JP3470066B2 - Semiconductor laser characteristic measuring method and characteristic measuring apparatus using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used in an optical pickup device and the like, and a method and a device for measuring optical characteristics of the device. More specifically, the invention relates to an image on a focal plane of laser light emitted from the semiconductor laser device. The present invention relates to a semiconductor laser characteristic measuring method and a characteristic measuring apparatus using the same, which measure a light emitting point image and a far field image on a non-focal plane.

[0002]

2. Description of the Related Art Among semiconductor laser characteristics, an optical axis shift angle representing a displacement of an optical axis of a laser beam from a normal direction and a half-value width of a far-field image representing a spread of the laser beam are controlled by a condenser lens. This is an important characteristic when applied to an optical pickup device or the like that needs to focus laser light on an optical disk. It also serves as a clue for estimating the structure of the semiconductor laser device.

For example, it is considered that a semiconductor laser device having a wide half-field width of a far-field image cannot strongly increase its output because of strong light confinement. On the other hand, an element with a narrow half-width of the far-field image has a weak light confinement and a high oscillation threshold current value, and thus cannot be operated for a long time. Therefore, the far-field pattern is produced with the optimum size, but it is usually different from the target.

On the other hand, the semiconductor laser device is manufactured so as to emit laser light in a direction perpendicular to the cleavage plane which is the emission surface. Further, the semiconductor laser device is manufactured so as to emit laser light in a direction perpendicular to the reference plane of the package. However, in practice, it is usually the case that the laser light is not emitted in the direction completely perpendicular to the emission surface in the semiconductor laser device, and in the semiconductor laser device, due to the tolerance of individual internal parts or the assembly tolerance, etc. It is customary that the light is not emitted in a direction completely perpendicular to.

As a method for measuring the full width at half maximum of the far-field pattern of the laser light of such a semiconductor laser device and semiconductor laser element, Japanese Patent Laid-Open No. 7-66472 discloses a method for measuring an optical axis shift angle. 214057 and Japanese Patent Laid-Open No. 9-307192.

[0006]

The measurement of the optical axis shift angle will be described in detail below. The measurement of the far-field image can be performed by a method similar to the measurement of the optical axis shift angle.

FIG. 9 shows an overall view of a conventional optical axis deviation angle measuring device (hereinafter referred to as "conventional example 1"). Semiconductor laser device 1
0 is fixed to the stem holder 24 and the light receiving device 20 is rotated to measure the intensity distribution in the angular direction. Also,
The optical axis shift angle is measured from the difference between the peak position of the intensity distribution and the optical axis reference.

In the optical axis shift angle measuring device of the first conventional example, the laser light incident on the light receiving device 20 is a part of the whole, and the signal output of the light receiving element 21 becomes small. In order to measure the peak position more accurately, the slit 22 may be provided in front of the light receiving element 21, but since the signal output of the light receiving element 21 becomes even smaller, the accuracy of the peak position deteriorates. Will end up.

As a method for solving the above-mentioned problems, the present applicant discloses in Japanese Patent Laid-Open No. 9-307192 a method for measuring an optical axis shift angle from a light emitting point position of a semiconductor laser device and a peak position of a far field image. (Hereinafter "Conventional example 2")
Call).

FIG. 10 shows an overall view of an optical axis deviation angle measuring device 500 of the second conventional example.

The condenser lens 40 and the CCD camera 60 are fixed to the case 50 and are movable integrally. CC
The D camera has a two-dimensional CCD element 61, and the two-dimensional CC
The image formed on D (hereinafter referred to as "CCD image") is displayed on a monitor (not shown) and is taken into the computer 70.

Here, the CCD is described as a representative of the light-receiving element array capable of measuring and displaying the intensity distribution of light, and is not limited to the charge-coupled element. Also, it does not have to be two-dimensional depending on the application.

