CN116231430A - Method and device for adjusting angle reflecting mirror in laser resonant cavity - Google Patents

Method and device for adjusting angle reflecting mirror in laser resonant cavity Download PDF

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Publication number
CN116231430A
CN116231430A CN202310037876.2A CN202310037876A CN116231430A CN 116231430 A CN116231430 A CN 116231430A CN 202310037876 A CN202310037876 A CN 202310037876A CN 116231430 A CN116231430 A CN 116231430A
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China
Prior art keywords
angle
mirror
reflecting mirror
laser
aperture diaphragm
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Inventor
彭锦
范元媛
林政吉
亓岩
颜博霞
周密
韩哲
韩春蕊
王宇
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Institute of Microelectronics of CAS
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Institute of Microelectronics of CAS
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Priority to CN202310037876.2A priority Critical patent/CN116231430A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/105—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08059—Constructional details of the reflector, e.g. shape

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

The present disclosure provides a method and apparatus for adjusting an angle mirror in a laser cavity, the method comprising: setting an OC coupling output mirror, and enabling the OC coupling output mirror, a laser gain medium of a laser and a front cavity mirror to form a sub-resonant cavity to generate reference laser; a first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror, and the angle reflecting mirror is adjusted to align the centers of the angle reflecting mirror and the aperture diaphragm; the angle reflector is placed according to the estimated reflection angle, a second aperture diaphragm is arranged in the reflection direction of the angle reflector to keep the pitch angle of the angle reflector unchanged, and the angle reflector is adjusted to enable reference laser reflected by the angle reflector to pass through the center of the second aperture diaphragm; the height of the angle reflecting mirror is adjusted, so that the reference laser is aligned with the center of the angle reflecting mirror again; the power of the reference laser reflected by the angle reflecting mirror is measured, and the yaw angle of the angle reflecting mirror is adjusted until the power is maximum.

Description

Method and device for adjusting angle reflecting mirror in laser resonant cavity
Technical Field
The disclosure relates to the technical field of lasers, and in particular relates to a method and a device for adjusting an angle reflector in a laser resonant cavity.
Background
Laser is one of the best technical achievements created by humans in the last century. From the development of solid state lasers to date, attention has been paid to them. Because of the characteristics of high peak power, large output energy, compact and durable layout and the like, the device is widely applied to various aspects of industry, agriculture, precision measurement and detection, communication and information processing, medical treatment, military and the like, and brings about revolutionary breakthrough in a plurality of fields. The resonant cavity is an indispensable component in the laser, and is an optical device which consists of two or more optical reflecting mirrors and can provide optical positive feedback. With the continued development of solid state lasers, the composition of the resonator becomes more and more complex, wherein also angular mirrors are frequently present in the resonator. When the angle reflector in the resonant cavity is accurately placed according to the incident angle of the coating, the loss in the resonant cavity is minimum, and the resonant cavity is easier to stabilize. However, accurate placement of the angle mirrors in the cavity at an angle is always a difficult problem, especially when multiple angle mirrors are present in the same cavity, and the adjustment process becomes more difficult.
The adjustment of the angle reflecting mirror in the resonant cavity of the existing laser generally adopts a method of using helium-neon laser and the like as collimated light, and then the position of the angle reflecting mirror is adjusted by estimating the general rotation angle of the reflecting mirror, so that the adjustment error is larger. For more complex cavity types such as a Z-shaped cavity, an X-shaped cavity, a ring-shaped cavity and the like, in order to make the structure of the resonant cavity more compact, the whole volume is smaller, the light path is often folded for multiple times, and the number of angle reflectors used in the resonant cavity is generally larger. Helium-neon laser is not only required to propagate in the cavities for a long distance, but also required to pass through a plurality of optical elements including a laser gain medium, a frequency-changing crystal, various lenses, a Q switch and the like, so that the intensity of the helium-neon laser becomes very weak, the light spot size becomes very large, and if the angle reflecting mirror in the resonant cavity is adjusted by the method, the operation becomes difficult. In addition, by estimating the placement angle of the angle mirror, the angle mirror has great contingency and randomness, and no specific measurement standard is adopted, so that a great deal of time and effort are wasted in actual operation.
Disclosure of Invention
In view of the above problems, the present invention provides a method and an apparatus for adjusting an angle mirror in a resonant cavity of a laser, so as to solve the above technical problems.
A first aspect of the present disclosure provides a method of adjusting an angle mirror in a laser cavity, the method comprising: an OC coupling output mirror is arranged between a laser gain medium and an angle reflecting mirror in a laser resonant cavity, so that the OC coupling output mirror, the laser gain medium and a front cavity mirror form a sub resonant cavity to generate reference laser; a first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror, and the pitch angle and the height of the angle reflecting mirror are adjusted, so that after the reference laser reaches the angle reflecting mirror through the center of the first aperture diaphragm, the light reflected by the angle reflecting mirror also passes through the center of the first aperture diaphragm and is aligned with the center of the angle reflecting mirror; the angle reflector is placed according to the estimated reflection angle, the pitch angle of the angle reflector is kept unchanged, a second aperture diaphragm which is equal to the first aperture diaphragm in height is arranged in the reflection direction of the angle reflector, the angle reflector is adjusted, and reference laser reflected by the angle reflector passes through the center of the second aperture diaphragm; adjusting the height of the angle reflecting mirror to enable the reference laser to be aligned with the center of the angle reflecting mirror again; and measuring the power of the reference laser reflected by the angle reflecting mirror, adjusting the yaw angle of the angle reflecting mirror until the power is maximum, and stopping adjustment.
According to an embodiment of the present disclosure, the method further comprises: a third aperture diaphragm is arranged behind the angle reflecting mirror, and the first aperture diaphragm and the third aperture diaphragm are equal in height; before adjusting the angle reflecting mirror, adjusting angles of the OC coupling output mirror and the front cavity mirror, enabling the reference laser to pass through centers of the first aperture diaphragm and the third aperture diaphragm, and enabling the reference laser to be horizontal.
According to an embodiment of the disclosure, when the angle mirror is a concave angle mirror, the adjusting the angle mirror, so that after the reference laser reaches the angle mirror through the center of the first aperture stop, the light reflected by the angle mirror also passes through the center of the first aperture stop, further includes: and attaching target paper to the angle reflecting mirror, adjusting the height of the angle reflecting mirror, and taking down the target paper after the reference laser is aligned with the center of the target paper to finish alignment of the reference laser with the center of the angle reflecting mirror.
According to an embodiment of the present disclosure, the method further comprises: and adjusting the second aperture diaphragm to be the same height as the first aperture diaphragm.
According to an embodiment of the present disclosure, the adjusting the height of the angle mirror to realign the reference laser light to the center of the angle mirror includes: and attaching target paper to the angle reflecting mirror, adjusting the height of the angle reflecting mirror, and taking down the target paper after the reference laser is aligned with the center of the target paper to finish alignment of the reference laser with the center of the angle reflecting mirror.
