Method for generating dual-wavelength pulse laser by using lens array

Abstract

The invention discloses a method for generating dual-wavelength pulse laser through a lens array. The method comprises the steps that a laser serves as a pump light source to emit a laser beam; the laser beam is adjusted through a beam shaping system; the adjusted laser beam is converted into a plurality of sub-beams by a microlens array 4f system; the plurality of sub-beams are reflected back and forth in the Fabry-Perot cavity; the reflection of the plurality of sub light beams in the Fabry-Perot cavity passes through the laser Raman crystal; and the plurality of sub light beams are emitted from the surface of the Fabry-Perot cavity to form a dual-wavelength pulse laser light source. The laser frequency conversion efficiency and the new wavelength power are remarkably improved, and the laser utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and particularly to a method for generating dual-wavelength pulsed laser by using a lens array. Background Art

[0002] As a new method of biomedical imaging, photoacoustic imaging technology shows great potential in medical applications. For different needs, a variety of photoacoustic imaging systems have been developed. With the in-depth research, the application limitations of single-wavelength pulsed laser sources in photoacoustic imaging are becoming increasingly apparent. Especially in the accurate measurement of key physiological parameters such as blood oxygen and blood flow, multi-wavelength pulsed laser sources have become necessary. Although researchers can meet this challenge by using multi-spectral pulsed laser sources or combining multiple pulsed laser sources with different wavelengths, these methods are often accompanied by high costs and an increase in system complexity.

[0003] To ensure the effectiveness of photoacoustic imaging technology for blood oxygen saturation diagnosis, the key lies in realizing a multi-wavelength pulsed laser source with a high pulse repetition frequency, fast wavelength switching, and sufficient pulse energy. In current photoacoustic imaging systems for blood oxygen measurement, the wavelength switching of multi-wavelength pulsed laser sources mostly relies on manual operation or host computer software control. This method significantly prolongs the wavelength switching time, thus limiting the complete acquisition of blood oxygen saturation information. Although pulsed lasers using broadband light sources can achieve multi-wavelength switching, the high cost brings a heavy economic burden to scientific research work and is not conducive to the promotion of scientific research activities. Pulsed laser can generate pulsed laser with new wavelength components through the effect of stimulated Raman scattering, which can not only reduce the research cost but also simplify the system equipment. Existing technologies often realize a multi-wavelength tunable laser source by coupling pump light into an optical fiber or focusing it onto a laser Raman crystal. However, due to the existence of damage thresholds, the laser power often needs to be attenuated to a relatively low level. Therefore, the pump light power is limited, and the energy of the generated new wavelength components is relatively low. Summary of the Invention

[0004] The embodiment of the present invention provides a method for generating dual-wavelength pulsed laser by using a lens array, so as to solve the problems in the prior art that the high cost of multi-wavelength pulsed laser sources is not conducive to the promotion of scientific research activities, and when realizing a multi-wavelength tunable laser source by coupling pump light into an optical fiber or focusing it onto a laser Raman crystal, there are damage thresholds, the laser power needs to be attenuated, the pump light power is limited, and the energy of the generated new wavelength components is relatively low.

[0005] On the one hand, the embodiment of the present invention provides a method for generating dual-wavelength pulsed laser by using a lens array, including: Using a laser as a pump light source to emit a laser beam; Adjusting the laser beam through a beam shaping system; The adjusted laser beam is converted into multiple sub-beams by the microlens array f system; The multiple sub-beams are reflected back and forth in the Fabry-Perot cavity; All the reflections of the multiple sub-beams in the Fabry-Perot cavity pass through the laser Raman crystal; The multiple sub-beams exit from the surface of the Fabry-Perot cavity to become a dual-wavelength pulsed laser light source.

[0006] In a possible implementation, before the laser beam of the laser passes through the beam shaping system for adjustment, it also passes through an optical attenuator for power adjustment.

[0007] In a possible implementation, the beam shaping system is used to integrally adjust the laser that has passed through the optical attenuator.

[0008] In a possible implementation, the microlens array f system consists of two lens arrays L and L with a focal length of f each, and two Fourier transform planes located between L and L. The input surface is located before L, and the input surface is used to place the optical information to be processed; the Fourier surface is located at the focal plane of L, and the Fourier surface is used to place the optical filter, and the Fourier surface is used for frequency domain modulation; the output surface is located at the focal plane of L, and the output surface is used to display the processed optical information.