FIG. 11 shows an example of the CCD image displayed on the monitor. (a) shows the display on the monitor, and (b) shows the intensity distribution in the X-axis direction including the light emitting point. Since the light emission point image C has a small spread, the coordinates X0 of the light emission point does not change much at any point of the light emission point, but coordinates near the peak are usually selected.

After measuring the coordinates of the light emitting point, the condenser lens 4
0 and the CCD camera 60 are set to Z which is the optical axis direction of the laser beam.
Move by ΔZ in the direction. Seen from the semiconductor laser device 10, it has moved to the position 111. As a result, C
The far-field image D is displayed on the CD image. The peak coordinate X1 of the far-field image D can be easily measured by analyzing it with the computer 70. The optical axis shift angle can be measured from the difference ΔX between the coordinate X0 of the light emission point image and the coordinate X1 of the far field image.

In the conventional example 2, as compared with the conventional example 1, all the light emitted from the semiconductor laser device is a light receiving element, which is a two-dimensional CCD.
Since the light is focused on 61, the output of the light receiving element becomes large.
In particular, if the far-field image is spread over the entire two-dimensional CCD, the signal-to-noise ratio can be maximized.

However, the optical axis shift angle is the coordinate X0 of the light emitting point.
Since it is calculated from the difference ΔX between the coordinates X1 of the peak of the far-field image and the movement amount ΔZ of the condenser lens 40 and the CCD camera 60, ΔZ must be monitored with high accuracy or always kept constant. The optical axis shift angle is the absolute value of Z,
That is, it changes depending on the positional relationship between the condenser lens, the CCD camera, and the semiconductor laser element. Therefore, if the condenser lens 40 and the CCD camera 60 are moved for each measurement, the measured value will gradually change.

ΔZ is usually as small as 0.2 to 0.3 mm, and the condensing lens 4 has many times with an error of 10 μm or less.
It was extremely difficult to move the 0 and the CCD camera 60 with good reproducibility and stop them accurately. In particular, it is necessary to use a good quality optical system in order to accurately observe the light emitting point, and the weight of the optical system to be moved becomes heavy. Therefore, it is necessary to use a servo motor or a pulse motor for the driving device and a ball screw or a cam for the driving mechanism. Furthermore, it was desirable to provide a precise linear guide.

The present invention has been made in order to solve the above problems, and it is a characteristic of a semiconductor laser that measures a far-field image of laser light emitted from a semiconductor laser device after measuring an emission point image. To provide a characteristic measuring method of a semiconductor laser and a characteristic measuring apparatus using the same, which can be changed from a light emitting point image measuring state to a far field image measuring state while maintaining good reproducibility and accuracy in measurement. To aim.

[0019]

The present invention has been made to achieve the above object, and a method for measuring characteristics of a semiconductor laser according to the present invention includes at least a condenser lens and a CCD.
In the method for measuring the characteristics of a semiconductor laser in which the emission point image of a semiconductor laser is measured as a CCD image, and the far-field image of the laser light emitted from the semiconductor laser element is measured as a CCD image, the condenser lens and the semiconductor are used. With laser
And the distance between the condenser lens and the CCD.
In a state where the CCD image is kept constant, the CCD image is obtained by inserting or extracting a correction plate made of a parallel plate in the optical path between the condenser lens and the semiconductor laser or between the condenser lens and the CCD. It is characterized in that the emission point image is changed to the far-field image.

Preferably, the CCD has a protective surface.
A CCD provided with glass, the correction plate is inserted to measure the light emission point image as a CCD image, and the correction plate is extracted to measure the far-field image as a CCD image.

Preferably, the coordinates of the emission point image in the CCD image are measured, the coordinates of the peak of the far field image in the CCD image are measured, and the coordinates of the emission point image in the CCD image and the peak of the far field image are measured. The optical axis shift angle of the semiconductor laser is measured from the coordinates in the CCD image of.

Preferably, the full width at half maximum of the far field image is measured from the CCD image.

