JPS63299183A - Laser generator - Google Patents

Abstract

PURPOSE:To prevent an output mirror from damaging due to dew condensation and to stabilize a laser output by cooling the mirror and a total-reflection mirror with a coolant passed from a cooler through a second heat exchanger to supply the coolant of stable temperature higher than the dew point temperature to cool a resonator. CONSTITUTION:An output mirror 9 and a total-reflection mirror 13 are formed in a pipe state, and held and supported through a predetermined interval by supporting rods 16, 17 having low expansion coefficient to pass coolant. A cooler 19 for supplying coolant of predetermined temperature and quantity to a resonator 18 and composed of a discharge tube 5, the mirrors 9, 13 and the rods 16, 17, etc., is provided. In a laser generator constructed in this manner, the mirrors 9, 13 are cooled with the coolant passed from the cooler 19 through a second heat exchanger 2. Thus, the laser generator in which the coolant of higher stable temperature than the dew point temperature is supplied to cool the resonator 18 to prevent the mirror 9 from damaging due to dew condensation and to stabilize a laser output can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a laser generator.

[Conventional technology]

In a laser generator, as described in Japanese Utility Model Application No. 58-20551, the heat loss generated when the laser beam passes through or is reflected by the output mirror is removed by cooling it with cooling water or the like. During cooling, dry air is blown to prevent condensation on the mirror surface, and a dedicated cooling device is installed for the optical system to supply water with a temperature above the dew point to prevent damage to the output mirror and stabilize it. It will be planned.

In addition, in order to prevent fluctuations in laser output caused by optical axis misalignment of the mirrors due to thermal deformation of the optical system support rod of the resonator, we stabilized thermal distortion by flowing water at a constant temperature through the support rod.
Output has been stabilized.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology requires that a cooling device with a water temperature higher than the dew point temperature be provided separately from a device that supplies cooling water for the laser gas for cooling the output mirror and the total reflection mirror, or that dry, clean air is produced to cool the output mirror. It was necessary to install piping to spray the water.

Furthermore, the water flowing to stabilize the thermal distortion of the support rod of the resonator is cooling water that cools the output mirror in order to prevent high voltage dielectric breakdown due to dew condensation on the surface of the support rod.

The present invention was made in view of the above points, and aims to supply cooling water with a stable temperature higher than the dew point temperature to cool the resonator, thereby preventing damage to the output mirror due to dew condensation and stabilizing the laser output. The object of the present invention is to provide a laser generating device that makes it possible.

[Means for solving problems]

The above object is achieved by cooling the output mirror and the total reflection mirror with cooling water that has passed through the second heat exchanger from the cooling device.

[Effect]

The desired purpose is achieved by cooling the output mirror and the total reflection mirror with cooling water that has passed through the second heat exchanger from the cooling device, which will be explained next.

The laser gas adiabatically compressed by the blower of the laser generator is described in the references (Nikkan Kogyo Shimbun, New Edition Compressor by Toshibe Kazumori,
According to formula 37) on page 30, blower inlet pressure Pl, gas temperature Tt ('K), blower outlet pressure Pa, gas temperature Tz (
'K), and the specific heat ratio of the laser gas is K, then 421 Tz=TxX (Pg/Pt)...
'(1). Here, blower inlet gas temperature T1
is the temperature of the gas cooled by the heat exchanger, and is constant regardless of the laser oscillation state. Further, the blower inlet and outlet gas pressures Pa and Pz are kept constant in order to keep the discharge conditions in the discharge tube constant. Therefore, the blower outlet gas temperature T
z is kept constant 0. For example, when a Roots blower is used, the pressure ratio Pa/Pz is usually about 2, and for carbon dioxide laser gas, the specific heat ratio K is 1.3 to 1.5, so the Roots blower outlet temperature Tx is about The temperature will be around 100℃. However, the oscillation efficiency decreases when performing laser oscillation due to the gas temperature at the blower outlet, so for carbon dioxide lasers, at least
After cooling to about ℃, air is blown into the discharge tube. Since the cooling conditions for the blower outlet gas are constant, such as gas temperature, gas pressure, and air flow rate, the temperature rise of the refrigerant (in most cases water) used for gas cooling depends on the oscillator output or discharge injection power level 9 The ambient temperature of the oscillator become independent of The temperature rise of the refrigerant depends on the refrigerant specific heat and flow rate of the heat exchanger that cools the blower outlet gas, and the exchange capacity of the heat exchanger.

