JPH11274612A - Solid laser oscillator and laser marking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make performing a stable operation for a long time, by preventing a sealing ring for cooling water which contacts to both terminal surfaces of a filter cylinder by a spring from degrading caused by exciting light radiation without accompanying with leaking of the cooling water. SOLUTION: This device is comprised of inserting holes 3a and 3b of a laser rod 1 and an exciting lamp 2 being provided, an O ring 6 which is equipped in a recess gap 5a formed on an end cap 5 and contact with a terminal face of a filter cylinder 3 by a spring, sealing a space between the terminal face of the filter cylinder 3 and the end cap 5 to support the filter cylinder 3, a light screen ring 7 being provided between an inside peripheral face of the recess gap 5 and the O ring 6. The light screening ring 7 shuts a gap t which is formed between the end gap 5 to allow an extension of the filter cylinder 3 caused by a thermal expansion, reflects an excitation light which is radiated from the exciting lamp 2 and directly irradiates the O ring 6 via the gap t and prevents the O ring 6 from degrading caused by the irradiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser oscillator such as a YAG laser and a laser marking apparatus using the same, and more particularly, to a structure of a laser chamber used as a source of stimulated emission light in these oscillators.

[0002]

2. Description of the Related Art A laser marking apparatus for irradiating a surface of various articles with a laser beam to mark a pattern such as a character or a figure can form an indelible pattern. Responsible Liability Act) has been receiving attention with the enforcement of the
A laser marking device using a solid-state laser typified by a G (yttrium, aluminum, garnet) laser provides high laser output, is easy to focus on a small spot, and can be used for metal, resin, ceramics, etc. It has been widely used in various industrial fields as a marking device capable of forming a fine pattern under non-contact irrespective of the material of the article.

[0003] Laser marking with a solid-state laser is performed by irradiating the surface of a target article with a solid-state laser beam emitted by a laser oscillator while appropriately scanning by the operation of a scanning optical system. The YAG laser oscillator incorporates a rod (laser rod) of an active substance, which is a rod-like crystal of YAG to which an appropriate amount of Nd (neodymium) is added, and a rod-shaped excitation lamp using a krypton arc lamp or the like. A laser chamber, and an output mirror and a reflection mirror which are arranged opposite to each other at a predetermined distance along an optical path of stimulated emission light emitted from the laser chamber as described later, and an aperture (mode) is provided between these mirrors. Selector, a Q switch, a laser shutter, and other necessary components.

[0004] The reflection mirror is a mirror capable of substantially total reflection, and the output mirror is a mirror having a reflectivity capable of transmitting a part of the irradiation light, and is a stimulated emission light emitted from the laser chamber. Is amplified during the multiple reflections between the output mirror and the reflection mirror, becomes a laser beam, passes through the output mirror, and is emitted to a scanning head having a built-in scanning optical system.

[0005] The aperture is a shielding plate in which an opening smaller than the diameter of the laser rod is aligned with the center of the optical path of the stimulated emission light, and has a mode selection function of suppressing unnecessary mode oscillation. This mode selection is necessary for improving the quality of marking. The Q switch cuts the optical path of the stimulated emission light reciprocating between the output mirror and the reflection mirror in a short cycle, and has a merit number (Q value) as a resonator.
And the operation of controlling the on / off of the laser beam at a high speed is performed.

In the solid-state laser oscillator as described above, the laser chamber, which is a source of stimulated emission light, efficiently irradiates the laser rod with high-intensity excitation light emitted by the excitation lamp, so that both ends of the laser rod are provided. The operation of emitting stimulated emission light from the device is performed, and is configured as shown in FIG.

In FIG. 1, reference numeral 1 denotes a laser rod, and 2 denotes an excitation lamp. These are inserted through separate insertion holes 3a and 3b formed in a filter tube 3, and are mounted on a base 4 together with the filter tube 3. It is horizontally supported between a pair of upright end caps 5.

