JP2020064895A - Semiconductor laser device - Google Patents

Abstract

To provide a semiconductor laser device that is easy to control, that is inexpensive, and that can perform APC of optical output from a plurality of semiconductor lasers.SOLUTION: A plurality of semiconductor lasers 11a, 11b arranged for each predetermined interval comprises: a condensing lens 22 that combines a laser beam from the plurality of semiconductor lasers 11a, 11b to an aperture 23; a digital mirror device 14 that are arranged between the plurality of semiconductor lasers 11a, 11b and the condensing lens 22; and a V/F conversion circuit 21 that controls optical output being output from the digital mirror device 14 by controlling the digital mirror device 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor laser device applicable to laser processing and a laser projector.

  When constant power control (APC) is performed using a single semiconductor laser, usually, a part of the laser light output from the semiconductor laser is detected by a photodiode so that the detected light amount becomes a constant value. The amount of current passed through the laser is controlled (Patent Document 1).

  On the other hand, when performing APC using a plurality of semiconductor lasers, the first method of connecting a plurality of semiconductor lasers in series and controlling the amount of current collectively, and a part or all of the plurality of semiconductor lasers There is a second method in which the semiconductor lasers are connected in parallel and the amount of current is controlled for each semiconductor laser connected in parallel.

JP, 2004-146523, A

  However, in the first method, although the control circuit is simple, the light output changes greatly with a small amount of current. Therefore, as the number of semiconductor lasers used increases, the accuracy of the amount of current becomes necessary. Further, a design corresponding to precise current control is required, and the device becomes expensive.

  On the other hand, in the second method, it is necessary to control the current amount individually for the semiconductor lasers connected in parallel. Therefore, as the number of semiconductor lasers used increases, complicated control becomes necessary and the control circuit becomes complicated. In addition, a design corresponding to a large current is required, which makes the device expensive.

  An object of the present invention is to provide a semiconductor laser device which is easy to control and inexpensive, and which can realize APC of optical output from a plurality of semiconductor lasers.

  In order to solve the above-mentioned problems, a semiconductor laser device according to a first aspect of the present invention is directed to a plurality of semiconductor lasers arranged at predetermined intervals, and an optical system for coupling laser light from the plurality of semiconductor lasers to an opening. A coupling device, a mirror device that is disposed between the plurality of semiconductor lasers and the optical coupling device, reflects the laser light from the plurality of semiconductor lasers, and guides the reflected laser light to the optical coupling device; A mirror device control unit is provided, which controls the optical output output from the mirror device by controlling the mirror device based on a part of the laser light reflected by the mirror device.

  According to a second aspect of the present invention, the mirror device has a large number of micromirrors, and each of the plurality of micromirrors is a digital mirror device controlled by the mirror device controller.

  4. The pulse signal having a pulse width according to the difference voltage between the average voltage obtained by averaging the voltages corresponding to the laser light output from the digital mirror device and the set voltage. And controlling the micromirrors of the digital mirror device by the converted pulse signal to control the optical output output from the digital mirror device to a predetermined value.

  According to a fourth aspect of the present invention, there are provided a plurality of semiconductor lasers arranged at predetermined intervals, an optical coupling element that couples laser light from the plurality of semiconductor lasers to an opening, and the plurality of semiconductor lasers and the optical coupling element. A mirror device which is disposed between the mirror devices and reflects the laser beams from the plurality of semiconductor lasers and guides the reflected laser beams to the optical coupling element; and an optical output coupled to the opening by controlling the mirror device. And a mirror device control unit for controlling the in-plane distribution of.

  According to a fifth aspect of the present invention, the mirror device has a large number of micromirrors, and each of the plurality of micromirrors is a digital mirror device controlled by the mirror device controller.

  The mirror device control section according to claim 6 divides the large number of micromirrors into a plurality of areas, and controls the micromirrors for each of the divided areas to control the optical output coupled to the opening. It is characterized by controlling the in-plane distribution.

