JP4765588B2 - FFP measuring apparatus and FFP measuring method - Google Patents

Description

  The present invention relates to an apparatus and method for measuring FFP (FAR FIELD PATTERN) of laser light emitted from a laser diode.

  Conventionally, in FFP measurement of a laser diode, there is a method in which a photodiode is used as a light receiving portion and this photodiode is rotated around the light emitting position of the laser diode (Japanese Patent Laid-Open No. 62-245128). However, since this method can only obtain one-dimensional information at a time, there is a problem that the shape of the three-dimensional radiation light is not known, and it takes too much measurement time to mechanically rotate the light receiving unit. There is also a problem.

  There is also a mechanism in which a plurality of light receiving bodies are arranged in parallel, a plurality of laser diodes are arranged in parallel to face each other, and the plurality of light receiving bodies are rotated around a parallel axis of the plurality of laser diodes (Japanese Patent Laid-Open No. Sho). 62-255843) has the same problem as the above method, and the cost increases because a large number of photoreceptors are used.

JP 62-245128 A JP-A-62-255843

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an FFP measurement apparatus and an FFP measurement method capable of measuring an FFP image quickly and two-dimensionally at a low cost.

The above-described problems include a first imaging system that images the laser diode mounted on the mounting table from a direction parallel to the first axis of the orthogonal coordinate system, and the emitted light from the light emitting point of the laser diode on the first axis. A second imaging system that captures an image from a direction parallel to a perpendicular second axis, and the first imaging system and a computer that inputs an image signal output from the second imaging system, are obtained by the first imaging system. Based on the first axial component and the second axial component of the distance between the light emitting point of the laser diode and the focal point of the lens of the second imaging system, a radiation image obtained by the second imaging system is obtained. A correction memory storing correction data for correction is built in the computer, obtained by the first imaging system, and based on the laser radiation direction from the light emitting point with reference to the outer shape of the laser diode. Of synchrotron image So as to correct the over click value, are solved by the FFP measuring device, characterized in that the true peak value and the full width at half maximum of the emitted light was such that operation of the laser diode.

Further, the above-described problems include a first imaging step of imaging the laser diode mounted on the mounting table from a direction parallel to the first axis of the orthogonal coordinate system, and radiation emitted from the light emitting point of the laser diode. A second imaging step of imaging from a direction parallel to a second axis perpendicular to one axis, a step of inputting the first and second image signals obtained in the first imaging step and the second imaging step to a computer; Based on the first axial component and the second axial component of the distance between the light emitting point of the laser diode obtained in the first imaging step and the focal point of the lens used in the second imaging step, the second imaging Supplying the second image signal to a memory storing correction data for correcting the radiation image obtained in the step, and obtaining the laser diode obtained in the first imaging step as a reference From the light emitting point Correcting the synchrotron radiation image based on the user radiation direction, and calculating the true peak value and full width at half maximum of the synchrotron radiation image by the correction by the correction data and the correction of the radiation direction by the outline reference. This is solved by the FFP measurement method characterized by the above.

  The FFP of the emitted light from the laser diode can be quickly and two-dimensionally measured at a low cost.

  Hereinafter, a laser diode FFP measuring apparatus and measuring method according to embodiments of the present invention will be described.

  FIG. 1 shows a schematic diagram of an FFP measuring apparatus, in which a laser diode 1 is mounted on a submount 2. A radiation imaging optical system 3 (comprising a lens and a camera) is disposed in the lateral direction, and a laser diode imaging optical system 4 (comprising a lens and a camera) is disposed immediately above the laser diode 1. It is installed. Image signals from the laser diode imaging optical system 4 and the emitted light imaging optical system 3 are supplied to a computer 5.

  As shown in FIG. 2, the computer 5 includes a focus memory 11, a focus-light emitting position distance calculation unit 12, a correction coefficient memory 13, a radiation direction calculation unit 14, a provisional full width at half maximum and provisional peak value calculation unit 15, and A half-value full-width / peak value calculation unit 16 and a peak value correction unit 17 are provided. Next, an operation method of the FFP measuring apparatus according to the embodiment of the present invention will be described.

