JPH04356981A - Laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a stable laser oscillator in which a resonator mirror, etc., is not dew-condensed. CONSTITUTION:An optical path is purged by part of dry air, part of the dry air is sprayed to a partially reflecting mirror 7, a totally reflecting mirror 8, an output detector 41, etc., by a dew-condensation preventive units 43, 44 to shut OFF the mirror 7, etc., from the atmosphere. On the other hand, the mirror 7, etc., is temperature-controlled by a temperature controller 12, and cooled with coolant. In this case, a flow rate of the air branched and fed, is varied or a flow rate of the coolant for cooling the mirror 7, etc., is varied during oscillation of a laser light or at the time of oscillation stop. A resonator mirror, etc., is not dew-condensed even during oscillation stop of a laser light.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a laser oscillator.
More specifically, the present invention relates to a laser oscillator that can prevent dew condensation on a resonator mirror or the like.

0002

5 is a schematic diagram showing an example of a conventional three-axis orthogonal CO2 laser oscillator disclosed in Japanese Patent Application Laid-Open No. 1-232779. They all intersect at right angles. In the figure, 1 is a laser oscillator, 2 is a vacuum container of the laser oscillator 1, and 3 is a discharge electrode provided in the vacuum container 2. 4 is a heat exchanger attached to the vacuum container 2; 5 is a blower of the heat exchanger 4;
6 is an excitation medium sealed within the vacuum container 2. 7 is a total reflection mirror, 8 is a partial reflection mirror, and both of these reflection mirrors 7 and 8 constitute a resonator mirror. 9 is a cosmetic cover that covers the laser oscillator 1. Reference numeral 10 denotes a duct attached to the cover 9 for safety reasons, and allows laser light to pass through the duct. Dry air 11 is generated by the dry air generator and enters the optical path from the dry air inlet 11a, and is purged by piping in the propagation direction A of the laser beam to prevent attenuation of the laser power and change in the characteristics of the laser beam. 12 is a total reflection mirror 7 and a partial reflection mirror 8
This is a temperature control device for the cooling water that cools the laser, and the temperature of the cooling water is always maintained at a constant temperature so that the initial performance and characteristics of both reflectors 7 and 8 will not change due to changes in outside air temperature, and the laser light characteristics will not change. do. 13 is a cooling water pump for circulating cooling water, and 14 is a flow of cooling water.

FIGS. 6 and 7 are a longitudinal cross-sectional view and a front view of an example of a mirror holder of a conventional laser oscillator disclosed in Japanese Patent Application Laid-Open No. 63-73575. A mirror holder 15 presses the total reflection mirror 7 or the partial reflection mirror 8, and is made of a highly thermally conductive material such as aluminum, so that the temperature of the cooling water is directly transmitted. 16 is a support rod that supports the mirror holder 15 in the vacuum container 2, 17 is a support point of the support rod 16, and 18 is a mirror that supports the total reflection mirror 7 or the partial reflection mirror 8 held down by the mirror holder 15 in the opposite direction. It's a presser foot. Reference numeral 19 denotes a micrometer head, which is rotated to change the angle of the total reflection mirror 7 or the partial reflection mirror 8 about a fulcrum constituted by the support rod 16 and the support point 17. 20 is a water path through which temperature-controlled cooling water flows into the mirror holder 15 to indirectly cool the total reflection mirror 7 or the partial reflection mirror 8. 21 is mirror presser 18
22 is an O-ring that seals between the vacuum container 2 and the mirror holder 18,
23 is a hole through which the laser beam passes.

Next, the operation of the laser oscillator constructed as described above will be explained using FIGS. 5, 6, and 7. When the cooling medium 6 is caused to flow between the discharge electrodes 3 by the blower 5, the excitation medium 6 is excited by the discharge generated by the discharge electrode 3 and emits light. This light is oscillated and amplified between a resonator mirror composed of a total reflection mirror 7 and a partial reflection mirror 8, and is taken out from the partial reflection mirror 8 through a duct 10 toward the outside A of the laser oscillator 1. On the other hand, the dry air 11 generated from the dry air generator is passed through piping in the propagation direction A of the laser beam.
will be purged. The excitation medium 6 heated by the discharge is cooled by the heat exchanger 4 and circulated again by the blower 5.

