JP2665102B2 - Laser light wavelength converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for an optical parametric oscillator, a harmonic generator, a sum or difference frequency generator, etc.
The present invention relates to an improvement in the structure of a laser beam wavelength conversion device that obtains a laser beam having a target wavelength by changing an incident angle of a pump light with respect to a crystal axis by rotating a nonlinear optical crystal.

[0002]

2. Description of the Related Art As shown in FIG. 5, an optical parametric oscillator, which is a conventional laser light wavelength conversion device, has a matching liquid 1 at a top of an opening of a housing 1 having a substantially rectangular cross section.
The lower part of the reduced diameter of the container 9 in which the non-linear optical crystal 1 is stored in a sealed state is fitted.
3 is mounted so as to be rotatable in the horizontal direction indicated by an arrow, and mirrors 14 and 14A made of a dielectric multilayer film are arranged on both right and left sides of the container 9, respectively. Have been.

A mounting bracket 2 having a substantially inverted L-shaped cross section is vertically mounted below a side wall inside the housing 1, and a motor shaft 3 is directed upward at a short side of the mounting bracket 2. A stepping motor 4 is fitted and hung, and a lower end of a rotating shaft 5 penetrating vertically through the upper center of the housing 1 is connected to a distal end of the motor shaft 3 via a coupling 6. The rotating shaft 5 includes a plurality of bearings 7
The plurality of bearings 7 are fitted inside the housing 1 and the container 9 respectively, and an oil seal 8 for maintaining a sealed state is provided between the plurality of bearings 7.
Are arranged around the rotating shaft 5. The rotating shaft 5 extends through the lower part of the container 9 vertically and protrudes into the inside.

On the other hand, the container 9 is constructed in a sealed structure,
An entrance window 11 made of quartz material adjacent to and facing the mirror 14 is fitted into the window hole on the left wall, and an emission window 11A made of quartz material and adjacent to and facing the mirror 14A is fitted into the window hole on the right wall. The entrance window 11 and the exit window 11A face each other at the same position.

The rotary table 12 is centered and mounted on the top of the rotary shaft 5, and a nonlinear optical crystal 13 is mounted in the center of the upper surface. The nonlinear optical crystal 13 is made of a crystal having a water absorbing property, such as Ba ₂ BO ₄ , urea, or KD ^* P, and has a characteristic that when it is exposed to outside air, it deteriorates and becomes unusable. However, when the nonlinear optical crystal 13 is used, a blocking structure for sealing the nonlinear optical crystal 13 inside the container 9 and blocking the nonlinear optical crystal 13 from outside air is indispensable.

Further, as shown in FIG. 5, the mirrors 14 and 14A are fitted into openings in the frame, and are arranged in the same position as in a clamping state in which the container 9 is clamped through a gap. The mirror 14 receives the excitation light 15 and the mirror 14A
Emit the oscillation light 16.

FIG. 6 is a block diagram showing a general configuration of a laser light wavelength converter using the nonlinear optical crystal 13. As shown in FIG.

[0008] Since the conventional wavelength conversion device for laser light is configured as described above, Nd-
Third harmonic laser light of YAG laser (wavelength λp = 355)
(nm) is incident on the mirror 14, an oscillating light 16 composed of a signal (wavelength λs) and an idler (wavelength λi) is generated based on optical parametric oscillation. When the stepping motor 4 is driven, the rotating shaft 5 rotates together with the motor shaft 3 to rotate the rotary table 13 in the azimuth direction, and the nonlinear optical crystal 13 rotates in the horizontal direction indicated by the arrow around the central axis 5a. The incident angle of the excitation light 15 with respect to the crystal axis is changed (phase matching), and the wavelength of the oscillation light 16 (λs · λ
i) changes continuously within a certain range (for example, 500 to 1230 nm).

When the nonlinear optical crystal 13 is rotated in azimuth to perform phase matching, the intensity of output light is adjusted when a harmonic generator, a sum frequency generator, and a difference frequency generator are used. (Maximum). Further, when an optical parametric oscillator is used, the effect that the wavelength with the highest conversion efficiency can be changed, in other words, the effect that the wavelength can be adjusted occurs.