  FIG. 3 shows an image of the emitted light of the laser diode 1 imaged by the emitted light imaging optical system 3.

  FIG. 4 shows imaging of the laser diode 1 imaged by the laser diode imaging optical system 4 and the submount 2 on which the laser diode 1 is mounted. As is well known, the fθ lens used in the synchrotron radiation imaging optical system 3 forms this image at a position proportional to the incident angle of the laser light from the light emitting point Q of the laser diode 1, and the proportionality coefficient is the focal length of the fθ lens. f.

  Therefore, according to this optical principle, in the X axis and Y axis as shown in FIG. 3, if the incident angle is taken on the horizontal axis and the light intensity is taken on the vertical axis as shown in FIG. In addition, the angle between the angles that are halved on both sides, that is, the half width, is also measured. In the embodiment of the present invention, measurement is performed in the X-axis direction and the Y-axis direction, respectively.

  As will be described later, the true peak value and full width at half maximum are obtained from the distance between the focal point P of the imaging lens of the radiated light imaging optical system 3 of the laser diode 1 and the light emission position Q of the laser diode 1. Before correction, the half-width and provisional peak values are referred to as provisional half-width and provisional peak values. In the computer 5, image signals are supplied to the provisional half-width and provisional peak value calculation unit 15.

  The focal point P of the lens of the imaging optical system 3 for the imaging light emitted from the laser diode 1 is stored in the computer 5 in the field of view of the laser diode imaging optical system 4. It is done. A laser diode whose radiation direction and half width are known is placed on the submount 2, and by moving the laser diode or the radiation imaging optical system 3, the image of the emitted light of the known laser diode matches a known value. Adjusted to obtain. The position of the light emitting point in the image of the optical system 4 at that time is the focal point P. FIG. 8 is a flowchart of the calibration work procedure. In the present invention, this position is stored in the focus memory 11 of the computer 5.

  Next, the laser diode 1 to be measured is placed on the submount 2. As described above, an image is picked up by the laser diode imaging optical system 4 immediately above. FIG. 4 shows this captured image.

  Furthermore, according to the embodiment of the present invention, the half-width full-width is multiplied by how much correction coefficient is applied to the captured radiation image by the output of the focus-light emitting position distance calculation unit 12 in the computer 5 of FIG. The correction coefficient memory 13 is provided to determine whether to obtain the peak value, and this correction coefficient is set in advance using the calibration laser diode for obtaining the above-mentioned focus.

  As shown in FIG. 9, when the emission point of the laser diode whose emission direction and half width are known, that is, the focal point P (which is stored in the focal point memory) and the emission point position of the laser diode 1 to be measured are defined as Q. In the coordinate axis shown by the distance PQ between them, the X direction component is X1 and the Z direction component is Z1. Before the measurement, the full width at half maximum and the amount of change of the peak value of the radiation image when the laser diode described above is used and the jig is used to move the X0 in the X direction are measured, and the change per unit length in the X direction is measured. The amount of correction is determined.

  Further, in the Z direction, Z0 is moved in the Z-axis direction by actually using a jig, and the amount of change in the half width and the peak value is obtained to obtain the correction amount in the unit length in the Z direction. Using the amount of change in the unit length in the X direction and the Z direction as a correction coefficient, how much correction is made with respect to the output from the focus-light emitting distance calculation unit 12 shown in FIG. Is supplied to the correction coefficient memory 13 to determine whether or not

  As described above, the intensity corresponding to each radiation angle from the laser beam is calculated from the image of the laser beam from the laser diode 1 (FIG. 3) based on the principle of the fθ lens. An intensity curve is obtained. The provisional half-value full-width and provisional peak value calculation unit 15 in the computer 5 in FIG. 2 is supplied to the provisional half-value full-width and peak value calculation unit 16. The correction value from the above-described correction coefficient memory 13 is input to this output, and the full width at half maximum and the peak value are calculated by the calculation unit 16 by synergizing them.

  As shown in FIG. 6, according to the present invention, the radiation angle of the laser beam from the light emitting point Q can be measured with reference to the outer shape of the laser diode.