FIG. 6 is a cross-sectional view of the filter tube 3 taken along line VI-VI of FIG. As shown in FIG.
A cylindrical body made of quartz glass having an oval cross section, and functions as an optical filter that transmits light in the absorption wavelength range of the laser rod 1. The insertion holes 3a and 3b are formed at two center positions in the cross section of the filter tube 3 as through holes that pass through the filter tube 3 in the longitudinal direction and are parallel to each other. The outside of the filter tube 3 is a diffuse reflection layer 30 having a predetermined thickness.
Covered by The diffuse reflection layer 30 has a slightly larger constraining tube 31 disposed outside the filter tube 3, and a barium sulfate (BaSO ₄₎ having a high light reflectivity is provided in an annular gap formed therebetween. ) Is packed, and both ends in the longitudinal direction of the filter tube 3 are solidified with an adhesive.

Each of the end caps 5 has a recess corresponding to the cross section of the filter tube 3 on the side facing each, and the filter tube 3 has both ends in the corresponding recess. It is fitted and supported. Further, the laser rod 1 and the excitation lamp 2 are supported by inserting respective protruding portions on both sides of the filter tube 3 into respective support holes formed at corresponding positions of the end caps 5, 5. As shown in FIG. 6, the laser rod 1 and the excitation lamp 2 supported in this way are coaxially positioned with an appropriate gap inside the insertion holes 3a and 3b.

Both ends of the laser rod 1 and the excitation lamp 2 are projected outside the end caps 5 and 5, and the excitation lamp 2 is turned on and emits light by power supply from a power supply socket (not shown) connected to the protruding end. It is made to do. This light is transmitted through the filter tube 3 and passes through the diffuse reflection layer 30.
The laser beam is diffused and reflected by the diffuse reflection tank 30 and efficiently irradiates the laser rod 1. In response to this irradiation, the laser rod 1 emits stimulated emission light from the protruding ends of the end caps 5 and 5 outside. The stimulated emission light is emitted as a laser beam by multiple reflection between the output mirror and the reflection mirror.

In the laser chamber 10 operating as described above, the conversion efficiency when the excitation light emitted from the excitation lamp 2 is converted into the stimulated emission light emitted from the laser rod 1 is at most only about several percent. The lighting of the excitation lamp 2 requires a large amount of electric power of several kW, and the amount of heat generated by the lighting is large. Therefore, the laser rod 1 and the excitation lamp 2 are combined with the filter tube 3 for accommodating them. In addition, a water cooling structure in which water is continuously cooled by cooling water continuously supplied from the outside is adopted.

As shown in FIG. 5, cavities are provided inside the end caps 5, 5 supporting both sides of the filter tube 3, and these are provided with water supply passages 4 formed at corresponding positions of the base 4.
O and the O-ring 6, which is in communication with the drain passage 41 and is interposed between the end face of the filter tube 3 and the O-ring wound around the support holes of the laser rod 1 and the excitation lamp 2, respectively. The cooling water inlet chamber 50 and the outlet chamber 51 are tightly sealed.

FIG. 7 is an enlarged view of the vicinity of the sealing portion formed by the O-ring 6. As shown in FIG. As shown in the drawing, the O-ring 6 is fitted into a concave groove 5a provided on the bottom of a concave portion provided in the end cap 5 for fitting the filter cylinder 3, and the bottom surface of the concave groove 5a and the end face of the filter cylinder 3 It is hit by a bullet. The O-ring 6 is located outside the openings of the insertion holes 3a and 3b of the laser rod 1 and the excitation lamp 2 as shown by a broken line in FIG. I have.

The cooling water of the laser chamber 10 is supplied to the base 4
The water is supplied to the water supply passage 40 from a water supply hose (not shown) connected to the side surface of the water supply passage, and is introduced into the introduction chamber 50 communicating with the water supply passage 40 as indicated by an arrow in FIG. The introduction room 50
As shown in FIG. 6, the openings of the insertion holes 3a and 3b have annular gaps on the outside of the laser rod 1 and the excitation lamp 2, respectively, and are introduced into the introduction chamber 50. The cooling water flows into the respective annular gaps and flows as high-speed turbulent flow toward the other end cap 5, during which the laser rod 1 and the excitation lamp 2 are moved from the outside and the filter tube 3
From the inside efficiently.

A drain hose (not shown) is connected to a drain passage 41 communicating with the outlet chamber 51 formed in the other end cap 5, and cooling water flowing through the insertion holes 3a and 3b is supplied to the outlet chamber 51. Then, it is discharged to a drain hose through a drain channel 41.

