Optical parametric amplification mode recognition system based on vortex pumping

Abstract

The utility model discloses an optical parametric amplification mode identification system based on vortex pumping. The optical parametric amplification mode identification system comprises a light source system, a vortex pumping generation system and an optical parametric amplification imaging system, the light source system emits two beams of signal light and pump light with different wavelengths; the vortex pump generation system comprises a pump light source and a spiral phase plate; the optical parametric amplification system comprises an imaging system, a nonlinear crystal and a camera; signal light and pump light are emitted into a nonlinear crystal through an imaging system, new idler frequency light is generated according to energy conservation and phase matching conditions, and then the idler frequency light is imaged to a detector camera through a lens; the spatial information of different features of the amplitude / phase target object can be modulated by regulating and changing the topological charge of the pump light, and the spatial information is detected and recorded by the camera, so that the effect of identifying different spatial feature modes of the target object is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of ultrafast optics and optical parametric amplification imaging, in particular to an optical parametric amplification pattern recognition system based on vortex pumping. Background Art

[0002] Ultrashort pulse-pumped optical parametric amplification (OPA) imaging technology, due to its high spatiotemporal resolution, high gain, wavelength conversion, and tunability, shows great potential for application in fields such as biomedicine, physics, and chemistry. For example, the ultrafast time-gating properties of pump light enable picosecond- to femtosecond-resolution observation of ultrafast physical or chemical processes. In biomedicine, using ultrashort laser pulses as event shutters enables tomographic imaging of thick tissues. Furthermore, the high gain of OPA imaging provides a new approach for non-destructive imaging under weak light illumination, while its high spatial resolution and wavelength conversion properties make it particularly useful in infrared imaging.

[0003] Traditional optical parametric amplification (OPA) imaging technology often uses pump light with a Gaussian spatial distribution. According to the phase matching conditions satisfied by the OPA process, the newly generated idler light will replicate the signal light carrying the object information. After OPA, people can obtain the same object information from both the amplified signal light and the idler light. In recent years, with the rise and rapid development of new light field technologies such as vortex beams, new highlights have been brought to OPA imaging technology. Optical parametric amplification using vortex light pumping can break the consistency between signal light and idler light. This is because the vortex phase of the pump light is only transferred to the idler light during the OPA process. Therefore, by setting up OPA in the Fourier spectrum plane of the imaging system, the amplified signal light retains the original bright field spatial imaging mode, while the idler light that obtains the vortex phase achieves the edge enhancement effect through the vortex phase contrast imaging mode. However, existing technologies are limited to vortex pump light with a topological charge of 1. By changing the topological charge of the pump light, the spatial information of different characteristics of the amplitude / phase target object can be modulated and imaged, thereby achieving the effect of identifying and extracting different spatial characteristic patterns of the target object. However, there is still a lack of corresponding technology. Utility Model Content

[0004] The utility model provides an optical parametric amplification mode recognition and feature extraction system based on vortex ultrashort pulse pumping.

[0005] The technical solution of the utility model is as follows:

[0006] An optical parametric amplification pattern recognition system based on vortex pumping, comprising:

[0007] A light source system, which outputs the required signal light and an ultrashort pulse pump light source;

[0008] A vortex ultrashort pulse pump light generation system includes a retarder, spiral phase plates of different orders, a first high-reflection mirror, and a first lens. The ultrashort pulse pump light source passes through the retarder and enters the spiral phase plates of different orders. The pump light source passes through the spiral phase plates of different orders. The first high-reflection mirror reflects the light beams passing through the spiral phase plates of different orders to the first lens. The first lens images the spiral phase plate into the nonlinear crystal of the optical parametric amplification imaging system, which is used to perform vortex phase filtering on the signal light carrying object information.