According to an embodiment of the present disclosure, the method further comprises: and after the angle reflecting mirror is adjusted, removing the first aperture diaphragm and the second aperture diaphragm.
A second aspect of the present disclosure provides an adjustment device for an angle mirror in a laser resonator, applied to the adjustment method according to any one of the first aspects, including: the OC coupling output mirror is arranged between the laser gain medium and the angle reflecting mirror in the laser resonant cavity, is coaxial with the laser gain medium and the reflecting mirror in the laser resonant cavity and is used for forming a sub-resonant cavity with the laser gain medium and the front cavity mirror to generate reference laser; the first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror and is used for assisting in adjusting the angle reflecting mirror so as to enable the reference laser to be aligned to the angle reflecting mirror; the second aperture diaphragm is arranged in the reflecting direction of the angle reflecting mirror and is used for assisting in calibrating the reflecting angle of the angle reflecting mirror in the adjusting process of the angle reflecting mirror; and the power meter is arranged behind the angle reflecting mirror and is used for measuring the power of the reference laser reflected by the angle reflecting mirror.
According to an embodiment of the present disclosure, the adjusting device further comprises: and the third aperture diaphragm is arranged behind the angle reflecting mirror, is equal to the first aperture diaphragm in height and is used for being matched with the first aperture diaphragm before adjusting the angle reflecting mirror so as to calibrate the reference laser in the horizontal direction.
According to an embodiment of the present disclosure, the adjusting device further comprises: and the triaxial adjusting frame is connected with the angle reflecting mirror and used for adjusting the height, front-back displacement and left-right displacement of the angle reflecting mirror.
The above at least one technical scheme adopted in the embodiment of the disclosure can achieve the following beneficial effects:
according to the adjusting method and the adjusting device for the angle reflecting mirror in the laser resonant cavity, the OC coupling output mirror is inserted behind the laser gain medium, so that the reflecting mirror, the laser gain medium and the OC coupling output mirror form a new sub resonant cavity, and the sub resonant cavity self-oscillates under the action of the end face pumping source to generate reference laser. By utilizing the reference laser, the aperture diaphragm, the target paper and the power meter can quickly and accurately adjust the angle reflecting mirror in the resonant cavity, and compared with the method for roughly estimating the reflecting angle by utilizing helium neon light in the prior art, the method for adjusting the angle reflecting mirror is quicker, simpler, more convenient and more accurate. The adjusting method is more suitable for the concave reflecting mirror plated with the incident angle high-reflection film, and the adjusting method does not need other precise equipment and is not limited by the application occasions. The adjusting device provided by the embodiment of the disclosure only comprises one OC coupling output mirror, an aperture diaphragm and a power meter, has few used elements, is quite simple in structure, quite easy to realize and low in cost, and is suitable for adjusting the angle reflecting mirror under most experimental scenes.
Drawings
For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 schematically illustrates a flow chart of a method for adjusting an angle mirror in a laser cavity provided by an embodiment of the present disclosure;
FIG. 2 schematically illustrates a schematic diagram of an adjusting device for an angle mirror in a V-folded cavity laser of emerald crystal according to an embodiment of the disclosure;
FIG. 3 schematically illustrates a schematic diagram of an adjustment device for an angle mirror in a tunable emerald according to an embodiment of the disclosure;
FIG. 4 schematically illustrates a schematic diagram of an adjustment device for an angle mirror in a Z-folded cavity laser of emerald crystal provided by an embodiment of the disclosure;
fig. 5 schematically illustrates a schematic diagram of an adjustment device for an angle mirror in a long cavity self-tuning Q emerald laser provided by an embodiment of the disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Some of the block diagrams and/or flowchart illustrations are shown in the figures. It will be understood that some blocks of the block diagrams and/or flowchart illustrations, or combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the instructions, when executed by the processor, create means for implementing the functions/acts specified in the block diagrams and/or flowchart.
The embodiment of the disclosure provides a method and a device for adjusting an angle reflector in a laser resonant cavity, wherein the adjusting device comprises the following steps: the OC coupling output mirror, the first aperture diaphragm, the second aperture diaphragm, the third aperture diaphragm and the power meter. The OC coupling output mirror is arranged between the laser gain medium and the angle reflecting mirror in the laser resonant cavity, is coaxial with the laser gain medium and the front cavity mirror in the laser resonant cavity, and is used for forming a sub-resonant cavity with the laser gain medium and the front cavity mirror to generate reference laser; the first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror and is used for assisting in adjusting the angle reflecting mirror so as to lead the reference laser to be aligned with the angle reflecting mirror; the second aperture diaphragm is arranged in the reflecting direction of the angle reflecting mirror and is used for assisting in calibrating the reflecting angle of the angle reflecting mirror in the adjusting process of the angle reflecting mirror; the third aperture diaphragm is arranged behind the angle reflecting mirror, is equal to the first aperture diaphragm in height and is used for being matched with the first aperture diaphragm before the angle reflecting mirror is adjusted to calibrate the reference laser in the horizontal direction; the power meter is arranged behind the second aperture diaphragm and is used for measuring the power of the reference laser after being reflected by the angle reflecting mirror.
Fig. 1 schematically illustrates a flowchart of a method for adjusting an angle mirror in a laser cavity according to an embodiment of the present disclosure.
As shown in fig. 1, a method for adjusting an angle mirror in a resonant cavity of a laser according to an embodiment of the present disclosure includes S110 to S150.
S110, setting an OC coupling output mirror between the laser gain medium and the angle reflecting mirror in the laser resonant cavity to enable the OC coupling output mirror, the laser gain medium and the front cavity mirror to form a sub resonant cavity to generate reference laser.
In this embodiment, the sub-resonator requires continually fine-tuned front and back mirrors after the oscillation laser is generated, up to the oscillation laser level. And the front cavity mirror and the OC coupling output mirror which are continuously finely adjusted can enable oscillation laser to pass through the centers of the two aperture diaphragms at the same time, and the oscillation laser at the moment is adjusted to be horizontal and can be used as reference laser.
S120, a first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror, and the pitch angle and the height of the angle reflecting mirror are adjusted, so that after the reference laser reaches the angle reflecting mirror through the center of the first aperture diaphragm, the light reflected by the angle reflecting mirror also passes through the center of the first aperture diaphragm and is aligned with the center of the angle reflecting mirror.
In this embodiment, the position of the first aperture stop is located between the OC coupling output mirror and the angle reflecting mirror, at this time, the position of the mirror surface of the angle reflecting mirror is approximately opposite to the reference laser, and the reference laser needs to vertically enter the mirror surface of the angle reflecting mirror after passing through the center of the aperture stop, that is, the reference laser after being reflected by the angle reflecting mirror still passes through the center of the aperture stop by adjusting the PITCH direction of the angle reflecting mirror.
