CN114414210A - Rapid measurement system and method for phase matching direction of laser frequency doubling crystal - Google Patents
Rapid measurement system and method for phase matching direction of laser frequency doubling crystal Download PDFInfo
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Abstract
The embodiment of the disclosure provides a system and a method for rapidly measuring the phase matching direction of a laser frequency doubling crystal, wherein the method comprises the following steps: shaping an incident laser beam into a tapered laser beam; irradiating the laser frequency doubling crystal with the conical laser beam; acquiring an emergent laser spot emitted from the laser frequency doubling crystal, wherein the emergent laser spot comprises a central stripe; and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot. Through the processing scheme disclosed by the invention, the operation is simple, the time consumption is short, and the phase matching direction of the laser frequency doubling crystal can be accurately measured.
Description
Technical Field
The invention belongs to the technical field of precision measurement of optical elements, relates to precision measurement of phase matching directions of frequency doubling crystal elements in high-power laser drivers in inertial confinement fusion devices, and particularly relates to a system and a method for quickly measuring the phase matching directions of laser frequency doubling crystals.
Background
The laser frequency doubling is to change the frequency of the incident laser to twice of the original frequency by utilizing the secondary nonlinear effect generated by the nonlinear crystal under the action of strong laser. In an inertial confinement fusion device, in order to improve the absorption efficiency of a target pellet on laser energy, the laser is generally required to be frequency-doubled, and the process of performing frequency doubling operation on the laser is generally realized by a large-caliber KDP (potassium dihydrogen phosphate) crystal. In practical application, through a special cutting mode, the direction perpendicular to the crystal surface can be theoretically ensured to be the direction with the highest frequency doubling efficiency, namely the phase matching direction. However, since the crystal growth process, the crystal processing process and the crystal assembly process all cause the optical uniformity and the surface precision inside the crystal to change, thereby causing the local phase matching direction to change, the phase matching direction of each KDP crystal needs to be measured before practical use.
The traditional method for measuring the phase matching direction of the KDP crystal in China is to use linear laser as fundamental laser and change the intensity of the outgoing double-frequency laser by adjusting the pitching and deflecting angles of the KDP crystal. When the light intensity of the double-frequency laser is strongest, the corresponding attitude of the KDP crystal is the phase matching direction of the crystal. The measuring method is complex in operation and time-consuming, and is difficult to accurately judge when the frequency doubling laser is strongest, so that a certain deviation exists in a measuring result. Therefore, there is a great importance and necessity for improving the measurement process of the phase matching angle of the KDP crystal.
Disclosure of Invention
In view of the above, embodiments of the present disclosure provide a system and a method for rapidly measuring a phase matching direction of a frequency doubling laser crystal, which at least partially solve the problems in the prior art.
In a first aspect, an embodiment of the present disclosure provides a method for rapidly measuring a phase matching direction of a frequency doubling laser crystal, where the method includes:
shaping an incident laser beam into a tapered laser beam;
irradiating the laser frequency doubling crystal with the conical laser beam;
acquiring an emergent laser spot emitted from the laser frequency doubling crystal, wherein the emergent laser spot comprises a central stripe; and
and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot.
According to a specific implementation manner of the embodiment of the present disclosure, after the step of irradiating the laser frequency doubling crystal with the tapered laser beam, the method further includes:
calculating the size of the spot of the conical laser beam on the surface of the laser frequency doubling crystal based on an original spot size, a beam divergence angle, and a beam divergence distance, wherein the original spot size indicates the size of the spot emitted from the laser, the beam divergence angle indicates the divergence angle of the conical laser beam, and the beam divergence distance indicates the size of the rear surface of the plano-concave lens to the surface of the laser frequency doubling crystal.
According to a specific implementation manner of the embodiment of the present disclosure, the step of obtaining the phase matching direction of the frequency doubling laser crystal based on the distance between the central stripe and the center of the emergent laser spot includes:
and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance, the divergence angle of the conical laser beam, the size of the light spot, the refractive index of the incident laser beam in the laser frequency doubling crystal, the refractive index of the emergent laser in the laser frequency doubling crystal and the distance between the laser frequency doubling crystal and the emergent laser light spot.
According to a specific implementation manner of the embodiment of the disclosure, the phase matching direction of the laser frequency doubling crystal is obtained according to the following formula:
wherein R is the size radius of the original light spot after beam expansion, and L1Is the distance between the plano-concave lens and the front surface of the frequency doubling crystal, alpha is the divergence angle of the conical laser beam, beta is the incident angle of the incident laser beam when the incident laser beam is incident on the frequency doubling crystal, gamma is the refraction angle of the incident laser beam, delta is the exit angle of the exit laser beam, noIs the refractive index of the incident laser beam in the laser frequency doubling crystal, neIs the refractive index of the emitted laser in the laser frequency doubling crystal, dKDPIs the thickness of the laser frequency doubling crystal. L is2Is the distance between the laser frequency doubling crystal and the emergent laser facula.
According to a specific implementation manner of the embodiment of the present disclosure, the method further includes:
when the central stripe is positioned below the center of the emergent laser spot, the laser frequency doubling crystal is rotated anticlockwise to obtain a phase matching direction; and is
And when the central stripe is positioned above the center of the emergent laser spot, the laser frequency doubling crystal is rotated clockwise to obtain the phase matching direction.
In a second aspect, a system for fast measurement of phase matching direction of a frequency doubling laser crystal is provided, the system comprising:
a laser (3) configured to emit an incident laser beam;
a plano-concave lens (6) configured to shape the incident laser beam into a tapered laser beam;
the laser frequency doubling crystal (7), the said conical laser beam irradiates the said laser frequency doubling crystal (7); and
an area array camera (11) configured to acquire an outgoing laser spot emitted from the laser frequency doubling crystal (7), wherein the outgoing laser spot comprises a central stripe; and
a processor configured to obtain a phase matching direction of the laser frequency doubling crystal (7) based on a distance of the central stripe from a center of the outgoing laser spot.
According to a specific implementation manner of the embodiment of the present disclosure, the system further includes:
a beam expander (4) configured to expand a diameter of the incident laser beam;
a beam shaper (5) for shaping the beam exiting from the beam expander (4) into a flat-top beam, and the plano-concave lens (6) for changing the exiting beam of the beam shaper (5) into a conical beam;
the optical filter (9) is used for filtering the fundamental frequency laser emitted from the laser frequency doubling crystal (7); and
and an attenuation sheet (10) for reducing the intensity of the laser light incident on the area array camera (11).
According to a specific implementation manner of the embodiment of the present disclosure, the system further includes:
an air-floating optical platform (1);
the backing plate (2), the high-power laser (3), the beam expander (4), the beam shaper (5) and the plano-concave lens (6) are sequentially arranged on the cushion block (2);
a two-dimensional moving platform (8), wherein the laser frequency doubling crystal (7) is arranged on the two-dimensional moving platform (8); and
a backing plate (12), the filter (9), the attenuation sheet (10) and the area array camera (11) are arranged on the backing plate (12), wherein
The pad (2), the two-dimensional moving platform (8) and the pad (12) are arranged on the air-floating optical platform (1).
According to a specific implementation of the disclosed embodiment, the rate laser (3) is a solid state laser with a wavelength of 1053 nm.
According to a specific implementation of the disclosed embodiment, the plano-concave lens (6) is used to change the outgoing beam of the beam shaper (5) into a conical beam with a divergence angle of 5 mrad.
According to a specific implementation manner of the embodiment of the disclosure, the photosensitive chip size of the area array camera (11) is 12.3mm × 12.3mm, the resolution is 20.2MP, and the horizontal and vertical pixel sizes are 2.74 μm × 2.74 μm.
In a third aspect, an embodiment of the present disclosure further provides an electronic device, where the electronic device includes:
at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method for fast measurement of the phase matching direction of the laser frequency doubling crystal in the first aspect or any implementation manner of the first aspect.
In a fourth aspect, the disclosed embodiments also provide a non-transitory computer-readable storage medium storing computer instructions for causing the computer to perform the method for fast measuring the phase matching direction of the laser frequency doubling crystal in the foregoing first aspect or any implementation manner of the first aspect.
In a fifth aspect, the present disclosure also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, where the computer program includes program instructions, and when the program instructions are executed by a computer, the computer executes the method for fast measuring the phase matching direction of the laser frequency doubling crystal in the foregoing first aspect or any implementation manner of the first aspect.
The method for rapidly measuring the phase matching direction of the laser frequency doubling crystal in the embodiment of the disclosure comprises the following steps: shaping an incident laser beam into a tapered laser beam; irradiating the laser frequency doubling crystal with the conical laser beam; acquiring an emergent laser spot emitted from the laser frequency doubling crystal, wherein the emergent laser spot comprises a central stripe; and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot. Through the processing scheme disclosed by the invention, the operation is simple, the consumption is short, and the phase matching direction of the laser frequency doubling crystal can be accurately measured.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is an overall structure diagram of a large-aperture laser frequency doubling crystal phase matching direction rapid measurement system of the present invention.
Fig. 2(a) is a front view of the phase matching direction fast measuring system of the large-aperture laser frequency doubling crystal of the invention.
Fig. 2(b) is a schematic diagram of the optimal phase matching angle calculation parameters.
FIG. 3 is a simulation diagram of the spot intensity distribution seen on the area-array camera of the large-aperture laser frequency doubling crystal phase matching direction rapid measurement system of the invention.
FIG. 4 is a schematic diagram of the phase matching direction fast measurement system of the large-aperture laser frequency doubling crystal according to the present invention.
FIG. 5 is a flow chart of the method for rapidly measuring the phase matching direction of the frequency doubling laser crystal according to the present invention.
FIG. 6 is a schematic diagram of a system for rapidly measuring the phase matching direction of a frequency doubling laser crystal according to the present invention.
Detailed Description
The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
The embodiments of the present disclosure are described below with specific examples, and other advantages and effects of the present disclosure will be readily apparent to those skilled in the art from the disclosure in the specification. It is to be understood that the described embodiments are merely illustrative of some, and not restrictive, of the embodiments of the disclosure. The disclosure may be embodied or carried out in various other specific embodiments, and various modifications and changes may be made in the details within the description without departing from the spirit of the disclosure. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the disclosure, one skilled in the art should appreciate that one aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present disclosure, and the drawings only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation, and the type, amount and ratio of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
The invention provides a system and a method for rapidly measuring a phase matching angle of a laser frequency doubling crystal, which are based on the requirement of meeting the requirements of a laser inertial confinement fusion device on rapidity and accuracy of measuring the phase matching angle of the large-caliber laser frequency doubling crystal.
The present invention will be described in further detail with reference to the accompanying drawings.
First, referring to fig. 1 and fig. 2(a), a system for rapidly measuring a phase matching angle of a laser frequency doubling crystal according to an embodiment of the present invention is described, and as shown in fig. 1, the system includes an air-floating optical platform 1, a pad 2, a high-power laser 3, a beam expander 4, a beam shaper 5, a plano-concave lens 6, a KDP crystal 7, a two-dimensional moving platform 8, a filter 9, an attenuation plate 10, an area-array camera 11, and a pad 12.
In the embodiment of the invention, the air-floating optical platform 1 is the basis of the whole rapid measurement system and is mainly used for isolating various vibrations, the size of the table top of the air-floating optical platform 1 can be 1400mm × 800mm × 100mm, and the material is stainless steel.
A cushion block 2 is arranged on the air-floating optical platform 1, and is used for adjusting the height of an optical element in the system, and specifically, a high-power laser 3, a beam expander 4, a beam shaper 5 and a plano-concave lens 6 are sequentially arranged on the cushion block 2. In the embodiment of the invention, the cushion block 2 has the size of 800mm multiplied by 500mm multiplied by 30mm, and the material is stainless steel.
The high power laser 3 may be a solid laser with a wavelength of 1053nm, and in the embodiment of the present invention, the output power is 1-1000 mw, and the output spot diameter is 1.5 mm.
The beam expander 4 is configured to expand the diameter of the laser beam emitted from the high power laser 3, and in the embodiment of the present invention, the incident aperture is 5mm, the exit aperture is 10mm, and the beam expanding magnification is 4, so as to expand the diameter of the laser beam emitted from the high power laser 3 to 6 mm.
The beam shaper 5 is used for shaping the Gaussian beam emitted from the beam expander 4 into a parallel beam, and the uniformity of the light intensity is less than 5%.
The plano-concave lens 6 is used to change the outgoing beam of the beam shaper 5 into a conical beam with a divergence angle of 5mrad (0.005rad) so that the incidence angle of the entire beam is continuously distributed between-5 mrad and 5mrad when the laser beam is incident on the KDP crystal 7.
The KDP crystal 7 is used to realize the frequency doubling effect of the laser, and is also the object to be measured, and is disposed on the two-dimensional moving platform 8, and the size of the KDP crystal can be the actual size in engineering application, i.e. 410mm × 410mm × 12.6 mm.
The two-dimensional moving platform 8 has the overall size of 375mm multiplied by 125mm multiplied by 40mm, can move in two directions parallel and vertical to the air-floating optical platform 1, has the moving precision of 0.1mm, is used for adjusting the position of laser irradiation on the KDP crystal 7, and is convenient for measuring the phase matching directions of different positions of the KDP crystal 7.
The optical filter 9 is used for filtering 1053nm fundamental frequency light, and is convenient for subsequent measurement of double frequency light by passing double frequency light with the wavelength of 526.5nm, the external dimension of the optical filter is phi 12.5mm, the effective aperture is more than 90%, the transmission band is 350 nm-560 nm, the cut-off band is 590 nm-850 nm, and the transmittance is more than 90%.
The attenuation sheet 10 is used for reducing the light intensity of laser incident to the area-array camera 1 so as to avoid damaging the camera, the external dimension of the attenuation sheet is phi 12.5mm, the effective aperture is larger than 90%, the light intensity transmittance T is 0.1, and the applicable wavelength range is 400nm-700 nm.
The area-array camera 11 has a photosensitive chip size of 12.3mm × 12.3mm, a resolution of 20.2MP, and horizontal and vertical pixel sizes of 2.74 μm × 2.74 μm. For the measuring system, the change of the light intensity of the light spot caused by the angle change of 10 mu rad can be distinguished, and the requirement on the measuring precision in engineering application can be met.
The pad 12 is used for adjusting the height of the optical element and is disposed on the air floating optical platform 1, and the optical filter 9, the attenuation sheet 10 and the area array camera 11 are disposed on the pad 12 to adjust the height, and the size is 500mm × 400mm × 30mm, and the material is stainless steel.
In the actual measurement process, a light spot image is obtained in the area-array camera 11, the distance d between the brightest light ray and the center of the light spot can be obtained, and the optimal phase matching angle of the KDP crystal 7 in the measurement can be obtained according to other physical parameters in the optical system, wherein the calculation formula is as follows:
wherein R is the spot size of the laser beam emitted from the beam expander 4, and L is1Is the distance between the plano-concave lens 6 and the front surface of the KDP crystal 7, alpha is the divergence angle of the laser beam after passing through the plano-concave lens 6, and beta is the incidence of the fundamental frequency laser to the KDP crystalThe incident angle of the body 7 is gamma which is the refraction angle of the fundamental frequency laser after entering the KDP crystal 7, and delta which is the emergent angle of the double frequency laser when emerging from the KDP crystal 7. n isoIs the refractive index of the fundamental frequency light as it propagates within the KDP crystal 7, neIs the refractive index of the double frequency light as it propagates within the KDP crystal 7. dKDPIs the thickness of the KDP crystal. L is2Is the distance between the lens of the area-array camera 11 and the back surface of the KDP crystal 7 (see fig. 2 (b)).
In an optical precision measurement environment meeting the grade 5 cleanliness requirement (according to the ISO14644-1 standard), the following steps are specifically performed:
step 1: fixing the backing plate 2 on the air-floating optical platform 1 to enable the left end face of the backing plate to be superposed with the left end face of the air-floating optical platform 1;
step 2: fixing a high-power laser 3 on the backing plate 2 through a threaded hole on the base;
and step 3: the beam expander 4 is mounted on the support frame and fixed to the backing plate 2 through a threaded hole in the support frame, at a distance of 125mm from the high power laser 3. The height of the supporting frame is adjusted to ensure that the axis of the beam expander 4 is superposed with the axis of the light outlet of the high-power laser 3;
and 4, step 4: the beam shaper 5 is mounted on a support frame and fixed to the backing plate 2 by means of a threaded hole in the support frame, the base of which is spaced 175mm from the base of the beam expander 3. Adjusting the height of the support frame to ensure that the axis of the beam shaper 5 is superposed with the axis of the beam expander 4;
and 5: the plano-concave lens 6 is mounted on a support frame and fixed to the backing plate 2 through a threaded hole in the support frame, with a base 100mm from the base of the beam shaper 4. Adjusting the height of the support frame to ensure that the axis of the plano-concave lens 5 is superposed with the axis of the beam shaper 4;
step 6: the KDP crystal 7 is installed on the supporting frame and is fixed on the two-dimensional moving platform 8 through a threaded hole in the supporting frame, the two-dimensional moving platform 8 is installed on the air flotation optical platform 1, the distance between the front surface of the KDP crystal 7 and the plane of the plano-concave lens 6 is kept to be 100mm, and the radius of a light spot on the KDP crystal is 3.5mm at the moment.
And 7: fixing the backing plate 12 on the air-floating optical platform 1 to make the right end surface of the backing plate coincide with the right end surface of the air-floating optical platform 1;
and 8: the filter 9 is mounted on a support frame and fixed to the backing plate 12 by means of threaded holes in the support frame. The height of the support frame is adjusted to make the axis of the optical filter 9 coincide with the axis of the plano-concave lens 6. The distance between the optical filter 9 and the rear surface of the KDP crystal 7 is 100 mm;
and step 9: the attenuation sheet 10 was mounted on a support and fixed to the backing plate 12 by means of threaded holes in the support so that the distance between the base of the attenuation sheet 10 and the base of the filter 9 was 75 mm. Adjusting the height of the support frame to ensure that the axis of the attenuation sheet 10 is superposed with the axis of the optical filter 9;
step 10: the area array camera 11 is mounted on the support frame and fixed on the backing plate 12 through the threaded hole on the support frame, so that the distance between the base of the area array camera 11 and the base of the attenuation 10 is 100 mm. Adjusting the height of the support frame to make the axis of the lens of the area-array camera 11 coincide with the axis of the attenuation sheet 10; at the moment, the distance between the lens of the area-array camera 11 and the rear surface of the KDP crystal 7 is 255 mm;
step 11: opening the matched software on a computer connected with the area-array camera 9 to prepare for observing the light intensity distribution of the emergent light spots;
step 12: turning on a switch of the high-power laser 3, and adjusting the power to stop when the light spot can be clearly observed in the matching software provided in the step 9; an almost circular spot (see fig. 3) is then visible on the screen, which spot is formed by a plurality of lateral stripes of different brightness. One of the stripes in the transverse direction is brightest, and the stripes on both sides of the transverse stripe take the transverse stripe as a symmetrical center, and the brightness is reduced in sequence along with the increase of the distance. When the phase mismatch angle (namely the angle of the KDP crystal needing to be adjusted when the phase is matched and the anticlockwise direction is taken as the positive direction) is positive, the brightest stripe is below the center of the light spot; when the phase mismatch angle is negative, the brightest stripe is above the center of the light spot; when there is no phase mismatch, the brightest fringe passes through the spot center.
Step 13: according to the light spots observed on a computer, the vertical distance d between the brightest line in the light spots and the center of the light spots is calculated, and the optimal phase matching angle of the KDP crystal 6 can be obtained by the following formula:
wherein, the numerical value 3 is the size radius of an emergent light spot in the beam expander 4, 100 is the distance between the plano-concave lens 6 and the front surface of the KDP crystal 7, beta is the incident angle of the fundamental frequency laser incident on the KDP crystal 7, gamma is the refraction angle of the fundamental frequency laser after entering the KDP crystal 7, and delta is the emergent angle of the double frequency laser when emerging from the KDP crystal 7. The value of 1.4941 is the refractive index of the fundamental light as it propagates through KDP crystal 7, and the value of 1.4707 is the refractive index of the double-frequency light as it propagates through KDP crystal 7. The value 12.6 is the thickness of the KDP crystal. The value 255 is the distance between the lens of the area-array camera 11 and the back surface of the KDP crystal 7. Beta is the phase matching angle of the crystal.
The embodiments of the present invention are described above specifically, and next, general embodiments of the present invention are described with reference to fig. 4 to 6.
First, referring to fig. 4, a method for rapidly measuring a phase matching direction of a frequency doubling laser crystal according to a general embodiment of the present invention is described, the method including:
s401: shaping the incident laser beam into a cone-shaped laser beam.
S402: and irradiating the laser frequency doubling crystal by the conical laser beam.
S403: and acquiring emergent laser spots emitted from the laser frequency doubling crystal, wherein the emergent laser spots comprise central stripes.
S404: and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot.
Specific implementation and operation of the above steps can be referred to the description made above with reference to fig. 1 to 3, and are not described again here.
Referring to fig. 5, according to a specific implementation manner of the embodiment of the present disclosure, after the step S402 of irradiating the laser frequency doubling crystal with the tapered laser beam, the method further includes:
s501: and acquiring the size of the light spot of the conical laser beam on the surface of the laser frequency doubling crystal.
According to a specific implementation manner of the embodiment of the present disclosure, the step of obtaining the phase matching direction of the frequency doubling laser crystal based on the distance between the central stripe and the center of the emergent laser spot includes:
and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance, the divergence angle of the conical laser beam, the size of the light spot, the refractive index of the incident laser beam in the laser frequency doubling crystal, the refractive index of the emergent laser in the laser frequency doubling crystal and the distance between the laser frequency doubling crystal and the emergent laser light spot.
And specifically, the phase matching direction of the laser frequency doubling crystal can be obtained according to the following formula:
wherein R is the size radius of the original light spot after beam expansion, and L1Is the distance between the plano-concave lens 6 and the front surface of the KDP crystal 7, β is the incident angle when the incident laser beam is incident on the laser frequency doubling crystal, γ is the refraction angle of the incident laser beam, δ is the exit angle of the exit laser, is the refractive index of the incident laser beam in the laser frequency doubling crystal, is the refractive index of the exit laser in the laser frequency doubling crystal, and is the thickness of the laser frequency doubling crystal. L2 is the distance between the laser frequency doubling crystal and the emergent laser spot.
According to a specific implementation manner of the embodiment of the present disclosure, the method further includes:
when the central stripe is positioned below the center of the emergent laser spot, the laser frequency doubling crystal is rotated anticlockwise to obtain a phase matching direction; and is
And when the central stripe is positioned above the center of the emergent laser spot, the laser frequency doubling crystal is rotated clockwise to obtain the phase matching direction.
Referring to fig. 6, the present invention provides a system for rapidly measuring the phase matching direction of a frequency doubling laser crystal, wherein the system comprises:
a laser 3 configured to emit an incident laser beam;
a plano-concave lens 6 configured to shape the incident laser beam into a tapered laser beam;
the laser frequency doubling crystal 7 is irradiated by the conical laser beam; and
an area-array camera 11 configured to acquire an outgoing laser spot emitted from the laser frequency doubling crystal 7, wherein the outgoing laser spot includes a central stripe; and
and the processor is configured to acquire the phase matching direction of the laser frequency doubling crystal 7 based on the distance from the central stripe to the center of the emergent laser spot.
The parts of the rapid measurement system for the phase matching direction of the laser frequency doubling crystal can be referred to the description above with reference to fig. 1-2, and are not described again here.
According to a specific implementation manner of the embodiment of the present disclosure, the system further includes:
a beam expander 4 configured to expand a diameter of the incident laser beam;
a beam shaper 5 for shaping the beam exiting from the beam expander 4 into a parallel beam, and the plano-concave lens 6 for changing the exiting beam of the beam shaper 5 into a cone beam;
the optical filter 9 is used for filtering the emergent laser emitted from the laser frequency doubling crystal 7; and
and an attenuation sheet 10 for reducing the intensity of the laser light incident on the area-array camera 11.
According to a specific implementation manner of the embodiment of the present disclosure, the system further includes:
an air-floating optical platform 1;
the cushion plate 2, the high-power laser 3, the beam expander 4, the beam shaper 5 and the plano-concave lens 6 are sequentially arranged on the cushion block 2;
the two-dimensional moving platform 8 is provided with the laser frequency doubling crystal 7; and
a pad 12, on which the filter 9, the attenuation sheet 10 and the area-array camera 11 are disposed, wherein
The pad 2, the two-dimensional moving stage 8, and the pad 12 are disposed on the air-floating optical stage 1.
According to a specific implementation manner of the embodiment of the present disclosure, the rate laser 3 is a solid laser with a wavelength of 1053 nm.
According to a specific implementation of the disclosed embodiment, the plano-concave lens 6 is used to change the outgoing beam of the beam shaper 5 into a cone beam with a divergence angle of 5 mrad.
According to a specific implementation manner of the embodiment of the present disclosure, the size of the photosensitive chip of the area-array camera 11 is 12.3mm × 12.3mm, the resolution is 20.2MP, and the horizontal and vertical pixel sizes are 2.74 μm × 2.74 μm.
An embodiment of the present disclosure further provides an electronic device, including:
at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method for rapidly measuring the phase matching direction of the laser frequency doubling crystal.
In a fourth aspect, the disclosed embodiments also provide a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the aforementioned method for fast measurement of the phase matching direction of the laser frequency doubling crystal.
In a fifth aspect, the disclosed embodiments also provide a computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions that, when executed by a computer, cause the computer to perform the aforementioned method for fast measurement of phase matching direction of a laser frequency doubling crystal.
The method for rapidly measuring the phase matching direction of the laser frequency doubling crystal in the embodiment of the disclosure comprises the following steps: shaping an incident laser beam into a tapered laser beam; irradiating the laser frequency doubling crystal with the conical laser beam; acquiring an emergent laser spot emitted from the laser frequency doubling crystal, wherein the emergent laser spot comprises a central stripe; and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot. Through the processing scheme disclosed by the invention, the operation is simple, the consumption is short, and the phase matching direction of the laser frequency doubling crystal can be accurately measured.
The above description is only for the specific embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present disclosure should be covered within the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.
Claims (11)
1. A method for rapidly measuring the phase matching direction of a laser frequency doubling crystal is characterized by comprising the following steps:
shaping an incident laser beam into a tapered laser beam;
irradiating the laser frequency doubling crystal with the conical laser beam;
acquiring an emergent laser spot emitted from the laser frequency doubling crystal, wherein the emergent laser spot comprises a central stripe; and
and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance from the central stripe to the center of the emergent laser spot.
2. The method for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 1, wherein after the step of irradiating the laser frequency doubling crystal with the tapered laser beam, the method further comprises:
calculating the size of the spot of the conical laser beam on the surface of the laser frequency doubling crystal based on an original spot size, a beam divergence angle, and a beam divergence distance, wherein the original spot size indicates the spot size of the laser emitted from the laser, the beam divergence angle indicates the divergence angle of the conical laser beam, and the beam divergence distance indicates the size of the rear surface of the plano-concave lens to the surface of the laser frequency doubling crystal.
3. The method according to claim 2, wherein the step of obtaining the phase matching direction of the frequency doubling laser crystal based on the distance from the central stripe to the center of the emergent laser spot comprises:
and acquiring the phase matching direction of the laser frequency doubling crystal based on the distance, the divergence angle of the conical laser beam, the size of the light spot, the refractive index of the incident laser beam in the laser frequency doubling crystal, the refractive index of the emergent laser in the laser frequency doubling crystal and the distance between the laser frequency doubling crystal and the emergent laser light spot.
4. The method for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 3, wherein the phase matching direction of the laser frequency doubling crystal is obtained according to the following formula:
wherein R is the size of the original light spot after being expanded, and L1Is the distance between the plano-concave lens and the front surface of the frequency doubling crystal, alpha is the divergence angle of the conical laser beam, beta is the incident angle of the incident laser beam when the incident laser beam is incident on the frequency doubling crystal, gamma is the refraction angle of the incident laser beam, delta is the exit angle of the exit laser beam, noIs the refractive index of the incident laser beam in the laser frequency doubling crystal, neIs the refractive index of the emitted laser in the laser frequency doubling crystal, dKDPIs the thickness of the laser frequency doubling crystal. L is2Is the distance between the CCD camera and the rear surface of the frequency doubling crystal.
5. The method for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 1, further comprising:
when the central stripe is positioned below the center of the emergent laser spot, the laser frequency doubling crystal is rotated anticlockwise to obtain a phase matching direction; and is
And when the central stripe is positioned above the center of the emergent laser spot, the laser frequency doubling crystal is rotated clockwise to obtain the phase matching direction.
6. A system for rapidly measuring the phase matching direction of a laser frequency doubling crystal is characterized by comprising:
a laser (3) configured to emit an incident laser beam;
a plano-concave lens (6) configured to shape the incident laser beam into a tapered laser beam;
the laser frequency doubling crystal (7), the said conical laser beam irradiates the said laser frequency doubling crystal (7); and
an area array camera (11) configured to acquire an outgoing laser spot emitted from the laser frequency doubling crystal (7), wherein the outgoing laser spot comprises a central stripe; and
a processor configured to obtain a phase matching direction of the laser frequency doubling crystal (7) based on a distance of the central stripe from a center of the outgoing laser spot.
7. The system for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 6, further comprising:
a beam expander (4) configured to expand a diameter of the incident laser beam;
a beam shaper (5) for shaping a fundamental mode gaussian beam exiting from the beam expander (4) into a flat-topped beam, and the plano-concave lens (6) for changing the exiting beam of the beam shaper (5) into a conical beam;
the optical filter (9) is used for filtering the fundamental frequency laser emitted from the laser frequency doubling crystal (7); and
and an attenuation sheet (10) for reducing the intensity of the laser light incident on the area array camera (11).
8. The system for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 7, further comprising:
an air-floating optical platform (1);
the backing plate (2), the high-power laser (3), the beam expander (4), the beam shaper (5) and the plano-concave lens (6) are sequentially arranged on the cushion block (2);
a two-dimensional moving platform (8), wherein the laser frequency doubling crystal (7) is arranged on the two-dimensional moving platform (8); and
a backing plate (12), the filter (9), the attenuation sheet (10) and the area array camera (11) are arranged on the backing plate (12), wherein
The pad (2), the two-dimensional moving platform (8) and the pad (12) are arranged on the air-floating optical platform (1).
9. The system for rapid measurement of the phase matching direction of the laser frequency doubling crystal according to claim 7, wherein the rate laser (3) is a solid laser with a wavelength of 1053 nm.
10. The system for rapid measurement of phase matching direction of laser frequency doubling crystals according to claim 7, characterized in that the plano-concave lens (6) is used to change the outgoing beam of the beam shaper (5) into a cone beam with a divergence angle of 5 mrad.
11. The system for rapidly measuring the phase matching direction of the laser frequency doubling crystal according to claim 7, wherein the size of a photosensitive chip of the area array camera (11) is 12.3mm x 12.3mm, the resolution is 20.2MP, and the horizontal and vertical pixel sizes are 2.74 μm x 2.74 μm.
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