position of the laser diode 1 is detected in a state where the laser diode 1 is supported on a photodiode 7 serving as a support table having electrodes 3 and the like.
The laser diode 1 used in this embodiment has an active layer at a position of 115 μm from the upper surface, and the width of the active layer is about 30 μm.

The method for detecting the light emitting position of the laser diode will be described below with reference to FIG.

First, the reference point of the pattern of the electrode 3 which serves as the reference of the light emitting position is obtained.

The emission of the laser diode 1 is stopped, and the upper surface of the photodiode 7 is covered with a halogen lamp (not shown).
The pattern of the electrode 3 is captured by the CCD camera 5. The CCD camera 5 converts the picked-up optical signal into an electric signal, then converts the electric signal into a digital signal by an A / D converter (not shown), and inputs the digital signal into the image processing device 6 as a digital image. The image processing device 6 identifies the pattern of the electrode 3 on the digital image by pattern matching the digital image and the pattern of the electrode 3 registered in advance. Since the reference point is set at a predetermined position of the pattern of the electrode 3, the position of the reference point on the digital image can be obtained.

Next, the light emitting position of the laser diode 1 is detected. First, the halogen lamp is turned off to cause the laser diode 1 to emit light. The CCD camera 5 focused on the active layer of the laser diode 1 images the light 2 emitted from the laser diode 1. CC
The D camera 5 converts the captured optical signal into an electrical signal,
The electric signal is converted into a digital signal by the A / D converter and input to the image processing device 6 as a digital image.

FIG. 2 shows the digital image input to the image processing device 6 output on the monitor screen. The luminescent image 9 is a grayscale image of the intensity of the light emitted from the laser diode 1 which is captured by the CCD camera 5 and digitally converted. Y is the scanning line direction of the digital image corresponding to the light emitting direction of the laser diode 1, and X is parallel to the upper surface of the laser diode 1 and
Is the scanning line direction of the digital image corresponding to the direction perpendicular to the light emitting direction of. Further, the reference point already obtained is located at a predetermined position of this digital image.

The image processing device 6 outputs the light intensity distribution waveform on the predetermined sampling line A, which is assumed to have the highest light intensity shown in FIG. 2, to the monitor screen as shown in FIG. From the light intensity distribution waveform output on this monitor screen, the light quantity of the laser diode 1 is determined by the CCD camera 5.
It is confirmed whether or not it is within the sensitivity range of, and if it is not within the sensitivity range, it is adjusted by the optical filter 4.

After the adjustment, the digital images in the window W that is predetermined so as to include the luminescent image 9 shown in FIG. 2 are added in the Y scanning line direction, and the light intensity distribution waveform of the added image is shown in FIG. Output to the monitor screen. The position of the light emitting point of the laser diode 1 to be obtained is the peak of the light intensity of the light intensity distribution waveform shown in FIG. Since the position of this light emitting point is obtained from the light intensity distribution waveform, an accurate position of the light emitting point can be obtained.

Since the position of the reference point has already been obtained, the position of the light emitting point from the reference point is found and the laser diode 1 is positioned so that the light emitting point is located at a predetermined position from the reference point.
Can be fixed to the photodiode 7.

FIG. 5 is a block diagram for explaining a light emitting position detecting method of the laser diode according to the second embodiment.
This embodiment is a case where the light emitting surfaces 8a and 8b of the laser diode 10 facing each other have a first light emitting point and a second light emitting point. Reference numeral 2a denotes light emitted from the light emitting surface 8a, and 2b denotes light emitted from the light emitting surface 8b. Thus, in the optical head device, the laser diode 10 having two light emitting points uses the light 2a from the light emitting surface 8a as a light source and the light 2b from the light emitting surface 8b as a monitor of the output light amount. A photodetector is provided opposite to the light emitting surface 8b to monitor the light. In this embodiment, a method of obtaining the positions of the first light emitting point and the second light emitting point and confirming the deviation amount of the light emitting direction from the light emitting surface 8a from the direction perpendicular to the surface 20 of the photodiode 7 will be described. It is a thing.

FIG. 6 is a plan view for explaining the principle of confirming the deviation amount θ of the light emitting direction from the light emitting surface 8a from the direction perpendicular to the surface 20 of the photodiode 7. In FIG. 6, X ′ is the direction of the surface 20 of the photodiode 7,
Y'is a direction orthogonal to X '. As shown in FIG.
From the difference ΔX ′ between the X ′ coordinate values of the first light emitting point and the second light emitting point, the deviation amount θ from the direction perpendicular to the light emitting direction of the light emitting surface 8a of the laser diode 10 and the surface 20 of the photodiode 7 is obtained. be able to.

A method for obtaining the deviation amount θ will be described below.

In the configuration diagram shown in FIG. 5, the laser diode 1 is perpendicular to the surface 20 of the photodiode 7.
CCs for imaging the electrode 3 as a reference pattern of the light emission positions of the light 2a and 2b and the light emission point from 0
A D camera 5 is provided. Other configurations are similar to those of the first embodiment shown in FIG.

First, the reference point of the pattern of the electrode 3 which becomes the reference of the light emitting position is obtained in the same manner as in the first embodiment.

Next, the positions of the first light emitting point and the second light emitting point of the laser diode 10 are detected. First, the halogen lamp is turned off and the laser diode 10 is caused to emit light. The CCD camera 5 focused on the active layer of the laser diode 10 images the light 2a and 2b emitted from the laser diode 10. The CCD camera 5 converts the captured optical signal into an electrical signal, and then A / D
The converter converts the electric signal into a digital signal and inputs it to the image processing device 6 as a digital image.