When the angle reflector is a concave angle reflector, the operation of aligning the reference light with the center of the angle reflector is needed, and the target paper is used to ensure that the reference light is aligned with the center of the angle reflector. Before the target paper is attached to the angle reflecting mirror, the reference light before and after being reflected by the angle reflecting mirror is subjected to the equal-height treatment. Then a first aperture stop is placed in front of the angle mirror, and the reference laser light needs to pass through the center of the first aperture stop. The PITCH of the angle mirror is adjusted until the reflected reference light also passes through the center of the first aperture stop, at which time the reference light heights before and after reflection are uniform. And then, attaching the target paper to the mirror surface of the angle reflecting mirror, and only adjusting the height of the angle reflecting mirror at the moment, so that the reference laser is aligned with the center of the target paper, and taking down the target paper to finish alignment of the reference laser with the center of the angle reflecting mirror.
When the angle reflector is a plane angle reflector, no target paper is needed to be pasted, and only the angle reflector is required to be opposite to the sub-resonant cavity, the height and the pitching of the angle reflector are continuously adjusted until the reference laser reflected by the angle reflector just passes through OC coupling output and the center of the first aperture diaphragm in the middle of the angle reflector.
In this embodiment, the angle mirror is placed on the triaxial adjusting frame and can move horizontally along the optical path, the horizontal and vertical optical path and the vertical and vertical optical path, and the front-back, left-right displacement and the height of the angle mirror can be adjusted.
S130, placing an angle reflector according to the estimated reflection angle, keeping the pitch angle of the angle reflector unchanged, setting a second aperture diaphragm in the reflection direction of the angle reflector, and adjusting the angle reflector to enable the reference laser reflected by the angle reflector to pass through the center of the second aperture diaphragm.
In this embodiment, the second aperture stop is at the same height as the first aperture stop.
The most common reflection angles in the angle mirror are 45 degrees, 30 degrees, 22 degrees and the like. In this example, the angle mirror used is a high reflection film with an incident angle of 22 ° and 45 °, and the wavelength is 700 to 800nm. When the angle mirror is placed at a substantially estimated reflection angle, in order to ensure that the pitch of the angle mirror before and after placement is unchanged, a second aperture stop having the same height as the first aperture stop needs to be provided in a direction facing the mirror surface of the angle mirror, and the angle mirror is finely adjusted so that the reference laser passes through the center of the second aperture stop.
And S140, adjusting the height of the angle reflecting mirror to enable the reference laser to be aligned with the center of the angle reflecting mirror.
In this embodiment, the placement position of the angle mirror is adjusted in the direction perpendicular to the reference optical path, so that the reference laser is aligned again with the center of the target paper on the angle mirror, and then the target paper on the angle mirror is removed.
Specifically, the operations of S120 and S130 have guaranteed that the heights of the reference laser light before and after being reflected by the angle mirror are consistent, and at this time, the reference laser light can be aligned with the center of the angle mirror again only by adjusting the position of the angle mirror on the perpendicular light path. And after the reference laser is aligned with the center of the target paper, the target paper is taken down, and the center of the reference laser alignment angle reflector is completed.
And S150, measuring the power of the reference laser reflected by the angle reflecting mirror, adjusting the yaw angle of the angle reflecting mirror until the power is maximum, and stopping adjustment.
In this embodiment, a power meter is placed in the direction of the angle mirror reflection, and the YAW (YAW) of the angle mirror is fine tuned until the measured power is maximum. When the reflection angle of the angle mirror is adjusted, the pitching of the angle mirror is already adjusted due to the operations of S120 and S130, and only the yaw of the angle mirror is needed to be finely adjusted.
And according to the steps S110-S150, sequentially adjusting an angle reflector included in the laser, and removing the first aperture diaphragm, the second aperture diaphragm, the third aperture diaphragm and the power meter after the angle reflector is adjusted.
The method for accurately and rapidly adjusting the angle mirror in the resonant cavity is described in detail below by means of some specific embodiments.
Fig. 2 schematically illustrates a schematic diagram of an adjusting device of an angle mirror in a V-folded cavity laser of emerald crystal according to an embodiment of the disclosure.
As shown in fig. 2, the V-folded cavity laser of emerald crystal provided in the embodiment of the present disclosure includes: the device comprises a pump source 1, a collimator 2, a half wave plate 3, a PBS polarization beam splitter prism 4, a half wave plate 5, a lens 6, a reflecting mirror 7, emerald crystal 8, an angle reflecting mirror 9, a polaroid 10, a quarter wave plate 11, a Q switch 12 and an output mirror 13; the whole resonant cavity structure is in a V-folded shape, wherein the intersection point of a first arm and a second arm is an angle reflecting mirror 9, and the first arm is sequentially provided with a pump source 1, a collimator 2, a half wave plate 3, a PBS polarization beam splitter prism 4, a half wave plate 5, a lens 6, a reflecting mirror 7, an emerald crystal 8 and the angle reflecting mirror 9; the second arm is provided with a polarizer 10, a quarter-wave plate 11, a Q-switch 12, and an output mirror 13 in this order.
The working principle of the resonant cavity is as follows: after passing through a linear polarized light generator formed by a half wave plate 3, a PBS (polarization beam splitter) prism 4 and a half wave plate 5 together, the pump source 1 collimated by the collimator 2 generates maximum horizontal linear polarized light, and the maximum absorption efficiency of the emerald crystal 8 can be obtained at the moment because the polarization direction of the maximum horizontal linear polarized light and the b axis of the emerald crystal 8 are parallel to each other, oscillation laser can be formed in a resonant cavity formed by the front cavity mirror 7 and the output mirror 13, and then pulse oscillation laser output can be realized through a Q-switched system formed by the polarizer 10, the quarter wave plate 11 and the Q switch 12 together; the OC coupling-out mirror 14, the first aperture stop 15, the third aperture stop 16, the second aperture stop 17 and the power meter 18 are all elements for adjusting the angle mirror in the resonator in the whole optical path, and need to be removed in the process of the final operation of the optical path. The overall cavity length is about 160mm, the distance from the mirror 7 to the angle mirror 9 is about 60mm, and the distance from the angle mirror 9 to the output mirror 13 is about 100mm. The reflecting mirror 7 and the angle reflecting mirror 9 are plane mirrors, which are plated with antireflection films for 638nm pumping light wave bands, wherein one side of the reflecting mirror 7 facing the cavity is plated with a high reflection film for 0 DEG incidence of 700-800 nm laser wave bands, and one side of the angle reflecting mirror 9 facing the cavity is plated with a high reflection film for 45 DEG incidence of 700-800 nm laser wave bands; the output mirror 13 is also a plane mirror coated with a dielectric film having a high reflection at a wavelength of 700 to 800nm, and has a reflectance of 99%. Both sides of the half wave plate 3 and the half wave plate 5 are plated with 638nm pump source high-permeability films. The lens 6 is a plano-convex lens, one side facing the resonant cavity is a plane, both sides are plated with 638nm high-transmission dielectric films with incidence of 0 DEG, and the focal length is 50mm.
