JP2006005212A - Semiconductor laser device for excitation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manage an excitation current to ensure that excitation energy for a semiconductor laser for excitation is maintained in a stable manner while the safety of a solid-state laser medium is ensured. <P>SOLUTION: An LD current measurement value obtained at an LD current measurement circuit 38 is provided to an LD power source 34 for the control of current feedback and also provided to a control unit 28 for the management of an LD current set value. Furthermore, an LD output measurement value obtained at an LD output measurement part 42 is provided to a control unit 28 for the management (automatic update) of the LD current set value. The control unit 28 automatically updates the LD current-LD output characteristics and an LD current maximum permissible value of a fiber coupling LD32 based on the LD current measurement value from the LD current measurement circuit 38 and LD output measurement value from the LD output measurement part 42, and automatically updates the LD current set value so that the LD output set value is kept constant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device for optically exciting a solid laser medium.

Lasers are used in the manufacturing industry, particularly in the fields of welding, cutting and marking and other surface treatments. Currently, the YAG laser is the solid-state laser most frequently used for laser processing. A YAG laser is a solid-state laser that generates YAG laser light having a fundamental wavelength of about 1 μm by exciting a YAG (Y ₃ Al ₅ O ₁₂ ) crystal in an optical resonator, and is continuous wave, pulsed, or Q-switched Operates with giant pulse oscillation by.

  Conventionally, a semiconductor laser or a laser diode (LD) has been used to optically excite a YAG laser. As one of the LD excitation methods, the laser light of the laser diode (LD) is passed through an optical fiber and a YAG rod is used. There is known an end face excitation type optical fiber coupling method, that is, a fiber coupling method, which condenses and irradiates one end surface of the optical fiber.

  In a fiber coupling type LD-pumped YAG laser, if the power (LD output) of the pumping LD laser beam that is concentrated and irradiated on one end surface of the YAG rod is too high, the YAG rod may be damaged. For this reason, it is important to appropriately limit the excitation LD output or LD current.

  Conventionally, the maximum allowable value of the LD current corresponding to the maximum allowable value of the pumping LD output that does not damage the YAG rod in the pumping laser diode (LD) to be used (mounted) at the time of manufacturing or shipping the laser device. And the LD current was set within the range of the LD current maximum allowable value or less.

  Further, the conversion efficiency of the pumping laser diode (LD) decreases due to deterioration over time, and a specified LD output cannot be obtained at the end. The lifetime of the excitation laser diode (LD) varies depending on the use environment and individual differences. Conventionally, the LD is replaced when the pump laser diode (LD) has reached its end of life, or as a preventive measure, the user or maintenance personnel inspect the LD output at an appropriate time, and use time The remaining life or replacement time was judged by taking the above into consideration.

  In addition, the excitation laser diode (LD) generates a considerable amount of heat during laser oscillation, and easily deteriorates due to thermal stress when the temperature is higher than a predetermined temperature. For this reason, a cooling mechanism for cooling or adjusting the temperature of the excitation laser diode (LD) to a constant temperature is used. Typically, the heat generated by the pumping laser diode (LD) is transferred to a radiator through, for example, a Peltier element, and the cooling fan wind is applied to the radiator to release heat from the radiator to the atmosphere. ing.

  The conventional pumping semiconductor laser device used for the above-described fiber coupling type LD pumped YAG laser has the following points to be improved.

  That is, in the LD-pumped YAG laser, it is necessary to increase the LD current set value for obtaining a desired YAG laser output in accordance with the degree of deterioration of the pumping laser diode (LD) with time. However, in order to protect the YAG laser, it is necessary to limit the set value of the LD current to be equal to or less than the maximum LD current allowable value. Conventionally, when the set value of the LD current approaches the maximum LD current allowable value (limit value) determined at the manufacturing stage or at the time of shipment, data of LD current-LD output characteristics is collected by manual inspection, and YAG The maximum allowable value of the LD current corresponding to the maximum allowable value of the excitation LD output that does not damage the rod is re-determined and updated. However, such a manual updating method not only requires a lot of time to collect characteristic data, but also may cause an input error when resetting (inputting) the maximum LD current allowable value. There were many accidents that caused damage to the YAG rod due to an input error of the allowable value.

  Conventionally, the function of monitoring the remaining life of the excitation laser diode (LD) has not been provided in the apparatus. For this reason, as described above, as the LD current maximum allowable value that can guarantee the safety of the YAG laser is reset many times and the set value of the LD current is increased, the life of the pumping laser diode (LD) is increased. It was suddenly exhausted, and the excitation energy suddenly decreased and the YAG laser output accompanying the sudden change decreased. This sometimes deteriorated the quality of laser processing and lowered the operating rate of the apparatus. In addition, there is a problem that the method in which a person inspects the LD output to determine the timing of LD replacement is difficult to manage, takes time and labor, and is easy to pass.