[0009] An optical parametric amplification (OPA) imaging system comprises an imaging system, a nonlinear crystal, and a camera. The imaging system is a 4f system and comprises a third lens and a second lens. A target object is placed in the object plane of the imaging system, and the nonlinear crystal is placed in the Fourier spectrum plane of the imaging system, acting as a nonlinear medium for optical parametric amplification. Idle light is generated by rotating the angle of the nonlinear crystal. Idle light is generated by adjusting the phase matching angle, and then imaged onto the camera through the second lens to obtain information about the target object. By regulating and changing the topological charge of the pump light, spatial information of different characteristics of the amplitude / phase target object is modulated and detected and recorded by the camera, thereby achieving the effect of identifying and extracting different spatial characteristic patterns of the target object.

[0010] Furthermore, the center distances between any two of the target object, the third lens, the nonlinear crystal, the second lens, and the camera are all focal lengths f.

[0011] Furthermore, the spiral phase plate has a structure with a stepped surface, and the optical path of the light wave passing through the spiral phase plate also presents a stepped spiral change. By changing the change period of the spiral phase, the topological charge of the vortex light beam is changed. Different topological charges will identify and extract different characteristic information of the object.

[0012] Furthermore, a beam combiner is provided between the third lens and the nonlinear crystal, and the first lens images the spiral phase plate and reflects it into the nonlinear crystal of the optical parametric amplification imaging system through the beam combiner, so as to perform vortex phase filtering on the illumination signal light carrying object information.

[0013] Furthermore, the nonlinear crystal is an OPA crystal.

[0014] Furthermore, the camera is a CCD camera.

[0015] Furthermore, by adjusting the polarization and time synchronization of the signal light and the pump light source and adjusting the phase matching angle to meet the phase matching conditions for optical parametric amplification, idler light is generated.

[0016] Furthermore, the light source system is a picosecond laser system with 10 Hz, 20 ps, ​​30 mJ, and 1064 nm & 532 nm dual-wavelength output, wherein 1064 nm is used as the illumination signal light to carry object information, and 532 nm is used as the pump light for optical parametric amplification.

[0017] Furthermore, the retarder includes two parallel high-reflection mirrors.

[0018] Furthermore, the illumination signal light output by the light source system passes through the second high-reflection mirror and the third high-reflection mirror in sequence and then passes through the imaging system to achieve spatial frequency modulation and analysis.

[0019] The signal light is irradiated on the target object so that it carries the information of the target object, and then passes through the imaging system together with the pump light and is incident on the nonlinear crystal placed on the Fourier spectrum plane of the imaging system. The pump light is converted into an ordinary Gaussian beam into an ultrashort pulse vortex light carrying a vortex phase by a spiral phase plate. According to the energy conservation and phase matching conditions, by adjusting the polarization, time synchronization and angle of the rotating crystal of the signal light and the pump light to meet the phase matching conditions for optical parametric amplification, idle light can be generated. The idle light is then imaged onto the camera through a lens to obtain the information of the target object. By regulating and changing the topological charge of the pump light, the spatial information of different characteristics of the amplitude / phase target object can be modulated and detected and recorded by the camera, thereby achieving the effect of identifying and extracting different spatial characteristic patterns of the target object.

[0020] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0021] The optical parametric amplification pattern recognition system based on vortex pumping proposed in this utility model has the following beneficial effects compared with the existing technology:

[0022] 1. This system can achieve pattern recognition with high imaging resolution and image contrast, thanks to the application of optical parametric amplification technology pumped by ultrashort pulses of vortices with different topological charges.

[0023] 2. By using spiral phase plates with different topological charges, this system can enhance the details of different feature information of the object, thereby improving the contrast and contour clarity of the image, making the details and structure of the imaged object more clearly visible.

[0024] 3. This system can image not only amplitude-type targets but also phase-type targets, which greatly improves the application range and recognition sensitivity.

