JP2002365019A - Detector of luminous point position of light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of accurately detecting the luminous point of a light emitting device in a state without sending a current, in which a barrier layer having no ridge structure widely distributes. SOLUTION: A detector of luminous point position of light emitting device detecting the luminous point of the light emitting device by image processing comprises an illumination means illuminating the light emitting device with light exciting the barrier layer of the light emitting layer, an imager for photographing the image of the light emitting device, an image processor having a means for detecting edge data of the barrier layer from the image photographed with the imager, and a memory for containing a shape model of the barrier layer. It is constituted to detect the luminous point of the light emitting device by matching the edge data of the excited barrier layer with the shape model of the barrier layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a device for detecting a light emitting point position of a light emitting element, and more particularly, to a light emitting element having a characteristic shape in an active layer, which detects a light emitting point with high accuracy in a non-energized state. The present invention relates to a light emitting element position detecting device for a light emitting element having a function.

[0002] Light emitting elements such as laser diodes are widely used as light sources for optical heads in magneto-optical disk devices, compact disk devices, DVD devices and the like. Mounting errors of optical components such as light-emitting elements and light-receiving elements cause reduction in power of received signals and signal errors, so that high-precision mounting of optical components is required.

[0003]

2. Description of the Related Art FIG. 1 is a schematic view of a conventional light emitting point detecting apparatus using an active method. The light emitting element 2 such as a laser diode (LD) is energized to emit a light beam 3 from the light emitting element 2. The light beam 3 passes through the objective lens 4, the neutral density filter 6, and the eyepiece 8, and is observed on the observation plane 10 of the observation device.

[0006] In FIG. 2, a curve 12 is a luminance distribution of the light beam observed on the observation plane 10. By detecting a luminance peak position of the luminance distribution 12, a light emitting point of the light emitting element can be detected, and accurate. The light emitting point position can be detected.

However, in the active method, a light emitting circuit of a light emitting element is required. In order to observe the light emitting element and another optical element in one optical system in an optical component assembling apparatus, a light beam such as a laser beam is required. The necessity of taking in and out of the beam neutralizing filter makes the whole assembling apparatus complicated and expensive. Furthermore, in the active method, since the light emitting element is energized to detect the light emitting point position, there is a fear that the light emitting element is electrostatically damaged, which leads to a decrease in yield.

Accordingly, a passive method capable of detecting a light emitting point of a light emitting element in a non-energized state has been studied.

FIG. 3 is an explanatory view of positioning in a conventional passive method. The light emitting element 2 has a pair of markers 14. The positions of the light emitting points of the pair of markers 14 and the light emitting elements 2 are determined in advance. For example, one marker 14 is set so as to indicate a light emitting point position.

[0008] A pair of markers 18 are also formed on the substrate 16. When the light emitting element 2 is mounted on the substrate 16, the marker 14 of the light emitting element 2 is aligned with the marker 18 on the substrate 16, so that the light emitting element 2 is formed. The light emitting element 2 is mounted at a predetermined position on the substrate 16, and the light emitting point position of the light emitting element 2 with respect to the substrate 16 is also the predetermined position.

In this method, there remain problems such as an increase in cost due to the creation of a marker and an error in recognition of a light emitting point position caused by an error in a marker position.

FIG. 4 is a schematic configuration diagram of a conventional passive method. The light emitting element 2 is mounted on a support 20 and the lighting device 2
2 irradiates the illumination light 23 to the light emitting element 2.

By the irradiation of the illumination light, photoluminescence light 24 is emitted from the light emitting element 2, and the photoluminescence light 24 passes through a wavelength selection filter 26 transmitting a predetermined band.
Is imaged. Reference numeral 30 denotes a computer for performing image processing.

FIG. 5 is a schematic view of an end face of a light emitting element from which a light emitting point position can be detected by a conventional passive method. FIG. 5 (A)
FIG. 5 is a schematic view of an end face of a light emitting element having a ridge structure, and FIG.
(B) is a schematic view of an end face of a light emitting element having a ridge structure with embedded electrodes.

In FIG. 5A, a lower cladding layer 34, an insulating film 36, and a current blocking layer 38 are laminated in this order on a substrate 32, and an active layer 40 is provided between a pair of current blocking layers 38. It is defined.

On the current blocking layer 38, an upper cladding layer,
An insulating film 44 is stacked, and a surface electrode 46 is formed on the insulating film 44. On the back surface of the substrate 32, a back electrode 48 is formed.

In the light emitting device having such a structure, the vicinity of the small active layer 40 defined between the pair of current blocking layers 38 is a light emitting region.

In the light emitting device having the buried electrode type ridge structure shown in FIG. 5, a lower cladding layer 34 is laminated on a substrate 32, and an active layer 50 is laminated on the lower cladding layer 34. An upper clad layer 42 is laminated on the active layer 50, and a surface electrode 46 is formed on the upper clad layer 42 via an insulating film 44.
'Is formed. A back surface electrode 48 is provided on the back surface of the substrate 32.
Are formed.

A curve 52 in FIG. 6 shows the observed luminance distribution of the photoluminescence light 24. The light emitting point can be detected by detecting the luminance peak position, and the accurate light emitting point position can be detected.

However, the conventional passive light emitting point position detecting device shown in FIG. 4 can be applied only to the light emitting device having the ridge structure as shown in FIG. 5, and the light emitting device having no ridge structure. Cannot be applied to

Furthermore, the reflected illumination light 23 and illumination light 2
Since the wavelength selection filter 26 that cuts the photoluminescence light (outgoing light) 24 scattered by the light source 3 is used, an image pickup device for another optical component, or a wavelength selection device when unnecessary, can be incorporated into the optical component assembling apparatus. A mechanism for retracting the filter 26 to the retracted position is required, and the component assembling apparatus becomes complicated and expensive.

In the detection using only the luminance distribution,
It is also conceivable that recognition errors may occur due to scattered light passing through the wavelength selection filter. In particular, when the band of the wavelength selection filter is wide, for example, there is a possibility that a damaged portion of the end face of the light emitting element or scattered light on the end face of the heat radiating plate may pass through the wavelength selection filter, and it is difficult to identify the light emission point portion.

[0021]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a light emitting element position detecting apparatus capable of detecting a light emitting point of a light emitting element in a non-energized state with high accuracy.

Another object of the present invention is to enable high-precision light-emitting point position detection even when the light-emitting element has a defect such as chipping or the like and / or when the light-emitting position cannot be estimated from the outer shape of the light-emitting element. It is to be.

Still another object of the present invention is to provide a light emitting device in which an active layer having no ridge structure is widely distributed.
It is to enable the light emitting point position detection.

Still another object of the present invention is to make it possible to detect the position of a light emitting point even when there is a point having high brightness near the light emitting point such as a heat sink.

Still another object of the present invention is to enable other optical components to be imaged by an optical system for detecting a light emitting point position.

[0026]

According to the present invention, in a light emitting point position detecting device for detecting a light emitting point of a light emitting element by image processing, the light emitting element is irradiated with light for exciting an active layer of the light emitting element. Illuminating means, an image capturing apparatus for capturing an image of the light emitting element, an image processing apparatus having means for detecting ridge line data of the active layer from an image captured by the image capturing apparatus, and storing a shape model of the active layer. A light-emitting point position of the light-emitting element, wherein the light-emitting point of the light-emitting element is detected by performing matching between the ridge line data of the active layer excited and emitted and the shape model of the active layer. A detection device is provided.

Light irradiation by the illuminating means preferably uses illuminating light near the emission wavelength of the light emitting element. Preferably, the irradiation of the illumination light is coaxial epi-illumination, and the light emitting point position detecting device further includes a wavelength selection filter that selectively transmits a wavelength of a predetermined band of the illumination light.

The image processing apparatus includes means for detecting a rotation angle of the light emitting element around the optical axis for making the active layer horizontal from an image of the light emitting element picked up by the image pickup apparatus, and rotating by the rotation angle at which the image is detected. Means for extracting an image near the active layer, and detecting a ridge line of the active layer from the cut image after rotation.

Preferably, the image processing apparatus creates ridge line data of the active layer in sub-pixel order by interpolating a luminance change between adjacent images. Matching between the shape model of the active layer and the ridge line data is performed by a cross-correlation method, or the image processing apparatus has means for converting the ridge line data to geometric data, and the matching between the geometric data of the active layer and the shape model is performed. Perform Preferably, matching is performed by weighting the vicinity of the light emitting point of the shape model.

[0030]

FIG. 7 is a schematic diagram showing a light emitting point position detecting device according to an embodiment of the present invention. A light emitting element 54 such as a laser diode is mounted on a support 56. 58 is a lighting device such as a halogen lamp,
The illumination light (excitation light) 59 for irradiating the end face of the light emitting element 54 is emitted.

When illuminating light 59 including short-wavelength light having energy higher than the energy gap of the effective band gap of the semiconductor forming the active layer is applied to light emitting element 54, the active layer of light emitting element 54 The photoluminescence light 60 is emitted from. The photoluminescence light 60 is input to the imaging device 62, and the light emitting element 54
Image of the end face of.

The image pickup device 62 has means for observing and recognizing the shape of the active layer of the light emitting element 54. Therefore, it is desirable that the imaging device 62 has an optical resolution and an image resolution capable of observing the shape of the active layer.

However, the light emitting element inspection for detecting the light emitting point position including the optical component assembling apparatus for performing the position recognition of other optical elements and the appearance inspection of the light emitting element using the image pickup system of the light emitting point position detecting apparatus. In the apparatus, since it is necessary to have a sufficiently wide field of view, sufficient optical resolution and image resolution may not be obtained.

In such a case, by limiting the wavelength of light incident on the image pickup system, chromatic aberration of the lens of the image pickup system can be reduced, and a clear image can be obtained. Further, by setting the above-mentioned wavelength near the emission wavelength (excitation wavelength) of the light-emitting element,
It is possible to clearly capture the active layer.

Reference numeral 64 denotes an image processing device such as a computer, which performs image processing on an image picked up by the image pickup device 62. The memory 66 stores a shape model of the active layer.

In order to simplify the structure of the image pickup system and the illumination system, it is desirable to use coaxial incident illumination as shown in FIG. 8A or 8B. 8, reference numeral 54 denotes a light-emitting element, 72 denotes an objective lens, 68 denotes a half mirror, 76 denotes an eyepiece, 70 denotes an objective lens 72 and an eyepiece 76.
A wavelength selection filter 78 for reducing the chromatic aberration of the image is an imaging plane.

As shown in FIG. 8A, the illumination light 59 and the reflected light 74 from the light emitting element 54 are both
0 is desirable, but the wavelength selection filter 70
If it is difficult to insert the light at this position due to the configuration of the apparatus, only the illumination light 59 may be passed through the wavelength selection filter 70 as shown in FIG.

The image pickup system according to the present invention does not need to make the optical axis perpendicular to the end face of the light emitting element, and can observe the end face of the light emitting element 54 through the reflection mirror 80 as shown in FIG. It is also possible to arrange the image pickup device so that the optical axis is parallel to the end face of the light emitting element.

FIG. 10 shows an end face shape of a light emitting element which can be detected by the light emitting point position detecting device of the present invention. A lower cladding layer 84 is laminated on a substrate 82, and an active layer 86 having a step portion 86 a is laminated on the lower cladding layer 84.
The light emitting portion exists in the step portion 86a of the active layer.

An upper cladding layer 88 is laminated on the active layer 86, and a current blocking layer 90 is laminated on the upper cladding layer 88. Further, a contact layer 92 is stacked on the current block layer 90.

Next, the light emitting point position detection according to the present invention will be described. When detecting the light emitting point position, it is necessary to focus on the end face of the light emitting element, but any method may be used for focusing.

FIG. 11 is a flowchart for detecting the light emitting point position, and FIG. 12 is a flowchart for detecting the ridge line of the active layer.
First, in step S10 of FIG. 11, the outer shape of the light emitting element is recognized. This outer shape recognition may be performed with such an accuracy that an image near the active layer can be cut out.

Next, based on the outer shape recognition result, step S
At 12, the rotation angle of the light emitting element around the optical axis for making the active layer horizontal is detected, and the image is rotated by the detected rotation angle. However, this rotation correction is a means for facilitating the detection of the active layer ridgeline described with reference to FIG. 12, and is not essential.

After the rotation correction, an image near the active layer is cut out in step S14, and the flow advances to step S16 to detect the ridge of the active layer. This active layer ridge line detection is constituted by a flow as shown in FIG.

The detection of the active layer ridge line of a light emitting element having a light emitting point at a step portion 86a of the active layer 86 as shown in FIG. 10 will be described with reference to the flowchart of FIG. 12 and FIGS.

FIG. 13 is a schematic view of an image near the cut active layer, and 94 denotes the active layer. FIG. 14 is a schematic diagram of the active layer luminance distribution.
Numeral 8 indicates the ridge line of the active layer.

First, in step S20 of FIG. 12, a local maximum point of luminance in an image near the active layer is searched for perpendicularly to the active layer. When the rotation correction in step S12 in FIG. 11 has been performed, a local maximum point of the luminance may be searched for in the vertical direction of the image.

If the image resolution of the image pickup device is not sufficient for the characteristic shape of the active layer, the estimation of the local maximum position in the order of sub-pixels is performed based on the luminance change between adjacent pixels of the detected local maximum. (Step S22). For this estimation, a quadratic approximation or the like can be used.

When the light emitting point of the light emitting element already bonded to the heat radiating plate is detected, as shown in FIG. 15, the luminance maximum point 100 at the ridge line of the active layer, such as irregular reflection of illumination light on the heat radiating plate, is detected. In addition, the maximum point 10 of luminance other than the ridge line of the active layer
2 is also detected. In such a case, it is apparent that the active layer ridge line data cannot be extracted by searching only the maximum luminance position.

Therefore, a straight line is detected from the maximum luminance point data shown in FIG. 15 (step S24), and points near the obtained straight line are extracted to extract ridge line data of the active layer (step S26).

Hough transform or the like can be used for straight line detection. In particular, since the Hough transform is performed only on the local maximum point data, straight line detection can be performed at a higher speed than in the case where the image is directly Hough transformed.

By matching the ridge line data of the active layer obtained in this manner with the shape model of the active layer of the light emitting element to be used stored in the memory 66 (step S18), the light emitting point of the light emitting element is obtained. Estimate the position.

The matching includes a method of matching the obtained ridge line data and the shape model by the cross-correlation method, and a method of matching the characteristic amount of the ridge line data converted into the geometric data and the characteristic amount of the shape model. is there.

By weighting and matching the vicinity of the light emitting point of the shape model, erroneous detection due to noise such as diffuse reflection can be prevented.

Since the imaging system of the present invention may have a relatively low optical resolution and image resolution, a wide field of view can be obtained, so that other optical components can be imaged. Therefore, the light emitting point position detecting device of the present invention can be used for an optical component assembling device or an optical element inspection device provided with the light emitting point position detecting device.

The present invention includes the following supplementary notes.

(Supplementary Note 1) In a light emitting element position detecting device for detecting a light emitting point of a light emitting element by image processing, an illumination means for irradiating the light emitting element with light for exciting an active layer of the light emitting element; An excitation device comprising: an imaging device that captures an image of the element; an image processing device that has means for detecting ridgeline data of the active layer from an image captured by the imaging device; and a memory that stores a shape model of the active layer. A light emitting point position detecting device for a light emitting element, wherein a light emitting point of a light emitting element is detected by matching ridge line data of the light emitting active layer with a shape model of the active layer.

(Supplementary Note 2) The light emitting element position detecting device according to Supplementary Note 1, wherein the illumination means uses illumination light near the emission wavelength of the light emitting element.

(Supplementary Note 3) The light emission according to Supplementary Note 2, wherein the irradiation of the illumination light is coaxial epi-illumination, and further includes a wavelength selection filter that selectively transmits a wavelength of a predetermined band of the illumination light. Device for detecting the light emitting point position of the element.

(Supplementary Note 4) The image processing apparatus includes: means for detecting a rotation angle of the light emitting element around the optical axis for making the active layer horizontal, from the image of the light emitting element taken by the image pickup apparatus; 2. The light emitting point position of the light emitting element according to claim 1, further comprising: means for rotating by the rotated angle, and means for cutting out an image near the active layer, and detecting a ridge line of the active layer from the cut out image after rotation. Detection device.

(Supplementary Note 5) The image processing apparatus creates ridge line data of an active layer in a sub-pixel order by interpolating a luminance change between adjacent pixels. Point position detector.

(Supplementary note 6) The light emitting element position detecting device for a light emitting element according to supplementary note 1, wherein matching between the shape model of the active layer and the ridge line data is performed by a cross-correlation method.

(Supplementary note 7) The image processing apparatus according to Supplementary note 1, wherein the image processing apparatus includes a unit that converts the edge line data into geometric data, and performs matching between the geometric data of the active layer and the shape model. Light emitting point position detecting device for light emitting element.

(Supplementary Note 8) The light emitting element position detecting apparatus for a light emitting element according to supplementary note 6 or 7, wherein weighting is performed near the light emitting point of the shape model to perform matching.

(Supplementary Note 9) An optical component assembling apparatus comprising the light emitting point position detecting device according to any one of claims 1 to 8.

(Supplementary Note 10) A light emitting element inspection device comprising the light emitting point position detecting device according to any one of claims 1 to 8.

[0067]

Since the present invention is constructed as described above in detail, even if the light emitting element has an external defect such as chipping and / or the light emitting position cannot be estimated from the outer shape of the light emitting element, the light emitting element can be used. In addition, it is possible to detect a light emitting point position with high accuracy in a non-energized state.

By inserting a wavelength selection filter near the excitation wavelength (emission wavelength) of the light emitting element into the optical path of the illumination light,
Reduce the chromatic aberration of the imaging system, increase the resolution of the imaging optical system,
It is possible to obtain shape data of the active layer beyond the resolution of the imaging optical system.

Since it is possible to widen the band of the wavelength selection filter or not use the wavelength selection filter, the imaging system of the present invention can be used for recognition of other optical components.

In the generation of the active layer ridge line data, the luminance change between adjacent pixels is interpolated, and the ridge line is estimated in the order of sub-pixels. The shape of the layer can be observed, and the light emitting point can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an active method.

FIG. 2 is a diagram showing a luminance distribution.

FIG. 3 is an explanatory diagram of positioning in a conventional passive method.

FIG. 4 is a schematic configuration diagram of a conventional passive method.

FIG. 5 is an end view of a light emitting device having a ridge structure.

FIG. 6 is a diagram showing a luminance distribution.

FIG. 7 is a schematic configuration diagram of a light emitting point position detecting device according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of coaxial epi-illumination.

FIG. 9 is a diagram illustrating an imaging system via a mirror.

FIG. 10 is a diagram showing an end face shape of a light emitting element capable of detecting a light emitting point according to the present invention.

FIG. 11 is a flowchart of light emitting point position detection according to the present invention.

FIG. 12 is a flowchart of active layer ridge line detection.

FIG. 13 is a schematic view of an active layer cutout image.

FIG. 14 is a schematic diagram of an active layer luminance distribution.

FIG. 15 is a diagram illustrating an example of luminance maximum data of an active layer.

[Explanation of symbols]

 54 Light-emitting element 58 Illumination device 62 Imaging device 64 Image processing device 68 Half mirror 70 Wavelength selection filter 78 Imaging surface 86 Active layer 96 Luminance distribution of active layer 98 Active layer ridgeline 100, 102 Maximum luminance point data

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiko Yabuki 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Shigeru Akama 4-chome, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 No. 1 Fujitsu Limited F term (reference) 2F065 AA03 CC00 FF04 JJ03 JJ26 LL22 QQ21 QQ24 QQ38 RR05

Claims (5)

[Claims] 1. A light emitting element position detecting device for detecting a light emitting point of a light emitting element by image processing, comprising: an illuminating means for irradiating the light emitting element with light for exciting an active layer of the light emitting element; An image processing apparatus having means for detecting ridge line data of the active layer from an image captured by the image capturing apparatus; and a memory for storing a shape model of the active layer. A light emitting element position detecting device for detecting a light emitting point of the light emitting element by matching the ridge line data of the active layer with the shape model of the active layer. 2. The light emitting point position detecting device for a light emitting device according to claim 1, wherein the light emitted by said lighting means uses illumination light near the emission wavelength of said light emitting device. 3. The illumination unit according to claim 1, wherein the illumination unit emits illumination light by coaxial epi-illumination, and further comprises a wavelength selection filter that selectively transmits a predetermined band of the illumination light. A light emitting point position detecting device for a light emitting element. 4. An image processing apparatus comprising: means for detecting a rotation angle of a light emitting element around an optical axis for making an active layer horizontal from an image of the light emitting element taken by the imaging device; 2. The light emitting element position detecting device according to claim 1, further comprising means for rotating by an angle, and means for cutting out an image near the active layer, and detecting a ridge line of the active layer from the cut out image after rotation. apparatus. 5. The image processing apparatus according to claim 1, wherein the image processing apparatus creates edge line data of an active layer in a sub-pixel order by interpolating a luminance change between adjacent pixels.
A light emitting point position detecting device for a light emitting element according to claim 1.