  Conventionally, when the excitation laser diode (LD) is turned off, the operation of the cooling unit is also stopped at the same time or immediately after that, which contributes to shortening the life of the excitation laser diode (LD). It was. That is, if the pumping laser diode (LD) and the cooling unit are stopped almost simultaneously, the heat of the cooling unit moves (backflows) to the pumping laser diode (LD), and the pumping laser diode (LD) is heated. LD temperature rises. As a result, the LD temperature exceeds a predetermined threshold value, which causes the pumping laser diode (LD) to deteriorate. A general laser diode (LD) is vulnerable to thermal stress, and the LD temperature does not change very rapidly. Conventionally, since LD temperature management is not performed accurately after the LD is extinguished, temperature stress is applied to the excitation laser diode (LD) to shorten its life.

  The present invention has been made in view of the above-described problems of the prior art, and has a function of managing the excitation current so as to stably maintain the excitation energy of the excitation semiconductor laser while ensuring the safety of the solid-state laser medium. It is an object of the present invention to provide a pumping semiconductor laser device comprising:

  Another object of the present invention is to provide a pumping semiconductor laser device having a function of monitoring the time or remaining life of a pumping semiconductor laser.

  Another object of the present invention is to provide a pumping semiconductor laser device that extends the life of the pumping semiconductor laser without applying temperature stress to the pumping semiconductor laser after it is turned off.

  In order to achieve the above object, a first pumping semiconductor laser device of the present invention generates a pumping semiconductor laser optically coupled to a solid-state laser medium and pumping laser light to the semiconductor laser. A laser power supply for supplying an excitation current for excitation, an excitation current measuring unit for measuring a current value of the excitation current, and an excitation laser output for measuring a laser output of the excitation laser light generated from the semiconductor laser A measurement unit; a pumping laser output maximum allowable value setting unit for setting a maximum allowable value of the laser output of the pumping laser light for the solid laser medium; a maximum allowable value and a measured value of the pumping laser output; and the pumping An excitation current maximum allowable value updating unit that updates the maximum allowable value of the excitation current for the semiconductor laser based on the measured current value.

  In the above configuration, the excitation current supplied to the pumping semiconductor laser and the laser output of the pumping laser light generated from the semiconductor laser are measured or monitored, so that pumping is performed according to the deterioration of the semiconductor laser over time. The change in the current-utilized laser output characteristic is tracked or grasped, and the maximum allowable value of the excitation current is automatically updated. Thereby, while ensuring the safety of the solid-state laser medium, it is possible to maintain the excitation energy stably by managing the excitation current to an optimum value, and to improve the reliability of the solid-state laser output.

  According to a preferred aspect of the present invention, an excitation laser output setting unit that sets a desired value smaller than the maximum allowable value of the excitation laser output for the laser output of the excitation laser light, and the excitation laser output for the excitation current are set. An excitation current set value calculation unit for obtaining a current set value corresponding to the set value is provided. In such a configuration, the excitation current set value for obtaining a desired excitation laser output is automatically updated in accordance with the change in the excitation current-excitation laser output characteristic.

  According to another preferred embodiment, the display unit that displays the maximum allowable value of the excitation current and the input unit that inputs a desired current set value within the range of the excitation current maximum allowable value or less for the excitation current Provided. In such a configuration, the current maximum allowable excitation current value is notified to the user from the apparatus side, and a desired excitation current that does not exceed the maximum allowable excitation current value is set and input from the user side to the apparatus.

  As a preferred aspect, the laser power supply unit controls the excitation current supplied to the excitation semiconductor laser by a constant current feedback control method so that the current measurement value obtained from the excitation current measurement unit matches the current setting value. To do.

  The second pumping semiconductor laser device of the present invention is a pumping semiconductor laser optically coupled to a solid-state laser medium and pumping for setting a desired laser output for the laser light generated from the pumping laser light. A laser power setting unit for supplying a pumping current to the semiconductor laser at a current value corresponding to a set value of the pumping laser output, and a maximum limit value of the pumping current according to the lifetime of the semiconductor laser An excitation current maximum limit value setting unit that sets the remaining lifetime of the semiconductor laser based on a difference between a current value of the excitation current supplied to the semiconductor laser from the laser power supply unit and the maximum excitation current limit value. And a remaining life determination unit for determination.