As described above, the conventional laser light wavelength converter has the function of rotating the rotary table 12 on which the nonlinear optical crystal 13 is mounted in the horizontal direction indicated by the arrow. There is no angle adjustment mechanism for adjusting the relative offset angle (initial setting angle) between the optical fiber and the nonlinear optical crystal 13 with high accuracy.

[0011]

The conventional laser light wavelength converter is constructed as described above, and is capable of accurately adjusting the relative offset angle (initial setting angle) between the rotation axis 5 and the nonlinear optical crystal 13. When an open-loop operation is to be performed based on calibration data measured in advance without monitoring the wavelength and intensity of the output light, the nonlinear optical crystal 13 is cut out. In addition, there is a problem that a high processing accuracy and an assembling accuracy are required for a fixing portion of the nonlinear optical crystal 13.

That is, there is a scale on the operation knob when the nonlinear optical crystal 13 of the optical parametric oscillator rotates, and it is desired to make the indicated value of the scale correspond to a predetermined wavelength, or to rotate the nonlinear optical crystal 13 of the optical parametric oscillator. If the stepping motor 4 has a mechanical origin position (a position where an index signal is output) and it is desired to make the origin position correspond to a predetermined output wavelength, and if the angle adjusting mechanism is not provided at all, the nonlinear optical crystal 13 is not provided. There is a problem that very high processing accuracy and assembling accuracy are inevitably required in the cutout and the fixing portion of the nonlinear optical crystal 13.

As a method for solving the above problem, a method for providing a wavelength converter with a structure for initially adjusting the offset angle of the nonlinear optical crystal 13 by the fixed portion for fixing the nonlinear optical crystal 13 to the rotary table 12 or the rotary table 12 itself. Can be considered. However, if this method is adopted, there is a risk that the nonlinear optical crystal 13 will always come into contact with the outside air when the offset angle is adjusted, and the nonlinear optical crystal 13 will be deteriorated. Therefore, in order to solve the above problem, it was necessary to adjust the offset angle by operating from the outside while the container 9 was sealed.

The present invention has been made in view of the above, and when the operation of an open loop is to be performed based on calibration data measured in advance without monitoring the wavelength and intensity of output light, the sealed state of the container is changed. It is an object of the present invention to provide a laser light wavelength converter that can easily adjust an offset angle without maintaining a high degree of processing accuracy and assembling accuracy for cutting out a nonlinear optical crystal and fixing a nonlinear optical crystal while maintaining the same. .

[0015]

According to the present invention, there is provided a wavelength conversion device for laser light, comprising: a sealed container having a window on a side surface and a through hole in a lower portion; a rotary table disposed in the container; And a non-linear optical crystal irradiated with laser light through a window of the container, and a turn through the through hole so as to seal the through hole of the container with a side surface thereof. A dynamic shaft, an angle adjusting mechanism for adjusting an angle of the rotating shaft in a rotation direction in a region outside the container, and a motor for rotating the rotating shaft together with the angle adjusting mechanism. This angle adjusting mechanism is used for initial setting of the angle of the nonlinear optical crystal.

Further, the angle adjusting mechanism is connected to a rotating plate through which the rotating shaft penetrates, a rotating arm fixed to the rotating shaft, and the rotating plate and the rotating arm. It is preferable to include a spike that exerts a force in the direction, and an adjusting screw attached to the turntable such that the tip of the spike comes into contact with the rotating arm in a direction opposite to the direction of rotation by the spike.

Further, another angle adjusting mechanism includes a rotating disk through which a rotating shaft passes, a worm wheel fixed to the rotating shaft, and a worm gear mounted on the rotating disk and meshing with the worm wheel. Is preferred.

Further, the wavelength conversion device for laser light according to the present invention is provided with a closed container having a window on a side surface and a through hole at a lower portion, a rotary table disposed in the container, A nonlinear optical crystal irradiated with laser light through a window of the container, a first rotating shaft mounted below the turntable, and a hole for accommodating the first rotating shaft in a longitudinal direction thereof; A second rotating shaft penetrating the through-hole and a rotation direction between the first and second rotating shafts in a region outside the container of the second rotating shaft so as to seal the through-hole at a side surface thereof. And a motor that rotates the second rotation shaft together with the angle adjustment mechanism.

