JPH08172235A - Temperature control system for semiconductor laser - Google Patents

Abstract

PURPOSE: To rapidly process the output of a temperature output sensor by a CPU by controlling the digital conversion of an analog signal by a controller, and inhibiting the relative operation of the CPU. CONSTITUTION: Since an A-D converter 5 can process only one analog signal, next data signal is reserved by a multiplexer 6 until a controller 10 finishes the digital conversion, and a sample and hold circuit 11 is controlled to a closed state. When the digital conversion is finished, the temperature sensor output after the conversion is sequentially written in the one memory of a dual-port memory 7. At the time of finishing the writing, an interrupt signal is output from the controller 10 to a CPU 9, the writing the sensor output in the memory is switched to the other memory, and the output is continuously written by the converter 5. The CPU 9 reads the memory in which the writing is already finished, and the CPU 9 can rapidly process the output separately independently from the writing of the converter 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control system for a semiconductor laser diode array that excites a solid-state laser, and more particularly to a temperature control system for a semiconductor laser that controls the temperature of the semiconductor laser so as to keep it within a predetermined range. Regarding

[0002]

2. Description of the Related Art In recent years, lasers have been used in a very wide range of fields such as information processing, measurement, material processing, communication and medical use. The types of this laser are classified into solid, gas, liquid, and semiconductor lasers. Among these lasers, the solid-state laser has a small amount of neodymium ion or chromium added to a solid material such as ruby or YAG crystal or glass as a laser active medium. A laser oscillator is used, and laser oscillation is performed by photoexcitation by irradiation of light energy.
This photoexcitation method includes a method using a lamp such as a Xe lamp and a Kr arc lamp, and a method using a semiconductor laser. Semiconductor laser pumping, which has better oscillation efficiency and longer life than lamp pumping, is preferable for solid-state lasers. Further, in order to obtain a more stable laser output, it is desirable that the oscillation wavelength of the semiconductor laser that excites the laser medium is stable.

However, in practice, a semiconductor laser diode array containing several to several tens of semiconductor lasers is used to separately oscillate pumping laser light, so that the oscillation wavelength is relative to the center wavelength. A variation of several nm will occur. Usually, the absorption spectrum width of the medium of the solid-state laser is about 2 to 10 nm from the center wavelength, and particularly in the case of YAG crystal to which neodymium is added, the absorption spectrum width is as narrow as about 2 nm, and the variation range described above is Since the absorption spectrum width is exceeded, the efficiency of exciting the neodymium ion becomes poor.

On the other hand, the oscillation wavelength of the pumping laser light output from the semiconductor laser diode array is easily affected by temperature changes, and its temperature dependence is 0.3 nm / ° C., and therefore the variation of the oscillated wavelength is further increased. Will grow. Therefore, in order to efficiently excite the medium of the solid-state laser, it is necessary to independently control the temperatures of the plurality of semiconductor laser diode arrays.

Therefore, conventionally, the output of the pumping laser light has been controlled by a temperature control system of a semiconductor laser diode array as shown in FIG.

In this conventional temperature control system, a plurality of semiconductor laser diode arrays 1 for exciting a solid-state laser and a Peltier element as a temperature controller for adjusting the temperature of these semiconductor laser diode arrays 1 are used as a thermal electric system. A cooler 2 (hereinafter abbreviated as TEC2), a temperature sensor 3 for measuring the temperature of the semiconductor laser diode array 1, and a sensor output amplifier for amplifying a temperature sensor output signal measured by the temperature sensor 3 to a processable level. 4 and this sensor output amplifier 4
A / D converter 5 for converting the analog signal of the temperature sensor output amplified by the digital signal into a digital signal, and a sample / hold 11 for outputting the analog signal of the temperature sensor output to the A / D converter 5 one by one. Plexer 6
And a RAM that writes the digitally converted temperature sensor output
17, the control until the analog signal of the temperature sensor output in the A / D converter 5 is converted into a digital signal, the temperature is calculated from this temperature sensor output, and this temperature and the set temperature data corresponding to the optimum wavelength are compared and calculated. And outputs a temperature correction command, and a D / A converter 12 that converts the temperature correction command into an analog signal because it is a digital signal.
And a power supply device 13 that supplies power to the TEC 2 based on the temperature correction command.

In the conventional temperature control of the semiconductor laser diode array 1 having such a structure, first, an analog signal of the temperature sensor output is transmitted from the temperature sensor 3 to the multiplexer 6. Then, the CPU 9 controls the switching of the sample hold 11, and the analog signal is passed through the A / D converter 5 to be converted into a digital signal. After the conversion, the CPU 9 reads the temperature sensor output, temporarily stores it in the RAM 17, calculates the temperature corresponding to the temperature sensor output, and further excites this temperature and the medium of the solid-state laser. The difference between the optimum temperature and the set temperature data is calculated, and a temperature correction command is output to the power supply device 13 so as to correct the difference. When the control of one semiconductor laser diode array 1 is completed, the next control is repeated according to the same procedure as described above.