[0009] In a possible implementation, the two mirror walls of the Fabry-Perot cavity are semi-reflective and semi-transmissive mirrors, and the reflectivity of the mirror walls is 50% - 99.99%.

[0010] On the other hand, an embodiment of the present invention provides a device for generating a dual-wavelength pulsed laser using a lens array, including: A laser, an optical attenuator, a beam shaping system, a microlens array f system, and a Fabry-Perot cavity are sequentially arranged along the optical path direction of the laser, and a laser Raman crystal is arranged in the Fabry-Perot cavity.

[0011] In a possible implementation, the laser Raman crystal is arranged between the two mirrors of the Fabry-Perot cavity.

[0012] In a possible implementation, the geometric cavity length of the Fabry-Perot cavity and the thickness of the laser Raman crystal satisfy that the optical path length of the beam for a single round trip in the Fabry-Perot cavity is n·LCM[λ / , λ / ].

[0013] In a possible implementation, the beam shaping system is movably connected to the optical attenuator and the microlens array f system, and the beam shaping system is one or more of a beam shape shaping module and an optical path shaping module.

[0014] A method for generating dual-wavelength pulsed laser using a lens array in the present invention has the following advantages: (1) Under the same laser output conditions and in a laser Raman crystal, the structure of the present application significantly improves the laser frequency conversion efficiency and the power of the new wavelength.

[0015] (2) Improve the laser utilization rate through a beam shaping system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a schematic flowchart of a method for generating dual-wavelength pulsed laser using a lens array provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a device for generating dual-wavelength pulsed laser using a lens array provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0019] Figure 1 It is a schematic flowchart of a method for generating dual-wavelength pulsed laser using a lens array provided by an embodiment of the present invention; An embodiment of the present invention provides a method for generating dual-wavelength pulsed laser using a lens array, including: Using laser 1 as a pump light source to emit a laser beam; Adjusting the laser beam through a beam shaping system 3; The adjusted laser beam is converted into multiple sub-beams by a microlens array 4f system 4; Multiple sub-beams are reflected back and forth in a Fabry-Perot cavity 5; All reflections of multiple sub-beams in the Fabry-Perot cavity 5 pass through a laser Raman crystal 6; Multiple sub-beams exit from the surface of the Fabry-Perot cavity 5 to become a dual-wavelength pulsed laser light source; Before the laser beam of the laser passes through the beam shaping system 3 for adjustment, it also passes through an optical attenuator 2 for power adjustment; The beam shaping system 3 is used to integrally adjust the laser that has passed through the optical attenuator 2.

[0020] Exemplarily, the laser is excited and emitted by the laser 1, and then passes through the optical attenuator 2 for power adjustment. The optical attenuator 2 is actually an adjustable polarization beam splitting attenuator. The laser power is adjusted through the optical attenuator 2, and then passes through the beam shaping system 3 to adjust the cross-sectional shape and orientation of the laser, and then the laser beam is converted into multiple sub-beams through the microlens array 4f system 4.

[0021] The laser 1 is selected according to the required laser wavelength.

[0022] In a possible embodiment, the microlens array 4f system 4 is composed of two lens arrays L1 and L2 with a focal length of f each and two Fourier transform planes located between the L1 and L2. The input plane is located in front of the L1, and the input plane is used to place the optical information to be processed; the Fourier plane is located at the focal plane of the L1, and the Fourier plane is used to place the optical filter, and the Fourier plane is used for frequency domain modulation; the output plane is located at the focal plane of the L2, and the output plane is used to display the processed optical information.

[0023] In a possible embodiment, the two mirror walls of the Fabry - Perot cavity 5 are semi - reflective and semi - transmissive mirrors, and the reflectivity of the mirror walls is 50% - 99.99%.

[0024] Exemplarily, the Fabry - Perot cavity 5 reflects the sub - beams emitted from the microlens array 4f system 4 through two semi - reflective mirrors, and at the same time makes the sub - beams pass through the Raman crystal and then emit from the two semi - reflective mirrors to become a dual - wavelength pulsed laser.

[0025] Figure 2 It is a schematic structural diagram of a device for generating a dual - wavelength pulsed laser using a lens array provided by an embodiment of the present invention; an embodiment of the present invention provides a device for generating a dual - wavelength pulsed laser using a lens array, including: A laser 1, an optical attenuator 2, a beam shaping system 3, a microlens array 4f system 4, and a Fabry - Perot cavity 5 are sequentially arranged along the optical path direction of the laser 1, and a laser Raman crystal 6 is arranged in the Fabry - Perot cavity 5.

[0026] In a possible embodiment, the laser Raman crystal 6 is arranged between the two mirrors of the Fabry - Perot cavity 5; The geometric cavity length of the Fabry-Perot cavity 5 and the thickness of the laser Raman crystal 6 satisfy that the optical path length of the light beam for a single round trip in the Fabry-Perot cavity 5 is 2n·LCM[λ1 / 2, λ2 / 2].

[0027] Exemplarily, where n is a positive integer, LCM represents the least common multiple, the excitation light wavelength is λ1, and the Raman light wavelength is λ2.

[0028] In a possible embodiment, the beam shaping system 3 is movably connected to the optical attenuator 2 and the microlens array 4f system 4, and the beam shaping system 3 is one or more of a beam shape shaping module and an optical path shaping module.

[0029] Exemplarily, the beam shaping system 3 includes one or more of a beam shape shaping module and an optical path shaping module. The beam shape shaping module is used to shape the deformed elliptical light into circular light, and the optical path shaping module is used to integrate the scattered laser. The beam shape shaping module and the optical path shaping module are installed or combined according to the usage situation, and beam shaping is achieved by replacing beam shape shaping modules and optical path shaping modules with different specifications.

[0030] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred examples as well as all changes and modifications falling within the scope of the present invention.

[0031] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for generating dual-wavelength pulsed laser using a lens array, characterized in that: include: Using the laser (1) as a pump light source to emit a laser beam; The laser beam is adjusted by a beam shaping system (3); The adjusted laser beam is converted into a plurality of sub-beams by a microlens array 4f system (4); The plurality of sub-beams are reflected back and forth in the Fabry-Perot cavity (5); The reflections of the plurality of sub-light beams in the Fabry-Perot cavity (5) all pass through a laser Raman crystal (6); The plurality of sub-light beams are emitted from the surface of the Fabry-Perot cavity (5) to become a dual-wavelength pulse laser light source.

2. The method for generating dual-wavelength pulsed laser using a lens array according to claim 1, characterized in that: The laser beam of the laser is also subjected to power adjustment by an optical attenuator (2) before being adjusted by the beam shaping system (3).

3. The method for generating dual-wavelength pulsed laser using a lens array according to claim 2, characterized in that: The beam shaping system (3) is used to integrate and adjust the laser light passing through the optical attenuator (2).

4. The method for generating dual-wavelength pulsed laser using a lens array according to claim 1, characterized in that: The microlens array 4f system (4) is composed of two lens arrays L1 and L2, both of which have a focal length of f, and two Fourier transform planes located between L1 and L2. The input plane is located in front of L1, and the input plane is used to place optical information to be processed. The Fourier surface is located at the focal plane of L1, the Fourier surface is used to place the optical filter, and the Fourier surface is used to perform frequency domain modulation; the output surface is located at the focal plane of L2, and the output surface is used to display the processed optical information.

5. The method for generating dual-wavelength pulsed laser using a lens array according to claim 1, characterized in that: The two reflector walls of the Fabry-Perot cavity (5) are semi-reflective and semi-transmissive reflectors, and the reflectivity of the reflector walls is 50%-99.99%.

6. A device for generating dual-wavelength pulsed laser using a lens array, characterized in that: include: A laser (1) is provided with an optical attenuator (2), a beam shaping system (3), a microlens array 4f system (4) and a Fabry Perot cavity (5) in sequence along the optical path direction of the laser (1), wherein a laser Raman crystal (6) is provided in the Fabry Perot cavity (5).

7. The device for generating dual-wavelength pulsed laser using a lens array according to claim 6, characterized in that: The laser Raman crystal (6) is arranged between two reflecting mirrors of the Fabry-Perot cavity (5).

8. The device for generating dual-wavelength pulsed laser using a lens array according to claim 7, characterized in that: The geometric cavity length of the Fabry Perot cavity (5) and the thickness of the laser Raman crystal (6) satisfy that the single round-trip optical path length of the light beam in the Fabry Perot cavity (5) is 2n·LCM[λ1 / 2, λ2 / 2].

9. The device for generating dual-wavelength pulsed laser using a lens array according to claim 6, characterized in that: The beam shaping system (3) is movably connected to the optical attenuator (2) and the microlens array 4f system (4), and the beam shaping system (3) is one or more of a beam shape shaping module and an optical path shaping module.

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