Further, the angle adjusting mechanism includes a screw tightening portion provided around the second rotation shaft and a set screw inserted into the screw tightening portion, and the screw tightening portion is tightened by the set screw. It is preferable that the first rotating shaft located inside the screw fastening portion is fastened by the second rotating shaft, and the first rotating shaft is arranged so that the relative position between the first and second rotating shafts is fixed.

[0020]

According to the present invention, the angle adjusting mechanism for adjusting the relative offset angle between the rotation axis and the nonlinear optical crystal with high accuracy is provided. It is possible to adjust the offset angle extremely easily, without giving a high processing accuracy and an assembling accuracy to the fixing portion of the. Further, since the offset angle can be adjusted while maintaining the sealed state of the container, it is expected that the risk of the nonlinear optical crystal being touched by outside air and being deteriorated during the adjustment of the offset angle can be reliably eliminated.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to one embodiment shown in FIGS. In the wavelength conversion device for laser light according to the present embodiment, a container 9 for maintaining a hermetically sealed state is placed on the top of a housing 1A. Is disposed so as to be able to rotate in the horizontal direction, and a swingable swing mechanism 29 that holds the mirrors 14 and 14A is connected to the left and right sides of the container 9 via a telescopic bellows 30, respectively. I have.

As shown in FIG. 1, the housing 1A has an opening lower portion fitted and mounted on a rotating plate fixing portion 17 having a substantially square plane, and the rotating plate fixing portion 17 has a rotating plate 18 having a substantially circular plane. Are mounted so as to be rotatable in the horizontal direction, and a rotary shaft 5A vertically penetrating through the upper center of the housing 1A is rotatably inserted into the center hole of the turntable 18 via a bearing 7. .

One side of the turntable fixing portion 17 is extended toward the front of FIG. 1, and the extended portion includes the turntable 18 and the rotating shaft 5.
A stepping motor (not shown) for rotating A through a gear is provided.

The turntable 18 rotates together with the rotation shaft 5A based on the driving of the stepping motor, but is used in a fixed manner when adjusting the offset angle (initial setting angle).

The rotating shaft 5A has an enlarged diameter rotating shaft 50 whose lowermost step is rotatably inserted into the center hole of the turntable 18 via a bearing 7 and penetrates the lower center of the container 9 vertically. The rotary table 1 is inserted in the upper elongated hole of the rotary shaft 50 so as to be vertically movable.
The crystal holder 23 is divided from a rotatable crystal rotation shaft 51 vertically centered and provided at the center of the lower surface of the crystal holder 23 located immediately below the crystal holder 2. An oil seal 8 that maintains a sealed state is provided between the upper outer peripheral surface of the diameter-enlargement rotating shaft 50 and the lower portion of the container 9.
Is fitted, and an oil seal 8 that maintains a sealed state is fitted between the upper inner peripheral surface of the diameter-enlarging rotating shaft 50 and the upper outer peripheral surface of the crystal rotating shaft 51.

A rotary arm 19 located just above the rotary disk 18 is fitted to a lower step portion of the diameter-enlarging rotary shaft 50.
As shown in FIG. 2, opposed pins 20 are implanted on the upper surface of the left side of the rotating arm 19 and the upper surface of the left side of the rotating disk 18, respectively. Rotating disk 18 with rotating arm 19 fixed
A restricting protrusion 21 for limiting the range of relative rotation from is stretched.

As shown in FIG. 2, a rotatable adjusting screw 22 abutting on the right side of the rotating arm 19 is mounted on the upper surface of the right side of the rotating disk 18 via a supporting portion. By being rotated at the time of adjusting the offset angle, the rotating arm 19 rotates in the counterclockwise direction indicated by the arrow while pulling the restricting ridge 21.

On the other hand, as shown in FIG. 1, the container 9 has an entrance window 11 formed in the left wall adjacent to and facing the mirror 14, and an exit window 1 adjacent to and facing the mirror 14A in the right wall.
1A, and the entrance window 11 and the exit window 11
A are opposite to each other. Further, the container 9 is filled with a gas (dry air, dry nitrogen or the like) or a liquid (fluorocarbon liquid or the like) (not shown) in a sealed state, and is used in a vacuum state.