Preferably, the C in the emission point image
The output level of the CD and the CCD of the far-field image
Make the output level approximately the same.

The semiconductor laser device characteristic measuring apparatus of the present invention has at least a condenser lens and a CCD, and after measuring the emission point image of the semiconductor laser as a CCD image,
The far-field image of the laser light emitted from the semiconductor laser device is CC
In a semiconductor laser measuring device for measuring as a D image , a parallel plate is provided in an optical path between the condenser lens and the semiconductor laser element or between the condenser lens and the CCD.
It is characterized in that a correction plate consisting of is provided so that it can be inserted and removed .

Preferably, the CCD has a protective surface.
It shall be the CCD glass is provided.

[0026] Preferably, the correction plate shall be the ND filter.

According to the present invention, by moving the correction plate which does not require the movement accuracy and the stop position accuracy, a constant optical path length movement amount can be obtained with reference to the light emitting point that can be used for the characteristic measurement of the semiconductor laser. A far field image can be generated.

Further, if the correction plate is inserted to measure the emission point image as a CCD image and the correction plate is extracted to measure the far-field image as a CCD image, the CC
It is possible to prevent the occurrence of a pseudo peak due to the protective glass provided on the surface of D.

Further, the full width at half maximum of the far field image is set to the CCD.
The characteristics of the semiconductor laser device or device can also be measured by measuring from the image.

Further, if an ND filter is used for the correction plate, the CCD output levels of the peak of the emission point image and the peak of the far field image can be made approximately the same, so that the optical axis shift angle and the far field image can be accurately measured. Ru can be used to measure the full width at half maximum.

[0031]

DETAILED DESCRIPTION OF THE INVENTION hereinafter, an embodiment of the reference to the drawings in detail the present invention.

[First Embodiment] The first embodiment will be described. FIG. 1 shows an overall view of an optical axis deviation angle measuring device 100 that is Embodiment 1 of the present invention. The procedure for observing the optical axis shift angle is shown in FIG.
The same parts as those of the optical axis deviation angle measuring device of Conventional Example 2 are denoted by the same reference numerals for simplicity. Also here, the CCD is described as a representative of the light receiving element array capable of measuring and displaying the intensity distribution of light, and is not limited to the charge coupled element. Also, it does not have to be two-dimensional depending on the application.

As shown in FIG. 1, the main configuration of the present embodiment is a CCD image by inserting or withdrawing it in the optical path between the condenser lens 40 and the semiconductor laser element 11 in the semiconductor laser device 10. A correction plate 30 for changing from a light emission point image to a far field image is provided.

As shown in FIG. 2, in the measurement in this embodiment, first, the semiconductor laser device 10 is fixed to the stem holder 24 of the optical axis deviation angle measuring device 100 (S).
1). By abutting the lower surface of the stem holder 24 and the upper surface of the stem 12 of the semiconductor laser device, the position of the semiconductor laser device 10 with respect to the optical axis deviation angle measuring device 100 is determined. The semiconductor laser device 10 has the N of the condenser lens 40.
Install on the larger side of A. This is a semiconductor laser device 1
This is for expanding the position of the light emitting point of No. 1 and observing with high accuracy.

First, with the correction plate 30 inserted in the optical path between the reference semiconductor laser device 10 and the condenser lens 40, the semiconductor laser element 11 is caused to emit light at a low current near the oscillation threshold (S2). The optical system of the condenser lens 40 and the two-dimensional CCD camera 60 is integrally moved in the Z direction and adjusted so that the emission point image of the semiconductor laser element 11 is displayed on a CRT (not shown) (S3). CC displayed on CRT in Fig. 3
A D image is shown. The light emission point image C has a small spread, as in the second conventional example. The condenser lens 40 and the two-dimensional CC
The case 50 that fixes the D camera 60 and forms an optical system also has an effect of preventing light from the outside from entering the two-dimensional CCD 61.

