JPH11326970A - Nonlinear crystal holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonlinear crystal holder which is inexpensive, has high performance and high quality and allows the easy reproduction of the initial performance and function even at the time of service and maintenance. SOLUTION: This holder has two holder blocks 2a, 2b holding the opposite two surfaces of a non-optical system of a nonlinear crystal 1 and a heat sink 3 mounted at the same direction end faces of these holder blocks. The holder blocks described above consist of material having a good thermal conductivity from at least the portion facing the nonlinear crystal 1 to the portion in contact with the heat sink 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonlinear crystal holder for holding a nonlinear optical crystal (hereinafter abbreviated as "nonlinear crystal") that generates a harmonic oscillation of a laser beam by passing the laser beam, and more particularly to a harmonic crystal holder. The present invention relates to a nonlinear crystal holder for stabilizing an oscillation laser beam and improving quality.

[0002]

2. Description of the Related Art A technique of making a laser beam incident on a nonlinear crystal to generate a harmonic laser beam having a wavelength different from that of the original laser beam is well known as wavelength conversion, and examples thereof are introduced in various documents. In addition, the nonlinear crystal absorbs the laser beam, especially during wavelength conversion, and changes the wavelength conversion efficiency and the like due to thermal deformation and non-uniform temperature distribution. There have been many reports on the temperature maintenance and exhaust heat structure of the nonlinear crystal to suppress the instability of the crystal.

For example, Japanese Patent Application Laid-Open No. 5-41557 discloses a structure in which a nonlinear crystal is embedded in a disk-shaped holder, a Peltier element with holes is brought into contact with the surface of the holder, and a heat sink with holes is further attached. Have been. Japanese Patent Application Laid-Open No. Hei 5-72577 discloses a structure in which a nonlinear crystal is fastened with screws using two copper metal plates having V-shaped grooves. Japanese Patent Application Laid-Open No. Hei 6-196775 discloses a structure in which a nonlinear crystal is maintained at a temperature higher than room temperature by a heater. Japanese Patent Application Laid-Open No. 6-196776 discloses a configuration in which Peltier elements are attached to two opposing surfaces of a nonlinear crystal.

FIG. 3 shows the configuration of a conventional nonlinear crystal holder disclosed in Japanese Patent Application Laid-Open No. 6-196776.
In the figure, reference numeral 1 denotes a prism-shaped nonlinear crystal, and two Peltier elements 14a and 14b are attached to two opposing surfaces. The wavelength-converted laser beam is emitted in the direction of the arrow in the figure. The laser beam slightly absorbed by the nonlinear crystal 1 during wavelength conversion raises the temperature of the nonlinear crystal 1 and induces thermal deformation of the crystal, thereby acting and operating to impair the stability of the wavelength-converted laser beam. Since the cooling temperature is sufficiently controlled by the two Peltier elements 14a and 14b,
A harmonic oscillation laser beam can be generated by stable wavelength conversion.

[0005]

The conventional nonlinear crystal holder is expensive because it has a structure in which Peltier elements are attached to two opposing surfaces of the nonlinear crystal, and the nonlinear crystal is cleaned or replaced. After reassembly at the time of service or maintenance, there were quality problems such as difficulty in reproducing the same performance / function. Structures such as embedding expensive nonlinear crystals in holders, properly tightening with screws, attaching Peltier elements, etc. are at the laboratory level without considering serviceability, maintainability, and service costs, such as industrial use At the product level, there were problems such as lack of practicality. In the past, some nonlinear crystal materials had deliquescence, and it was necessary to maintain them at high temperatures.However, with recent technology, high-quality non-linear crystals that operate at room temperature have also emerged, and commercialization has been rapid. Tend to expand.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an inexpensive, high-performance, high-quality non-linear crystal holder that can easily reproduce the original performance and function even during service and maintenance. The purpose is to provide.

[0007]

A non-linear crystal holder according to the present invention is a non-linear crystal holder for holding a non-linear crystal that generates a harmonic oscillation of the laser beam by passing the laser beam. It comprises two holder blocks for sandwiching two opposing surfaces of a non-optical system of a crystal, and a heat sink attached to an end surface of the holder block in the same direction. The portion up to the portion in contact with the heat sink is made of a material having good thermal conductivity.

Further, the heat sink is a Peltier element.

In addition, the two holder blocks have a pressing means for pressing the two opposing surfaces of the nonlinear crystal with a constant force.

[0010] The two holder blocks have moving direction restricting means for restricting the moving direction in the direction sandwiching the nonlinear crystal.

Further, the end faces of the two holder blocks in the same direction attached to the heat sink are simultaneously processed in a state combined with the movement direction restricting means.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a structural diagram showing a nonlinear crystal holder according to Embodiment 1 of the present invention, and FIG. 2 shows a cross section taken along line AA of FIG. Reference numeral 1 denotes a non-linear crystal, which has a prism shape, and emits a laser beam whose wavelength is converted in the direction of the arrow in the figure. Nonlinear crystal 1
The two opposing surfaces are sandwiched between two holder blocks 2a and 2b. A thermoelectric (Peltier) element 3 is in contact with the end faces B of the holder blocks 2a and 2b in the same direction, and the thermoelectric (Peltier) element 3 Holder blocks 2a, 2
The cooling block 4 is in contact with the surface on the opposite side in contact with b.

The cooling block 4 is provided with a cooling water passage 11, a cooling water inlet 12, and a cooling water outlet 13. The holder block 2b is provided with two counterbore holes 10a and 10b. The compression coil springs 8a and 8b are inserted into the holder block 2b, and the stepped screws 9a and 9b are screwed into the holder block 2a to assemble the nonlinear crystal 1. It is configured to hold by pressure.

Although not shown, the holder blocks 2a, 2b and the thermoelectric (Peltier) have the same structure as described above.
The element 3, the thermoelectric (Peltier) element 3, and the cooling block 4 are configured to be held at a constant pressing force.

The holder block 2a is provided with two driving pin holes 6a and 6b, and the parallel pins 5a and 6b are provided.
5b are driven into each other and the opposing holder blocks 2b
Are provided with fitting pin holes 7a and 7b for fitting with the parallel pins 5a and 5b. The parallel pins 5a, 5b and the mating pin holes 7a, 7b are two holder blocks 2.
a and 2b are configured as means for restricting the moving direction in the direction sandwiching the nonlinear crystal 1.

Stepped screws 9a, 9b and parallel pin 5
As shown in FIG. 1, the arrangements of a and 5b are arranged so as to be out of phase with each other, so that the nonlinear crystal 1 is uniformly pressed by the compression coil spring. Before holding and assembling the nonlinear crystal 1, in a state where the two holder blocks 2 a and 2 b are assembled, both end faces B in the same direction, that is, a surface in contact with the thermoelectric (Peltier) element 3 are simultaneously processed in the assembled state. You.

The material of the holder blocks 2a, 2b is aluminum, copper, or the like, which is a metal having good heat conductivity (not limited to the above metals as long as it has good heat conductivity and exhibits a certain level of mechanical strength). Therefore, in the processing method, after performing ordinary machining, ultra-precision polishing is performed to achieve the required flatness and surface roughness.

In the experiment, the size of the nonlinear crystal was 5 × 5 ×
In the case of 15 mm, the size of the entire holder block is 2
5 × 25 × 25 mm, and the flatness of the end face B is 0.00
By setting the surface roughness to 5 mm and the surface roughness to 0.002 mm or less, a result was obtained in which the thermal resistance could be reduced to a required limit value or less.

1 and 2, holder blocks 2a, 2b
Has a structure in which a thermoelectric (Peltier) element 3 is in contact with the end face B of the non-linear crystal 1. When a Peltier element is used, the temperature control accuracy of the nonlinear crystal 1 becomes ± 0.1 ° C. It has been confirmed by calculation that the beam output stability can achieve ± 1% or less. As described above, it is possible to generate a stable harmonic oscillation laser beam with a simple structure and at low cost.

In addition, since the heat sink is formed of a Peltier element, it is possible to generate an inexpensive and more stable high quality harmonic oscillation laser beam.

[0021] Further, since the two holder blocks are provided with means for pressing the two opposing surfaces of the nonlinear crystal with a constant force, the contact surface pressure becomes constant, and the cooling temperature control accuracy is improved. A harmonic oscillation laser beam having a certain quality can be generated for service and maintenance.

Further, the two holder blocks have means for restricting the moving direction in the direction sandwiching the nonlinear crystal, so that the accuracy of holding the nonlinear crystal is improved, and a certain quality is provided for service and maintenance. A harmonic oscillation laser beam can be generated.

The end faces in the same direction attached to the heat sinks of the two holder blocks are simultaneously processed in a state combined with the movement direction regulating means, so that
The contact heat transfer effect between the two holder blocks and the heat sink and the balance of the exhaust heat of the two holder blocks are improved, and the cooling temperature control accuracy is improved. As a result, the harmonic oscillation laser beam can be stabilized and the holder can be used for service and maintenance. Even if the block is removed, the contact surface can be easily assembled with good reproducibility without requiring any advanced technology, so that a high-quality nonlinear crystal holder can be provided.

In applications where the output stability of the laser beam is not so important, the Peltier element is expensive, so that the cooling block 4 is directly brought into contact with the holder blocks 2a and 2b and the temperature of the nonlinear crystal 1 is controlled by water cooling temperature control. Control is simpler and cheaper. In the above embodiment, the positioning of the nonlinear crystal 1 is facilitated to determine the fixed position by providing a step on the contact surface of the nonlinear crystal 1 of the holder block 2a. It is not limited to. Holder blocks 2a, 2b
Needless to say, the required contact surface of the non-linear crystal 1 must have the required surface accuracy.

The means for pressing the holder blocks 2a, 2b against the non-linear crystal 1 with a constant force is not limited to the structure using the compression coil springs 8a, 8b as in this embodiment. The structure may be used.
Means for restricting the moving direction of the holder blocks 2a, 2b in the direction sandwiching the non-linear crystal 1 is the engagement pin holes 7a, 7b.
The structure is not limited to the structure using the b and the parallel pins 5a and 5b, but may be another guide structure such as a dovetail groove or a ball spline.

Although the holder blocks 2a and 2b are made of a material having good heat conductivity, at least a portion from a portion facing the nonlinear crystal to a portion in contact with the heat sink is made of a material having good heat conductivity. May be configured. In any case, the same effects as those of the nonlinear crystal holder according to the first embodiment of the present invention can be obtained.

[0027]

As described above, according to the present invention, there is provided a nonlinear crystal holder for holding a nonlinear crystal that generates a harmonic oscillation of the laser beam by passing the laser beam, and the non-optical system of the nonlinear crystal. And a heat sink attached to the end surface of the holder block in the same direction. The holder block has good heat conduction at least from a portion facing the nonlinear crystal to a portion in contact with the heat sink. By using a material having the property, there is an effect that a laser beam having a simple and inexpensive structure and a stable harmonic oscillation can be generated.

In addition, since the heat sink is formed of a Peltier element, there is an effect that a low-cost and more stable high-quality harmonic oscillation laser beam can be generated.

Further, since the two holder blocks have the pressing means for pressing the two opposing surfaces of the nonlinear crystal with a constant force, the contact surface pressure becomes constant and the cooling temperature control accuracy is improved. In addition, there is an effect that a harmonic oscillation laser beam having a certain quality can be generated for service and maintenance.

Further, since the two holder blocks have moving direction regulating means for regulating the moving direction in the direction sandwiching the nonlinear crystal, the holding accuracy of the nonlinear crystal is improved,
There is an effect that a harmonic oscillation laser beam having a certain quality can be generated for service and maintenance.

The end faces in the same direction attached to the heat sinks of the two holder blocks are simultaneously processed in a state where they are combined with the movement direction restricting means.
The contact heat transfer effect between the two holder blocks and the heat sink and the balance of the exhaust heat of the two holder blocks are improved, and the cooling temperature control accuracy is improved. As a result, the harmonic oscillation laser beam can be stabilized and the holder can be used for service and maintenance. Even if the block is removed, the contact surface can be easily assembled with good reproducibility without requiring any advanced technology, and thus it is possible to provide a high-quality nonlinear crystal holder.

[Brief description of the drawings]

FIG. 1 is a front view showing a nonlinear crystal holder according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view of the nonlinear crystal holder taken along line AA of FIG. 1;

FIG. 3 is a configuration diagram of a conventional nonlinear crystal holder.

[Explanation of symbols]

1 nonlinear crystal, 2a, 2b holder block, 3
Thermoelectric (Peltier) element, 4 cooling block, 5a, 5b
Parallel pin 6a, 6b Driving pin hole, 7a, 7b Mating pin hole, 8a, 8b Compression coil spring, 9a, 9b Stepped screw, 10a, 10b Counterbore hole, 11 Cooling channel, 1
2 cooling water inlet, 13 cooling water outlet, 14a, 14b
Peltier element.

Claims (5)

[Claims] 1. A nonlinear crystal holder for holding a nonlinear crystal that generates a harmonic oscillation of the laser beam by passing the laser beam, wherein the holder holds two opposing surfaces of a non-optical system of the nonlinear crystal. One holder block and a heat sink attached to the same direction end surface of the holder block, wherein the holder block is made of a material having good thermal conductivity at least from a portion facing the nonlinear crystal to a portion in contact with the heat sink. A nonlinear crystal holder characterized in that: 2. The nonlinear crystal holder according to claim 1, wherein the heat sink is a Peltier device. 3. The nonlinear crystal holder according to claim 1, wherein the two holder blocks have a pressing means for pressing the two opposing surfaces of the nonlinear crystal with a constant force. 4. The nonlinear crystal holder according to claim 1, wherein the two holder blocks have moving direction regulating means for regulating a moving direction in a direction sandwiching the nonlinear crystal. 5. The nonlinear crystal holder according to claim 4, wherein the end faces in the same direction attached to the heat sink of the two holder blocks are simultaneously processed in a state combined with the movement direction restricting means.