As shown in FIG. 1, the rotary table 12 is formed to have a substantially convex cross section.
Non-linear optical crystal 1 positioned at entrance window 11 and exit window 11A
3 and the nonlinear optical crystal 13 is made of Ba ₂
It is composed of a crystal such as BO ₄ , urea, or KD ^* P.

The right side of the rotary table 12 and the crystal holder 2
3, a pivoting fulcrum 24 having a substantially circular cross section that allows the rotating table 12 to swing in the vertical direction is interposed between the rotating table 12 and the crystal holder 23. In addition, a flare spring 25 that urges the rotary table 12 downwardly is stretched. On the left side of the turntable 12, an operation hole 26 is formed, and
A crystal tilt angle adjusting screw 27 for adjusting the degree of compression of No. 5 is rotatably screwed. The crystal tilt angle adjusting screw 27 is
When the tilt angle of the nonlinear optical crystal 13 is initially set, the container 9 is opened and rotated.

On the left side of the crystal holder 23, a rotatable crystal height adjusting screw 2 located immediately below the operation hole 26 is provided.
8 is screwed into contact with the upper end of the diameter-enlargement rotation shaft 50, and the crystal rotation shaft 51 moves up and down based on the rotation operation of the crystal height adjusting screw 28, and the non-linear movement with respect to the entrance window 11 and the exit window 11 A. The height of the optical crystal 13 is adjusted. The crystal height adjusting screw 28 is designed to be opened and rotated when the height of the nonlinear optical crystal 13 is initially set.

On the other hand, as shown in FIG. 1, the lifting mechanism 29 has a cylindrical frame 290 having a cylindrical shape with a substantially convex cross section.
A flange 291 having a substantially annular shape is fitted to the bellows. Between the flange 291 and the side wall of the container 9, a bellows 30 for sealing the mirror 14 or the mirror 14 </ b> A is connected, and the lower part of the flange 291 and the container are connected. Between the side walls 9, a swinging fulcrum 292 having a substantially circular cross section that allows the cylindrical frame 290 to swing in the left-right direction is interposed and rotatably pivoted.

An oil seal 293 for maintaining a sealed state is fitted inside the cylindrical frame 290.
A spacer 2 for fitting the circular mirror 14 or the mirror 14A which overlaps with the oil seal 293 and pressing the mirror 14 or the mirror 14A without damaging it.
94 is overlapped and fitted to the mirror 14 or the mirror 14A.

At the top of the side wall of the container 9, a flange 2 is provided.
A mirror tilt angle adjusting screw 295 abutting on the upper part of the screw 91 is rotatably screwed into the cylindrical window frame 290 in a horizontal direction based on the rotation operation of the mirror tilt angle adjusting screw 295. And the mirror 14 or the mirror 14A facing the emission window 11A.

The block diagram shown in FIG. 6 is also applicable to the laser light wavelength converter according to the present invention.

Therefore, when the operation is to be performed in an open loop based on calibration data measured in advance without monitoring the wavelength and intensity of the output light, the offset angle is adjusted while maintaining the sealed state of the container 9. After the turntable 18 is fixed, the adjusting screw 22 may be manually rotated in one direction.

Then, the adjusting screw 22 rotates and the rotating arm 19 advancing precisely and abuts is rotated in the direction of the arrow in FIG. 2, and the rotating arm 19 together with the rotating shaft 5 A pulls the limiting projection 21 in the same direction. The relative offset angle between the rotation axis 5A and the nonlinear optical crystal 13 can be adjusted with high accuracy.

According to the above configuration, since the angle adjusting mechanism including the rotary arm 19 and the like for adjusting the relative offset angle between the rotation axis 5A and the nonlinear optical crystal 13 with high accuracy is provided, The offset angle can be very easily and precisely adjusted without giving a high degree of processing accuracy or assembling accuracy to the cutout of the optical crystal 13 and the fixing portion of the nonlinear optical crystal 13. Furthermore, since the offset angle can be easily adjusted while maintaining the sealed state of the container 9, it is expected that the risk of the nonlinear optical crystal 13 being exposed to outside air and deteriorating when the offset angle is adjusted can be reliably eliminated. .