In the conventional temperature control system, the CPU 9 is involved in the operations from the control of the sample hold 11 to the output of the temperature correction command of the semiconductor laser diode array 1 as shown in FIG. If the temperature control of one semiconductor laser diode array 1 is not completed, the next temperature control cannot be performed, and when the temperature correction command is issued, the oscillation wavelength has already fluctuated and the allowable spectral width is reduced. In some cases, it has exceeded.

Further, as shown in the timing chart of FIG. 6, the work requiring the longest processing time among the controls performed by the CPU 9 is the A / D conversion work, and while the CPU 9 is performing this process, Since other work cannot be processed, the whole process was delayed and the efficiency was poor.

The present invention has been made in view of these points, and an object of the present invention is to provide a semiconductor laser temperature control system capable of rapidly controlling the temperature of a large number of semiconductor lasers with a one-chip CPU.

[0011]

In order to achieve the above-mentioned object, the temperature control system for a semiconductor laser according to claim 1 of the present invention irradiates a medium of a solid-state laser with excitation laser light of a specific wavelength for excitation. A plurality of semiconductor lasers for
A temperature controller for individually adjusting the temperature of each of these semiconductor lasers, a temperature sensor for individually measuring the temperature of each of the semiconductor lasers, and an analog signal of the temperature sensor output measured by the temperature sensor A / D converter for converting to a digital signal, and a multiplexer for temporarily holding the analog signal of the temperature sensor output when the temperature sensor output is output to the A / D converter and sequentially outputting the analog signal after completion of the digital conversion processing. A first memory having at least two storage units for writing the temperature sensor output digitally converted by the A / D converter; and a second memory storing calibration temperature data corresponding to the temperature sensor output. The error between the memory and the calibration temperature data and the set temperature data in the second memory corresponding to the temperature sensor output written in the first memory is calculated and compared. It has a CPU that outputs a temperature correction command to the temperature controller so as to perform correction, and a control unit that digitally converts the analog signal of the temperature sensor output and controls the timing of a series of flows until it is processed by the CPU. It is characterized by that.

The semiconductor laser temperature control system according to claim 2 of the present invention is characterized in that in claim 1, the semiconductor laser is a semiconductor laser diode array.

[0013]

According to the present invention having the above-described structure, the analog signals of the temperature sensor output measured by the temperature sensor are sequentially transmitted to the multiple presser and temporarily held.
Then, when the previous analog signal is digitally converted by the A / D converter and written in the first memory having at least two storage units, the next analog signal is converted from the multiplexer to the A / D conversion by the control unit. Is controlled so that it is output to the container. In this way, the analog signals of the temperature sensor output are converted into digital one after another and sequentially written in the first memory. Then, at the time when the writing to all of the one storage unit is completed, a read command is output from the control unit to the CPU, and the writing to the storage unit is switched to the writing to another storage unit. Continue to write the digitally converted temperature data to. Therefore, the temperature sensor output read by the CPU is read only from the storage unit in which writing has already been completed. On the other hand, the CPU sequentially compares the calibration temperature data in the second memory, which corresponds to the temperature sensor output read from the storage unit, with the preset temperature data that can be the optimum wavelength for exciting the solid-state laser medium. , Commands are sequentially sent to the TEC to correct the temperature difference, and the Peltier effect of the TEC absorbs or radiates heat from the semiconductor laser to adjust the temperature to the set temperature.

Therefore, the CPU is not involved in the control for converting the analog signal of the temperature sensor output into a digital signal, and can process only the temperature sensor output after the digital conversion, so that the temperature control of the semiconductor laser can be performed at high speed. Can be done. Further, since the second memory has at least two storage units, writing of the digitally converted temperature sensor output and reading by the CPU can be efficiently processed at the same time.

[0015]