On the other hand, the cooling water is controlled to a constant temperature by a cooling water temperature control device 12, is circulated as a cooling water flow 14 by a cooling water pump 13, cools the mirror holder 15 in a water path 20, and is indirectly The total reflection mirror 7 and the partial reflection mirror 8 are cooled.

[0006]

[Problem to be Solved by the Invention] The conventional laser oscillator configured as described above does not emit laser light when the surrounding humidity is high or when the outside temperature becomes higher than the control temperature of the cooling water. That is, there is a problem in that dew condensation occurs on the reflecting mirror when the oscillation of the laser beam is stopped.

In order to solve the above-mentioned problems, a technique for preventing dew condensation on the output mirror by spraying dry gas onto the output mirror is disclosed in Japanese Patent Laid-Open Nos. 58-121692 and 1983. -105585. FIG. 8 is a longitudinal sectional view showing an example of a laser oscillator disclosed in Japanese Patent Application Laid-Open No. 121692/1982. This laser oscillator has a discharge tube body 25 filled with a mixed gas 24.
, at least a pair of reflecting mirrors 26 provided at both ends and inside of the discharge tube body 25, a cathode 27A and an anode 27B,
One output mirror 29 generates a glow discharge between both electrodes 27A and 27B, converts the mixed gas 24 into laser light, resonates between both reflecting mirrors 26, and outputs the laser light to the outside.
The laser beam from the output mirror 29 is passed through the workpiece 30.
, a focusing lens 31 corresponding to the output mirror 29 , and an enclosing portion 32 that surrounds the space between at least one of the output ports and the output mirror 29 . Further, the surrounding portion 32 is provided with a supply port 33 and an exhaust port 34, and the supply port 33 is provided with a dehumidifier 35. In this way, by constantly blowing dry gas onto the output mirror 29, dew condensation is prevented from forming on the outer surface of the output mirror 29, and cracking of the output mirror 29 is prevented.

[0008] Furthermore, a technique for supplying dry gas from a cylinder to a supply port via a hose was disclosed in Japanese Patent Laid-Open No. 58-1287.
It is disclosed in Japanese Patent No. 81, and a similar technique is also disclosed in
It is also disclosed in Japanese Patent Application Laid-Open No. 58-20551.

However, in the conventional laser transmitter as described above, there is insufficient technology to prevent condensation on the reflecting mirror, etc.
When dry air is blown onto the reflector, etc., there is a risk that dust or the like will adhere to the reflector, causing the reflector to burn out during laser beam oscillation. In addition, when the laser beam stops oscillating when the heat source disappears, the reflector etc. becomes excessively cooled, causing dew condensation on the reflector, etc., and the sealing of the laser oscillator is insufficient, allowing moist air from outside to enter the interior. Condensation sometimes formed on the reflector, etc. Furthermore, there is a fear that gas convection may occur near a reflecting mirror or the like during laser beam oscillation, causing a change in the characteristics of the laser beam itself.

The present invention was made in order to solve various problems that occur when preventing dew condensation on a reflecting mirror, etc., as described above. Condensation may form on the reflector etc. when the laser beam stops oscillating, humid air from outside may enter the interior and condensate on the reflector etc., gas convection may occur and the laser beam may The object of the present invention is to obtain a laser oscillator whose characteristics do not change.

[0011]

[Means for Solving the Problems] A laser oscillator according to the present invention is provided with a branching device, a shutter, etc. to change the amount of dry air blown onto a resonator mirror, a detection device, etc. Further, the laser oscillator according to the present invention is provided with a water flow switching device to change the flow of cooling water flowing to the resonator mirror.