Therefore, by restricting the flow rate of the refrigerant, a refrigerant having a stable temperature above the dew point can be obtained. In other words, if the gas flow rate, piping, etc. of the path through which the gas flows is determined, the work performed by the blower will also be determined.In other words, if the gas temperature, pressure, flow rate, etc. at the blower inlet are constant, the temperature, gas pressure, etc., at the outlet will also be fixed. become. In this way, the heat exchanger on the outlet side of the blower has gas temperature,
Pressure, flow rate, etc. enter under certain conditions. Therefore, if the temperature and amount of refrigerant 1, such as cooling water, for cooling this gas are kept constant and flows into the heat exchanger on the outlet side of this blower, the temperature difference between the inlet and the outlet will be constant. Therefore, by adjusting the flow rate of cooling water flowing into the heat exchanger on the outlet side of the blower, the temperature of the cooling water exiting from this heat exchanger can be brought to a temperature higher than the dew point.

Since the refrigerant (cooling water) having a temperature higher than this dew point temperature is used to cool the output mirror and the total reflection mirror, it is possible to cool the output mirror without causing dew condensation on the output mirror. Furthermore, since this refrigerant is passed through the support rod of the resonator, it is possible to maintain the support rod at a constant temperature without causing dew condensation.

[Example] The present invention will be described below based on the illustrated example. FIG. 1 shows an embodiment of the invention. As shown in the figure, the laser gas is fed under pressure by a Roots blower 1, and a second heat exchanger 2 and a third heat exchanger 3 are arranged on the exit side to cool the compressed and heated laser gas, and a gas connection pipe 4 connected by. When the laser gas exiting the third heat exchanger 3 passes through the discharge tube 5, it is excited by a glow discharge generated between discharge electrodes 7 and 8 connected to a high voltage power source 6. A part of the discharge input energy is extracted from the output mirror 9 as laser light.

The remainder is stored in the laser gas as heat, and is taken away by cooling water when passing through the first heat exchanger 10.

The output mirror 9 is attached to an output mirror support plate 11 and fixed by an output mirror holder 12 provided with a hole through which cooling water passes. Similarly, the total reflection mirror 13 is fixed by a total reflection mirror support plate 14 and a total reflection mirror holder 15.

These output mirrors9. Connecting bellows 5a and 5b are provided between the total reflection mirror 13 and the discharge tube 5.

The output mirror 9 and the total reflection mirror 13 are processed into pipe shapes and have a support rod 16 with a low expansion coefficient that allows cooling water to pass through.
, 17 at a predetermined interval. and discharge tube 5. Output It19. A cooling device 2!19 is provided for supplying a constant temperature and amount of cooling water to the resonator 18, which is composed of the total reflection mirror 13, support rods 16, 17, and the like. In this embodiment of the laser generator configured as described above, the output mirror 9. The total reflection mirror 13 is cooled with cooling water that has passed through the second heat exchanger 2 from the cooling device 19.

By doing this, cooling water with a stable temperature higher than the dew point temperature is supplied to cool the resonator 18, preventing damage to the output mirror 9 due to dew condensation, and stabilizing the laser output. By supplying cooling water at a stable temperature higher than the dew point temperature for cooling, it is possible to obtain a laser generator that can prevent damage to the output mirror 9 due to dew condensation and stabilize the laser output.