FIG. 3 shows a second embodiment of the present invention. In this case, the relative offset angle between the turntable 18 and the nonlinear optical crystal 13 is determined using a worm gear. It is adjusted with high precision.

In this embodiment, a worm wheel 31 is fitted to the enlarged diameter rotating shaft 50 of the rotating shaft 5A instead of the rotating arm 19, and the worm wheel 31 is A worm gear 32 that meshes is provided rotatably via a support instead of the adjusting screw 22, and an operation knob 33 is fitted to an end of the worm gear 32. Other parts are the same as in the above embodiment.

Therefore, when the operation is to be performed in an open loop based on the calibration data measured in advance without monitoring the wavelength and intensity of the output light, the offset angle is adjusted while maintaining the sealed state of the container 9. After the turntable 18 is fixed, the knob 33 of the worm gear 32 may be manually rotated in one direction.

Then, the worm gear 32 rotates to precisely rotate the geared worm wheel 31 in the direction of the arrow in FIG. 3, and the worm wheel 31 rotates clockwise relative to the rotating shaft 5A. The relative offset angle between the rotation axis 5A and the nonlinear optical crystal 13 can be adjusted with high accuracy.

According to the above configuration, since the angle adjusting mechanism composed of the worm gear for adjusting the relative offset angle between the rotating shaft 5A and the nonlinear optical crystal 13 with high precision is provided, the nonlinear optical crystal 13 is provided. It is possible to very easily and precisely adjust the offset angle without giving a high degree of processing accuracy or assembling accuracy to the cutout of the 13 and the fixing portion of the nonlinear optical crystal 13. Furthermore, since the offset angle can be easily adjusted while maintaining the sealed state of the container 9, it is expected that the risk of the nonlinear optical crystal 13 being exposed to outside air and deteriorating when the offset angle is adjusted can be reliably eliminated. .

FIGS. 4A, 4B, and 4C show a third embodiment of the present invention. In this case, the diameter increasing rotation shaft 50 and the crystal rotation shaft 51 are used. The relative offset angle between the rotation axis 5A and the non-linear optical crystal 13 is adjusted with high precision by utilizing the relative rotation of.

In this embodiment, a screwing portion 34 having a substantially C-shaped flat cross section is formed from a part of the peripheral wall of the enlarged diameter turning shaft 50 that accommodates the crystal turning shaft 51. A set screw 35 for controlling the relative rotation of the crystal rotation shaft 51 from the diameter-enlargement rotation shaft 50 is screwed between the curved ends separated from each other. Other parts are the same as those in the above embodiments.

Therefore, when the operation is to be performed in an open loop based on calibration data measured in advance without monitoring the wavelength and intensity of the output light, the offset angle is adjusted while maintaining the sealed state of the container 9. After loosening the set screw 35, the crystal rotation shaft 51 may be manually rotated relative to the diameter-enlargement rotation shaft 50 by an appropriate amount.

According to the above configuration, since a simple angle adjusting mechanism for adjusting the relative offset angle between the rotation axis 5A and the nonlinear optical crystal 13 with high accuracy is provided, the nonlinear optical crystal 13 The offset angle can be very easily and precisely adjusted without giving a high degree of processing accuracy or assembling accuracy to the cutout and the fixing portion of the nonlinear optical crystal 13.
Furthermore, since the offset angle can be easily adjusted while maintaining the sealed state of the container 9, it is expected that the risk of the nonlinear optical crystal 13 being exposed to outside air and deteriorating when the offset angle is adjusted can be reliably eliminated. .

[0048]

As described above, according to the present invention, an angle adjustment mechanism for adjusting an initial setting angle between the rotation axis and the nonlinear optical crystal is operated from the outside of the container for maintaining the sealed state. It is remarkable that the offset angle can be very easily and precisely adjusted without applying a high degree of processing accuracy and assembly accuracy to the cutting out of the nonlinear optical crystal and the fixing part of the nonlinear optical crystal. Has a significant effect. Furthermore, since the offset angle can be adjusted while maintaining the sealed state of the container, a remarkable effect that the risk of the nonlinear optical crystal being exposed to outside air and deteriorating when the offset angle is adjusted can be expected to be reliably eliminated. There is.