0012

[Operation] During laser beam oscillation, dry air is flowed to purge the optical path, and while laser beam oscillation is stopped, dry air is also flowed to the resonator mirror, etc., or the flow rate is changed. During laser beam oscillation, temperature-controlled cooling water cools the resonator mirror, and when laser beam oscillation is stopped, cooling water does not flow to the resonator mirror. Or change the flow rate.

[0013]

Embodiment FIG. 1 is a schematic diagram showing an embodiment of the present invention. Note that the same or corresponding parts as in the conventional example shown in FIG. Reference numeral 40 denotes a dry air unit that generates dry air 11 with dust and moisture removed, and is placed outside to avoid organic matter generated within the factory. . Reference numeral 41 denotes an output detection device that detects a portion of the laser light coming out of the total reflection mirror 7 and monitors the laser light output from the partial reflection mirror 8. 42 is a dry air inlet 11 for directing the dry air generated in the dry air unit 40.
A first dry air passage 43 is a second dry air passage branched from the first dry air passage 42, which blows dry air onto the partial reflection mirror 8 to isolate it from the outside air and cause dew condensation on the partial reflection mirror 8. prevent the occurrence of 44 is a third dry air passage branched from the second dry air passage 43, which blows dry air onto the total reflection mirror 7 and the output detection device 41 to isolate them from the outside air and prevent dew condensation from occurring.

Next, the operation of this embodiment constructed as described above will be explained. A cooling medium 6 is caused to flow between the discharge electrodes 3 by the blower 5, and the discharge generated by the discharge electrodes 3 excites the excitation medium 6 to emit light. This light resonates and is amplified between a resonator mirror composed of a total reflection mirror 7 and a partial reflection mirror 8, and is extracted from the partial reflection mirror 8 through a duct 10 toward the outside A of the laser oscillator 1. On the other hand, the dry air 11 generated in the dry air unit 40 is purged in the beam propagation direction A by the first dry air passage 42. Further, the dry air 11 generated in the dry air unit 40 is branched from the first dry air passage 42 to second and third dry air passages 43 and 44, and is sent to the partial reflection mirror 8, the total reflection mirror 7, the output detection device 41, etc. It is blown on and blocks the outside air. The excitation medium 6 heated by the discharge is cooled by the heat exchanger 4 and circulated again by the blower 5.

On the other hand, the cooling water is controlled to a constant temperature by a cooling water temperature control device 12, and is circulated within the laser oscillator 1 as a cooling water flow 14 by a cooling water pump 13.
The water path 20 cools the mirror holder 15 and indirectly cools the total reflection mirror 7 and the partial reflection mirror 8.

In the above embodiment, dry air is blown onto the partial reflecting mirror 7, etc. to block outside air, so temperature control is performed when there is no heat load on the partial reflecting mirror 7, etc., that is, when the laser beam oscillation is stopped. There is no possibility of over-cooling due to the cooled water. For example, if the outside air temperature is sufficiently higher than the controlled cooling water temperature or the humidity is high, overcooling will cause the temperature to drop below the dew point, resulting in dew condensation on the front of the partial reflecting mirror 7, etc.; however, in this embodiment, dry air Since the dew point is sprayed onto areas where dew condensation should not occur to avoid exposure to the outside air, the dew point temperature is relatively low only in the peripheral areas of the partial reflecting mirror 7, etc., making it difficult for dew condensation to occur. In this way, no dew condensation occurs on the outer surface of the resonator mirror, and stable beam characteristics can be obtained without the laser light characteristics changing due to absorption or scattering of the laser light by condensed water during laser light oscillation. In addition, an output detection device that employs an integrating sphere method or the like can also detect normal output without condensation, so safety can be maintained.

[0017] Also, the dry air is supplied to the dry air unit 4.
Since dust and moisture are removed by the 0, dust does not adhere to the partial reflecting mirror 7, etc., and the partial reflecting mirror 7, etc. will not be burnt out during oscillation, resulting in longer life and more stable beams. In particular, when the dry air unit 40 is placed outdoors, the beam characteristics will not be distorted by organic matter generated within the factory. Further, in this embodiment, since the dry air conventionally used for purging the optical path is used as is, there is no need to install a new dry air unit.