In other words, a cooling device 19 that supplies a constant amount of water at a constant temperature.
The cooling water 20 indicated by the arrow in the figure that has exited is divided into cooling water 21a that enters the third heat exchanger 3 and cooling water 22a that is sent to the second heat exchanger 2. The cooling water 21b that has passed through the third heat exchanger 3 passes through the first heat exchanger 1o, and then passes through the cooling system! ! Return to 19. Second
The flow rate of the cooling water 22a flowing into the heat exchanger 2 is adjusted by the flow rate adjustment valve 23, and the cooling water 22b becomes cooling water 22b and enters the second heat exchanger 2. The cooling water 220 that exits the second heat exchanger 2 has a dew point. temperature is maintained above the temperature. The cooling water 22c leaving the second heat exchanger 2 passes through the support rods 16 and 17, and then passes through the total reflection mirror 13. The output mirror 9 is cooled. The cooling water 22g that has exited the output mirror holder 12 joins the cooling water 21c that has exited the first heat exchanger 10 and returns to the cooling device 19. That is, the cooling water 20 that has exited the cooling device 19 is divided into cooling water 22a.
.

22b, 22c, 22d, 22e, and 22f become the cooling water 22g, which is the other branched water of the cooling water 20.

It joins with the cooling water 21c that has passed through the cooling water 21a and 21b, becomes the cooling water 24, and returns to the cooling device 19. Of these, cooling water 22c that has passed through the second heat exchanger 2 from the cooling device 19
Total reflection mirror 13. Although the output mirror 9 is cooled, the temperature, pressure, and flow rate of the laser gas flow exiting the Roots blower 1 are constant without being affected by the ambient temperature or discharge conditions as described above, so the amount of heat exchanged by the second heat exchanger 2 is becomes constant by keeping the amount of cooling water 22b constant. Since the cooling water 22c leaving the second heat exchanger 2 is first flowed to the support rods 16 and 17,
Output that changes depending on the size of the laser output! ! 9 and total reflection fi13
The expansion and contraction of the support rods 16 and 17 due to changes in temperature conditions is suppressed regardless of the loss of the support rods 16 and 17. Further, since the cooling water 22f having a temperature higher than the dew point is passed through, dew condensation on the output mirror 9 can be prevented. Since the flow rate of the cooling water 22b of the second heat exchanger 2 is restricted, the laser gas exiting the second heat exchanger 2 is transferred to the discharge tube 5.
The gas is not cooled by the time it is sent to the third
The heat exchanger 3 cools the laser beam again to a temperature that does not impair laser oscillation efficiency.

In this way, according to this embodiment, by sending stable cooling water at a temperature above the dew point temperature to the support rod of the resonator, it is possible to stabilize the expansion and contraction of the support rod due to thermal strain to a constant amount, thereby improving the stability of the output. is ensured.

Further, the cooling water having a temperature equal to or higher than the dew point temperature is used to cool the output mirror, and the output mirror can be cooled without causing dew condensation, thereby extending its life. Furthermore, no special cooling device is required to obtain cooling water above the dew point temperature, simplifying the operation and maintenance of the oscillator cooling system.

[Invention effect]

As described above, the present invention supplies cooling water with a temperature higher than the dew point temperature to cool the resonator, thereby preventing damage to the output mirror due to dew condensation and stabilizing the laser output. It is possible to obtain a laser generator that can supply a higher level of cooling water, prevent damage to the output mirror due to dew condensation, and stabilize the laser output.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a laser generator according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A resonator composed of a discharge tube that excites laser gas by discharge, an output mirror disposed opposite to each other across the discharge tube, a total reflection mirror, and a support rod that supports the discharge tube; A roots blower that pumps and supplies laser gas to a discharge tube, a first heat exchanger that cools the laser gas heated by discharge in the discharge tube, and a second heat exchanger that cools the laser gas compressed and heated by the roots blower. , the first and second heat exchangers are supplied with cooling water at a constant temperature and amount from a cooling device, and the output mirror is supported by an output mirror support plate and an output mirror holder connected to one end of the support rod. In the laser generator, the total reflection mirror is supported by a total reflection mirror support plate and a total reflection mirror holder connected to the other end side of the support rod, and the output mirror and the total reflection mirror are connected to the cooling device. A laser generator characterized in that the laser generator is cooled by cooling water that has passed through the second heat exchanger. 2. The laser emitting device according to claim 1, wherein the support rod is hollow and is kept at a constant temperature by cooling water that has passed through the second heat exchanger.