Incidentally, FIG. 3 shows an example of the CCD image displayed on the monitor in the present embodiment,
(a) shows the display on the monitor, and (b) shows the intensity distribution in the X-axis direction including the light emitting point.

After that, the lower surface of the stem holder 24 and the upper surface of the stem 12 of the semiconductor laser device 10 are brought into contact with each other, whereby the positional accuracy of the light emitting point of the semiconductor laser in the optical axis direction is determined.
Even in a bad case, it can be suppressed to ± 80 μm or less, usually ± 30 μm or less. This accuracy was sufficient for measuring the optical axis shift angle. With the above, the adjustment of the optical axis shift angle measuring device is completed, and the reference semiconductor laser device is removed.

Next, the semiconductor laser device to be measured is fixed to the stem holder (S4). The light is emitted at a low current to measure the position coordinates of the light emission point image, for example, the X coordinate (S5). The optical path is like a dotted line. Next, pull out the correction plate 30 from the optical path.
(S6), and effectively the condenser lens 40 and the CCD camera 6
0 has moved in the direction away from the measured semiconductor laser device side, and when viewed from the semiconductor laser device 11, FIG.
This means that the semiconductor laser element 111 has been moved to the position. As a result, in the optical path of the laser beam emitted from the semiconductor laser element 11, the condensing point represented by the intersection moves from the two-dimensional CCD to the condensing lens 40 side as shown by the solid line, and the far field of FIG. Image D is generated. At this time, since the far-field image D spreads widely, the peak of the far-field image is usually smaller than the peak of the emission point image C with respect to the CCD output level.

In the present embodiment, the two-dimensional CCD 6
A transparent glass plate having a thickness of 1 mm is used as the correction plate 30 in order to generate a far-field image that can be exactly accommodated in 1. The weight of the correction plate 30 is several tens of grams, and the stop position in the X direction, Z
The axial position may change slightly. Therefore, the correction plate 3
For the movement of 0, an air cylinder, a servomotor or the like which can move at high speed and is inexpensive can be used. Further, the effective amount of movement of the condenser lens 40 and the CCD camera 60 in the Z-axis direction is determined by the thickness and the refractive index of the correction plate 30, and therefore is stable and does not change even after repeated movements.

After loading the far-field image of FIG. 3 into a computer, the X coordinate X1 of the peak of the far-field image is calculated (S
8), the optical axis shift angle of the semiconductor laser device to be measured is measured from the difference between the X-coordinate X0 of the emission point image (S9). This is similar to the case of Conventional Example 2. Actually, the relationship between the rotation angle θ when the reference semiconductor laser device is rotated by a certain angle and the movement amount ΔX of the X coordinate on the two-dimensional CCD is measured in advance, and ΔX is calculated to calculate θ. In the optical axis shift angle measuring device of the present embodiment, a 20 × condenser lens is used. Two
In the entire dimensional CCD 61, the movement amount ΔX of the X coordinate and the optical axis shift angle θ were substantially proportional.

After the measurement, the correction plate 30 is inserted again into the optical path (S10), and the semiconductor laser device to be measured is replaced (S1).
1 and S4), the same measurement is continued.

It is also possible to measure the far-field pattern characteristic of the semiconductor laser by using the optical axis shift angle measuring method and measuring apparatus of this embodiment.

That is, in step S8 of FIG. 2, the X coordinate of the peak of the far-field image is calculated, and at the same time, the peak is sandwiched on a straight line in the X-axis direction including the peak and the value is halved. Calculate the X coordinate interval of two points
By converting the distance between θ and θ into a divergence angle, the full width at half maximum θh of the far-field image in the direction including the pn junction surface of the semiconductor laser element can be measured. This is because, in the present embodiment, the direction including the pn junction surface of the semiconductor laser device corresponds to the X direction of the two-dimensional CCD.
On the other hand, the full width at half maximum θv of the far-field image in the direction perpendicular to the pn junction surface of the semiconductor laser device also becomes ½ of the value of the peak, sandwiching the peak on the straight line in the Z-axis direction including the peak 2 The distance between the Y coordinates of two points may be calculated, and the distance between ΔY and θ may be converted into the spread angle.