The crystal in the cavity is emerald (Cr 3+ ：BeAl 2 O 4 ) The two end faces of the crystal are coated with 700-800 nm wavelength antireflection films, and in order to inhibit the thermal lens effect of the laser crystal and improve the stability of output power and the quality of light beams, the emerald crystal is wrapped by indium foil and placed in a copper block fixture which is designed and processed by self, and is connected with a circulating water cooling system, and the water temperature is controlled at 20 ℃.
In the Q-switched system, the polaroid 10 must be incident at Brewster angle, both sides of the quarter wave plate 11 are plated with dielectric films with high transmittance at 700-800 nm wavelength, the Q switch 12 adopts BBO, RTP, LGS electro-optical or acousto-optic Q switch which can realize high-repetition frequency turn-off, and both light-transmitting end surfaces of the crystal of the Q switch 12 are plated with antireflection films with the wavelength of 700-800 nm.
In this embodiment, the angle mirror 9 divides the whole optical path into two parts, which are not on the same optical axis, and deflects the light in the optical path once in the resonant cavity, so that the structure of the resonant cavity is more compact, and the length of the resonant cavity is further shortened. The angle mirror 9 in this case is a flat 45 ° angle mirror, and the efficiency of reflection is highest when the laser light is incident at an angle of 45 °. The adjustment method of the flat 45 ° angle mirror will be described in detail by this case.
The reflectivity of the dielectric film with 638nm wavelength high transmission and the side facing the laser crystal is 97% for 700-800 nm wavelength high reflection is plated on both sides of the inserted OC coupling output mirror 14. In the angular mirror adjustment, the position to be inserted into the resonator is located in the middle of the emerald crystal 8 and the angular mirror 9, and the mirror 7, the emerald crystal 8 and the OC coupling-out mirror 14 are located on the same optical axis.
In the adjustment of the angle mirror 9, first a first aperture stop 15 and a third aperture stop 16 need to be placed in the middle of the OC coupling-out mirror 14 and the angle mirror 9 and behind the angle mirror 9. The reflecting mirror 7 is used as a front cavity mirror, a sub-resonant cavity for generating reference light is formed together with the emerald crystal 8 and the OC coupling output mirror 14, after oscillation laser is generated, the reflecting mirror 7 and the OC coupling output mirror 14 are required to be continuously adjusted, the oscillation laser passes through the centers of the first aperture diaphragm 15 and the third aperture diaphragm 16 (the two diaphragms are equal in height) at the same time, and the oscillation laser is used as reference laser for adjusting the angle reflecting mirror.
And then placing the reflecting surface of the angle reflecting mirror 9 opposite to the sub resonant cavity, continuously adjusting the PITCH of the angle reflecting mirror 9, and enabling the reference laser to enter the plane of the angle reflecting mirror 9 at 0 DEG, wherein the light reflected by the reference laser through the angle reflecting mirror just passes through the center of the first aperture diaphragm 15, so as to ensure the consistency of the heights of the reference laser before and after passing through the angle reflecting mirror.
Finally, the angle reflector 9 is placed according to the estimated angle, the YAW of the angle reflector 9 is rotated, the angle reflector 9 is placed according to the estimated 45 degrees (the angle reflector and the triangular paper board can be used for being used), the PITCH of the angle reflector before and after rotation needs to be ensured to be unchanged after the angle reflector is placed, at the moment, a second aperture diaphragm 17 (the aperture diaphragm is as high as the first two diaphragms) needs to be placed at one side of the rear side of the angle reflector 9, which is close to the Q-switching system, and when reference light passes through the centers of the two diaphragms at the same time, the height of the reference light before and after reflection of the angle reflector 9 is unchanged, namely the PITCH of the angle reflector before and after rotation is unchanged. A power meter 18 is then placed behind the angle mirror 9 on the side close to the Q-switched system for measuring the reference light power reflected by the angle mirror 9. Since the angle reflector 9 is placed according to the estimated angle, the error between the placement angle and 45 degrees is larger at the time, under the condition that the reference light is ensured to be aligned with the center of the angle reflector 9, the power measured by the power meter 18 is the maximum by finely adjusting the YAW of the angle reflector 9, the placement position of the angle reflector 9 is the best at the moment, and then the power meter 18 added in the light path is removed, so that the adjustment of the angle reflector is completed. By means of the reference laser, the reference light can return to the original path until the position of the last output mirror 13 is adjusted, and the aperture diaphragm added in the whole light path is removed.
Fig. 3 schematically illustrates a schematic diagram of an adjustment device for an angle mirror in a tunable emerald according to an embodiment of the disclosure.
As shown in fig. 3, the angle mirror adjustment apparatus in a tunable emerald laser provided in an embodiment of the present disclosure includes: the device comprises a pump source 1, a collimator 2, a half wave plate 3, a PBS polarization beam splitter prism 4, a half wave plate 5, a lens 6, a reflecting mirror 7, an emerald crystal 8, an angle reflecting mirror 9, a wavelength tuning element 10, a quarter wave plate 11, a Q switch 12 and an output mirror 13; the overall resonator shape is still V-shaped, with the node of the first and second arms being the angular mirror 9.
The working principle of the resonant cavity is as follows: the pumping light emitted by the pumping source 1 is collimated by the collimator 2 and then passes through the linear polarized light generator formed by the half wave plate 3, the PBS (polarization beam splitter) 4 and the half wave plate 5 together to generate the maximum horizontal linear polarized light, the maximum horizontal linear polarized light is used for pumping the emerald crystal 8 to generate oscillation laser, and the oscillation laser finally realizes the output of the pulse laser with tunable wavelength through the wavelength tuning element and the Q-switched system. The OC coupling-out mirror 14, the first aperture stop 15 and the third aperture stop 16, the second aperture stop 17 and the power meter 18 in the optical path are elements for adjusting the angle mirror in the resonant cavity, which need to be removed when the optical path runs last. The overall resonator length is about 300mm, the distance from the mirror 7 to the angle mirror 9 is about 140mm, and the distance from the angle mirror 9 to the output mirror 13 is about 160mm. The half wave plate 3 and the half wave plate 5 in the light path are both plated with 638nm light anti-reflection dielectric films which are incident at 0 degrees. The lens 6 is a plano-convex lens, one side facing the resonant cavity is a plane, both sides are plated with a 638nm light full-transmission dielectric film with incidence of 0 DEG, and the focal length is 50mm. The laser crystal in the resonant cavity is emerald crystal, and the coating and cooling modes are the same as those of the case 1.