The present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of a temperature system for a semiconductor laser according to the present invention. In the system of this embodiment, a semiconductor laser diode array 1 using a plurality of semiconductor lasers for irradiating and exciting a solid-state medium such as a YAG rod with a laser light for excitation having a specific wavelength, and these semiconductor laser diode arrays. 1 individually arranged TEC2 as a temperature controller for adjusting the temperature by heat absorption and heat dissipation utilizing the Peltier effect, and a temperature sensor individually arranged in the semiconductor laser diode array 1 for measuring each temperature by a thermocouple or the like. 3, a sensor output amplifier 4 for amplifying the temperature sensor output signal measured by the temperature sensor 3 to a processable level, and an analog signal of the temperature sensor output amplified by the sensor output amplifier 4 for the next RAM 7 or The A / D converter 5 that performs digital conversion to enable processing by the CPU 9 is transmitted one after another. The amplified analog signal of the temperature sensor output is temporarily held when it is output to the A / D converter 5, and after the digital conversion by the A / D converter 5, the sample hold 11 is opened and closed to sequentially output the analog signal. It has a multiplexer 6 for outputting and two storage sections for writing the signal of the temperature sensor output digitally converted by the A / D converter 5, and one of the storage sections is written. Sometimes, the dual port memory 7 corresponding to the first memory capable of proceeding with the writing and reading processes at the same time so as to be read from the other storage unit, and the calibration which is the temperature data calculated based on the output of each temperature sensor. The ROM 8 as the second memory for storing temperature data and the temperature corresponding to the temperature sensor output written in the dual port memory 7 are stored in the ROM 8. From the calibration temperature data reading and CPU9 outputs a temperature correction command to correct the temperature and the set temperature data and the error comparison operation to the respective semiconductor laser diode, the sample and hold 1
1 is controlled so that the next analog signal is input from the multiplexer 6 after the conversion processing of one analog signal by the A / D converter 5 is completed, or the A / D converter 5 outputs the next analog signal. On the other hand, the timing is controlled so that the converted data is written to the dual port memory 7, and when the writing to one storage unit of the dual port memory 7 is finished, the writing is switched to the other storage unit. A command is issued, and the CPU 9 is caused to read the temperature sensor output from the memory unit in which the writing has been completed, and the corresponding calibration temperature data is read from the ROM 8 to obtain this calibration temperature data and each semiconductor laser diode. From the multiplexer 6 to the CPU 9 such as controlling to perform comparison calculation with the set temperature data of the array 1.
A control unit 10 for controlling timing so that a series of flows relating to temperature data up to
A D / A converter 12 for converting a digital signal of data relating to the temperature correction command of the semiconductor laser diode array 1 output from the PU 9 into an analog signal, and the semiconductor laser receiving the analog-converted temperature correction command data It comprises a power supply device 13 for supplying power to the TEC 2 so that the temperature of the diode array 1 becomes a set temperature.

Next, the operation of this embodiment will be described.

Each of the plurality of semiconductor laser diode arrays 1 individually oscillates a laser beam for excitation having a specific wavelength, and irradiates the medium of the solid-state laser with the specific wavelength converged by a lens or the like. Therefore, the error in the wavelength of each semiconductor laser diode array 1 greatly affects the converged wavelength, and finally affects the output efficiency of the solid-state laser light oscillated from the solid-state laser medium. Therefore, in this embodiment, the temperature adjustment is controlled independently for each semiconductor laser diode array 1 to reduce the wavelength error.

That is, the analog signal of the temperature sensor output of each semiconductor laser diode array 1 measured by each temperature sensor 3 is amplified to a level that can be processed by the sensor output amplifier 4 and sequentially output to the multiplexer 6. Is temporarily suspended. Where A /
Since the D converter 5 can process only one analog signal at a time, the control unit 10 holds the next data signal in the multiplexer 6 until the digital conversion of the A / D converter 5 is completed. Then, the sample hold 11 is controlled to be closed. When the digital conversion is completed, the next analog signal is sent and the temperature sensor output after the digital conversion is sequentially written in one of the storage units of the dual port memory 7. Then, when writing to all of the one storage units is completed, a signal such as an interrupt signal is output from the control unit 10 to the CPU 9, and the temperature sensor output is written to the other storage unit. Switch to the same as above
The / D converter 5 continues to write the temperature sensor output.

Therefore, the CPU 9 will read from the side of the memory unit where the writing has already been completed, and the CPU 9 can process the temperature sensor output at a high speed independently of the writing of the A / D converter 5.

On the other hand, the CPU 9 compares and calculates the calibration temperature data in the ROM 8 corresponding to the temperature sensor output read from the dual port memory 7 and the set temperature data of each of the semiconductor laser diode arrays 1, and calculates these. A temperature correction command is output to the TEC 2 so that the temperature difference can be corrected to a temperature at which the excitation laser light having the optimum wavelength can be oscillated in the solid laser medium such as the YAG rod.
The temperature correction command is converted into an analog signal by the D / A converter 12 and output to the power supply device 13 that supplies power to the TEC 2. When electric power is supplied from the power supply device 13 to the TEC 2,
EC2 causes heat to be emitted from the semiconductor laser diode array 1 by the Peltier effect of the Peltier element,
Alternatively, it is absorbed and held at the set temperature.