  According to the present invention, the mirror device reflects the light output from the plurality of semiconductor lasers, and the mirror device control unit controls the mirror device based on a part of the laser light reflected by the mirror device. Since the light output outputted from the digital mirror device is controlled by the above, it is possible to provide a semiconductor laser device which is simple and inexpensive to realize APC of light output from a plurality of semiconductor lasers.

It is a block diagram of a semiconductor laser device of a first embodiment of the present invention. It is a figure which shows ON / OFF of PWM control of the digital mirror device in the semiconductor laser device of the 1st Example of this invention. It is a block diagram of a semiconductor laser device of a second embodiment of the present invention. It is a figure which shows the 1st example of the in-plane distribution of the optical output couple | bonded with the opening part from the digital mirror device controlled by the DMD control part of the semiconductor laser apparatus of 2nd Example. It is a figure which shows the 2nd example of in-plane distribution of the optical output couple | bonded with the opening part from the digital mirror device controlled by the DMD control part of the semiconductor laser apparatus of 2nd Example.

(First embodiment)
Hereinafter, semiconductor laser devices according to embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a semiconductor laser device according to a first embodiment of the present invention. The semiconductor laser device 1 includes a plurality of semiconductor lasers 11a and 11b, lenses 12a and 12b, a constant current circuit 13, a digital mirror device (DMD) 14, a beam splitter 15, a lens 16, a photodiode (PD) 17, and I / V conversion. The circuit 18, an averaging circuit 19, a comparison circuit 20, a V / F conversion circuit 21, and a condenser lens 22 are provided.

  The semiconductor laser device 1 is formed with a circular opening 23 for guiding the laser light emitted from the condenser lens 22 to the end face of the optical fiber provided outside the semiconductor laser device 1. The opening 23 has a diameter of 1000 μm or less.

  In FIG. 1, the plurality of semiconductor lasers is two, but the plurality of semiconductor lasers may be three or more, and the respective semiconductor lasers are arranged at predetermined intervals.

  The constant current circuit 13 supplies a constant drive current to the semiconductor lasers 11a and 11b to drive the semiconductor lasers 11a and 11b. The plurality of semiconductor lasers 11a and 11b are driven by the constant current circuit 13 and a constant drive current flows, whereby they are excited and emit laser light. The lenses 12a and 12b are collimating lenses, are arranged to face the semiconductor lasers 11a and 11b, and collimate the laser beams from the semiconductor lasers 11a and 11b.

  The digital mirror device 14 corresponds to the mirror device of the present invention, is arranged between the plurality of semiconductor lasers and the beam splitter 15, reflects the laser light from the plurality of semiconductor lasers, and reflects the reflected laser light to the beam splitter 15. Lead to. In the digital mirror device 14, each micro mirror of a large number of micro mirrors is controlled by the V / F conversion circuit 21.

  The mirror surface of each micromirror of the digital mirror device 14 can be tilted by ± predetermined angles, and by driving an electrode provided under the mirror surface, “ON” (+ predetermined angle) and “OFF” (−predetermined angle) can be obtained. It has two states.

  When the micro mirror is “ON”, the laser light is reflected and output to the beam splitter 15, and when the micro mirror is “OFF”, the laser light is not output to the beam splitter 15. The digital mirror device 14 reflects the laser light from the plurality of semiconductor lasers 11a and 11b, and controls the duty of the micro mirrors “ON” and “OFF”, that is, PWM (pulse width modulation) control to control the laser light. Output.

  The beam splitter 15 transmits the laser light from the digital mirror device 14 and guides it to the condenser lens 22 and reflects a part of the laser light to guide it to the lens 16. The condenser lens 22 corresponds to the optical coupling element of the present invention, condenses the laser light from the beam splitter 15 and couples it to the opening 23.

  The lens 16 guides the laser light from the beam splitter 15 to the photodiode 17.

  The photodiode 17, the I / V conversion circuit 18, the averaging circuit 19, the comparison circuit 20, and the V / F conversion circuit 21 correspond to the mirror device control unit of the present invention which controls the digital mirror device 14.