In the present embodiment, the optical axis shift angle of the semiconductor laser device is measured only by the X coordinate, but this is the case when the semiconductor laser device is incorporated in an optical pickup or the like.
This is because it is necessary to set the optical axis shift angle of the direction to a certain value or less.

Further, by loading the CCD image into a computer and analyzing it, not only the peak of the far-field image but also the coordinates of the center of gravity, which is the average value of the intensity × coordinates, can be calculated. If the intensity fluctuates like a wave,
It is effective to use the coordinates of the center of gravity when the shape is asymmetrical as shown in FIG. 3 and the average value thereof is desired to be evaluated, or when the optical axis deviation angle is to be measured two-dimensionally. It goes without saying that the optical axis shift angle in any direction can also be measured by the same method.

In the present embodiment, the far-field image is generated by observing the emission point image with the correction plate inserted and removing the correction plate 30. The reason for this will be described with reference to FIG.

The correction plate 30 is extracted and the emitted laser light is C
If the correction plate 30 is inserted into the optical path from the state of being imaged on the CD, the condensing point moves to the side far from the condensing lens, contrary to the above case. At this time, as shown in FIG.
It is incident on the dimensional CCD 61. Usually, the CCD is provided with a protective glass 611 on its surface to protect the device. When the convergent light enters the two-dimensional CCD 61 as described above, a part of the light is reflected by the two-dimensional CCD and converges to the CCD.
The two-dimensional CCD 6 is reflected again on the surface of the protective glass 611.
Incident on 1. The light reflected by the surface of the CCD protection glass 611 and incident on the two-dimensional CCD 61 again appears as a pseudo spot on the CCD image and is displayed on the computer 70 as C.
It becomes an obstacle when capturing the CD image and calculating the peak of the far-field image. It also causes a large error when calculating the far-field characteristics.

On the other hand, when a light emission point image is generated with the correction plate 30 inserted and the correction plate 30 is removed to generate a far-field image, on the contrary, the focus point position is close to the focus lens 40. Become. For this reason, since it converges before the two-dimensional CCD 61,
As shown in FIG. 4B, divergent light enters the two-dimensional CCD.
As a result, there is no occurrence of pseudo spots as shown in FIG. This problem does not occur when the CCD protective glass is not present on the CCD surface or is sufficiently thick.

[Second Embodiment] FIG. 5 shows an overall view of a semiconductor laser characteristic measuring apparatus 200 according to the second embodiment. The present embodiment is different from the first embodiment in that a transparent parallel plate is used as the correction plate 30 in the first embodiment, whereas an ND filter 31 is used. Except for this, it is the same as the first embodiment. The ND filter 31 has a light transmittance of about several percent and has almost no wavelength dependency of the transmittance in the wavelength range of the semiconductor laser.

In the semiconductor laser device, the ratio of the output light intensity to the input current changes dramatically at a current value below the current value called the oscillation threshold and a current value above the oscillation threshold. In the first embodiment, the amount of current passed through the semiconductor laser device is set to about the oscillation threshold current value. As described above, it is common that the peaks of the emission point image and the peaks of the far-field image are several times different in signal magnitude. However, in order to accurately measure the coordinates of the peak and the half-value width of the far-field image, it is desirable that the magnitude of the signal at the peak be close to the maximum value of the CCD signal output. That is, the peak of the emission point image and the peak of the far-field image are
It is desirable that the CCD signal outputs are about the same.

In the present embodiment, the correction plate 31 consisting of an ND filter is inserted when measuring a light emitting point having a large peak light intensity, and the ND filter is removed when measuring a far field image having a small peak light intensity. Therefore, as shown in FIG. 6, the peak CCD output level of the emission point image C and the peak CCD output level of the far-field image D could be made approximately the same.

FIG. 6 shows an example of the CCD image displayed on the monitor in this embodiment.
(a) shows the display on the monitor, and (b) shows the intensity distribution in the X-axis direction including the light emitting point.

[Third Embodiment] FIG. 7 shows an overall view of a semiconductor laser characteristic measuring apparatus according to a third embodiment.

In this embodiment, the correction plate 30 is an ND filter and the CCD camera 62 with an electronic shutter is used as in the semiconductor laser characteristic measuring apparatus of the second embodiment. The other points are the same as those in the first embodiment. Also, CCD camera 6 with electronic shutter
In No. 2, control is always performed so that the signal magnitude of the largest signal portion becomes the maximum value of the output.

When measuring semiconductor laser devices having various oscillation thresholds, the current value set in S2 of FIG. 2 may exceed the oscillation threshold of the semiconductor laser device under test. The reason why the ND filter is used for the correction plate is to prevent a signal exceeding the control range of the electronic shutter from entering.

By using a CCD with an electronic shutter, such a problem can be prevented.
Since the output levels can be the same, more accurate coordinates of the light emitting point image can be calculated, and the optical axis shift angle and the half-value width of the far field image can be measured more accurately.

[0057] Figure 8 is intended to indicate an example of a CCD image displayed on the monitor in the present embodiment, (a) represents a display monitor, the intensity of the X-axis direction including the light emitting points (b) Represents the distribution. As shown in FIG. 8, in the present embodiment, as in the case of the above-described second embodiment, when measuring a light-emitting point having a large peak light intensity, a correction plate 31 made up of an ND filter is inserted to measure the peak light intensity. Since the ND filter is removed when measuring a small far-field image, the peak CCD output level of the emission point image C and the peak CCD output level of the far-field image D can be made approximately the same.

Although the above description has been given for the semiconductor laser device, the same applies to the case of a semiconductor laser device. However,
In order to prevent the destruction of the semiconductor laser device, it is usually necessary to cause the semiconductor laser device to emit light with a pulse current, and to press the collet against the device to flow a current.
In the measurement of the semiconductor laser device as in the above embodiment, the lower surface of the stem holder 24 is placed on the semiconductor laser device 1.
Although the positioning was performed so as to abut the upper surface of the stem 12 of 0, the measurement of the semiconductor laser device may be performed by positioning the reference position and measuring the optical axis shift angle.

[0059]

As is apparent from the above description, according to the present invention, by moving the correction plate which is not required to have the movement accuracy and the stop position accuracy, it is possible to use it for the characteristic measurement of the semiconductor laser. It is possible to generate a far-field image with a constant amount of movement of the optical path length based on the point.

Further, by inserting a correction plate, the emission point image is CC
Measure as a D image, pull out the correction plate and make a far-field image C
If measured as a CD image, it will be installed on the surface of the CCD.
It is possible to prevent the generation of pseudo peaks due to the protective glass that has been formed.

If the half-width of the far-field pattern is measured from the CCD image, the far-field pattern characteristic of the semiconductor laser device or device can be measured.

Further, if an ND filter is used for the correction plate, the CCD output levels of the peak of the emission point image and the peak of the far field image can be made approximately the same, so that the optical axis shift angle and the far field image can be accurately measured. Ru can be used to measure the full width at half maximum.

[Brief description of drawings]

FIG. 1 is an overall view of an optical axis deviation angle measuring device for a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method of measuring an optical axis shift angle of a semiconductor laser according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a two-dimensional CCD image in the optical axis deviation angle measuring device for a semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a principle of generating a pseudo peak in a CCD image.

FIG. 5 is an overall view of an optical axis deviation angle measuring device for a semiconductor laser according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a two-dimensional CCD image in an optical axis shift angle measuring device for a semiconductor laser according to a second embodiment of the present invention.

FIG. 7 is an overall view of an optical axis deviation angle measuring device for a semiconductor laser according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating a two-dimensional CCD image in an optical axis shift angle measuring device for a semiconductor laser according to a third embodiment of the present invention.

FIG. 9 is a diagram showing an overall view of an optical axis deviation angle measuring device for a semiconductor laser of Conventional Example 1.

FIG. 10 is a diagram showing an overall view of an optical axis deviation angle measuring device for a semiconductor laser of Conventional Example 2.

FIG. 11 is a diagram illustrating a two-dimensional CCD image in an optical axis shift angle measuring device for a semiconductor laser of Conventional Example 2.

[Explanation of symbols]

10 ... Semiconductor laser device 11 ... Semiconductor laser device 30 ... Transparent parallel plate correction plate 31 ... ND filter correction plate 40 ... Condensing lens 60 ... CCD camera 61 ... CCD

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-7-66472 (JP, A) JP-A-9-138957 (JP, A) JP-A-8-235630 (JP, A) JP-A-64- 20403 (JP, A) JP 7-202347 (JP, A) JP 9-307192 (JP, A) JP 7-5032 (JP, A) JP 61-253441 (JP, A) JP-A-60-142276 (JP, A) JP-A-8-233571 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01S 5/00-5/50 G01M 11/00 H01L 21/66

Claims (8)

(57) [Claims] 1. After measuring the emission point image of a semiconductor laser as a CCD image using at least a condenser lens and a CCD, a far-field image of a laser beam emitted from the semiconductor laser is C
In a method of measuring characteristics of a semiconductor laser for measuring as a CD image , a distance between the condenser lens and the semiconductor laser, and
State in which the distance between the condenser lens and the CCD is kept constant
Then, by inserting or extracting a correction plate made of a parallel plate into or out of the optical path between the condenser lens and the semiconductor laser or between the condenser lens and the CCD, the CC
A method for measuring characteristics of a semiconductor laser, characterized in that a D image is changed from the light emission point image to the far field image. 2. The method for measuring characteristics of a semiconductor laser according to claim 1, wherein the CCD has a surface provided with a protective glass.
The correction plate is inserted, the emission point image is measured as a CCD image, the correction plate is extracted, and the far-field image is CCD.
A method for measuring characteristics of a semiconductor laser, which comprises measuring as an image. 3. The method for measuring characteristics of a semiconductor laser according to claim 1, wherein coordinates of the emission point image in a CCD image are measured, and coordinates of a peak of the far-field image in the CCD image are measured. A method for measuring characteristics of a semiconductor laser, wherein an optical axis shift angle of the semiconductor laser is measured from coordinates of a point image in a CCD image and coordinates of a peak of the far-field image in the CCD image. 4. The method for measuring characteristics of a semiconductor laser according to claim 1, wherein the half width of the far-field image is measured from the CCD image. 5. The half according to any one of claims 1 to 4.
In the method of measuring the characteristics of a conductor laser, the output level of the CCD and the far
The output level of the CCD in the visual field image is made substantially the same.
A method for measuring characteristics of a semiconductor laser. 6. At least a condensing lens and a CCD are provided, and after measuring the emission point image of the semiconductor laser as a CCD image, the far-field image of the laser light emitted from the semiconductor laser is C
In a characteristic measuring device of a semiconductor laser for measuring as a CD image , a parallel plate is provided in an optical path between the condenser lens and the semiconductor laser or between the condenser lens and the CCD.
A semiconductor laser characteristic measuring device characterized in that a correction plate is provided so that it can be inserted and removed . 7. The semiconductor laser characteristic measuring device according to claim 6 , wherein the CCD has a protective glass on its surface.
Semiconductor laser characteristic measuring device according to claim der Rukoto. 8. The semiconductor laser characteristic measuring apparatus according to claim 6 , wherein the correction plate is an ND filter.