The angle reflector 9 is a plano-concave reflector, one side of the concave surface faces the emerald crystal, and is plated with a dielectric film which totally reflects 700-800 nm light and 638nm light incident at 22 degrees, so that the effect of totally reflecting oscillation laser and filtering residual pump light is achieved, and the effect of folding a light path is also achieved.
Both sides of the reflecting mirror 7 are plated with an antireflection film for 638nm pump light wave band, wherein the side facing the cavity is also plated with a high reflection film for 0 DEG incidence of 700-800 nm laser wave band; the output mirror 13 is a plane mirror plated with a dielectric film having a high reflectivity of 99% for wavelengths of 700-800 nm. The wavelength tuning element is composed of three birefringent filters with a certain thickness ratio, and the birefringent filters are placed at brewster angles in the optical path, so that not only the wavelength tuning effect is achieved on the oscillating laser, but also the polarization effect is achieved on the oscillating laser, which saves one polarizer in the latter Q-switched system, and other elements in the Q-switched system, such as the quarter-wave plate 11 and the Q-switch 12, are the same as those used in case 1.
In this embodiment the angle mirror 9 is a plano-concave 22 ° angle mirror, the reflection efficiency of which is highest when the oscillating laser light is incident at 22 °. The adjustment method of the 22 ° plano-concave angle mirror will be described in detail by this case.
The two sides of the OC coupling output mirror 14 are plated with 638nm wavelength high-transmission films, and the side facing the emerald crystal 8 is plated with a dielectric film with high reflectivity of 95-97% for 700-800 nm wavelength.
In adjusting the angle mirror, it is first necessary to place an OC coupling-out mirror between the emerald crystal 8 and the angle mirror 9. The reflecting mirror 7, the emerald crystal 8 and the OC coupling-out mirror 14 are arranged on the same optical axis, and the reflecting mirror 7, the emerald crystal 8 and the OC coupling-out mirror 14 together form one sub-resonator of the large resonator for generating the collimated reference laser. The alignment laser must be horizontal, and in order to ensure the alignment laser level, a first aperture stop 15 and a third aperture stop 16 are placed in the middle of the OC coupling output mirror 14 and the angle mirror 9 and behind the angle mirror 9, and the front and back mirrors of the sub-resonator are continuously trimmed until the oscillation laser passes through the centers of the two aperture stops at the same time, and the oscillation laser at this time remains in the horizontal direction.
And then adjusting the reference laser to align with the center of the plano-concave 22-degree angle reflecting mirror, fixing the plano-concave 22-degree angle reflecting mirror on a triaxial adjusting frame when adjusting, and enabling the reference laser to vertically enter the plane of the angle reflecting mirror through adjusting the PITCH and YAW of the angle reflecting mirror, namely, enabling the reference laser to still pass through the center of the first aperture diaphragm 15 after being reflected by the angle reflecting mirror 9. And then pasting target paper cut in advance on the plane of the angle reflecting mirror, and then adjusting the height of the angle reflecting mirror under the condition of ensuring that PITCH and YAW are unchanged, so that reference laser is just vertically incident on the center of the target paper, and the adjustment of the reference laser aligning to the center of the plano-concave 22-degree angle reflecting mirror is completed.
Finally, the YAW of the angle reflector 9 is rotated, the angle reflector 9 is placed according to the estimated angle, and the placed angle can be estimated by means of a protractor and a triangular paperboard. In the whole process, the PITCH direction of the front and rear angle reflectors 9 needs to be consistent, at this time, a second aperture diaphragm 17 which is equal in height to the first aperture diaphragm 15 and the third aperture diaphragm 16 needs to be placed at one side, close to the Q-switching system, of the rear side of the angle reflectors 9, and when reference light passes through the centers of the first aperture diaphragm 15 and the second aperture diaphragm 17 at the same time, the height of the reference light before and after reflection by the angle reflectors 9 is unchanged, that is, the PITCH of the angle reflectors before and after rotation is unchanged. The power meter 18 is then placed between the 22 ° angle mirror 9 and the wavelength tuning element 10 for measuring the power of the reference laser light after reflection by the angle mirror. Before measuring the power, since the angle mirror is placed at the estimated angle, the estimated placement angle has a larger deviation from 22 °, so that the power measured by the power meter 18 can be maximized by fine tuning the YAW of the angle mirror while keeping the angle mirror PITCH unchanged and the reference laser aligned with the center of the angle mirror 9. The angle of placement of the angle mirror 9 is then optimal, up to which the adjustment of the angle mirror is completed. The power meter 18 in the optical path then needs to be removed. After the position of the last output mirror 13 is adjusted, the reference light can return to the original path on the whole optical path, and the OC coupling output mirror 14 in the optical path and all aperture diaphragms used in the adjustment process are removed.
Fig. 4 schematically illustrates a schematic diagram of an adjusting device of an angle mirror in a Z-folded cavity laser of emerald crystal according to an embodiment of the disclosure.
Referring to fig. 4, a schematic diagram of an adjusting device for an angle mirror in a Z-folded cavity laser with emerald crystal is shown, and the optical path includes: the device comprises a pump source 1, a collimator 2, a half wave plate 3, a PBS polarization beam splitter prism 4, a half wave plate 5, a lens 6, a reflecting mirror 7, emerald crystal 8, an angle reflecting mirror 9, an output mirror 10 and a reflecting mirror 11; the reflecting mirror 7 and the reflecting mirror 11 are respectively arranged at two ends of the light path of the large resonant cavity, and the reflecting mirror 7, the emerald crystal 8 and the reflecting mirror 11 together form an oscillation resonant cavity of the whole light path. In this embodiment, in order to make the resonator structure more compact and shorten the length of the resonator, the angle mirror 9 and the output mirror 10 fold the entire optical path twice. The OC coupling output mirror 13, the first aperture diaphragm 14, the third aperture diaphragm 15, the power meter 16, the second aperture diaphragm 17, the power meter 18 and the aperture diaphragm 19 in the whole optical path are all components for adjusting the angle reflecting mirror in the resonant cavity, and the components need to be removed in the final operation process of the optical path.