  The photodiode 17 corresponds to the detector of the present invention and detects the laser light from the lens 16. The I / V conversion circuit 18 converts the current I corresponding to the laser light from the photodiode 17 into a voltage value V. The averaging circuit 19 averages the voltage values converted by the I / V conversion circuit 18.

  The comparison circuit 20 compares the average voltage averaged by the averaging circuit 19 with the optical output setting voltage, and outputs the difference voltage between the average voltage and the optical output setting voltage to the V / F conversion circuit 21.

  The V / F conversion circuit 21 corresponds to the conversion circuit of the present invention, converts the difference voltage output from the comparison circuit 20 into a pulse signal having a pulse width according to the difference voltage, and uses the converted pulse signal as a digital mirror device. The optical output output from the digital mirror device 14 is controlled to a predetermined value by controlling on / off of each of the micromirrors 14 in FIG.

  Next, the operation of the semiconductor laser device of the first embodiment configured as described above will be described. First, laser light from the plurality of semiconductor lasers 11a and 11b is guided to the digital mirror device 14 via the lenses 12a and 12b.

  Many micromirrors of the digital mirror device 14 are PWM-controlled to control the laser light from the plurality of semiconductor lasers 11a and 11b to the beam splitter 15. A part of the laser light from the digital mirror device 14 is reflected by the beam splitter 15 and detected by the photodiode 17 via the lens 16.

  The current I corresponding to the laser light from the photodiode 17 is converted into a voltage value V by the I / V conversion circuit 18, and the voltage value converted by the I / V conversion circuit 18 is averaged by the averaging circuit 19. It

  The difference voltage between the average voltage averaged by the averaging circuit 19 and the optical output setting voltage is output from the comparison circuit 20 to the V / F conversion circuit 21. The difference voltage output from the comparison circuit 20 is converted by the V / F conversion circuit 21 into a pulse signal having a pulse width according to the difference voltage, and the converted pulse signal controls on / off of the micromirror of the digital mirror device 14. That is, PWM control is performed.

  FIG. 2 shows ON / OFF of the PWM control of the digital mirror device 14. As shown in FIG. 2, PWM control is performed by changing the duty of ON (ON) and OFF (OFF) of the pulse signal. Av shown in FIG. 2 is the average power of the pulse signal.

  Thereby, the light output output from the digital mirror device 14 can be controlled to a predetermined value.

  That is, the APC of the optical output from the plurality of semiconductor lasers 11a and 11b can be realized only by keeping the amount of current flowing through the plurality of semiconductor lasers 11a and 11b constant and controlling the amount of reflected light of the digital mirror device 14. A semiconductor laser device that is easy to control and inexpensive can be provided.

(Second embodiment)
FIG. 3 is a configuration diagram of a semiconductor laser device according to a second embodiment of the present invention. The semiconductor laser device 1a according to the second embodiment includes a plurality of semiconductor lasers 11a and 11b, lenses 12a and 12b, a constant current circuit 13, a digital mirror device 14, a DMD controller 24, and a condenser lens 22.

  The configurations of the plurality of semiconductor lasers 11a and 11b, the lenses 12a and 12b, the constant current circuit 13, and the digital mirror device 14 are the same as those in the first embodiment, and therefore the description thereof will be omitted. Here, only the DMD control unit 24 will be described.

  The DMD control unit 24 corresponds to the mirror device control unit of the present invention, divides a large number of micromirrors of the digital mirror device 14 into a plurality of areas, and controls the micromirrors on and off for each of the divided areas. Controls the in-plane distribution of the light output coupled to the section 23.

  FIG. 4 shows a first example of the in-plane distribution of the optical output coupled from the digital mirror device 14 controlled by the DMD control unit 24 to the opening 23. The in-plane distribution of light output is, for example, the in-plane distribution at the end face of a circular optical fiber.

  In the first example of the in-plane distribution of the optical output shown in FIG. 4, the DMD control unit 24 divides a large number of micromirrors MM into two upper and lower areas AE1 and AE2, and a plurality of micromirrors in the divided areas AE1. All of the MMs are turned on (100% off), and all of the plurality of micromirrors MM in the divided area AE2 are turned off (100% off).