[0016]

However, in the laser chamber 10 as described above, the O-rings 6, 6 elastically contacting both end surfaces of the filter tube 3 are deteriorated early during the operation, and the O-ring 6, 6 6, the cooling water leaks from the sealing position.

When leakage of the cooling water occurs, there is a risk of causing an accident such as a short circuit in peripheral devices of the laser chamber 10 and also a barium sulfate powder constituting the diffuse reflection layer 30 outside the filter tube 3. When the cooling water is absorbed by the body and evaporates inside the cooling water, there is a possibility that the quartz glass filter cylinder 3 and the laser rod 1 and the excitation lamp 2 therein may be damaged. It is an important issue to prevent the O-rings 6 and 6 from deteriorating.

As described above, the O-rings 6 and 6 are in elastic contact with the end surface of the filter tube 3, and the filter tube 3 is heated by the heat generated by the excitation lamp 2 during operation. Therefore, it is considered that deterioration can be reduced by using a material having excellent heat resistance as the O-rings 6, 6.
However, even in this case, the deterioration prevention effect actually obtained is small, and the leakage of the cooling water cannot be effectively prevented. O-rings 6, 6
The same applies when other types of sealing rings, such as X-rings and V-rings, are used instead.

As described above, conventionally, the filter tube 3
In order to prevent the deterioration of the sealing rings (O-rings 6 and 6) for sealing both ends of the sealing ring and to eliminate the above-mentioned inconvenience caused by leakage of the cooling water, frequent replacement of the sealing ring is required. As a result, there is a problem that stable operation cannot be performed for a long period of time.

The present inventor conducted a detailed investigation to clarify the cause of the deterioration of the O-ring 6, and as a result,
Is not caused by the heat transmitted from the filter tube 3 in elastic contact therewith, but by the action of the high-intensity excitation light emitted from the excitation lamp 2, particularly between the end surface of the filter tube 3 and the end surface of the end cap 5. It has been found that the action is mainly caused by the action of the excitation light that is directly applied to the O-ring 6 through the determined gap t (see FIG. 7).

The gap t is necessary to allow the thermal expansion of the filter tube 3. When the gap t is substantially zero, the excitation light is directly irradiated on the O-ring 6. Is reduced, and the deterioration of the O-ring 6 due to this can be alleviated. On the other hand, when the filter tube 3 heated with the emission of the excitation lamp 2 expands in the axial direction due to thermal expansion, the end face of the end cap 5 is strongly applied. There is a possibility that the filter tube 3 may be mechanically damaged by being pressed.

As shown in FIG. 7, a gap is secured between the filter cylinder 3 and the end cap 5 in the radial direction of the fitting portion together with the gap t between the end faces thereof. Also, similar gaps are provided between the diffuse reflection layer 30 outside the filter tube 3 and the end cap 5, and these gaps allow the dimensional change of the filter tube 3 due to thermal expansion, thereby causing breakage. This is a configuration for preventing

As described above, the gap t between the filter tube 3 and the end cap 5 is necessary to prevent the filter tube 3 from being damaged due to thermal expansion, but the existence of the gap t is directly caused by the excitation light. Irradiation may cause deterioration of the O-ring 6 and cause the above-described inconvenience caused by leakage of the cooling water.

The present invention has been made in view of the above circumstances, and effectively prevents direct irradiation of excitation light to a sealing ring elastically contacting both end surfaces of a filter tube, thereby improving sealing performance. It is an object of the present invention to provide a solid-state laser oscillator capable of performing stable operation for a long time without causing a decrease and leakage of cooling water, and a laser marking device using the same.

[0025]

According to a first aspect of the present invention, there is provided a solid-state laser oscillator comprising: a filter tube including a laser rod and an insertion hole for an excitation lamp; and a diffuse reflection layer surrounding the outside of the filter tube. A support member for supporting both ends together with the protrusions of the laser rod and the excitation lamp on each side, and a mounting member mounted in a concave groove provided in the supporting member and elastically contacting an end face of the filter tube; A sealing ring for sealing the outside of the hole in a liquid-tight manner, and introducing cooling water into the inside of the insertion hole sealed by the sealing ring to cool heat generated by emission of the excitation lamp. In a solid-state laser oscillator including a laser chamber having a configuration, a light-shielding ring is provided between the inner peripheral surface of the concave groove and the sealing ring, the light-shielding ring being interposed by abutting one side to an end surface of the filter cylinder. Is characterized by That.