  In the above configuration, the process of changing (increasing) the current value of the excitation current according to the deterioration of the pumping semiconductor laser with time is monitored, and when the monitoring value reaches a monitoring value lower than the maximum excitation current limit value by a predetermined value. An alarm can be given to the effect that the service life is approaching.

  According to a third aspect of the present invention, there is provided a pumping semiconductor laser optically coupled to a solid-state laser medium and a pumping current for causing the semiconductor laser to generate pumping laser light. A laser power supply unit that supplies a current value of the laser, a laser output measurement unit that measures a laser output of the excitation laser beam generated from the semiconductor laser, and a minimum of the excitation laser output according to the lifetime of the semiconductor laser An excitation laser output minimum limit value setting unit for setting a limit value; and the semiconductor laser based on a difference between the measured value of the excitation laser output obtained from the laser output measurement unit and the minimum excitation laser output limit value. A remaining life determination unit for determining the remaining life of

  In the above configuration, the process in which the laser output changes (decreases) in accordance with the time-dependent deterioration of the pumping semiconductor laser is monitored, and when a monitoring value that is higher than the minimum limit value of the pumping laser output by a predetermined value is reached. An alarm can be given to the effect that the service life is approaching.

  A fourth pumping semiconductor laser device of the present invention supplies a pumping semiconductor laser optically coupled to a solid-state laser medium and a pumping current for causing the semiconductor laser to generate pumping laser light. The semiconductor power supply unit, a first temperature measuring unit for measuring the temperature of the semiconductor laser, and the semiconductor laser temperature measurement value obtained from the first temperature detecting unit maintained at a set temperature. A cooling unit for cooling the laser; a second temperature measuring unit for measuring the temperature of the cooling unit; and turning off the laser power supply unit to stop laser oscillation of the semiconductor laser, and then performing the second temperature detection. An operation control unit that monitors the temperature of the cooling unit based on a temperature measurement value obtained from the unit, and stops the operation of the cooling unit after the temperature of the cooling unit has decreased to a predetermined value.

  In the above configuration, the operation of the cooling unit continues even if the laser power supply unit is turned off and the laser oscillation of the semiconductor laser is stopped. As a result, the temperature of the cooling unit decreases with time while the temperature of the semiconductor laser is maintained at the set temperature. Then, the operation of the cooling unit is stopped after the temperature of the cooling unit drops to a predetermined value, whereby the semiconductor laser is held near the set temperature and is not subjected to thermal stress.

  According to a preferred aspect of the present invention, the operation control unit stops the operation of the cooling unit when the temperature of the cooling unit substantially matches the temperature of the semiconductor laser.

  As another preferred embodiment, the operation control unit may compare the temperature of the cooling unit and the temperature of the semiconductor laser, and stop the operation of the cooling unit when the difference between the two decreases to a predetermined value or less. Alternatively, the operation control unit may stop the operation of the cooling unit when the temperature of the cooling unit divides the predetermined reference value.

  According to a preferred aspect of the present invention, the cooling unit includes an electronic cooler coupled to the semiconductor laser and a heat dissipation unit connected to the electronic cooler. The electronic cooler is composed of, for example, a Peltier element, and transfers heat generated by the semiconductor laser to the heat radiating portion. The heat radiating section preferably has a heat radiator made of a heat radiating member and a cooling fan that applies air to the heat radiator, and radiates heat received from the semiconductor laser through the electronic cooler to the atmosphere. discharge. The second temperature measurement unit may detect the temperature of the radiator.

  According to a preferred aspect of the present invention, the excitation laser beam is condensed and irradiated onto one end surface of the solid-state laser medium. Typically, a semiconductor laser is optically coupled to a solid state laser medium via an optical fiber. In this case, the first optical lens is disposed between the semiconductor laser and the one end surface of the optical fiber, and the second optical lens is disposed between the other end surface of the fiber and the one end surface of the solid-state laser medium, The pumping laser light from the semiconductor laser is incident on one end surface of the optical fiber through the first optical lens, propagates through the optical fiber, and exits from the other end surface of the optical fiber before the second optical lens. Through one end of the solid-state laser medium.

  According to the pumping semiconductor laser device of the present invention, with the configuration and operation as described above, the pumping current is managed so as to stably maintain the pumping energy of the pumping semiconductor laser while ensuring the safety of the solid-state laser medium. Can do. It is also possible to properly monitor the time or remaining life of the pumping semiconductor laser, and extend the life of the pumping semiconductor laser without applying temperature stress to the pumping semiconductor laser after it is turned off. it can.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a configuration of an LD-pumped YAG laser device for laser processing according to an embodiment of the present invention. This LD-excited solid-state laser device has a Q-switch type YAG laser oscillation unit 10 and an electro-optical excitation unit 12 for optically exciting a YAG rod 18 in the YAG laser oscillation unit 10. Here, the pumping semiconductor laser device of the present invention is applied to the electro-optic pumping unit 12.