The half wave plate 3 and the half wave plate 5 in the whole light path are coated with 638nm light anti-reflection dielectric films which are incident at 0 degrees. The lens 6 is a plano-convex lens, one side facing the resonant cavity is a plane, and both sides are plated with 638nm light full-transmission dielectric films incident at 0 degrees. The laser crystal in the resonant cavity is emerald crystal, and the two ends are plated with 700-800 nm light antireflection film, and the temperature is controlled at 20 ℃. The reflecting mirror 7 and the output mirror 10 are plane mirrors, both surfaces of the plane mirrors are plated with 638nm wavelength antireflection dielectric films, wherein the reflecting mirror 7 is plated with 0 DEG incidence 700-800 nm wavelength total reflection dielectric films towards one side of the cavity, and the output mirror 10 is plated with 22 DEG incidence 700-800 nm wavelength high reflection dielectric films towards one side of the cavity, and the reflectivity is 99%; the angle reflector 9 and the reflector 11 are both plano-concave reflectors, wherein one side of the concave surface of the angle reflector 9 faces the emerald crystal, and is plated with a dielectric film which totally reflects 700-800 nm light incident at 22 degrees and totally transmits 638nm light, so that laser can be totally reflected and oscillated, and residual pump light can be filtered; one side of the concave surface of the reflecting mirror 11 faces the resonant cavity and is plated with a 700-800 nm light total reflection dielectric film which is incident at 0 degrees.
In this embodiment, the angle mirror 9 and the output mirror 10 are both angle mirrors, which divide the whole optical path into three parts, and the two arms are not on the same optical axis, so that the light is folded twice in the resonant cavity. The adjustment method of the angle mirror 9 and the output mirror 10 will be described in detail by this case.
When the angle reflectors are adjusted, firstly, a piece of OC coupling output mirror 13 is needed to be inserted between the emerald crystal 8 and the angle reflector 9, the piece of OC coupling output mirror 13 adopts a double-sided coating process, both ends of the piece of OC coupling output mirror are coated with 638nm wavelength antireflection films, wherein one surface facing the resonant cavity is coated with a dielectric film with high reflection to 700-800 nm wavelength, and the reflectivity can be 95-97%. At this time, the reflecting mirror 7, the emerald crystal 8 and the OC coupling output mirror 14 are positioned on the same optical axis to form a sub-resonator for generating the reference light, and the sub-resonator is positioned inside the large resonator and shares the front cavity mirror and the laser gain medium with the large resonator. The OC coupling-out mirror 13 is required to be as close as possible to the emerald crystal 8 in the sub-resonator so that the loss of the entire sub-resonator is very low and the reference laser is easily generated. After the sub-resonant cavity generates the oscillation laser, the front and back cavity mirrors are continuously adjusted until the oscillation laser is in a horizontal state, specifically, a first aperture diaphragm 14 and a third aperture diaphragm 15 are arranged between the OC coupling output mirror 14 and the angle reflecting mirror 9 and behind the angle reflecting mirror 9, the two aperture diaphragms are of equal height, and the oscillation laser passes through the centers of the two aperture diaphragms simultaneously through the continuously adjusted reflecting mirror 7 and the OC coupling output mirror 13, so that the reference light is in the horizontal state.
Secondly, the angle reflecting mirror 9 is a plano-concave 22 DEG reflecting mirror, and when the angle reflecting mirror is adjusted, reference laser is required to be aligned with the center of the plano-concave 22 DEG angle reflecting mirror, specifically, the reflecting surface of the angle reflecting mirror 9 is placed opposite to the resonant cavity, and the reference laser is vertically incident into the plane of the angle reflecting mirror 9 through adjusting the PITCH of the reflecting mirror 9, namely, the reference laser still passes through the center of the first aperture diaphragm 14 after being reflected by the reflecting mirror 9. And then pasting target paper cut in advance on the plane of the angle reflecting mirror, and under the condition that the PITCH of the reflecting mirror 9 is kept unchanged, only adjusting the vertical height of the angle reflecting mirror 9 perpendicular to the reference light to enable the reference laser to be coaxial with the center of the target paper, wherein the reference laser is aligned with the center of the plano-concave 22-degree angle reflecting mirror.
The PITCH of the angle mirror is then kept unchanged, the angle mirror is placed at the estimated angle, and the angle can be estimated by means of some auxiliary tool, such as a protractor, a triangular cardboard, etc. In order to keep the PITCH of the angle mirror unchanged during the placement, a second aperture stop 17 is placed between the mirror 9 and the mirror 10, which stop is of equal height as the first aperture stop 14. When the reference light passing through the center of the first aperture diaphragm 14 after the angle mirror is placed according to the estimated angle still passes through the center of the second aperture diaphragm 17 after being reflected by the mirror 9, the reference light passing through the front and rear of the mirror 9 is equal in height, that is, the PITCH of the angle mirrors before and after placement is unchanged.
Finally, due to the fact that the reflection angle and 22 degrees are greatly deviated, a power meter 16 needs to be placed behind the reflecting mirror 9 in the direction close to the output mirror 10, and under the condition that the reference light is guaranteed to be aligned with the center of the reflecting mirror 9, the adjustment state of the plano-concave 22-degree reflecting mirror is optimal when the power measured by the power meter 17 is maximum through fine adjustment of the YAW of the angle reflecting mirror 9. After the adjustment of the angle mirror 9 is completed, the power meter 17 can be removed.
The output mirror 10 is a flat 22 deg. mirror, and the efficiency of reflection is highest when incident light having a wavelength of 700 to 800nm is incident at 22 deg.. When adjusting the output mirror 10, a fourth aperture diaphragm 19 having the same height as the second aperture diaphragm 17 is required to be placed between the output mirror 10 and the reflecting mirror 11, so that the reference laser light passing through the front and rear of the output mirror 10 passes through the centers of the second aperture diaphragm 17 and the fourth aperture diaphragm 19 at the same time, so as to ensure that the height of the reference laser light before and after reflection by the output mirror 10 remains unchanged. After the output mirror 10 is rotated by the estimated angle, the PITCH may be slightly changed, and in this case, in order to ensure that the heights of the reference laser light before and after being reflected by the output mirror 10 are uniform, the PITCH of the output mirror 10 needs to be finely adjusted, so that the reference laser light passes through the centers of the second aperture stop 17 and the fourth aperture stop 19 at the same time, and the PITCH before and after the placement of the output mirror 10 is unchanged. A power meter 18 is then placed between the output mirror 10 and the mirror 11 for measuring the power reflected by the output mirror 10. While keeping the PITCH of the output mirror 10 unchanged, the YAW of the output mirror 10 is fine-tuned until the power measured by the power meter 18 is maximum, at which point the adjustment of the output mirror 10 is completed and the power meter 18 is removed.
After the last reflecting mirror 11 is placed, that is, the reference laser in the whole light path can return in the original path after being reflected by the reflecting mirror 11, the OC coupling output mirror 13, all aperture diaphragms and the power meter in the whole light path can be removed.
Fig. 5 schematically illustrates a schematic diagram of an adjustment device for an angle mirror in a long cavity self-tuning Q emerald laser provided by an embodiment of the disclosure.