  If the laser diode 1 is rectangular as shown in FIG. 6A, a straight line parallel to the long side m is defined as d. On the other hand, if the deviation angle of the laser beam α is α, it becomes as shown in the figure, but this is not perpendicular to the short side n of the laser diode 1 but is inclined in the α direction as shown. I would like to know this inclination angle α. According to the present invention, as shown in FIG. 6B, the laser diode 1 is inclined and placed on the submount 2 as can be seen from the captured image on the submount 2. ing. This inclination angle is β with respect to the straight line d parallel to the long side m of the laser diode 1 described above. Of course, this β is not the tilt angle α of the laser beam with respect to the actual laser diode 1. As shown in FIG. 6B, the laser diode 1 is inclined γ with respect to a straight line d ′ parallel to the long side m of the laser diode 1. Here, the true inclination angle α (radiation direction) is determined as γ−β = α.

  That is, by this outer shape recognition, the radiation direction of the laser beam from the light emitting point Q of the laser diode 1 can be obtained as γ-β by this outer shape recognition. This calculation is calculated by the radiation direction calculation unit 14 in the computer 5, and this result can be corrected as a deviation angle of the peak value with respect to the output of the peak value calculation unit 17.

  The above operation is shown in the flowchart of FIG. That is, assuming that image processing is started in step S0, the laser light emission optical system 3 and the laser diode imaging optical system 4 respectively perform the laser light emission light image and the submount 2 in the next step S1. An outline image of the laser diode 1 is acquired. Next, in step S2, a tentative full width at half maximum and a deviation angle or peak value are obtained from the radiation image.

  Next, in step S3, the light emission point Q of the laser diode 1 imaged by the laser diode imaging optical system 4 is input. That is, the distance between the focal point P and the light emitting point Q is calculated, and the full width at half maximum of the laser diode 1 is corrected by applying a correction coefficient to the distance components X1 and Z1 in the X-axis and Z-axis directions. . Further, in step S4, the deviation angle or peak value of the laser diode 1 is calculated from the distance X1 component and the Z1 component between the light emitting point Q and the focal point P.

  Finally, the angle α is calculated from the external image of the laser diode 1 imaged by the laser diode imaging optical system 4 in step S5, and the correct peak is obtained by correcting the deviation angle or peak value of the laser diode 1 based on the calculation result. A value is obtained. As described above, the image processing ends in step Se.

  As shown by the routine in the flowchart of FIG. 7, it is determined whether or not the measurement result is within a predetermined quality. Non-defective products are sorted based on the determination result. Therefore, the measurement ends.

  According to the present embodiment, as shown in FIG. 4, alignments 10a and 10b are formed at both ends of the submount 2, and die bonding in a later process is obtained in this embodiment based on the alignments 10a and 10b. The obtained data such as the radiation direction and the half-value width can be supplied from the computer 5 to the die bonding apparatus, and the position can be set in the die bonding apparatus based on the radiation direction.

  The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

  For example, in FIG. 4, only the submount 2, the laser diode 1, and the alignments 10a and 10b are shown, but a PIN diode is generally used for adjusting the output of the laser diode 1. You may build this on the submount.

  In the above embodiment, only the X axis and the Z axis (layer direction XZ) in the orthogonal direction have been described. However, the laser diode imaging optical system 4 shown in FIG. Obtained from the radiation imaging optical system 3 by imaging the laser diode 1 in a plane that rotates 90 degrees around the optical axis of the system 3 and is determined by the Z axis and the Y axis instead of the X axis and the Z axis. You may make it obtain | require the gap angle of the half value width and peak value with respect to the X-axis and the Y-axis of the emitted light image.

  However, in FIG. 1, the radiation direction was measured in the ZX plane. On the other hand, since it is known that the radiation direction hardly changes with respect to the YZ plane in the vertical direction, this operation may be omitted. In this plane, since the structure can be controlled in the unit of nm as a manufacturing process, there is almost no problem of the deviation angle.

  In the above embodiment, the fθ lens is used as the lens of the radiation imaging optical system, but a Fourier transform lens may be used instead. In this case, the correction of the full width at half maximum in the flowchart of FIG. 8 can be omitted from the characteristics of the lens. However, the fθ lens is advantageous in terms of cost.