In the present invention, a light-shielding ring is interposed between the sealing ring and the inner peripheral surface of the mounting groove for the sealing ring.
The light-shielding ring is brought into contact with the end face of the filter tube to close a gap formed between the filter tube and the support member, and reflects excitation light applied to the sealing ring through the gap to seal the gap. Prevents the stop ring from deteriorating.

[0027] The solid-state laser oscillator according to the second invention comprises:
The light-shielding ring is characterized in that the surface of a metal core is plated with gold.

In the present invention, the surface of a metal core is plated with gold to form a light-shielding ring, a predetermined strength is secured by the core, and a gap between the sealing ring and the inner peripheral surface of the concave groove is formed. In the mounted state interposed in the filter member, one side thereof is brought into contact with the end face of the filter cylinder to securely maintain a desired mounting posture for closing a gap between the filter member and the gold plating on the surface of the core material. The layer reflects the excitation light with high efficiency and effectively prevents the excitation light from irradiating the sealing ring.

A laser marking apparatus according to the present invention is characterized in that the solid-state laser oscillator according to the first or second invention is provided as a source of a laser beam for marking.

In the present invention, by providing a laser chamber capable of preventing leakage of cooling water, stable operation can be performed for a long period of time without frequent maintenance work for replacing the sealing ring. The resulting laser marking device is configured.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a front view showing the overall configuration of a laser marking device provided with a solid-state laser oscillator according to the present invention.

As shown in the figure, the solid-state laser oscillator according to the present invention has a laser chamber 10 inside a box-shaped support case 11.
Is provided. The configuration of the laser chamber 10 is the same as that shown in FIG. 5, and includes a base 4 fixed to a bottom plate of a support case 11, and a pair of end caps as support members erected on the upper surface of the base 4. 5 and 5, a filter tube 3 horizontally supported between these end caps 5 and 5, a laser rod 1 and an excitation lamp 2 housed in the filter tube 3.

The end caps 5, 5 are provided on both sides in the width direction of the base 4 with support rods 52, 52 spanned therebetween.
(Only one side is shown), the base 4 is positioned at a predetermined distance in the longitudinal direction. The filter tube 3 has both ends fitted into recesses formed in the opposing surfaces of the end caps 5, 5, and is supported with a sealing structure described later between each. The laser rod 1 and the excitation lamp 2 respectively inserted into the insertion holes 3a, 3b penetrating the cylinder 3 are supported outside the end caps 5, 5 with both ends protruding, and as shown in FIG. It is positioned coaxially with an annular gap inside the other insertion holes 3a and 3b.

A power supply socket (not shown) is connected to a protruding end of the excitation lamp 2 to the outside of the end caps 5, 5, and the excitation light emitted from the excitation lamp 2 by the power supply from the socket is, as described above, The light passes through the filter tube 3, is diffusely reflected by the diffuse reflection layer 30 outside the filter tube 3, and is efficiently radiated to the laser rod 1. The stimulated emission light is emitted as shown by a dashed line in FIG.

On one side of the laser chamber 10, there is an aperture A and an output mirror M on the optical path of the stimulated emission light to the same side.
_{And 1} are arranged in this order. Also laser chamber 10
The optical path of the stimulated emission light on the other side is controlled by a pair of mirrors 14 and 15 inside a mirror holder 13 arranged at an appropriate distance on the same side.
Are folded in opposite directions at the upper position, this folded optical path, the Q-switch 16 and the reflection mirror M ₂ are arranged in parallel in this order.

The output mirror M ₁ is a mirror having a reflectivity capable of partially transmitting light, and is attached to the optical path of the stimulated emission light emitted from the laser chamber 10 with the center of the mirror surface facing the center. . The aperture A is a shielding plate having a small-diameter opening corresponding to the diameter of the laser rod 1 that emits stimulated emission light, and is mounted so that the center of the opening is aligned with the optical path of the stimulated emission light.