As shown in fig. 5, the optical path of the angle mirror adjusting device in the long cavity self-tuning Q emerald laser includes: the device comprises a pump source 1, a collimator 2, a half wave plate 3, a PBS polarization beam splitter prism 4, a half wave plate 5, a lens 6, a reflecting mirror 7, an emerald crystal 8, a reflecting mirror 9, an output mirror 10, a reflecting mirror 11 and a reflecting mirror 12; the whole resonant cavity is in a W shape, the reflecting mirror 9, the output mirror 10 and the reflecting mirror 11 fold the whole resonant cavity three times, and the whole resonant cavity is divided into four parts. The cavity length of the whole resonant cavity is about 1330mm, the reflecting mirror 7 and the reflecting mirror 12 are plane reflecting mirrors, the reflecting mirror 9 and the reflecting mirror 11 are plane concave reflecting mirrors with the curvature of 300mm, and the inner sides of the plane concave reflecting mirrors are plated with high reflection films of the laser wave bands of 700-800 nm. Wherein, both sides of the reflecting mirror 7 are plated with an antireflection film for 638nm pump light wave band; the output mirror 10 is also a plane mirror coated with a dielectric film having a high reflection at a wavelength of 700 to 800nm, and has a reflectance of 99%. In addition, for the temperature control of the emerald crystal, a TEC temperature control device is used to maintain the temperature of the emerald crystal at 20 ℃. The pump source 1 is an LD pump of 638nm, the collimator 2 is a C40SMA-B fiber collimator produced by Thorlabs company, the focal length is 40mm, and the antireflection film is 650-1050nm. Both sides of the half wave plate 3 and the half wave plate 5 are plated with 638nm high-transmission films, and the center wavelength transmitted by the PBS polarization beam splitter prism 4 is 638nm. The OC coupling output mirror 13, the first aperture diaphragm 14, the third aperture diaphragm 15, the power meter 16, the second aperture diaphragm 17, the power meter 18, the fourth aperture diaphragm 19, the power meter 20 and the fifth aperture diaphragm 21 in the whole optical path are all elements for adjusting the angle reflecting mirror in the resonant cavity, and all the elements need to be removed when the optical path runs at last.
In this embodiment the angle mirrors have mirror 9, output mirror 10 and mirror 11 which fold the entire light path three times, with no light path on one axis before and after each fold. The adjustment method of the angle mirror will be described in detail by this case.
Before adjusting these angle mirrors, an OC coupling output mirror 13 is first inserted between the emerald crystal 8 and the reflecting mirror 9, so that the reflecting mirror 7, the emerald crystal 8 and the OC coupling output mirror 13 are coaxial, and the reflecting mirror 7, the emerald crystal 8 and the OC coupling output mirror 13 together form a sub-resonant cavity for generating reference laser light, and when the laser light is oscillated, the reference light of the angle mirrors can be used as the reference light for adjusting the angle mirrors. In order to make the oscillation laser level specific, two contour processing first aperture diaphragm 14 and third aperture diaphragm 15 are placed behind the OC coupling output mirror, and the front and back cavity mirrors are continuously adjusted until the oscillation laser passes through the centers of the two aperture diaphragms at the same time, the oscillation laser at this time is kept level, and the laser output at this time is used as reference laser.
Second, the mirror 9 is a 22 ° mirror, and when the incident light is incident at 22 °, the reflected light loss is minimal. During adjustment, the reference laser is required to be aligned with the center of the angle reflecting mirror 9, specifically, the reflecting mirror 9 is placed opposite to the sub-resonant cavity, and the reference laser is vertically incident into the plane of the angle reflecting mirror after passing through the center of the first aperture diaphragm 14 by adjusting the PITCH and YAW of the angle reflecting mirror 9, that is, the reference laser still passes through the center of the first aperture diaphragm 14 after being reflected by the angle reflecting mirror 9. And then, attaching target paper cut in advance in the mirror surface of the angle reflecting mirror, and adjusting the height of the angle reflecting mirror under the condition that PITCH and YAW of the angle reflecting mirror 9 are unchanged, so that reference laser is just vertically incident on the center of the target paper, and the adjustment of the reference laser aligning to the center of the plano-concave 22-degree angle reflecting mirror is completed.
Then, the angle reflecting mirror 9 is placed according to the estimated angle, the angle reflecting mirror YAW is required to be continuously rotated in the placing process, in order to ensure that the PITCH direction of the angle reflecting mirror is unchanged before and after rotation, a second aperture diaphragm 17 is required to be placed between the output mirror 10 and the reflecting mirror 9, and the second aperture diaphragm 17 and the first aperture diaphragm 14 are subjected to equal-height treatment so as to further ensure that the heights of the reference laser before and after reflection by the angle reflecting mirror 9 are kept consistent. When the light rays before and after the reference light is reflected by the mirror 9 pass through the centers of the first aperture stop 14 and the second aperture stop 17 at the same time, the PITCH of the angle mirror before and after rotation is unchanged.
When the angle mirror is placed at an estimated angle, the point at which the reference laser light is incident on the mirror 9 is deviated from the center of the mirror surface due to a slight displacement shift of the mirror surface of the angle mirror, and it is necessary to re-align the reference laser light to the center of the mirror 9 by adjusting the displacement of the mirror 9.
Finally, a power meter 16 is placed between the mirror 9 and the output mirror 10 for measuring the reference light power reflected by the mirror 9. Since the angle mirror is placed at the estimated angle, which is still a certain difference between the placement angle and the optimum value, it is ensured that the reference light is aimed at the center of the angle mirror 9, by fine tuning the YAW of the mirror 9 until the power measured by the power meter 16 is maximum, at which time the adjustment of the mirror 9 is completed, after which the power meter 16 can be removed.
The output mirror 10 is a flat 22 deg. mirror and the efficiency of reflection is highest when the incident light is incident at 22 deg.. When the output mirror 10 is adjusted, a fourth aperture stop 19 having the same height as the first aperture stop 14 is interposed between the output mirror 10 and the reflecting mirror 11, and the height of the reference laser beam passing through the output mirror 10 is adjusted by the fourth aperture stop 19 so that the height is kept at a constant value, that is, the reference laser beam passing through the center of the second aperture stop 17 is incident on the output mirror 10, and the reflected reference laser beam passes through the center of the fourth aperture stop 19. The PITCH of the output mirror 10 is then kept unchanged, and the output mirror 10 is rotated to be placed at the estimated angle. Because of the large error in the estimated placement angle, a power meter 18 is placed between the output mirror 10 and the reflecting mirror 11 to measure the reference light power reflected by the output mirror 10, and the power meter 18 is removed after the adjustment of the output mirror 10 is completed by fine-tuning the YAW of the output mirror 10 until the power measured by the power meter 18 is maximized.
The mirror 11 is a plano-concave 22 ° mirror, and the adjustment method is the same as the adjustment of the mirror 9, and a fifth aperture stop 21 is disposed between the mirror 11 and the mirror 12 to calibrate the height of the reference light before and after passing through the mirror 11. After aligning the reference laser light with the center of the mirror 11, keeping the pitch unchanged, rotating the mirror 11 to be placed at an estimated angle, and then adjusting the displacement of the mirror 11 to align the reference light with the center of the mirror 11 again. Since the angle of placement is estimated to deviate from the optimal position, a power meter 20 is placed between the mirror 11 and the mirror 12 to measure the reference light power reflected by the mirror 11, and the power meter 20 is removed after the adjustment of the mirror 11 is completed by fine-tuning the YAW of the mirror 11 until the power measured by the power meter 20 is maximized.
After the position of the last reflecting mirror 12 is placed, namely, the light in the whole light path can return to the original path after passing through the reflecting mirror 12, the OC coupling output mirror 13 and the aperture diaphragm in the whole light path can be removed.
According to the adjusting method and the adjusting device for the angle reflecting mirror in the laser resonant cavity, the OC coupling output mirror is inserted behind the laser gain medium, so that the front cavity mirror, the laser gain medium and the OC coupling output mirror form a new sub-resonant cavity, and the sub-resonant cavity is self-excited to oscillate under the action of the end face pumping source to generate reference laser. By utilizing the reference laser, the aperture diaphragm, the target paper and the power meter can quickly and accurately adjust the angle reflecting mirror in the resonant cavity, and compared with the method for roughly estimating the reflecting angle by utilizing helium neon light in the prior art, the method for adjusting the angle reflecting mirror is quicker, simpler, more convenient and more accurate. The adjusting method is more suitable for the concave reflecting mirror plated with the incident angle high-reflection film, and the adjusting method does not need other precise equipment and is not limited by the application occasions. In addition, the adjusting device only comprises an OC coupling output mirror, an aperture diaphragm, target paper and a power meter, has few used elements, is quite simple in structure, quite easy to realize and low in cost, and is suitable for adjusting the angle reflecting mirror under most experimental scenes.
Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.
While the present disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. The scope of the disclosure should, therefore, not be limited to the above-described embodiments, but should be determined not only by the following claims, but also by the equivalents of the following claims.

Claims (9)

1. A method of adjusting an angle mirror in a laser cavity, the method comprising:
an OC coupling output mirror is arranged between a laser gain medium and an angle reflecting mirror in a laser resonant cavity, so that the OC coupling output mirror, the laser gain medium and a front cavity mirror in the laser form a sub-resonant cavity to generate reference laser;
A first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror, the angle reflecting mirror is adjusted, and after the reference laser reaches the angle reflecting mirror through the center of the first aperture diaphragm, the light reflected back through the angle reflecting mirror also passes through the center of the first aperture diaphragm and is aligned with the center of the angle reflecting mirror;
the angle reflector is placed according to the estimated reflection angle, a second aperture diaphragm is arranged in the reflection direction of the angle reflector to keep the pitch angle of the angle reflector unchanged, and the angle reflector is adjusted to enable the reference laser reflected by the angle reflector to pass through the center of the second aperture diaphragm;
adjusting the height of the angle reflecting mirror to enable the reference laser to be aligned with the center of the angle reflecting mirror again;
and measuring the power of the reference laser reflected by the angle reflecting mirror, adjusting the yaw angle of the angle reflecting mirror until the power is maximum, and stopping adjustment.
2. The adjustment method according to claim 1, characterized in that the method further comprises:
a third aperture diaphragm is arranged behind the angle reflecting mirror, and the first aperture diaphragm and the third aperture diaphragm are equal in height;
Before adjusting the angle reflecting mirror, adjusting angles of the OC coupling output mirror and the front cavity mirror to enable the reference laser to pass through centers of the first aperture diaphragm and the third aperture diaphragm at the same time, and enabling the reference laser to be horizontal.
3. The adjustment method according to claim 1, wherein when the angle mirror is a concave angle mirror, the adjusting the angle mirror so that the reference laser light reaches the angle mirror through the center of the first aperture stop, the light reflected back through the angle mirror also passes through the center of the first aperture stop, further comprises:
and attaching target paper to the angle reflecting mirror, adjusting the height of the angle reflecting mirror, and taking down the target paper after the reference laser is aligned with the center of the target paper to finish alignment of the reference laser with the center of the angle reflecting mirror.
4. The adjustment method according to claim 1, characterized in that the method further comprises:
and adjusting the second aperture diaphragm to be the same height as the first aperture diaphragm.
5. The adjustment method of claim 1, wherein the adjusting the height of the angle mirror to realign the reference laser to the center of the angle mirror comprises:
And attaching target paper to the angle reflecting mirror, adjusting the height of the angle reflecting mirror, and taking down the target paper after the reference laser is aligned with the center of the target paper to finish alignment of the reference laser with the center of the angle reflecting mirror.
6. The adjustment method according to claim 1, characterized in that the method further comprises:
and after the angle reflecting mirror is adjusted, removing the first aperture diaphragm, the second aperture diaphragm and the power meter.
7. An adjustment device for an angle mirror in a laser resonator, applied to the adjustment method as set forth in any one of claims 1 to 6, comprising:
the OC coupling output mirror is arranged between the laser gain medium and the angle reflecting mirror in the laser resonant cavity, is coaxial with the laser gain medium and the front cavity mirror in the laser resonant cavity, and is used for forming a sub-resonant cavity with the laser gain medium and the front cavity mirror to generate reference laser;
the first aperture diaphragm is arranged between the OC coupling output mirror and the angle reflecting mirror and is used for assisting in adjusting the angle reflecting mirror so as to enable the reference laser to be aligned to the angle reflecting mirror;
The second aperture diaphragm is arranged in the reflecting direction of the angle reflecting mirror and is used for assisting in calibrating the reflecting angle of the angle reflecting mirror in the adjusting process of the angle reflecting mirror;
and the power meter is arranged behind the angle reflecting mirror and is used for measuring the power of the reference laser reflected by the angle reflecting mirror.
8. The adjustment device of claim 7, further comprising:
and the third aperture diaphragm is arranged behind the angle reflecting mirror, is equal to the first aperture diaphragm in height and is used for being matched with the first aperture diaphragm before adjusting the angle reflecting mirror so as to calibrate the reference laser in the horizontal direction.
9. The adjustment device of claim 7, further comprising:
and the triaxial adjusting frame is connected with the angle reflecting mirror and used for adjusting the height, front-back displacement and left-right displacement of the angle reflecting mirror.
CN202310037876.2A 2023-01-10 2023-01-10 Method and device for adjusting angle reflecting mirror in laser resonant cavity Pending CN116231430A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310037876.2A CN116231430A (en) 2023-01-10 2023-01-10 Method and device for adjusting angle reflecting mirror in laser resonant cavity

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310037876.2A CN116231430A (en) 2023-01-10 2023-01-10 Method and device for adjusting angle reflecting mirror in laser resonant cavity

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CN116231430A true CN116231430A (en) 2023-06-06

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