  The YAG laser oscillating unit 10 is formed by arranging a YAG rod 18 and a Q switch 20 on a straight line between a pair of resonator mirrors 14 and 16 arranged to face each other in parallel. On one end face 18a of the YAG rod 18, a fiber coupling LD (laser diode) 32 of the electro-optical excitation unit 14 to be described later is optically connected via the optical fiber 22, the collimating lens 24, the condensing lens 26, and the resonator mirror 14. Is bound to. The resonator mirror 14 is coated with a reflection film for totally reflecting light having the oscillation wavelength of the YAG laser, and with a transmission film or an antireflection film for transmitting the excitation laser beam EB. Yes.

  The YAG rod 18 is optically pumped by end face excitation as described above, and generates a YAG fundamental wave (for example, 1064 nm) light with a continuous wave (cw). The YAG fundamental wave light is confined between the resonator mirrors 14 and 16 and amplified. The Q switch 20 is composed of, for example, an acousto-optic Q switch. The control unit 28 drives the Q switch 20 by a high-frequency electric signal that is temporarily interrupted at a predetermined cycle via the Q switch driver 30. By this Q switch operation, every time a high-frequency electrical signal is interrupted in the optical resonator, a laser beam LB having a very high peak power is generated and output from the output mirror 16. The giant pulse YAG laser beam LB is applied to a workpiece (not shown) through an appropriate optical system (not shown).

The electro-optic exciting unit 12 includes a fiber coupling LD 32, and a LD power source 34 for supplying pumping current clogging LD current I _L to the fiber coupling LD 32. The fiber coupling LD 32 performs a laser oscillation operation by recombination of electrons and holes with the LD current I _L from the LD power source 34, and generates excitation laser light EB in the vicinity of, for example, 800 nm. The excitation laser beam EB generated by the fiber coupling LD 32 is incident on one end surface of the optical fiber 22 through an optical lens (not shown). The LD power source 34 controls the LD current I _L by a current feedback control method so as to coincide with the LD current set value (command value) I _S given from the control unit 28. The excitation laser beam EB incident on one end surface of the optical fiber 22 propagates through the optical fiber 22 and exits radially from the other end surface, and is converted into parallel light by the collimator lens 24 before being collected by the condenser lens 26. The condensed light passes through the resonator mirror 14 and is incident on one end surface 18 a of the YAG rod 18 to give excitation energy to the YAG rod 18.

In the electro-optical excitation unit 12, a current sensor 36 for detecting the LD current I _L, and the LD current measurement circuit 38 for determining the measured value of LD current I _L output signal based on the current sensor 36 is provided. The LD current measurement value obtained by the LD current measurement circuit 38 is given to the LD power source 34 for current feedback control and also to the control unit 28 for management (automatic update) of the LD current set value.

Further, the electro-optical excitation unit 12 includes a mirror 40 and an LD output measurement unit 42 for monitoring the power (LD output) of the excitation laser beam EB generated by the fiber coupling LD 32. The mirror 40 reflects a part (for example, 1%) of the excitation laser beam EB before the incident end face of the optical fiber 22. The LD output measurement unit 42 has a photoelectric conversion element and a measurement circuit, receives the reflected light _MEB from the mirror 40 and converts it into an electrical signal, and measures the power (LD output) of the laser beam EB by signal processing. Find the value. The LD output measurement value obtained by the LD output measurement unit 42 is sent to the control unit 28 for management (automatic update) of the LD current set value.

  The control unit 28 may be constituted by a microcomputer, and controls the entire apparatus or each unit, and performs data processing such as calculation, setting, and updating. The operation panel 44 has an input unit and a display unit, and functions as a man-machine interface between the control unit 28 and a human.

In this LD-excited solid-state laser device, the excitation laser beam EB generated by the electro-optic excitation unit 12 as described above is applied to the one end face 18a of the YAG rod 18 by a fiber coupling method in a concentrated manner. It is necessary to limit the power (LD output) of the excitation laser beam EB so as not to damage it. In this embodiment, the control unit 28 uses the LD current measurement value provided from the LD current measurement circuit 38 and the LD output measurement value provided from the LD output measurement unit 42 to determine the LD current-LD of the fiber coupling LD 32. The output characteristics and the LD current maximum allowable value I _max are automatically updated, and the LD current set value Is is automatically updated so that the LD output set value Ps is maintained constant in the constant LD output mode.

