JP2012068352A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ophthalmological medical equipment and laser beam equipment which are highly reliable by preventing breakage of a wavelength conversion section during laser emission.SOLUTION: A light source device comprises: a fundamental wave laser light source 101 which outputs a fundamental wave 106; a wavelength conversion section 110 which receives the fundamental wave 106 from the fundamental wave laser light source 101 and outputs a higher harmonic 111; a temperature setting section 115 which heats and cools the wavelength conversion section 110; a temperature control section 400 which controls the temperature setting section 115; and a laser source control section 300 which controls the fundamental wave laser light source 101 so that the output of the higher harmonic 111 from the wavelength conversion section 110 becomes a target value. A light amount limiting section 700 for limiting a light emitting amount of the fundamental wave 106 from the fundamental wave laser light source 101 changes the maximum light emitting amount of the fundamental wave from the fundamental wave laser light source 101 in accordance with a temperature control direction of the temperature control section 400.

Description

  The present invention relates to a light source device including, for example, a wavelength conversion element for converting a wavelength of a fundamental wave, which is light of a fundamental wavelength, by a nonlinear optical effect and outputting a harmonic.

A conventional light source device has the following configuration.
That is, a fundamental wave laser light source that outputs a fundamental wave, a wavelength conversion unit that receives a fundamental wave from the fundamental wave laser light source and outputs a harmonic, a temperature setting unit that heats and cools the wavelength conversion unit, A temperature control unit that controls a temperature setting unit; and a laser light source control unit that controls the fundamental laser light source so that a harmonic output from the wavelength conversion unit becomes a target value. Is a configuration in which the temperature of the temperature setting unit is changed, the temperature at which the output of the harmonics output from the wavelength conversion unit becomes maximum is detected from the temperature measurement unit, and the temperature is set as the phase matching temperature. (For example, see Patent Document 1).

JP 2007-233039 A

The problem in the conventional example is that the reliability of the light source device is lowered.
That is, in the prior art, it is necessary to learn the phase matching temperature in order to appropriately set the conversion efficiency of the wavelength conversion unit that is the wavelength conversion element, but the output of the wavelength conversion unit is extremely high when performing this learning. This causes a phenomenon in which the reliability of the apparatus is reduced. As a result of earnest examination of this cause, the inventor has found that this cause lies in learning of the phase matching temperature.

Specifically, in this learning, with the fundamental wave input to the wavelength conversion unit, the temperature of the temperature setting unit is changed from the low temperature side to the high temperature side, and the temperature at which the harmonic output of the wavelength conversion unit is maximized is searched. Alternatively, the temperature of the temperature setting unit was changed from the high temperature side to the low temperature side to search for the temperature at which the harmonic output of the wavelength conversion unit was maximum, but the temperature was shifted from the high temperature side to the low temperature side near the phase matching temperature. In doing so, the phenomenon that the output of the wavelength conversion unit suddenly and extremely increases and the wavelength conversion unit is damaged was found.
As a result, the reliability of the light source device is reduced.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to prevent damage to a wavelength conversion unit used inside a light source device and improve the reliability of the light source device.

  In order to achieve this object, the present invention includes a fundamental laser source that outputs a fundamental wave, a wavelength converter that inputs a fundamental wave from the fundamental laser source and outputs a harmonic, and the wavelength converter. A temperature setting unit that heats and cools the temperature control unit, a temperature control unit that controls the temperature setting unit, and a laser light source control that controls the fundamental laser light source so that the harmonic output from the wavelength conversion unit becomes a target value And a light amount limiting unit that limits a light emission amount of the fundamental wave from the fundamental wave laser light source, and switches a maximum light emission amount of the fundamental wave from the fundamental wave laser light source according to a temperature control direction of the temperature control unit. It is a composition, which achieves the intended purpose.