According to the present invention, a rotation axis is constituted by the diameter expansion rotation axis and the crystal rotation axis, and the rotation axis and the nonlinear optical crystal are interposed between the diameter expansion rotation axis and the crystal rotation axis. The angle adjustment mechanism that adjusts the initial setting angle of the non-linear optical crystal can be operated from the outside of the container that maintains the sealed state, so that the cutting and cutting of the nonlinear optical crystal and the fixing part of the nonlinear optical crystal have high processing accuracy and assembly accuracy. This has a remarkable effect that the offset angle can be finely adjusted very easily without performing the method.
Furthermore, since the offset angle can be adjusted while maintaining the sealed state of the container, a remarkable effect that the risk of the nonlinear optical crystal being exposed to outside air and deteriorating when the offset angle is adjusted can be expected to be reliably eliminated. There is.

[Brief description of the drawings]

FIG. 1 is an overall view showing a laser beam wavelength converter according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a diagram corresponding to FIG. 2, showing a second embodiment of the laser beam wavelength converter according to the present invention.

FIG. 4 is an explanatory diagram showing a third embodiment of the wavelength conversion device for laser light according to the present invention.

FIG. 5 is an overall view showing a conventional laser light wavelength converter.

FIG. 6 is a block diagram showing a general configuration of a wavelength conversion device for laser light.

[Explanation of symbols]

1.1A ... housing, 5.5A ... rotating shaft, 9 ... container,
11: entrance window, 11A: exit window, 12: rotary table,
13: nonlinear optical crystal, 14 / 14A: mirror, 18 ...
Rotating disc, 19: rotating arm, 21: limiting spline, 22: adjusting screw, 31: worm wheel, 32: worm gear, 34: screw tightening part, 35: set screw, 50: expanding rotary shaft, 51: crystal rotation Moving axis.

Claims (5)

(57) [Claims] 1. A wavelength conversion device for laser light, comprising: a sealed container having a window on a side surface and a through-hole at a lower portion; a rotary table arranged in the container; A non-linear optical crystal irradiated with laser light through the window, and a turn attached to the lower part of the rotary table and penetrating the through-hole so as to seal the through-hole of the container with a side surface thereof. A dynamic shaft, an angle adjusting mechanism that adjusts an angle of the rotating shaft in a rotation direction in a region outside the container, and a motor that rotates the rotating shaft together with the angle adjusting mechanism. A wavelength conversion device for laser light, comprising: 2. The angle adjusting mechanism, wherein: a rotating disk through which the rotating shaft passes; a rotating arm fixed to the rotating shaft; a rotating arm connected between the rotating disk and the rotating arm; And an adjusting screw attached to the turntable such that a tip of the arm applies a force in a predetermined rotational direction, and an end of the arm contacts the rotary arm in a direction opposite to the rotational direction of the arm. The wavelength conversion device for laser light according to claim 1, wherein: 3. The angle adjusting mechanism includes: a rotating disk through which the rotating shaft passes; a worm wheel fixed to the rotating shaft; a worm gear attached to the rotating disk and meshing with the worm wheel; The wavelength conversion device for laser light according to claim 1, further comprising: 4. A wavelength conversion device for laser light, comprising: a sealed container having a window on a side surface and a through hole at a lower portion; a rotary table disposed in the container; A nonlinear optical crystal irradiated with laser light through the window, a first rotating shaft mounted below the rotating table, and a hole for accommodating the first rotating shaft in a longitudinal direction thereof. A second pivot axis penetrating the through-hole so as to seal the through-hole of the container with a side surface thereof, and a first pivot and a second pivot in a region of the second pivot axis outside the container. A wavelength conversion device for laser light, comprising: an angle adjustment mechanism that adjusts an angle in a rotation direction between two rotation axes; and a motor that rotates the second rotation axis together with the angle adjustment mechanism. 5. The angle adjusting mechanism includes a screw tightening portion provided around the second rotation shaft and a set screw inserted into the screw tightening portion, and the screw tightening portion is controlled by the set screw. By tightening, the first rotating shaft located inside the screw fastening portion is fastened by the second rotating shaft, and the relative position between the first and second rotating shafts is fixed. 5. The wavelength conversion device for laser light according to claim 4, wherein: