JP4017269B2 - Parallel light generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a parallel light generator that obtains high-output parallel light using laser light emitted from an LD array.
[0002]
[Prior art]
FIG. 6 shows a configuration of a conventional parallel light generator. The LD array 31 is sandwiched between a pair of electrode plates 32a and 32b from both sides and disposed in a cooling device 39. FIG. The laser light emitted from the LD array 31 is condensed by a fast AXIS collimator lens 34, a slow AXIS collimator lens 35, and a condenser lens 36, and this laser light is oscillated between a laser medium 37 and an output mirror 38. To generate parallel light. Pure water circulates in the cooling device 39, and the heat of the LD array 31 is exhausted through the electrode plates 32a and 32b.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, it is necessary to align the laser medium and the output mirror in order to oscillate the laser, and to perform mode matching between the condensing optical system and the laser medium. It was. Further, since the arrangement distance of the oscillation system cannot be shortened, a loss due to the spread of the laser beam occurs, and the conversion efficiency is limited to 30 to 40%. Furthermore, pure water is circulated to cool the electrode plate through which the heat of the LD array is conducted. However, if the purity of the pure water is reduced, the electrode is electrolyzed, resulting in a decrease in conductivity or the entry of external ground noise. As a result, the LD array is broken.
[0004]
An object of the present invention is to provide a parallel light generator configured to obtain high-output parallel light with a simple structure.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a parallel light generator according to a first invention of the present application includes an LD array configured by arranging a plurality of laser diodes on a straight line, and an insulation formed to have the same thickness as the LD array. The body is sandwiched between a pair of electrode blocks excellent in electrical conductivity and thermal conductivity, and a flat plate is formed on the surface where the laser beam emitting end face of the LD array and the pair of electrode blocks are formed flush with each other . An oscillation plate made of a laser beam and having both planes as reflection surfaces for the light emitted from the LD array is arranged in close contact, and power is supplied from the pair of electrode blocks to the LD array. It is characterized by.
[0006]
According to the configuration of the first invention, the laser light from the LD array is converted into parallel light by the oscillation plate and emitted. Since parallel light can be obtained with a simple configuration and adjustment is not necessary, its manufacture is easy. In addition, since the heat of the LD array and the oscillation plate is radiated from the closely contacted electrode block, high output parallel light can be easily generated.
[0007]
In the above configuration, the optical axis is aligned with the optical axis of the laser light emitted from the LD array, and a coating that highly transmits light with a wavelength of 1064 nm and totally reflects light with a wavelength of 800 to 810 nm is applied and reflected. Oscillation is facilitated and light that has not been absorbed can be achieved by arranging a concave mirror formed on the outer surface side of the oscillation plate with a curvature that focuses on the position close to the LD array in the oscillation plate. Is reused, so efficient conversion is performed.
[0008]
In addition, the parallel light generator according to the second invention of the present application for achieving the above object is formed with an LD array formed by arranging a plurality of laser diodes in a straight line and the same thickness as the LD array. Insulators and intermediate electrode plates having an area at least 10 times larger than the planar area of the LD array and having high thermal conductivity in the plane direction are alternately arranged and laminated in a plurality of stages, and this laminate is electrically conductive. And sandwiching between a pair of electrode blocks excellent in heat resistance and thermal conductivity, and a flat plate-like surface on which the laser light emitting end face of the LD array, the intermediate electrode plate, and the pair of electrode blocks are formed flush with each other the oscillation plate has a reflecting surface for the light both planes made from the laser medium is emitted from the LD array adhesion arranged, each LD array via each intermediate electrode plate from the pair of electrode block Characterized by comprising configured to power the.
[0009]
According to the configuration of the second invention, the laser light from the plurality of LD arrays can be converted into parallel light by the oscillation plate and emitted, so that high-output parallel light can be generated. In addition, since the heat of each LD array is conducted and dissipated from the intermediate electrode plate to the electrode block, it is easy to generate high-power parallel light.
[0010]
Oscillating plate, the plate which is parallel planes cut YVO ₄ crystal is 0.5% to 3% of Nd doped 0.3~1.5mm thickness, reflective coating and contacts the opposite surface thereof with LD array It is preferable to form by applying.
[0011]
The oscillation plate has a thickness t (mm), an Nd doping amount n (%), and a power density P (w / mm ² ) at the contact surface with the laser diode, P · t · n = 10 ⁴ . It is preferable to form so as to satisfy the conditions.
[0012]
The parallel light generators according to the first and second inventions are hermetically sealed by a transparent window disposed at a distance from the surface of the oscillation plate to generate natural convection due to heat generation of the oscillation plate. The cooling effect is improved by arranging the pure water to be cooled by the pure water enclosed in the heat exchanger and the heat exchange by the heat exchanger. Higher output parallel light can be generated.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0014]
1A and 1B show a configuration of a parallel light generator according to a first embodiment of the present invention. FIG. 1A is a front view and FIG. 1B is a side view.
[0015]
In FIG. 1, an LD array 1 is configured by arranging a plurality of LDs (laser diodes) 2 on a line, and is sandwiched between a pair of electrode blocks 10a and 10b together with an insulator 9 having the same thickness. By supplying power from the power supply 11 between the electrode blocks 10a and 10b, each LD2 of the LD array 1 emits light. The exit end face of the LD array 1 is formed flush with the electrode blocks 10a and 10b, and the oscillation plate 12 is disposed in close contact with the exit end face of the LD array 1. With this structure, heat generated from each LD 2 of the LD array 1 and heat due to loss generated in the oscillation plate 12 can be efficiently released to the electrode blocks 10a and 10b. Since the electrode blocks 10a and 10b are formed in a block-shaped heat capacity having a large shape and are exhausted to a support (not shown) that supports the electrode blocks 10a and 10b, heat is reliably released.
[0016]
As shown in FIGS. 2A and 2B, the laser light emitted from the LD 2 is ± 5 degrees (slow AXIS light) in the surface direction of the LD array 1 and ± 20 degrees (fast AXIS light) in the thickness direction. The oscillation angle is converted into parallel light by the oscillation plate 12 and emitted. The configuration conditions of the oscillation plate 12 will be described below.
[0017]
The oscillation plate 12 is obtained by applying a total reflection coating to the contact surface with the LD 2 on a plate obtained by cutting a 0.5 to 3% Nd-doped YVO ₄ crystal into a thickness of 0.3 to 1.5 mm in parallel plane. , 90 to 98% of the reflective coating is applied to the opposite surface with respect to the wavelength of 1064 nm. The oscillation plate 12 can be oscillated by configuring the following parameters as follows.
[0018]
LD2 emission density = P (w / mm ² ), where P ≧ 10 ⁴ w / mm ²
The thickness of the oscillation plate 12 = t (mm), where 0.3 ≦ t ≦ 1.5 mm
Nd doping amount = n (%), where 0.5 ≦ n ≦ 3
Then, the constituent condition of the oscillation plate 12 is expressed by the following formula (1) with the output side coat being 90 to 98% at 1064 nm.
[0019]
P · t · n ≧ 10 ⁴ (1)
For example, when P = 10 ⁴ (w / mm ² ), t = 0.5 (mm), and n = 3 (%), P · t · n = 10 ⁴ · 0.5 · 3 = 1.5 × 10 ⁴ ≧ 10 ⁴ , and oscillation is possible.
[0020]
This configuration condition is the minimum condition, and it is possible to obtain a conversion efficiency of 60% or more, which is called a theoretical limit value, by appropriately selecting the ratio of each parameter. When the Nd doping amount is as high as 3%, the thickness of the oscillation plate 12 can be formed to 0.3 to 0.5 mm, but diffraction is generated in the oscillation plate 12 due to the occurrence of thermal distortion. Oscillation is likely to occur and the oscillation is likely to be unstable. Therefore, it is preferable to set the Nd doping amount to 1 to 2% and the thickness to about 0.5 to 1 mm.
[0021]
FIG. 3 shows a configuration in which the concave mirror 22 that totally reflects the light emitted from the LD 2 is disposed. As shown in the drawing, the optical axis of the concave mirror 22 is arranged on the center axis of the light emitted from the LD 2. ing. The concave mirror 22 is coated so as to totally reflect the light emitted from the LD 2 and transmit the light of 1064 nm. The curvature of the reflecting surface is on the center axis as close as possible to the LD 2 in the oscillation plate 12. It is formed to collect light. With the configuration using the concave mirror 22, the light from the LD 2 that has not been absorbed at the same time as causing oscillation at a low threshold is reused, so that it can be efficiently converted into parallel light.
[0022]
The same effect can be obtained by using a concave cylindrical lens or a diffraction grating provided with a coat that totally reflects the light from the LD 2 instead of the concave mirror 22.
[0023]
FIGS. 4A and 4B show the configuration of the parallel light generator according to the second embodiment. FIG. 4A is a front view and FIG. 4B is a side view.
[0024]
As shown in the figure, the parallel light generator according to the second embodiment is configured by stacking a plurality of LD arrays 1. The LD array 1 is laminated in a plurality of stages through an intermediate electrode plate 13 together with an insulator 9 having the same thickness and an area of 10 times or more, and is sandwiched between a pair of electrode blocks 10a and 10b. The insulator 9 is formed of a material having good thermal conductivity such as AlN, and the intermediate electrode plate 13 is excellent in electrical conductivity and thermal conductivity such as a gold thin plate, a copper gold plating plate, and a graphite sheet. It is made of material. Since the graphite sheet has a thermal conductivity difference of 10: 1 or more between the surface direction and the thickness direction, the area of the insulator 9 is set to be 10 times or more larger than the area of the LD array 1 as described above. ing. The output end face side of the LD array 1 of the intermediate electrode plate 13 and the electrode blocks 10a and 10b is formed flush with the output end face, and is in close contact with the LD array 1, the intermediate electrode plate 13, and the electrode blocks 10a and 10b. Since the oscillation plate 12 is disposed, heat generated in the oscillation plate 12 is also conducted to the electrodes 10a and 10b, and is exhausted to the external radiator 14 in contact with the electrode blocks 10a and 10b.
[0025]
In the above configuration, power supplied from the power source 11 connected between the pair of electrode blocks 10a and 10b is supplied to each LD array 1 via each intermediate electrode plate 13, and is emitted from the emission end face of each LD array 1. The laser beam is converted into parallel light by the oscillation plate 12 and emitted.
[0026]
FIGS. 5A and 5B show the configuration of the parallel light generator according to the third embodiment. FIG. 5A is a front view and FIG. 5B is a side view.
[0027]
In FIG. 5, the LD array 1 is sandwiched between a pair of electrode blocks 15 a and 15 b together with an insulator 9 having the same thickness, and a cooling device 19 with the oscillation plate 12 disposed on the laser light emission end face side. It is arranged in the inside. The cooling device 19 is formed in a sealed structure with its front side closed by the emission window 18, and a heat exchanger 23 for cooling pure water filled therein is arranged. A power source 11 is connected to the electrode blocks 15a and 15b through electrode bars 16a and 16b, respectively.
[0028]
In the above configuration, since the channel width of the interval in which the laminar flow is maintained is formed between the surface of the oscillation plate 12 and the emission window 18, when pure water rises by taking heat from the oscillation plate 12, Natural convection occurs without causing the Schallen phenomenon, and the oscillation plate 12 is efficiently cooled. Further, since the heat of the LD array 1 is conducted to the electrode blocks 10a and 10b and the electrode blocks 10a and 10b are cooled with pure water, the LD array 1 is also efficiently cooled. Since pure water is cooled by the heat exchanger 23, the heat dissipation effect of the apparatus is high, and higher output parallel light can be generated.