  As a result, the light output can be obtained only in the area AE1, and the in-plane distribution of the light output can be changed for each area.

  FIG. 5 shows a second example of the in-plane distribution of the optical output coupled from the digital mirror device 14 controlled by the DMD control unit 24 to the opening 23.

  In the second example of the in-plane distribution of the optical output shown in FIG. 5, the DMD control unit 24 divides a large number of micromirrors MM into three regions AE3, AE4, AE5 on a concentric circle, and has the divided regions AE3. All of the plurality of micro mirrors MM are turned on (100% on), 80% of the plurality of micro mirrors MM in the divided area AE3 are turned on (80% on), and the plurality of micros in the divided area AE5 are turned on. Turn off all mirrors MM (100% off).

  As a result, the light output, that is, the brightness of the three areas AE3, AE4, AE5 can be changed on the concentric circle, and the areas AE5, AE4, and AE3 can be brightened in this order.

  The DMD control unit 24 is not limited to the first and second examples of the in-plane distribution of the light output, and controls the on / off of the plurality of micromirrors MM for each area to thereby determine the surface of the light output. The inner distribution can be changed for each area.

  The present invention is not limited to the semiconductor laser devices of the first and second embodiments. In the semiconductor laser devices of the first and second embodiments, the digital mirror device is illustrated as the mirror device, but the mirror device is not limited to the digital mirror device, and the mirror device is controlled by the mirror device control unit and the mirror device is controlled. Any other device may be used as long as the device can control the light output from the device.

  The present invention can be applied to laser processing and a laser projector.

1 Semiconductor Laser Devices 11a, 11b Semiconductor Lasers 12a, 12b, 16 Lens 13 Constant Current Circuit 14 Digital Mirror Device (DMD)
15 Beam splitter 17 Photodiode (PD)
18 I / V conversion circuit 19 Averaging circuit 20 Comparison circuit 21 V / F conversion circuit 22 Condensing lens 23 Opening 24 DMD control unit MM Micromirror

Claims (6)

A plurality of semiconductor lasers arranged at predetermined intervals,
An optical coupling element for coupling laser light from the plurality of semiconductor lasers to the opening,
A mirror device that is disposed between the plurality of semiconductor lasers and the optical coupling element and that guides the reflected laser light from the plurality of semiconductor lasers to the optical coupling element.
A mirror device control unit that controls an optical output output from the mirror device by controlling the mirror device based on a part of the laser light reflected by the mirror device;
A semiconductor laser device comprising:   2. The semiconductor laser device according to claim 1, wherein the mirror device has a large number of micromirrors, and each of the plurality of micromirrors is a digital mirror device controlled by the mirror device controller. .   The mirror device control unit converts a difference voltage between an average voltage obtained by averaging the voltages corresponding to the laser light output from the digital mirror device and a set voltage into a pulse signal having a pulse width according to the difference voltage, and converting the pulse signal. 3. The semiconductor laser device according to claim 2, wherein the optical output output from the digital mirror device is controlled to a predetermined value by controlling each of the micro mirrors of the digital mirror device by the generated pulse signal. A plurality of semiconductor lasers arranged at predetermined intervals,
An optical coupling element for coupling laser light from the plurality of semiconductor lasers to the opening,
A mirror device that is disposed between the plurality of semiconductor lasers and the optical coupling element and that guides the reflected laser light from the plurality of semiconductor lasers to the optical coupling element.
A mirror device controller that controls the in-plane distribution of the optical output coupled to the opening by controlling the mirror device;
A semiconductor laser device comprising:   5. The semiconductor laser device according to claim 4, wherein the mirror device has a large number of micromirrors, and each of the plurality of micromirrors is a digital mirror device controlled by the mirror device controller. .   The mirror device control unit divides the large number of micromirrors into a plurality of regions, and controls the micromirrors for each of the divided regions to control the in-plane distribution of light output coupled to the opening. The semiconductor laser device according to claim 5, wherein:

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