According to such a configuration, the opening and closing of the sample hold 11 which is conventionally performed by the CPU,
Since the control unit 10 does not involve the CPU 9 by performing the digital conversion of the analog signal that consumes the most time, and the writing control to the dual port memory 7, etc., the CPU 9 does not control the temperature as shown in FIG. Calibration temperature data corresponding to the sensor output is read from the ROM 8 and the temperature and each semiconductor laser diode array 1 are read.
Since only the temperature data that is compared and calculated with the set temperature data in (1) is processed, the temperature of the semiconductor laser diode array 1 can be controlled at an extremely high speed.

Here, in FIG. 2, FIG. 3, FIG. 5 and FIG. 6, the work in which the CPU according to the present invention is involved and the conventional C
Compare timing charts for work involving a PU.

The letters in the figure correspond to the work contents of the CPU 9 shown in the flow charts of FIGS. 2 and 5, respectively. As shown in FIG. 3, since the work to be performed by the CPU 9 in the present invention can be limited to the calculation of the temperature correction amount and its output, the conventional CPU 9 shown in FIG.
It can be seen that the processing time can be markedly reduced as compared with the processing time when the D conversion is also controlled, and the entire control processing can be efficiently performed.

Further, since the dual port memory 7 has two storage sections, one storage section writes the analog-converted temperature sensor output, and the other storage section writes the C signal.
Since the PU 9 reads the temperature sensor output so that writing and reading can proceed at the same time, the CPU
9 can efficiently perform processing relating to temperature data.

Further, in order to deal with the problem that the allowable control temperature range of the semiconductor laser diode array 1 is narrow and even a slight temperature change is affected, a nonlinear function is conventionally used from the temperature sensor output measured by the temperature sensor. The calibration temperature data calculated by calculation is used as the ROM 8 as a comparison table of the temperature sensor output and the calibration temperature data.
The CPU 9 can read the calibration temperature data in a shorter time, and can instantly perform the comparison calculation between the actual calibration temperature data and the set temperature data.

The present invention is not limited to the above-mentioned embodiments, but can be modified as necessary.

[0028]

As described above, according to the temperature control system for a semiconductor laser of the present invention, the control section controls the digital conversion of the analog signal which requires the most processing time and does not involve the CPU. Therefore, the CPU reads only the calibration temperature data corresponding to the temperature sensor output read from the first memory from the second memory, and only performs the temperature data processing for comparing and calculating the calibration temperature data with the set temperature data of each semiconductor laser diode. Therefore, the temperature of the semiconductor laser can be quickly controlled, and the work can be efficiently processed.

The second memory has at least two storage units.
Therefore, the temperature data converted into analog data is written in one storage unit, and the temperature data is read by the CPU in the other storage unit so that writing and reading can proceed at the same time. Data can be processed.

Further, since the calibration temperature data corresponding to each temperature sensor output calculated by the non-linear function calculation is integrated in the ROM as the comparison table, the CPU can read the calibration temperature data in a shorter time, and the set temperature data can be read. It is possible to instantly perform a comparison operation with.

Therefore, the throughput of the temperature control system of the semiconductor laser can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a temperature control system for a semiconductor laser according to the present invention.

FIG. 2 is a flowchart of work involving a CPU according to an embodiment of the present invention.

FIG. 3 is a timing chart of work involving a CPU according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a conventional semiconductor laser temperature control system.

5 is a flowchart of the work involving the conventional CPU shown in FIG.

FIG. 6 is a timing chart of work involving the conventional CPU shown in FIG.

[Explanation of symbols]

 1 Semiconductor Laser Diode Array 2 TEC 3 Temperature Sensor 4 Sensor Output Amplifier 5 A / D Converter 6 Multiplexer 7 Dual Port Memory 8 ROM 9 CPU 10 Control Unit 11 Sample Hold 12 D / A Converter 13 Power Supply Device 17 Conventional RAM

Claims (2)

[Claims] 1. A plurality of semiconductor lasers for irradiating a medium of a solid-state laser with excitation laser light of a specific wavelength for excitation, and temperature controllers each of which is provided for adjusting the temperature. A temperature sensor which is arranged in each of the semiconductor lasers to measure the temperature, an A / D converter which converts an analog signal of the temperature sensor output measured by the temperature sensor into a digital signal, and an analog signal of the temperature sensor output Is temporarily output when output to the A / D converter and sequentially outputs analog signals after completion of digital conversion processing, and the temperature sensor output digitally converted by the A / D converter is written. A first memory having at least two storage units for storing, and a second memory storing calibration temperature data corresponding to the temperature sensor output,
Outputs a temperature correction command to the temperature controller so that the calibration temperature data in the second memory corresponding to the temperature sensor output written in the first memory and the set temperature data are compared and calculated to correct the error. A temperature control system for a semiconductor laser, comprising: a CPU for controlling the temperature of the output of the temperature sensor; 2. The temperature control system for a semiconductor laser according to claim 1, wherein the semiconductor laser is a semiconductor laser diode array.