In the above explanation, the dry air conventionally used for purging the optical path is used as is, but the dry air may be drawn from a new dry air unit. Further, although the above description has been made regarding the case where dry air is used as the gas, any dry gas such as nitrogen gas that does not absorb laser light or change the beam characteristics may be used. Furthermore, the reflecting mirror 8
, the case where dry air is blown onto the total reflection mirror 7 and the output detection device 41 has been shown, but dry air may also be blown onto things that are cooled with temperature-controlled cooling water and are in contact with the outside air, such as optical path mirrors, phase retarders, lenses, etc. Good too.

FIG. 2 is a schematic diagram showing another embodiment of the present invention. Reference numeral 45 denotes a first dry air passage 42 through which dry air flows through the optical path duct 10, and first and second dry air passages which are dew condensation prevention devices.
A gas flow direction switching device that switches the flow rate ratio of dry air flowing into the dry air passages 43 and 44 of the dry air 11.
is branched into an optical path purging direction B and a direction C for spraying to prevent dew condensation on the reflecting mirrors 7 and 8.

In this embodiment configured as described above, during laser beam oscillation, the gas flow direction switching device 45 causes dry air to flow only in the optical path purge direction B, that is, in the direction of the first dry air passage 42, and the laser beam is When the oscillation of
The dry air is also flowed in the direction of the dry air passages 43 and 44.

As described above, in this embodiment, when the laser beam is oscillated, the dry air does not flow in the direction C that prevents dew condensation, so the transport of the laser beam caused by the dry air crossing the laser beam is prevented. Changes in propagation characteristics due to disturbances do not occur, and stable propagation characteristics can be obtained.

In the above embodiment, the gas flow direction switching device 45 only switches the direction in which the dry air flows, but it also changes the flow rate of the dry air in the optical path purge direction B or the direction C in which it is sprayed to prevent dew condensation on the reflecting mirrors 7 and 8. It may be changed. Further, although the characteristics of the laser beam are stabilized, the propagation characteristics may be intentionally changed depending on the application.

FIG. 3 is a schematic diagram showing still another embodiment of the present invention. 46 is an airtight cover that hermetically covers the laser oscillator 1, and 47 is a shutter that is attached outside the dry air inlet 11a of the duct 10 and opens and closes the passage of the duct 10. 48 is a laser oscillator 1 and a sealing cover 46
At the outlet of the dry air sealed inside, the total reflection mirror 7 of the cover 46 is arranged so that the dry air flows to both the reflection mirrors 8 and 7.
It is located at the bottom of the side.

The operation of this embodiment configured as described above will be explained. First, the dry air generated from the dry air generator is purged in the beam propagation direction A through piping. Next, when the oscillation of the laser beam is stopped, the shutter 47 is closed, the duct 10 is sealed, and the dry air is supplied to the laser oscillator 1.
flows to the side. At this time, the laser oscillator 1
Since the airtight cover 6 is sealed in a partially open state, a positive pressure is created by the dry air, and outside air does not enter into the airtight cover 46. For this reason, in this embodiment, the dew point temperature near the reflectors 7 and 8 can be increased without allowing moist air from outside to enter even if the dew condensation prevention devices 43 and 44 shown in FIGS. 1 and 2 are not particularly provided. No condensation occurs and stable beam characteristics are obtained.

In the above embodiment, the gas flow direction switching device shown in FIG. 2 may be further provided. In this way, the flow rate of dry air can be changed while the laser beam is being emitted or stopped, so that the laser beam characteristics do not change, or conversely, it can be intentionally changed.

FIG. 4 is a schematic diagram showing another embodiment of the present invention. 49 is a first water flow switching device using a B contact that closes while the laser beam is oscillating; 50 is the A that opens while the laser beam is oscillating.
This is a second water flow switching device using contacts.