Here, the automatic update function of the control unit 28 will be described with reference to FIG. 2, the straight line L _a having the maximum slope is LD current -LD output characteristics of the fiber coupling LD32 immediately after shipment or maintenance. P _max is a maximum allowable value (constant value) of the LD output that does not damage the YAG rod 18 of the YAG laser oscillation unit 10. I _maxa is the initial value of the LD current maximum allowable value I _max, corresponds to P _max on the LD current -LD output characteristics L _a.

In the constant LD output mode, the control unit 28 variably controls the LD current set value (command value) Is for the LD power source 34 so that the LD output measured value from the LD output measuring unit 38 is maintained at the set value Ps. Automatically update and automatically update the LD current-LD output characteristics using linear interpolation or the like. Normally, as the fiber coupling LD 32 deteriorates with time, the slope of the LD current-LD output characteristic decreases as L _a → L _b → L _c, and the LD current set value Is corresponding to the LD output set value Ps is I _a → It gradually increases as I _b → I _c . On the other hand, the control unit 28 automatically updates the LD current maximum allowable value I _max corresponding to the LD output maximum allowable value P _max every time the LD current-LD output characteristic is updated as I _maxa → I _maxb → I _maxc. At each time point, it is confirmed that the LD current set value Is is equal to or less than the LD current maximum allowable value I _max .

  With the automatic update function in the control unit 28 as described above, the electro-optic excitation unit 12 can always supply a constant excitation energy to the YAG laser oscillation unit 10 regardless of the deterioration of the fiber coupling LD 32 over time. As a result, this LD-pumped YAG laser device eliminates the need for manual inspection or resetting that is complicated and prone to input errors, maintains the output of the YAG laser beam LB constantly, and provides constant quality laser processing characteristics. Obtainable.

Note that the LD output set value Ps can be arbitrarily changed as necessary or in the variable LD output mode. Also in this case, the control unit 28 confirms that the LD current set value Is corresponding to the changed LD output set value Ps is equal to or less than the LD current maximum allowable value I _max . Further, a function of automatically updating only the LD current-LD output characteristic and the LD current maximum allowable value I _max is provided. For example, as shown in FIG. 3, the LD current maximum allowable value I _max automatically updated by the control unit 28 (shown in the figure). In the example, 36.0 A) is displayed on the operation panel 44 and the user can input a desired LD current set value Is (28.0 A in the illustrated example).

Next, the second feature in this embodiment will be described. In the automatic update function as described above, the LD current for obtaining a constant LD output set value Ps increases as the cumulative operating time of the fiber coupling LD 32 increases. As described above, even if the LD current increases, there is no possibility of damaging the YAG rod 18 of the YAG laser oscillation unit 10 as long as the LD current is maximum allowable value I _max or less. However, there is a permissible limit or lifetime for the deterioration of the fiber coupling LD 32 over time, and if the automatic update of the LD current set value Is is continued, the lifetime of the fiber coupling LD 32 will eventually expire, and the desired LD output Ps Cannot be maintained.

In this embodiment, as shown in FIG. 4, the control unit 28 causes the LD current maximum limit value I _e corresponding to the life of the fiber coupling LD 32 and a monitoring value lower than the maximum limit value I _e by a predetermined value ΔI. I _b is set, the set value Is or the measured value of the LD current is monitored, and an alarm is output to notify that the life is near when the monitored value I _b is exceeded (t _b ). Further, when the maximum limit value I _e is reached, it is notified that the life has reached at that time (t _e ). Such an alarm or notification is performed through the operation panel 44.

  In this way, the device monitors the remaining life of the LD fiber coupling LD32 and outputs the monitoring result in a timely manner, so that the user knows when to replace the LD in advance and does not affect the operation status of the device or the laser processing operation. The LD can be exchanged in a timely manner.

When the LD current is made constant, the LD output decreases as the cumulative operating time of the fiber coupling LD 32 increases as shown in FIG. In this case, the set value or measured value of the LD output is monitored, an alarm is output to notify that the life is near when the predetermined monitored value P _b is exceeded (t _b ), and the limit value _Pe is reached. it may be so when you will notice that the life has come at that point in time (t _e).

  FIG. 6 shows a configuration of the electro-optical excitation unit 12 in another embodiment. In the figure, parts having the same configurations or functions as those in FIG.

  In this embodiment, the cooling unit for cooling or adjusting the temperature of the fiber coupling LD 32 to a constant temperature is composed of, for example, an electronic cooler 50 made of a Peltier element and a radiator 54 with a cooling fan 52. The electronic cooler 50 is provided thermally coupled to the fiber coupling LD 32 and moves the heat generated from the fiber coupling LD 32 toward the radiator 54 at a variable controllable rate. The electronic cooler power source 56 drives and controls the electronic cooler 50 under the control of the control unit 28. The radiator 54 is composed of, for example, a heat radiating member having heat radiating fins, and the heat received from the fiber coupling LD 32 via the electronic cooler 50 is released into the atmosphere by receiving the wind from the air cooling fan 52 on the heat radiating fins. To do. The cooling fan power supply 58 drives and controls the cooling fan 52 under the control of the control unit 28.

The temperature of the fiber coupling LD 32 is measured by the temperature sensor 60. While the fiber coupling LD 32 is turned on, that is, during the laser oscillation operation, the control unit 28 receives the LD temperature measurement value from the temperature sensor 60 and performs electronic cooling so that the LD temperature measurement value matches the set temperature T _s. The operation of the electronic cooler 50 and the cooling fan 52 is controlled through the cooler power supply 56 and the cooling fan power supply 58. In this embodiment, a temperature sensor 62 for measuring the temperature of the radiator 54 is also provided. As will be described below, the control unit 28 receives the measured value of the radiator temperature from the temperature sensor 62 after turning off the fiber coupling LD 32, and operates the LD cooling unit after the radiator temperature falls to a predetermined level. It is supposed to stop.

FIG. 7 shows the operation control of the LD cooling unit in this embodiment. As described above, while the fiber coupling LD 32 is lit, the temperature (LD temperature) of the fiber coupling LD 32 is set to the set value T _s by the cooling operation of the LD cooling unit (the electronic cooler 50 and the cooling fan 52). Maintained. The radiator 54 heat generated by the fiber coupling LD32 is sent through the cooler 50, the temperature of the radiator 54 is higher than the LD temperature, further to a temperature higher than the predetermined LD upper limit temperature T _Q Maintained. Here, the LD upper limit temperature T _Q is a threshold temperature at which thermal stress occurs in the fiber coupling LD 32 when the LD temperature exceeds this.

When the fiber coupling LD 32 is extinguished, that is, when the LD power source 34 is stopped, the control unit 28 continues the operation of the LD cooling unit and continues the temperature of the radiator 54 via the temperature sensor 62. To monitor. As shown in FIG. 7, after the LD is extinguished, heat is not generated in the fiber coupling LD 32, and therefore, heat transfer or inflow from the fiber coupling LD 32 to the radiator 54 is reduced, and heat input in the radiator 54 is reduced. The balance of heat dissipation is lost (heat dissipation is greater than heat input), and the temperature of the radiator 54 decreases monotonously. On the other hand, the fiber coupling LD32 is to receive continuously the temperature control by the LD cooling unit, LD temperature is maintained at the same temperature T _s to the previous LD off. As a result, the radiator temperature divides the LD upper limit temperature T _Q and eventually falls to the LD temperature (T _s ). When the temperature of the radiator 54 falls to the LD temperature (T _s ), the control unit 54 stops the operation of the LD cooling unit at this point. After this, the LD temperature and the radiator temperature gradually change toward the ambient temperature. Usually, the ambient temperature is set to the LD upper limit temperature _TQ or less, so there is no problem.

According to the operation control of the LD cooling unit as described above, not to LD temperature after LD off exceeds the LD upper limit temperature T _Q, and hence there is no need to provide the thermal stress to the fiber coupling LD 32.

Although it is possible to stop the operation of the LD cooling section when the radiator temperature divides the LD upper limit temperature T _Q , the LD temperature may rise and exceed the LD upper limit temperature T _Q depending on the residual heat. is there. Therefore, it is most desirable to stop the operation of the LD cooling unit at the time when the radiator temperature reaches the LD temperature or around that time.

FIG. 8 shows, as a reference example, changes in LD temperature and radiator temperature (time characteristics) when the operation of the LD cooling unit is stopped simultaneously with the extinction of LD (that is, in the prior art). In this case, when the operation of the LD cooling unit stops, the heat of the radiator 54 moves (backflows) to the fiber coupling LD 32 via the electronic cooler 50 rather than being released into the atmosphere, and the LD temperature rapidly increases. It rises and exceeds the LD upper limit temperature T _Q. As a result, the fiber coupling LD 32 is subjected to thermal stress and accelerates deterioration.

  The present invention has been described based on the preferred embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical idea. Various modifications can be made to the configuration within 12 or the configuration of each part. Further, the configuration of each part in the YAG laser oscillation unit 10 can be variously modified, and a solid-state laser other than the YAG laser is also possible. The present invention is also applicable to a pumping semiconductor laser device that is different from the fiber coupling method.

It is a block diagram which shows the structure of the LD excitation YAG laser apparatus for laser processing by one Embodiment of this invention. It is a figure for demonstrating the automatic update function in embodiment. It is a figure which shows an example of the display screen in embodiment. It is a figure for demonstrating the effect | action of the LD lifetime monitoring function in embodiment. It is a figure for demonstrating the effect | action of the LD lifetime monitoring function in embodiment. It is a block diagram which shows the structure of the electro-optical excitation part in another embodiment of this invention. It is a figure for demonstrating the operation control of the LD cooling part in embodiment. It is a figure for demonstrating the operation control of the conventional LD cooling part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 YAG laser oscillation part 12 Electro-optical excitation part 18 YAG rod 22 Optical fiber 28 Control part 32 Fiber coupling LD
34 LD power supply 36 Current sensor 38 LD current measurement circuit 40 Mirror 42 LD output measurement unit 44 Operation panel 50 Electronic cooler 52 Cooling fan 54 Radiator 60, 62 Temperature sensor

Claims (20)

A pumping semiconductor laser optically coupled to a solid state laser medium;
A laser power supply for supplying an excitation current for generating laser light for excitation in the semiconductor laser;
An excitation current measuring unit for measuring a current value of the excitation current;
An excitation laser output measuring unit for measuring a laser output of the excitation laser light generated from the semiconductor laser;
An excitation laser output maximum allowable value setting unit for setting a maximum allowable value of the laser output of the excitation laser light for the solid-state laser medium;
An excitation semiconductor laser device comprising: an update unit that updates a maximum allowable value of the excitation current for the semiconductor laser based on a maximum allowable value and a measured value of the excitation laser output and a measured value of the excitation current. An excitation laser output setting unit for setting a desired value smaller than the maximum allowable value of the excitation laser output for the laser output of the excitation laser light;
The pumping semiconductor laser device according to claim 1, further comprising: a pumping current set value calculation unit that obtains a current setting value corresponding to a set value of the pumping laser output for the pumping current. A display unit for displaying the maximum allowable value of the excitation current;
2. The pumping semiconductor laser device according to claim 1, further comprising: an input unit that inputs a desired current set value within a range of the pumping current within a maximum allowable value of the pumping current.   The laser power source unit controls the excitation current supplied to the semiconductor laser by a constant current feedback control method so that a current measurement value obtained from the excitation current measurement unit matches the current setting value. The semiconductor laser device for excitation according to claim 3. A pumping semiconductor laser optically coupled to a solid state laser medium;
An excitation laser output setting unit for setting a desired laser output for the laser light generated from the excitation laser light;
A laser power supply for supplying the semiconductor laser with an excitation current at a current value corresponding to a set value of the excitation laser output;
An excitation current maximum limit value setting unit for setting a maximum limit value of the excitation current according to the lifetime of the semiconductor laser;
A pumping semiconductor laser comprising: a lifetime determining unit that determines a remaining lifetime of the semiconductor laser based on a difference between a current value of the pumping current supplied from the laser power supply unit to the semiconductor laser and a maximum limit value of the pumping current apparatus.   The pumping semiconductor laser device according to claim 5, wherein the life determination unit outputs an alarm when the difference divides a predetermined value. A pumping semiconductor laser optically coupled to a solid state laser medium;
A laser power supply for supplying an excitation current for generating a laser beam for excitation in the semiconductor laser at a desired current value;
A laser output measuring unit for measuring a laser output of the excitation laser beam generated from the semiconductor laser;
An excitation laser output minimum limit value setting unit for setting a minimum limit value of the excitation laser output according to the lifetime of the semiconductor laser;
A pumping semiconductor comprising: a remaining lifetime determining unit that determines a remaining lifetime of the semiconductor laser based on a difference between the measured value of the pumping laser output obtained from the laser output measuring unit and the minimum limit value of the pumping laser output Laser device. A pumping semiconductor laser optically coupled to a solid state laser medium;
A laser power supply for supplying an excitation current for generating laser light for excitation in the semiconductor laser;
A first temperature measurement unit for measuring the temperature of the semiconductor laser;
A cooling unit that cools the semiconductor laser so that the measured value of the semiconductor laser temperature obtained from the first temperature detection unit is maintained at a set temperature;
A second temperature measuring unit for measuring the temperature of the cooling unit;
After the laser power supply unit is turned off to stop laser oscillation of the semiconductor laser, the temperature of the cooling unit is monitored based on a temperature measurement value obtained from the second temperature detection unit, and the temperature of the cooling unit is monitored. An excitation semiconductor laser device comprising: an operation control unit that stops the operation of the cooling unit after the temperature drops to a predetermined value.   The pumping semiconductor laser device according to claim 8, wherein the control unit stops the operation of the cooling unit when the temperature of the cooling unit substantially matches the temperature of the semiconductor laser.   9. The pumping semiconductor according to claim 8, wherein the operation control unit compares the temperature of the cooling unit with the temperature of the semiconductor laser, and stops the operation of the cooling unit when the difference between the two decreases to a predetermined value or less. Laser device.   The pumping semiconductor laser device according to claim 8, wherein the operation control unit stops the operation of the cooling unit when the temperature of the cooling unit divides a predetermined reference value. The cooling unit is
An electronic cooler coupled to the semiconductor laser;
The pumping semiconductor laser device according to any one of claims 8 to 11, further comprising: a heat dissipation unit connected to the electronic cooler.   The pumping semiconductor laser device according to claim 12, wherein the electronic cooler includes a Peltier element.   The semiconductor laser device for excitation according to claim 12 or 13, wherein the heat radiating section includes a heat radiator made of a heat radiating member and a cooling fan that applies air to the heat radiator.   The pumping semiconductor laser device according to claim 14, wherein the second temperature measurement unit detects the temperature of the radiator. A pumping semiconductor laser optically coupled to a solid state laser medium;
An excitation laser output setting unit for setting a desired laser output for the laser light generated from the excitation laser light;
A laser power supply for supplying the semiconductor laser with an excitation current at a current value corresponding to a set value of the excitation laser output;
An excitation current measuring unit for measuring a current value of the excitation current;
An excitation laser output measuring unit for measuring a laser output of the excitation laser light generated from the semiconductor laser;
An excitation laser output maximum allowable value setting unit for setting a maximum allowable value of the laser output of the excitation laser light for the solid-state laser medium;
An update unit for updating the maximum allowable value of the excitation current for the semiconductor laser based on the maximum allowable value and measured value of the excitation laser output and the measured value of the excitation current;
An excitation current maximum limit value setting unit for setting a maximum limit value of the excitation current according to the lifetime of the semiconductor laser;
A pumping semiconductor laser comprising: a lifetime determining unit that determines a remaining lifetime of the semiconductor laser based on a difference between a current value of the pumping current supplied from the laser power supply unit to the semiconductor laser and a maximum limit value of the pumping current apparatus. A pumping semiconductor laser optically coupled to a solid state laser medium;
A laser power supply for supplying an excitation current for generating laser light for excitation in the semiconductor laser;
An excitation current measuring unit for measuring a current value of the excitation current;
An excitation laser output measuring unit for measuring a laser output of the excitation laser light generated from the semiconductor laser;
An excitation laser output maximum allowable value setting unit for setting a maximum allowable value of the laser output of the excitation laser light for the solid-state laser medium;
An update unit for updating the maximum allowable value of the excitation current for the semiconductor laser based on the maximum allowable value and measured value of the excitation laser output and the measured value of the excitation current;
A first temperature measurement unit for measuring the temperature of the semiconductor laser;
A cooling unit that cools the semiconductor laser so that the measured value of the semiconductor laser temperature obtained from the first temperature detection unit is maintained at a set temperature;
A second temperature measuring unit for measuring the temperature of the cooling unit;
After the laser power supply unit is turned off to stop laser oscillation of the semiconductor laser, the temperature of the cooling unit is monitored based on a temperature measurement value obtained from the second temperature detection unit, and the temperature of the cooling unit is monitored. An excitation semiconductor laser device comprising: an operation control unit that stops the operation of the cooling unit after the temperature drops to a predetermined value.   The pumping semiconductor laser device according to any one of claims 1 to 17, wherein the pumping laser beam is focused and irradiated on one end surface of the solid-state laser medium.   The semiconductor laser device for excitation according to any one of claims 1 to 18, wherein the semiconductor laser is optically coupled to the solid-state laser medium via an optical fiber. A first optical lens is disposed between the semiconductor laser and one end surface of the optical fiber, and a second optical lens is disposed between the other end surface of the fiber and one end surface of the solid-state laser medium. ,
The excitation laser light from the semiconductor laser is incident on one end surface of the optical fiber through the first optical lens, propagates in the optical fiber, and exits from the other end surface of the optical fiber. The pumping semiconductor laser device according to claim 19, which enters the one end surface of the solid-state laser medium through the second optical lens.

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