1 is a schematic diagram of an FFP measurement apparatus according to an embodiment of the present invention. The block diagram which shows the part in connection with this invention in the computer 5 in FIG. FIG. 2 is a front view of a radiation image obtained by the radiation imaging optical system in FIG. 1. The top view of the captured image obtained by the optical system for laser diode imaging in FIG. A graph for explaining the full width at half maximum. The schematic plan view which shows a radiation direction on the basis of the external shape of a laser diode. FIG. 6A is a diagram in which the light emitting point of the laser diode is on a straight line parallel to the long side m of the laser diode. FIG. 6B is a diagram showing the inclination and radiation direction of the laser diode from actual imaging, and is a diagram for obtaining the radiation direction from this. The flowchart which shows the operation procedure of an apparatus. The flowchart which shows the procedure of the calibration operation | work for calculating | requiring a focus. The chart which shows the X component and Z component of the distance between the focus P and the light emission point position Q of a laser diode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser diode, 2 ... Submount, 3 ... Synchrotron radiation imaging optical system, 4 ... Laser diode imaging optical system, 5 ... Computer, 11 ... Focus memory, 12・ ・ ・ Focus-light emitting position distance calculation unit, 13 ... Correction coefficient memory, 14 ... Radiation direction calculation unit, 15 ... Provisional half-value full-width, provisional peak value calculation unit, 16 ... Half-value full-width, Peak value calculation unit, 17 ... peak value correction unit

Claims (6)

A first imaging system for imaging a laser diode mounted on a mounting table from a direction parallel to a first axis of an orthogonal coordinate system; and a second axis perpendicular to the first axis for emitted light from the light emitting point of the laser diode A second imaging system for imaging from a direction parallel to the first imaging system and a computer for inputting an image signal output from the first imaging system and the second imaging system, and emitting light of the laser diode obtained by the first imaging system Correction for correcting the radiation image obtained by the second imaging system based on the first axial component and the second axial component of the distance between the point and the focal point of the lens of the second imaging system A correction memory storing data is incorporated in the computer, and is obtained by the first imaging system. The peak of the radiation image is obtained based on the laser radiation direction from the light emitting point with reference to the outer shape of the laser diode. Correct value In the so that, FFP measuring apparatus that calculates the true peak value and the full width at half maximum of the emitted light of the laser diode. The FFP measurement apparatus according to claim 1, wherein the imaging lens of the second imaging system is an fθ lens or a Fourier transform lens. An alignment is provided on the mounting table, and the mounting table on which the laser diode is mounted is aligned on a heat sink by the alignment, and a signal indicating the radiation direction is received from the computer and die-bonded on the basis of the radiation direction. The FFP measuring apparatus according to claim 1 or 2. A first imaging step of imaging the laser diode mounted on the mounting table from a direction parallel to the first axis of the orthogonal coordinate system; and a second light perpendicular to the first axis for the emitted light from the light emitting point of the laser diode. Obtained in the first imaging step, a second imaging step of imaging from a direction parallel to the axis, a step of inputting the first and second image signals obtained in the first imaging step and the second imaging step to a computer, and the first imaging step. Radiation light obtained in the second imaging step based on the first axial component and the second axial component of the distance between the light emitting point of the laser diode and the focal point of the lens used in the second imaging step A step of supplying the second image signal to a memory storing correction data for correcting an image, and a laser from the light emitting point obtained in the first imaging step and based on the outer shape of the laser diode Based on radial direction FFP measurement method as the emitted light image; and a step of correcting, calculates the true peak value and the full width at half maximum of the radiation image by the correction and the correction of the radiation direction of the outer shape reference by the correction data Te. The FFP measurement method according to claim 4, wherein the imaging lens of the second imaging system is an fθ lens or a Fourier transform lens. An alignment is provided on the mounting table, and the mounting table on which the laser diode is mounted is aligned on a heat sink by the alignment, and a signal indicating the radiation direction is received from the computer and die-bonded on the basis of the radiation direction. The FFP measurement method according to claim 4 or 5.