[0029]
Although the third embodiment shows an example in which the parallel light generator shown in the first embodiment is arranged in the cooling device 19, the LD array shown in the second embodiment is shown. A configuration in which 1s are stacked can also be applied.
[0030]
【The invention's effect】
As described above, according to the present invention, since the laser beam emitted from the LD array is converted into parallel light by the oscillation plate, high-output parallel light can be generated with a simple structure. In addition, since the structure has excellent thermal conductivity, high-output parallel light can be generated efficiently.
[Brief description of the drawings]
FIG. 1A is a front view and FIG. 1B is a side view showing a configuration of a parallel light generator according to a first embodiment.
2A is a plan view and FIG. 2B is a side view for explaining conversion into parallel light by an oscillation plate.
FIG. 3 is a side view showing a modification of the first embodiment.
4A is a front view and FIG. 4B is a side view showing a configuration of a parallel light generator according to a second embodiment.
5A is a front view and FIG. 5B is a side view showing a configuration of a parallel light generator according to a third embodiment.
FIG. 6 is a side view showing a configuration of a parallel light generating device according to the prior art.
[Explanation of symbols]
1 LD array 2 LD (laser diode)
9 Insulators 10a, 10b, 15a, 15b Electrode block 12 Oscillation plate 13 Intermediate electrode plate 18 Output window 19 Cooling device 22 Concave mirror

Claims (6)

An LD array configured by arranging a plurality of laser diodes in a straight line and an insulator formed to have the same thickness as the LD array are provided between a pair of electrode blocks excellent in electrical conductivity and thermal conductivity. And a plane formed of a flat plate laser medium on a surface in which the laser beam emission end face of the LD array and the pair of electrodes are formed flush with each other , and both planes are reflection surfaces for light emitted from the LD array. A parallel light generator, comprising: an oscillation plate arranged in close contact, and configured to supply power to the LD array from the pair of electrode blocks.   Arranged so that the optical axis coincides with the optical axis of the laser light emitted from the LD array, a coating that highly transmits light with a wavelength of 1064 nm and totally reflects light with a wavelength of 800 to 810 nm is applied, and the reflection surface is within the oscillation plate. 2. The parallel light generator according to claim 1, wherein a concave mirror formed with a curvature that focuses on a position close to the LD array is disposed on the outer surface side of the oscillation plate. An LD array configured by arranging a plurality of laser diodes in a straight line, an insulator formed to have the same thickness as the LD array, and an area at least 10 times larger than the planar area of the LD array, The intermediate electrode plates having high thermal conductivity are alternately arranged and laminated in a plurality of stages, and this laminate is sandwiched between a pair of electrode blocks excellent in electrical conductivity and thermal conductivity, and the LD array A laser light emitting end face, the intermediate electrode plate, and a surface on which the pair of electrode blocks are formed to be flush with each other, are formed of a flat plate laser medium, and both planes are reflecting surfaces for light emitted from the LD array. An apparatus for generating parallel light, wherein an oscillation plate is arranged in close contact, and power is supplied to each LD array from each of the pair of electrode blocks via each intermediate electrode plate. Oscillating plate, the plate which is parallel planes cut YVO ₄ crystal is 0.5% to 3% of Nd doped 0.3~1.5mm thickness, reflective coating and contacts the opposite surface thereof with LD array The parallel light generator according to claim 1, wherein the parallel light generator is formed. The oscillation plate has a condition of P · t · n = 10 ⁴ among its thickness t (mm), Nd doping amount n (%), and power density P (w / mm ² ) at the contact surface with the laser diode. The parallel light generator according to claim 1, wherein the parallel light generator is formed so as to be satisfied.   Arranged in a cooling device hermetically sealed by a transparent window provided with a space to generate natural convection due to heat generation of the oscillation plate between the surface of the oscillation plate and enclosed in this cooling device The parallel light generator according to claim 1 or 3, wherein the parallel light generator is configured to be cooled by pure water, and the heat of the pure water is exhausted by a heat exchanger.

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