  As described above, the present invention provides a fundamental wave laser light source that outputs a fundamental wave, a wavelength conversion unit that inputs a fundamental wave from the fundamental wave laser light source and outputs a harmonic, and heats and cools the wavelength conversion unit. A temperature setting unit, a temperature control unit that controls the temperature setting unit, and a laser light source control unit that controls the fundamental laser light source so that the harmonic output from the wavelength conversion unit becomes a target value, The light quantity limiting unit that limits the emission amount of the fundamental wave from the fundamental laser light source is configured to switch the maximum emission amount of the fundamental wave from the fundamental laser light source according to the temperature control direction of the temperature control unit. Therefore, it is possible to prevent the wavelength conversion unit used inside the light source device from being damaged.

  That is, in the present invention, the light quantity limiting unit that limits the light emission amount of the fundamental wave from the fundamental laser light source is the maximum emission of the fundamental wave from the fundamental laser light source according to the temperature control direction of the temperature control unit. By switching the amount, a sudden increase in harmonics can be prevented, and as a result, damage to the wavelength conversion unit used in the light source device can be prevented.

The block diagram which shows the structure of the light source device of Embodiment 1 of this invention. Block diagram of a laser light source control unit in Embodiment 1 of the present invention The block diagram of the temperature control part in Embodiment 1 of this invention The block diagram of the light quantity restriction | limiting part in Embodiment 1 of this invention The figure which shows the relationship between the temperature of a wavelength conversion part and harmonic output in case the light quantity of the fundamental wave in Embodiment 1 of this invention is constant. Wavelength conversion light output characteristic diagram in APC control in Embodiment 1 of the present invention

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the light source device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, a fundamental laser beam source 101 includes a semiconductor laser 102 and a fiber 103 using a Yb-doped fiber, a total reflection fiber Bragg grating 104 (hereinafter abbreviated as total reflection FBG 104), and a partial fiber Bragg grating. 105 (hereinafter, abbreviated as partially reflective FBG 105). Laser light output from the semiconductor laser 102 enters the total reflection FBG 104 and is resonated between the total reflection FBG 104 and the partially reflection FBG 105 via the fiber 103. As a result, the light incident on the fiber 103 from the semiconductor laser 102 is excited and output from the partially reflected FBG 105 as a fundamental wave 106 with a narrowed spectral width.

  In the present embodiment, a semiconductor laser 102 that outputs a laser beam having a wavelength of about 915 nm is used as the fundamental laser source 101, and the laser beam having a wavelength of 915 nm is resonated between the total reflection FBG 104 and the partial reflection FBG 105, The partial reflection FBG 105 is configured to output light having a wavelength of 1064 nm.

  That is, in this embodiment, the fundamental wave 106 output from the fundamental wave laser light source 101 is a laser beam having a wavelength of 1064 nm.

  The fundamental wave 106 output from the fundamental wave laser light source 101 passes through the reflection mirror 107 and the reflection mirror 108, and is collected by the condenser lens 109 onto the wavelength conversion unit 110 formed of a nonlinear optical crystal. In this embodiment, an MgO: LiNbO 3 crystal element (MgLN element) having a domain-inverted structure is used as the nonlinear optical crystal. When the fundamental wave 106 input to the wavelength conversion unit 110 having this structure passes through the wavelength conversion unit 110, a part of the fundamental wave 106 is converted into a second harmonic 111 (hereinafter referred to as harmonic 111). . The harmonic wave 111 is output from the wavelength converter 110 together with the fundamental wave 106 that has not been converted to the harmonic wave 111.

  The harmonic wave 111 output from the wavelength converter 110 and the fundamental wave 106 that has not been converted to the harmonic wave 111 are adjusted to parallel light or an appropriate NA by the recollimating lens 112.

  The harmonic wave 111 that has passed through the recollimating lens 112 and the fundamental wave 106 that has not been converted into the harmonic wave 111 are band-separated from the harmonic wave 111 and the fundamental wave 106 using the wavelength filter 114. At this time, the fundamental wave 106 that has not been converted into the harmonic 111 passes through the wavelength filter 114 and is absorbed by the IR absorber 118. On the other hand, the harmonic 111 is reflected by the wavelength filter 114 and output to the monitoring filter mirror 117. That is, the wavelength filter 114 can output only the component of the harmonic 111.

  The wavelength conversion unit 110 is held by a holding member such as an aluminum table, and is disposed on the temperature setting unit 115 so that the temperature can be kept at a predetermined set temperature. In the present embodiment, the temperature setting unit 115 is configured by a Peltier element capable of highly accurate temperature adjustment. Further, the temperature of the wavelength conversion unit 110 is detected by a temperature sensor 116 such as a thermistor and transmitted to the temperature control unit 400. The temperature control unit 400 controls increase / decrease of the drive current to the temperature setting unit 115 and inversion of the polarity of the drive current so that the temperature signal output from the temperature sensor 116 becomes the set temperature. In addition, the temperature setting unit 115 can control the wavelength conversion unit 110 to be heated and cooled by the drive current output from the temperature control unit 400 so that the temperature is set to a predetermined temperature.

  Among the harmonics 111 separated by the wavelength filter 114, a part of the light reflected by the monitoring filter mirror 117 is input to the light detection unit 113. On the other hand, most of the harmonics 111 pass through the monitoring filter mirror 117 and are guided to the treatment position and the processing position as an output of the light source device by an optical fiber, a light guide plate (not shown) or the like.

The light detection unit 113 detects the light amount of the input harmonic 111, converts it into an electric signal (hereinafter, this electric signal is described as a light amount detection signal), and outputs it. The light amount detection signal output from the light detection unit 113 is input to the laser light source control unit 300. By this laser light source control unit 300, the fundamental laser light source 101 performs APC (Auto Power Control) control for making the output of the harmonic 111 constant via the laser light source driving unit 150.
[Description of APC control]
Details of the APC control will be described with reference to FIG.

  FIG. 2 is a block diagram showing a configuration of laser light source control unit 300 according to Embodiment 1 of the present invention.

  As shown in FIG. 2, the light amount detection signal output from the light detection unit 113 is converted into a digital signal by an AD converter 308 built in the laser light source control unit 300 and input to the differential arithmetic unit 301. In addition, the target value of the harmonic 111 set by the CPU unit 200 as the target light amount setting unit is also input to the differential calculator 301.

  The differential arithmetic unit 301 calculates the difference between the above-described digital light quantity detection signal and the target value of the harmonic 111 and outputs the difference as an error signal. The output error signal is gain-adjusted by a gain adjusting unit 302 that is a multiplier. The gain-adjusted error signal (hereinafter referred to as optical error output) is branched into two signals.

  One optical error output has proportional compensation 304, integral compensation 305, and phase compensation 306 inside a digital filter 303 composed of a multiplier, an adder, and a delay so as to ensure an appropriate frequency characteristic and D range. The output optical error output is transmitted as a laser drive signal to the light amount limiting unit 700 via the DA converter 307. The laser driving signal transmitted to the light amount limiting unit 700 is limited to an appropriate driving limit (described later) and transmitted to the laser driving unit 150.

  The laser light source driving unit 150 amplifies the current of the laser driving signal input from the laser light source control unit 300 via the light amount limiting unit 700 by a driving circuit composed of a power MOS or the like, and is an excitation light source of the fundamental laser light source 101. The output of a certain semiconductor laser 102 is increased or decreased. That is, the amount of light of the fundamental wave 106 output from the fundamental wave laser light source 101 is controlled by the current output from the laser light source driving unit 150. As a result, the amount of harmonics 111 output from the wavelength conversion unit 110 can be controlled to be a set target value.

In the present embodiment, the APC control is performed using the harmonics 111 separated by the wavelength filter 114. However, a part of the fundamental wave 106 separated by the wavelength filter 114 is detected, and the APC is detected. The laser light source control unit 300 can also perform APC control of the fundamental laser light source 101 so that the detected light amount has a predetermined relationship with the target value.
[Explanation of temperature controller]
Next, details of the temperature control unit 400 will be described below.

FIG. 3 is a block diagram showing a configuration of temperature control unit 400 according to Embodiment 1 of the present invention. The temperature control unit 400 converts the set temperature from the CPU unit 200 into an analog value by the DA converter 401 built in the temperature control unit 400. The difference between the converted analog value and the current temperature of the wavelength conversion unit 110 obtained from the temperature sensor 116 attached to the temperature setting unit 115 is calculated by the differential calculator 403, and the calculation result is used as a temperature error signal. And output to the gain adjustment unit 402. The temperature error signal is amplified by the gain adjustment unit 402, and the increase / decrease of the drive current and the inversion of the polarity of the drive current are controlled and output to the temperature setting unit 115. The temperature setting unit 115 performs heating and cooling using the temperature error signal amplified by the gain adjustment unit 402 so that the wavelength conversion unit 110 reaches the set temperature, and maintains the wavelength conversion unit 110 at a predetermined set temperature. Perform temperature control.
[Explanation of light intensity limiter]
Next, details of the light quantity limiting unit 700 will be described with reference to FIGS. 1, 4, 5, and 6.

  FIG. 4 is a block diagram showing the configuration of the light quantity limiting unit 700 according to Embodiment 1 of the present invention.

  FIG. 5 is a diagram showing the relationship between the temperature of the wavelength conversion unit 110 and the output of the harmonics 111 when the amount of light of the fundamental wave 106 in Embodiment 1 of the present invention is constant.

  FIG. 6 is a wavelength-converted light output characteristic diagram in APC control according to Embodiment 1 of the present invention.

  As shown in FIGS. 1 and 4, the laser drive signal transmitted from the laser light source control unit 300 is input to the non-damaged light amount determination unit 702. The non-damaged light quantity determination unit 702 reads out the non-damaged light quantity stored in advance from the non-damaged light quantity storage unit 701 and compares it with the laser drive signal.

Here, the non-damaged light amount will be described in detail.
In general, the semiconductor laser 102 has a limit in the amount of light that can be output, and is damaged when a drive current exceeding the limit is applied. Therefore, it is necessary to limit the drive current so as not to exceed the drive limit of the semiconductor laser 102, and the maximum light amount of the fundamental wave 106 that can be output from the fundamental laser light source 101 is determined by this restriction. The non-damaged light quantity storage unit 701 stores a light quantity that does not damage the semiconductor laser 102 (non-damaged light quantity) as a first maximum light emission quantity.

Further, the wavelength conversion unit 110 uses a MgO: LiNbO ₃ crystal element (MgLN element) having a domain-inverted structure. However, when the harmonics are generated more than a predetermined light amount, the element itself is damaged. There is damage resistance inherent to the conversion element (hereinafter referred to as element damage resistance). Therefore, it is necessary for the laser light source control unit 300 to control the harmonics 111 to be less than the amount of light that can withstand element damage, and to prevent the wavelength conversion unit 110 from being damaged. In general, the MgLN element according to the present embodiment has an element damage resistance with respect to the green light quantity of about 2 [W] to 3 [W].

The amount of green light, that is, the amount of harmonics 111 is
The amount of harmonics 111 [W] = the amount of fundamental waves [W] × wavelength conversion efficiency.

  As shown in FIG. 5, when the fundamental wave 106 has a constant light amount, the wavelength conversion unit 110 changes the harmonic output, that is, the wavelength conversion efficiency depending on the temperature of the wavelength conversion unit 110, and the wavelength conversion efficiency becomes maximum at the phase matching temperature. ing.

If the wavelength conversion efficiency in the phase matching state of the wavelength conversion unit 110 (hereinafter referred to as the maximum wavelength conversion efficiency) is 20%, when the fundamental wave 106 is input by 10 [W] or more, the harmonic 111 The amount of light is 2 [W] or more, and there is a possibility of element damage. The amount of light of the fundamental wave 106 that may cause element damage at this maximum wavelength conversion efficiency is
Light quantity of fundamental wave [W] = Harmonic light quantity [W] of element damage tolerance ÷ Maximum wavelength conversion efficiency can be obtained, and the light quantity of this fundamental wave is calculated as the second maximum light emission quantity (second non-damaged light quantity). Is stored in the non-damaged light quantity storage unit 701.

  In general, in order to eliminate the possibility of element damage of the wavelength conversion unit 110, the light quantity of the fundamental wave 106 may be limited so that the harmonic wave 111 does not exceed the element damage resistance even at the maximum wavelength conversion efficiency. . However, when the temperature of the wavelength conversion unit 110 deviates from the phase matching state and the conversion efficiency decreases, there is a possibility that the light quantity of the fundamental wave 106 is insufficient and the harmonic 111 of the target light quantity cannot be obtained.

That is, in order to obtain a desired harmonic 111 with respect to a decrease in conversion efficiency (temperature error with respect to the phase matching temperature), the amount of light of the fundamental wave 106 is made sufficiently larger than the second maximum light emission amount to increase the control margin of APC control. It is desirable to ensure.
On the other hand, there is a relationship that the risk of breakage due to generation of harmonics 111 exceeding the element breakage resistance of the wavelength conversion unit 110 is increased.

  The non-damaged light quantity determination unit 702 limits the laser drive signal to the first maximum light emission amount or less when the laser drive signal is greater than or equal to the first maximum light emission amount. The laser drive signal limited to the first maximum emission amount or less and the second maximum emission amount are transmitted to the light amount restriction command unit 704.

  On the other hand, the set temperature transmitted from the CPU unit 200 to the temperature control unit 400 is also transmitted to the temperature direction determination unit 703. When the set temperature changes from the current set temperature, the temperature direction determination unit 703 determines whether the change is in the heating direction or the cooling direction, and transmits the determination to the light amount restriction command unit 704.

  The light amount restriction command unit 704 is set based on the laser drive signal and the second maximum light emission amount that are limited to the first maximum light emission amount or less from the non-damaged light amount determination unit 702 and the temperature direction from the temperature direction determination unit 703. When the temperature change is in the cooling direction, the laser drive signal limited to the first maximum emission amount or less is limited to the second maximum emission amount or less. The reason for this will be described in detail below.

FIG. 6 shows harmonics when the temperature of the wavelength conversion unit 110 is changed from the point A on the low temperature side to the point E on the high temperature side from the phase matching temperature and from the point E on the high temperature side to the point A on the low temperature side. 111 represents a change in the output light quantity. A dotted line a in the figure indicates the target light quantity by the APC control, and a dotted line b in the figure indicates the light quantity that is resistant to element damage of the wavelength conversion unit 110. Further, the section BFC in the figure shows the theoretical output of the harmonic 111 when the fundamental wave 106 is in the first maximum light emission amount state.
[Explanation when changing from point A to high temperature side]
When the temperature of the wavelength conversion unit 110 is a point A lower than the phase matching temperature, the fundamental wave 106 has reached the first maximum light emission amount by APC control, but the harmonic wave 111 has not obtained a desired light amount, and the APC. The control is in a failed state. In this state, when the temperature of the wavelength conversion unit 110 is raised, the output of the harmonics 111 changes (hereinafter referred to as normal characteristics) as indicated by the section ABCDE.

  In the section AB, the temperature of the wavelength conversion unit 110 rises and approaches the phase matching temperature, so that the conversion efficiency increases and the output of the harmonic 111 also increases. At this time, the wavelength conversion unit 110 generally absorbs a part of the fundamental wave 106 and the harmonic wave 111 and converts it into heat (hereinafter referred to as light absorption). It has a feature that changes the temperature of the element itself. In addition, light absorption is caused by the phenomenon that the absorption of infrared light increases due to the presence of visible light (Green Induced Infra-red Absorption: hereinafter abbreviated as GRIIRA). Presumed to be accelerated. In the section B-C, it is an area where APC control is possible, and the light quantity of the fundamental wave 106 is controlled so that the harmonic wave 111 has a constant target light quantity. As described above, this APC-controllable region has a margin for reduction in conversion efficiency as the light amount of the fundamental wave 106 increases, and can widen the APC-controllable region, that is, the section B-C.

In the section C-D-E, the conversion efficiency of the wavelength conversion unit 110 decreases and the fundamental wave 106 reaches the first maximum light emission amount, but the APC control fails and the output of the harmonic 111 decreases. .
[Explanation when changing from point E to lower temperature]
On the other hand, the case where the temperature of the wavelength conversion part 110 is lowered from the case where the temperature of the wavelength conversion part 110 is higher than the phase matching temperature is described.

  At point E, the fundamental wave 106 has the APC control broken and the first maximum light emission amount is inputted. When the temperature is lowered in this state, the wavelength converter 110 changes at the point G when the output of the harmonic 111 changes due to the normal characteristics of the interval E-D-C-B-A and when it changes to the interval E-D-G. May be damaged.

When the wavelength conversion unit 110 is damaged, the first maximum light emission amount is
It was a case where the second maximum light emission amount (= higher harmonic light amount [W] ÷ maximum wavelength conversion efficiency) of device damage resistance was exceeded.

  Although the cause of damage to the wavelength converter 110 has not been clarified in detail, it can be estimated that the following phenomenon occurs.

  In the state where the fundamental wave 106 is equal to or greater than the second maximum light emission amount at the point E, the conversion efficiency increases because the temperature of the wavelength conversion unit 110 decreases as it approaches the phase matching temperature. As the conversion efficiency increases, the amount of harmonics 111 (green light) increases. However, light absorption by GRIIRA also increases and the amount of heat generation increases. The increase in the amount of generated heat increases the temperature of the wavelength conversion unit 110, and the conversion efficiency decreases due to the temperature increase of the wavelength conversion unit 110. That is, in section DG, the conversion efficiency increase due to the temperature decrease of the wavelength conversion unit 110 and the conversion efficiency decrease due to the increase in the amount of heat generated are balanced under a certain condition (hereinafter, this state). Is called an abnormal characteristic). When the temperature of the wavelength conversion unit 110 is further lowered from this abnormal characteristic state, section DG, the balance between the increase in conversion efficiency and the decrease in conversion efficiency due to the increase in heat generation is lost, and the normal characteristic is restored from point G. At this time, the transition from the abnormal characteristic to the normal characteristic is rapidly performed faster than the response speed of the APC control. Therefore, the theoretical amount of green light (point F) shown in section C-FB from point G is generated. It is presumed that the green light quantity at the point F exceeds the element damage resistance light quantity of the wavelength converter 110 indicated by the dotted line b, and the wavelength converter 110 is damaged.

  Therefore, in order to prevent the wavelength conversion unit 110 from being damaged, it is only necessary that the abnormal characteristic is not generated, or the first maximum light emission amount when the abnormal characteristic occurs is limited to the second maximum light emission amount or less. It is estimated to be. In order to solve this point, damage to the wavelength conversion unit 110 is prevented by limiting the light amount of the fundamental wave 106 to the second maximum light emission amount by the light amount restriction command unit 704 of FIG.

  In this embodiment, the light quantity restriction command unit 704 is used to control the fundamental wave 106 to be equal to or less than the second maximum light emission amount. However, when the fundamental wave 106 is equal to or greater than the second maximum light emission amount. Is used as a temperature control target change prohibition command that prohibits the change of the temperature control target and allows the change of the temperature control target if it is less than the second maximum light emission amount, thereby preventing the occurrence of abnormal characteristics May be.

  As described above, when the set temperature of the wavelength conversion unit 110 changes in the heating direction, the fundamental wave 106 can be driven to the first maximum light emission amount, so that the margin of APC control can be widened. When the set temperature of the wavelength conversion unit 110 changes in the cooling direction, the fundamental wave 106 is limited to be equal to or less than the second maximum light emission amount, thereby preventing the wavelength conversion unit 110 from being damaged.

  In the present embodiment, the method for preventing damage to the wavelength conversion unit 110 has been described. However, by setting the second maximum light emission amount to a light amount that does not generate abnormal characteristics, the generation of abnormal characteristics is prevented and the rapid harmonics 111 are generated. It is also possible to prevent fluctuations in the above.

  Furthermore, in the present embodiment, the method of limiting the fundamental wave 106 to the second maximum light emission amount or less when the set temperature of the wavelength conversion unit 110 changes in the cooling direction has been described. It is also possible to prevent the portion 110 from being damaged.

Further, in the present embodiment, the method of limiting the maximum light emission amount of the fundamental wave 106 by providing a restriction on the laser drive command has been described. However, when the light amount of the fundamental wave 106 is detected and the fundamental wave 106 exceeds the maximum light emission amount. May be limited by switching from APC control for keeping the output of the harmonic wave 111 constant to APC control for keeping the light amount of the fundamental wave 106 constant.
Further, the light quantity restriction command unit 704 switches from the second maximum light emission amount to the first maximum light emission amount when the temperature control is stabilized after the set temperature is changed or after a predetermined time has elapsed.

  In the above, power control and temperature control are converted from analog signals to digital signals by AD converters, and after digital control, they are converted to analog signals by DA converters and driven. However, instead of this, all can be realized as an analog circuit.

  The laser light source device of the present invention is suitable as a light source device for highly reliable ophthalmic treatment equipment, laser processing equipment and the like because it can widen the margin of APC control, prevent damage to the wavelength conversion section, and always emit light stably. is there.

101 Fundamental Laser Light Source 102 Semiconductor Laser 103 Fiber 104 Total Reflection FBG
105 Partially reflective FBG
106 Fundamental Wave 107 Reflecting Mirror 108 Reflecting Mirror 109 Condensing Lens 110 Wavelength Conversion Unit 111 Harmonic Wave 112 Recollimating Lens 113 Photodetection Unit 114 Wavelength Filter 115 Temperature Setting Unit 116 Temperature Sensor 117 Monitoring Filter Mirror 118 IR Absorber 150 Laser Light Source Drive Unit 200 CPU unit 300 laser light source control unit 301 differential operation unit 302 gain adjustment unit 303 digital filter 304 proportional compensation 305 integral compensation 306 phase compensation 307 DA converter 308 AD converter 400 temperature control unit 401 DA converter 402 gain adjustment unit 403 Differential computing unit 700 Light amount limiting unit 701 Non-damaged light amount storage unit 702 Non-damaged light amount determination unit 703 Temperature direction determination unit 704 Light amount restriction command unit

Claims (5)

A fundamental laser source that outputs a fundamental wave;
A wavelength converter that inputs a fundamental wave from the fundamental laser light source and outputs a harmonic,
A temperature setting unit for heating and cooling the wavelength conversion unit;
A temperature control unit for controlling the temperature setting unit;
A laser light source controller that controls the fundamental laser light source so that the output of the harmonics from the wavelength converter becomes a target value;
A light source configured to switch the maximum light emission amount of the fundamental wave from the fundamental laser light source according to the temperature control direction of the temperature control unit, wherein the light amount restriction unit that restricts the light emission amount of the fundamental wave from the fundamental laser light source apparatus. 2. The light source according to claim 1, wherein the maximum emission amount of the fundamental wave from the fundamental wave laser light source is configured such that a harmonic output when the wavelength conversion efficiency of the wavelength conversion unit is maximum is less than element damage resistance. apparatus. The light amount limiting unit is configured to reduce the maximum light emission amount of the fundamental wave of the fundamental laser light source to a first maximum light emission amount or less when the temperature control direction of the temperature control unit is heating, and to a second value when cooling. The light source device according to claim 1, wherein the light source device is configured to be limited to a maximum light emission amount or less. 4. The light source device according to claim 1, wherein the light quantity limiting unit is configured to make the second maximum light emission amount smaller than the first maximum light emission amount. 5. The second maximum light emission amount of the light amount limiting unit makes the maximum light emission amount of the fundamental wave of the fundamental laser light source smaller than the fundamental light amount that damages the element when the wavelength conversion unit is at the phase matching temperature. The light source device according to claim 1, wherein the light source device is configured.

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