The reflecting mirror M ₂ is a mirror capable of substantially total reflection, and is mounted with the center of the mirror surface facing the folded optical path. Thus arranged the reflection mirror M ₂ is induction in the optical path of the stimulated emission light, including a folded optical path, will be facing separating the output mirror M ₁ and the predetermined distance, emanating from the laser chamber 10 emitted light is amplified during the multiple reflections between the output mirror M ₁ and the reflection mirror M ₂ to become a laser beam, it is sent out through the output mirror M _1.

At this time, the aperture A performs a mode selecting action for suppressing the oscillation of an unnecessary mode and optimizing the mode of the transmitted laser beam. Q switch 16
Enhances the merit of the resonator between the output mirror M ₁ and the reflection mirror M ₂ (Q value), to generate a population inversion of excited atoms, an action to take out the laser pulses with high output. These apertures A and Q switch 16, similarly to the reflection mirror M _2, it is mounted correctly positioned in the folded optical path.

As shown in FIG. 1, the laser marking device includes a scanning head H having a scanning optical system built in, outside the end wall of the supporting case 11 which is the laser beam sending side of the solid-state laser oscillator configured as described above. The laser beam emitted from the solid-state laser oscillator as described above is introduced into the scanning head H, and is scanned by the operation of an optical system incorporated in the scanning head H. Condenser lens L attached to the part (the lower part in FIG. 1)
Then, the target object is irradiated with the mark through the scanning trajectory to perform marking of a pattern such as a character or a figure.

Now, in the solid-state laser oscillator and the laser marking device configured as described above, a feature of the present invention resides in the configuration of the laser chamber 10 serving as a source of stimulated emission light.

The overall configuration of the laser chamber 10 is shown in FIG.
And the same as the conventional laser chamber 10 shown in FIG.
A filter tube 3 made of quartz glass whose outside is covered with a diffuse reflection layer 30 is mounted on a base together with a laser rod 1 and an excitation lamp 2 respectively inserted through insertion holes 3a and 3b formed through the filter tube 3. 4 is supported laterally between a pair of end caps 5 and 5 which are attached at a suitable length on the top 4.

Inside one end cap 5, a cooling water introduction chamber 50 communicating with a water supply passage 40 formed in the base 4 is provided.
However, inside the other end cap 5, a cooling water outlet chamber 51 communicating with a drain passage 41 formed in the base 4 is formed, respectively, and accommodates the laser rod 1, the excitation lamp 2, and these. The filter tube 3 is an inlet chamber 50 through a water supply passage 40.
The cooling water introduced into the chamber and discharged through the outlet chamber 51 and the drain passage 41 flows at high speed through the annular gap between the laser rod 1 and the excitation lamp 2 and these insertion holes 3a and 3b. It is configured to be water-cooled.

The feature of the present invention lies in the structure of the sealing portion for sealing the space between the filter cylinder 3 and the end cap 5 so as to maintain the liquid-tight state of the introduction chamber 50 or the discharge chamber 51 as described above. FIG.
Is a cross-sectional view of the vicinity of the sealing portion on the introduction chamber 50 side.
Is sealed by fitting an O-ring 6 into a groove 5a provided around the bottom of a recess formed in the end cap 5 so as to fit the end of the filter tube 3 and fitting the O-ring 6 into the groove. This is performed by elastically contacting the end face of the filter tube 3 facing the opening side of 5a.

The O-ring 6 is arranged so as to go around the outside of the openings of the insertion holes 3a and 3b of the laser rod 1 and the excitation lamp 2, as in the conventional laser chamber 10 shown in FIGS. The outsides of these openings are collectively sealed. A predetermined gap t is formed between the end surface of the filter tube 3 where the O-ring 6 elastically contacts and the end surface of the end cap 5 so as to allow thermal expansion of the filter tube 3 due to heat generation of the excitation lamp 2. . The gap t is ensured in the assembly stage by adjusting the length of the support rods 52, 52 and changing the distance between the end caps 5, 5.

In the present invention, a light-shielding ring 7 is fitted on the inner peripheral surface of the concave groove 5a in which the O-ring 6 is mounted, as shown in FIG. The peripheral edge on one side is brought into contact with the end face of the filter tube 3 and the gap t
Is interposed so as to cover the entire circumference.