FIG. 7 shows the digital image input to the image processing device 6 output on the monitor screen. The luminescent image 15 is the light 2a emitted from the laser diode 10.
The luminescent image 16 is a grayscale image of the intensity of the emitted light 2b captured by the CCD camera 5 and digitally converted.
Y is the scanning line direction of the digital image with respect to the emission direction of the laser diode 10, and X is the scanning line direction of the digital image that is parallel to the upper surface of the laser diode 10 and is perpendicular to the emission direction of the laser diode 10. . Further, the reference point already obtained is located at a predetermined position of this digital image.

The image processing apparatus 6 outputs a light intensity distribution waveform on the predetermined sampling line A1 which is assumed to have the highest light intensity of the luminescent image 15 shown in FIG. 7 to the monitor screen. From the light intensity distribution waveform output on this monitor screen, it is confirmed whether the light amount of the light 2a emitted from the laser diode 10 is within the sensitivity range of the CCD camera 5, and if it is not within the sensitivity range, the optical filter 4 is used for adjustment. To do.

After the adjustment, the digital images in the window W1 predetermined to include the luminescent image 15 shown in FIG. 7 are added in the Y scanning line direction, and the light intensity distribution waveform of the added image is obtained. The position of the first light emission can be obtained from this light intensity distribution waveform.

Similarly, the amount of light 2b emitted from the laser diode 10 by the optical filter 4 is C from the light intensity distribution waveform on the sampling line A2 on the emission image 16.
The CD camera 5 is adjusted so that it falls within the sensitivity range.

After the adjustment, the digital images in the window W2 predetermined to include the luminescent image 16 shown in FIG. 7 are added in the Y scanning line direction to obtain the light intensity distribution waveform of the added image. The position of the second light emission is obtained from this light intensity distribution waveform.

As shown in FIG. 6, the laser diode 10 is detected based on the positional deviation between the first light emitting point and the second light emitting point.
Direction of the light emitting surface 8a of the
It is possible to obtain the deviation amount θ from the vertical direction with respect to.

Since the position of the reference point has already been obtained, the positions of the first light emitting point and the second light emitting point from the reference point can be obtained.

Therefore, the laser diode 10 is located so that the first light emitting point is located at a predetermined position from the reference point and the light emitting direction from the first light emitting point is perpendicular to the surface 20 of the photodiode 7. Can be fixed to the photodiode 7.

[0048]

As described above, according to the present invention, 1
Since the reference point and the light emitting position of the light emitting element are obtained using the CCD camera of the stand, the light emitting position of the light emitting element can be easily detected. Since the light emitting position of the light emitting element is detected by the light intensity distribution waveform, the detection accuracy can be improved. Since the amount of light is adjusted by the optical filter so that it falls within the sensitivity range of the CCD camera, it is not necessary to adjust the light emission output of the light emitting element.

Further, the laser diode can be adjusted to emit light accurately in the direction perpendicular to the surface of the photodiode arranged parallel to the light emitting surface of the laser diode.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining a light emitting position detection method of a laser diode according to a first embodiment.

FIG. 2 is a diagram showing a digital image output on a monitor screen of the image processing apparatus.

FIG. 3 is a diagram showing a light intensity distribution on a sampling line.

FIG. 4 is a diagram showing a light intensity distribution in a window region.

FIG. 5 is a configuration diagram for explaining a second embodiment.

FIG. 6 is a diagram for explaining a deviation between a light emitting direction and a surface of a photodiode from a vertical direction.

FIG. 7 is a diagram showing a digital image output on a monitor screen of an image processing apparatus for explaining a second embodiment.

FIG. 8 is a sectional view of a laser diode.

FIG. 9 is a perspective view of a laser diode on a photodiode.

[Explanation of symbols]

 1,10 Laser diode (light emitting element) 2,2a, 2b Light emitted from laser diode 3 Electrode (pattern) 4 Optical filter 5 CCD camera (imaging device) 6 Image processing device 9,15,16 Emission image

Claims (6)

[Claims] 1. A method for detecting a light emitting position of a light emitting element placed on a support, wherein an image pickup device is arranged in a direction perpendicular to a light emitting surface of the light emitting element, and light from the light emitting surface is imaged. A method for detecting a light emitting position of a light emitting element, characterized by detecting the light emitting position of the light emitting element by image-processing an image captured by an imaging device. 2. A method for detecting a light emitting position of a light emitting element, which is placed on a support and has a first light emitting point and a second light emitting point on opposite light emitting surfaces, wherein the light emitting element is arranged parallel to the light emitting surface of the light emitting element. An image pickup device is arranged in a direction perpendicular to a predetermined surface on the support base to pick up light from the facing light emitting surface, and the image picked up by the image pickup device is subjected to image processing to perform the first light emission. The positions of the light emitting point and the second light emitting point are detected, and the displacement of the light emitting surface of the light emitting element from the predetermined surface of the support base is confirmed based on the detected positions of the first light emitting point and the second light emitting point. A method for detecting a light emitting position of a light emitting element, comprising: 3. The light emitting element light emitting position detecting method according to claim 1, wherein the image pickup device is focused on the active layer of the light emitting element. 4. The image pickup device is arranged so as to pick up an image of a pattern on the support base that serves as a reference of a light emitting position of the light emitting element, and the image is picked up by the image pickup device. The light emitting position detecting method for the light emitting element according to claim 1, wherein a reference point serving as a reference for a light emitting position of the light emitting element is detected. 5. The light emitting position of the light emitting element according to claim 1, wherein an optical filter is used to adjust the light amount so that the light amount of the light emitting element falls within the sensitivity range of the imaging device. Detection method. 6. A light emitting position detection of the light emitting element by converting an image obtained by the image pickup device into a digital image, and processing the digital image corresponding to a light emitting direction of the light emitting element to obtain a light intensity distribution waveform. The light emitting position detecting method of the light emitting element according to claim 1, wherein