A method for generating dual-wavelength pulsed laser light using a lens array

Abstract

The application discloses a method for generating a dual-wavelength pulsed laser by using a lens array, which comprises the following steps: a laser is used as a pumping light source to emit a laser beam; the laser beam is adjusted by a beam shaping system; the adjusted laser beam is converted into a plurality of sub-beams by a micro-lens array 4f system; the plurality of sub-beams are reflected back and forth in a Fabry-Perot cavity; the reflection of the plurality of sub-beams in the Fabry-Perot cavity is subjected to a laser Raman crystal; and the plurality of sub-beams are emitted from the surface of the Fabry-Perot cavity to become a dual-wavelength pulsed laser source. The application significantly improves the laser frequency conversion efficiency and the power of a new wavelength, and improves the utilization rate of the laser.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a method for generating dual-wavelength pulsed lasers using a lens array. Background Technology

[0002] Photoacoustic imaging technology, as a novel method for biomedical imaging, has demonstrated enormous potential for medical applications. Various photoacoustic imaging systems have been developed to meet different needs. However, with the advancement of research, the limitations of single-wavelength pulsed laser sources in photoacoustic imaging are becoming increasingly apparent, particularly in the precise measurement of key physiological parameters such as blood oxygenation and blood flow, where multi-wavelength pulsed laser sources are essential. Although researchers can address this challenge by employing multispectral pulsed laser sources or combining multiple pulsed laser sources of different wavelengths, these methods often come with high costs and increased system complexity.

[0003] To ensure the effectiveness of photoacoustic imaging technology for blood oxygen saturation diagnosis, the key lies in achieving a multi-wavelength pulsed laser source with high pulse repetition frequency, rapid wavelength switching, and sufficient pulse energy. Currently, in photoacoustic imaging systems used for blood oxygen measurement, wavelength switching of multi-wavelength pulsed laser sources mostly relies on manual operation or host computer software control. This 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 imposes a heavy economic burden on research work, hindering its progress. Pulsed lasers, through stimulated Raman scattering, can generate pulsed lasers with new wavelength components, reducing research costs and simplifying system equipment. Existing technologies often achieve multi-wavelength modulated laser sources by coupling pump light into optical fibers or focusing it onto a laser Raman crystal. However, due to the existence of a damage threshold, the laser power often needs to be attenuated to a low level. Therefore, the pump light power is limited, resulting in low energy of the generated new wavelength components. Summary of the Invention

[0004] This invention provides a method for generating dual-wavelength pulsed lasers using a lens array, which addresses the problems of existing multi-wavelength pulsed laser sources, such as high cost hindering scientific research, pump light coupling into optical fibers or focusing onto laser Raman crystals to achieve multi-wavelength modulated laser sources, damage thresholds, laser power attenuation, limited pump light power, and low energy of the generated new wavelength components.

[0005] On one hand, embodiments of the present invention provide a method for generating dual-wavelength pulsed laser using a lens array, comprising:

[0006] The laser is used as a pump source to emit a laser beam;

[0007] The laser beam is adjusted by a beam shaping system;

[0008] The adjusted laser beam is converted into multiple sub-beams by the microlens array f system;

[0009] The multiple sub-beams are reflected back and forth within the Fabry-Poirot cavity;

[0010] The reflections of the multiple sub-beams in the Fabry-Perot cavity all pass through a laser Raman crystal;

[0011] Multiple sub-beams are emitted from the surface of the Fabry-Perot cavity to become a dual-wavelength pulsed laser source.

[0012] In one possible implementation, the laser beam of the laser is further power-regulated by an optical attenuator before being adjusted by the beam shaping system.

[0013] In one possible implementation, the beam shaping system is used to integrate and adjust the laser light passing through the optical attenuator.

[0014] In one possible implementation, the microlens array f system consists of two lens arrays L and L, each with a focal length of f, and two Fourier transform planes located between L and L. The input plane is located in front of L and is used to place the optical information to be processed. The Fourier plane is located at the focal plane of L and is used to place optical filters and perform frequency domain modulation. The output plane is located at the focal plane of L and is used to display the processed optical information.

[0015] In one possible implementation, the two reflector walls of the Fabry-Perot cavity are semi-reflective and semi-transparent mirrors with a reflectivity of 50% - 99.99%.

[0016] On the other hand, embodiments of the present invention provide an apparatus for generating dual-wavelength pulsed laser using a lens array, comprising:

[0017] The laser includes, in sequence along its optical path, an optical attenuator, a beam shaping system, a microlens array system, and a Fabry-Perot cavity, wherein a laser Raman crystal is disposed within the Fabry-Perot cavity.

[0018] In one possible implementation, the laser Raman crystal is disposed between the two mirrors of the Fabry-Perot cavity.

[0019] In one possible implementation, the geometric cavity length of the Fabry-Poirot cavity and the thickness of the laser Raman crystal satisfy the condition that the single round-trip optical path length of the beam within the Fabry-Poirot cavity is n·LCM[λ / , λ / ].

[0020] In one 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.

[0021] The method for generating dual-wavelength pulsed laser using a lens array in this invention has the following advantages:

[0022] (1) Under the same laser output conditions and laser Raman crystal, the structure of this application significantly improves the laser frequency conversion efficiency and new wavelength power.

[0023] (2) Improve laser utilization through beam shaping system. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic flowchart illustrating a method for generating dual-wavelength pulsed laser using a lens array, provided by an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a device for generating dual-wavelength pulsed laser using a lens array, provided as an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Figure 1 This is a flowchart illustrating a method for generating dual-wavelength pulsed laser using a lens array, as provided in an embodiment of the present invention. The method includes:

[0029] Laser 1 is used as a pump source to emit a laser beam;

[0030] The laser beam is adjusted by the beam shaping system 3;

[0031] The adjusted laser beam is converted into multiple sub-beams by the microlens array 4f system 4;

[0032] The multiple sub-beams are reflected back and forth within the Fabry-Poirot cavity 5;

[0033] The reflections of the multiple sub-beams in the Fabry-Perot cavity 5 all pass through the laser Raman crystal 6;

[0034] Multiple sub-beams are emitted from the surface of the Fabry-Perot cavity 5 to form a dual-wavelength pulsed laser source;

[0035] Before the laser beam of the laser is adjusted by the beam shaping system 3, it also undergoes power adjustment by the optical attenuator 2.

[0036] The beam shaping system 3 is used to integrate and adjust the laser light that has passed through the optical attenuator 2.

[0037] For example, the laser is excited and emitted by laser 1, and then the power is adjusted by optical attenuator 2. The optical attenuator 2 is actually an adjustable polarization beam splitter attenuator. The laser power is adjusted by optical attenuator 2, and then the cross-sectional shape and orientation of the laser are adjusted by beam shaping system 3. Finally, the laser beam is converted into multiple sub-beams by microlens array system 4f.

[0038] Laser 1 is selected according to the required laser wavelength.

[0039] In one possible embodiment, the microlens array 4f system 4 consists of two lens arrays L1 and L2, each with 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 is used to place the optical information to be processed. The Fourier plane is located at the focal plane of L1 and is used to place optical filters and perform frequency domain modulation. The output plane is located at the focal plane of L2 and is used to display the processed optical information.

[0040] In one possible embodiment, the two reflector walls of the Fabry-Perot cavity 5 are semi-reflective and semi-transparent mirrors with a reflectivity of 50% - 99.99%.

[0041] For example, the Fabry-Perot cavity 5 reflects the sub-beam emitted from the microlens array 4f system 4 through two semi-reflective mirrors, and at the same time, the sub-beam passes through a Raman crystal and is emitted from the two semi-reflective mirrors to become a dual-wavelength pulsed laser.

[0042] Figure 2This is a schematic diagram of a device for generating dual-wavelength pulsed laser using a lens array, provided by an embodiment of the present invention. The device includes:

[0043] 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 arranged sequentially along the optical path of the laser 1. A laser Raman crystal 6 is disposed in the Fabry-Perot cavity 5.

[0044] In one possible embodiment, the laser Raman crystal 6 is disposed between the two mirrors of the Fabry-Perot cavity 5;

[0045] The geometric cavity length of the Fabry-Poirot cavity 5 and the thickness of the laser Raman crystal 6 satisfy the condition that the single round-trip optical path length of the beam within the Fabry-Poirot cavity 5 is 2n·LCM[λ1 / 2, λ2 / 2].

[0046] For example, n is a positive integer, LCM represents the least common multiple, the excitation wavelength is λ1, and the Raman wavelength is λ2.

[0047] In one 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.

[0048] For example, 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 deformed elliptical light into circular light, and the optical path shaping module is used to integrate scattered laser light. The beam shape shaping module and the optical path shaping module are installed or used in combination according to the usage. Beam shaping is achieved by replacing the beam shape shaping module and the optical path shaping module with those that do not meet the specifications.

[0049] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0050] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

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

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

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 that has passed 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) consists of two lens arrays L1 and L2 with a focal length of f and two Fourier transform planes located between L1 and L2. The input surface is located in front of L1 and is used to place the optical information to be processed. The Fourier surface is located at the focal plane of L1, and is used to place optical filters and perform frequency domain modulation; the output surface is located at the focal plane of L2, and 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-transparent reflectors with a reflectivity of 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) arranged sequentially along the optical path of the laser (1). A laser Raman crystal (6) is provided inside 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 disposed between the two mirrors of the Fabry-Perot cavity (5).

8. The apparatus for generating dual-wavelength pulsed laser using a lens array according to claim 7, characterized in that, The geometric cavity length of the Fabry-Poirot cavity (5) and the thickness of the laser Raman crystal (6) satisfy that the single round-trip optical path length of the beam in the Fabry-Poirot cavity (5) is 2n·LCM[λ1 / 2, λ2 / 2], where n is a positive integer, LCM represents the least common multiple, the excitation wavelength is λ1, and the Raman wavelength is λ2.

9. The apparatus 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). The beam shaping system (3) is one or more of the beam shape shaping module and the optical path shaping module.

Images