FIG. 3 is an explanatory view of the procedure for assembling the sealing portion. As shown in the figure, the light-shielding ring 7 is a ring-shaped member having a rectangular cross-section, and has a metal core formed on the outer peripheral surface of the concave groove 5a. (Au) The plating is applied.

The light-shielding ring 7 is pushed into the inner peripheral surface of the concave groove 5a in which the O-ring 6 is fitted as shown by an arrow in the figure, and the filter cylinder 3 is pushed into the end cap 5 in this state. As shown in FIG. 2, the O-ring 6 and the concave groove
It is interposed between the inner peripheral surface of the filter 5a and the inner peripheral surface of the filter tube 3a, and the elasticity of the O-ring 6 provides a mounting state in which one peripheral edge is in contact with the end surface of the filter tube 3.

The width W of the light-shielding ring 7 is set so that the gap t can be closed in the mounted state shown in FIG. 2 and the thermal expansion of the filter cylinder 3 can be allowed by entering the concave groove 5a. It is set to be larger than the gap t and smaller than the depth D of the concave groove 5a. Although there is no dimensional restriction on the thickness of the light-shielding ring 7, the thickness of the light-shielding ring 7 is equal to or equal to the width W so as not to cause excessive deformation of the O-ring 6 at the elastic contact portion with the light-shielding ring 7 as shown in FIG. It is better to set it below this. The configuration of the sealing portion as described above is performed not only on the introduction chamber 50 side shown in FIG.

As described above, the laser chamber 10 sorts the excitation light emitted from the excitation lamp 2 by the filter effect of the filter tube 3 and diffuses and reflects light near the excitation wavelength to the diffuse reflection layer 30 to irradiate the laser rod 1. The laser rod 1 emits stimulated emission light, and water is cooled by cooling water flowing from the introduction chamber 50 to the extraction chamber 51 to absorb the heat generated at this time. Is allowed by the gap secured between the filter tube 3 and the end cap 5.

At this time, the excitation light emitted from the excitation lamp 2 passes through the gap between the filter tube 3 and the end cap 5 and irradiates the O-ring 6 having the above-described sealing action between the two. However, in the present invention, the gap t is closed by the light-shielding ring 7 interposed as described above, and the surface of the light-shielding ring 7 has gold (Au) having good light reflectance. ), The excitation light is reflected by the surface of the light-blocking ring 7 and does not directly irradiate the O-ring 6.
The intensity of the excitation light applied to the O-ring 6 is reduced, and the deterioration of the O-ring 6 caused by the action of the excitation light can be greatly reduced.

The surface of the light-shielding ring 7 having such an action can firstly reflect light with high efficiency. Secondly, the surface of the light-shielding ring 7 can be exposed to high-intensity excitation light. Third, the laser rod 1 and the excitation lamp 2 do not generate ions and maintain good reflectivity without causing deterioration such as oxidation.
Fourth, it is necessary not to contaminate the pure water used as the cooling water for the filter tube 3. Fourth, it is necessary to endure heating by the excitation lamp 2, and gold (Au) is a substance that can satisfy all of these conditions. ) Is optimal.

In the mounted state shown in FIG. 2, the light-shielding ring 7 must be securely in contact with the end face of the filter tube 3 to reliably maintain the posture for closing the gap t. Rigidity that does not deform under external force applied during use is required. For this reason, the light-blocking ring 7 has a configuration in which the surface of a metal core is plated with gold as described above. As the material of the core material, an appropriate metal material can be used, but in practice, copper (Cu) is used as a material that is easy to mold and easy to gold-plate. In addition, the light shielding ring 7
Is not limited to a rectangular shape as shown in the figure, and an appropriate cross-sectional shape such as a circle, an ellipse, and a triangle can be adopted.

FIG. 4 is an enlarged sectional view showing the vicinity of a sealing portion at an end of a filter tube 3 according to another embodiment of the present invention. In this embodiment, the above-described light-shielding ring 7 is interposed between the O-ring 6 and the inner peripheral surface of the concave groove 5a for mounting the O-ring 6, and the filter in which the O-ring 6 elastically contacts. A reflecting layer 8 made of gold (Au) is formed on the end face of the tube 3.