In this embodiment configured as described above,
During oscillation of the laser beam, the first water flow switching device 49 is closed, the second water flow switching device 50 is opened, and the cooling water is directed to the reflecting mirror 7.
, 8. When the laser beam oscillation is stopped, the first water flow switching device 49 opens and the second water flow switching device 50 closes, so that the cooling water does not flow to the reflecting mirrors 7 and 8 but circulates around the cooling water temperature adjustment device 12. It becomes a closed circuit. In this way, when the laser beam oscillation is stopped, the cooling water does not flow to the reflecting mirrors 7 and 8, and the reflecting mirrors 7 and 8 follow the outside temperature, so there is no excessive cooling and no condensation occurs, resulting in stable laser beam characteristics. can get.

[0028]

Effects of the Invention As is clear from the above description, the present invention allows dry air to flow through a reflecting mirror or the like to isolate it from outside air, or to change its flow rate, or to flow dry air when laser light oscillates or when oscillation is stopped. Since the amount of cooling water is varied, no condensation occurs on the reflector, etc. Furthermore, since dust and the like are removed from the dry air by the dry air unit, there is no possibility of dust adhering to the reflecting mirror or the like and causing burnout.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the present invention.

FIG. 3 is a schematic diagram showing still another embodiment of the present invention.

FIG. 4 is a schematic diagram showing another embodiment of the present invention.

FIG. 5 is a schematic diagram showing an example of a conventional laser oscillator.

FIG. 6 is a longitudinal cross-sectional view showing an example of a mirror holder of a conventional laser oscillator.

FIG. 7 is a front view of FIG. 6.

FIG. 8 is a vertical cross-sectional view showing another example of a conventional laser oscillator.

[Explanation of symbols]

1 Laser oscillator 2 Vacuum container 3 Discharge electrode 4 Heat exchanger 5 Blower 6 Excitation medium 7 Total reflection mirror 8 Partial reflector 9 Cover 10 Duct 11 Dry air 11a dry air inlet 12 Temperature control device 13 Cooling water pump 14 Cooling water flow 40 Dry air unit 41 Output detection device 42 First dry air passage 43 Second dry air passage 44 Third dry air passage 45 Gas flow direction switching device 46 Sealed cover 47 Shutter 48 Exit 49 First water flow switching device 50 Second water flow switching device

Claims (5)

[Claims] 1. A laser oscillator comprising a resonator mirror, a water path for cooling water to cool the resonator mirror, etc., wherein the laser oscillator is provided with a dry air unit for generating dry air, and a laser oscillator connected to the dry air unit is provided. A laser oscillator comprising: a dry air passage for sending the dry air for purging into the light optical path duct; and a dew condensation prevention device connected to the dry air unit and blowing the dry air onto a detection device, the resonator mirror, etc. . 2. The laser oscillator according to claim 1, further comprising a gas flow direction switching device for switching the flow rate ratio of dry air flowing into the optical path duct and the dew condensation prevention device. 3. In a laser oscillator comprising a resonator mirror, a water path for cooling water to cool the resonator mirror, etc., the laser oscillator is hermetically sealed with an airtight cover, and the airtight cover is provided with an inlet for dry air generated by a dry air unit. What is claimed is: 1. A laser oscillator characterized in that a shutter for opening and closing the optical path duct is provided in the optical path duct for laser light connected to the sealing cover. 4. The laser oscillator according to claim 3, further comprising a gas flow rate switching device for changing the flow rate of dry air. 5. A laser oscillator comprising a resonator mirror, a water path for flowing cooling water for cooling the resonator mirror, and the like, wherein a temperature control device for controlling the temperature of the cooling water is provided, and the resonator mirror is cooled. A laser oscillator comprising a water flow switching device that changes the flow rate of temperature-controlled cooling water during laser beam oscillation and when laser beam oscillation is stopped.