According to this structure, the excitation light directly irradiated through the gap t is reflected by the light-shielding ring 7 and, as indicated by the arrow in the drawing, the diffuse reflection layer 30 is formed.
The excitation light radiated toward the end face of the filter tube 3 after being diffused and reflected by the O-ring 6 is reflected by the reflection layer 8 and the intensity of the excitation light radiated to the O-ring 6 Is greatly reduced, and the deterioration of the O-ring 6 caused by the action of the excitation light can be more effectively prevented.

The reflection layer 8 can be formed by attaching a gold foil to the end face of the filter tube 3 or by depositing gold. Further, the formation range of the reflection layer 8 does not need to cover the entire end face of the filter tube 3 and may include at least the periphery of the elastic contact portion with the O-ring 6.

In the above embodiment, the case where the O-ring 6 is used as the sealing ring for sealing the end of the filter tube 3 has been described. However, other types of sealing such as X-ring and V-ring are used. It goes without saying that a stop ring may be used.

[0057]

As described above in detail, in the solid-state laser oscillator according to the present invention, a sealing ring for sealing between the end surface of the filter tube in which the laser rod and the excitation lamp are inserted and the supporting member, A light-shielding ring is interposed between the mounting groove and one end of the filter cylinder so as to abut against the end face of the filter cylinder, and is secured between the filter cylinder and the support member to absorb the thermal expansion of the filter cylinder. Because the gap is closed, the excitation light that is directly applied to the sealing ring through the gap is reflected by the light-blocking ring, and the degradation of the O-ring due to the action of the excitation light can be suppressed. Leakage of the cooling water for cooling the lamp and the filter tube can be reliably prevented, and the inconvenience associated with the leakage can be obviated.

Further, since the light-shielding ring is formed by plating the surface of a metal core with gold, the excitation light can be efficiently reflected and the state of contact with the end face of the filter tube is impaired. Therefore, direct irradiation of the excitation light can be reliably prevented.

Further, the laser marking device according to the present invention is provided with the laser chamber capable of effectively preventing the leakage of the cooling water, so that the laser marking device is stable for a long time without inconvenience caused by the leakage of the cooling water. The present invention has an excellent effect, for example, such that it is possible to perform the operation in a suitable manner.

[Brief description of the drawings]

FIG. 1 is a front view showing the overall configuration of a laser marking device provided with a solid-state laser oscillator according to the present invention.

FIG. 2 is an enlarged cross-sectional view near a sealing portion at an end of a filter tube.

FIG. 3 is an explanatory diagram of a procedure for assembling a sealing unit shown in FIG. 2;

FIG. 4 is an enlarged sectional view showing the vicinity of a sealing portion at an end of a filter tube according to another embodiment of the present invention.

FIG. 5 is a sectional view of a laser chamber.

FIG. 6 is a cross-sectional view of the filter tube taken along line VI-VI in FIG.

FIG. 7 is an enlarged cross-sectional view near a sealing portion at an end of a filter tube in a conventional laser chamber.

[Explanation of symbols]

 Reference Signs List 1 laser rod 2 excitation lamp 3 filter tube 3a insertion hole 3b insertion hole 4 base 5 end cap 5a concave groove 6 O-ring 7 light-shielding ring 8 reflection layer 10 laser chamber 30 diffuse reflection layer

Claims (3)

[Claims] 1. A filter cylinder having a laser rod and an excitation lamp insertion hole and a diffuse reflection layer surrounding the outside thereof, and the laser rod and the excitation lamp protruding portions at both ends of the filter cylinder toward respective sides. And a sealing ring mounted in a concave groove provided on the supporting member and elastically contacting the end surface of the filter cylinder to seal the outside of the mounting hole in a liquid-tight manner, In a solid-state laser oscillator including a laser chamber configured to introduce cooling water into the insertion hole sealed by the sealing ring and to cool heat generated by emission of the excitation lamp, A solid-state laser oscillator, comprising: a light-shielding ring interposed between a peripheral surface and the sealing ring with one side abutting on an end surface of the filter cylinder. 2. The solid-state laser oscillator according to claim 1, wherein said light-shielding ring is formed by applying gold plating to a surface of a metal core material. 3. A laser marking device comprising the solid-state laser oscillator according to claim 1 or 2 as a source of a marking laser beam.