[0025] 4. Thanks to the wavelength conversion characteristics of optical parametric amplification, the illumination signal light of this system can be extended not only to the visible light-near infrared region, but also to the mid-infrared band. This system is suitable for wide-field non-destructive imaging mode under weak light illumination, making it play a great role in biomedical diagnosis, security monitoring and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of an optical parametric amplification pattern recognition system based on vortex pumping provided by the utility model;

[0027] Figure 2 This is a diagram showing an implementation example of an optical parametric amplification pattern recognition system based on vortex pumping provided by the utility model;

[0028] Figure 3 yes Figure 2 Specific implementation case renderings;

[0029] Among them, 1-light source system, 2-retarder, 3-spiral phase plate, 4-first high-reflective mirror, 5-first lens, 6-second high-reflective mirror, 7-third high-reflective mirror, 8-target object, 9-third lens, 10-beam combiner, 11-nonlinear crystal, 12-second lens, 13-camera. DETAILED DESCRIPTION

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0031] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0032] like Figure 1 、 Figure 2 As shown, an optical parametric amplification pattern recognition system based on vortex pumping provided by the embodiment of the present invention includes: a light source system 1, a vortex ultrashort pulse pump light generation system, and an optical parametric amplification imaging system;

[0033] The light source system 1 produces the required signal and pump ultrashort pulse lasers. In a preferred embodiment, the light source system 1 is a picosecond laser system with dual-wavelength outputs of 10 Hz, 20 ps, ​​30 mJ, and 1064 nm and 532 nm. The 1064 nm wavelength serves as the illumination signal light carrying object information, while the 532 nm wavelength serves as the pump light for optical parametric amplification.

[0034] The vortex ultrashort pulse pump light generation system includes a delay device 2, a spiral phase plate 3 of the same order, a first high-reflection mirror 4, and a first lens 5. The delay device 2 is used for time synchronization of the vortex ultrashort pulse pump light and the illumination signal light.

[0035] The 532nm pump light output by the light source system 1 passes through the retarder 2 and enters the spiral phase plates 3 of different orders. After passing through the spiral phase plates 3 of different orders, the pump light forms a vortex ultrashort pulse laser beam with different topological charges. By designing the surface thickness of the spiral phase plates 3 to be stepped, the optical path length of the light wave passing through them also exhibits a stepped spiral variation, i.e., it carries a phase factor of the vortex structure, thus generating a vortex beam. By varying the period of the spiral phase variation, the topological charge of the vortex beam can be controlled.

[0036] The first high-reflection mirror 4 reflects the vortex ultrashort pulse laser beam to the first lens 5, and the first lens 5 images the spiral phase plate 3 and reflects it through the beam combiner 10 to the nonlinear crystal 11 of the optical parametric amplification imaging system for vortex phase filtering of the illumination signal light carrying object information.

[0037] The retarder 2 includes two parallel high-reflection mirrors placed on a precision displacement platform.

[0038] The optical parametric amplification imaging system includes an imaging system, a nonlinear crystal 11, and a CCD camera 13. The imaging system is a 4f system, including a third lens 9 and a second lens 12, with the beam combiner 10 disposed between the third lens and the nonlinear crystal. The third lens 9 and the second lens 12 have a focal length of f, the target object 8 is placed in the object plane of the imaging system, and the nonlinear crystal 11 is placed in the Fourier spectrum plane of the imaging system, acting as a nonlinear medium for optical parametric amplification. The 1064nm illumination signal light output by the light source system 1 passes through the second high-reflection mirror 6 and the third high-reflection mirror 7 in sequence, and then is modulated and analyzed in spatial frequency by the imaging system. The 532nm pump light output by the light source system 1 is modulated and analyzed in spatial frequency by the vortex ultrashort pulse pump light generation system.

[0039] Specifically, 1064nm idler light is generated by controlling the polarization of the 1064nm illumination signal light and 532nm pump light output by the light source system 1, adjusting the retarder 2 to synchronize the illumination signal light and pump light, and rotating the nonlinear crystal 11 to meet the phase matching conditions for optical parametric amplification. By designing a non-collinear angle between the illumination signal light and the vortex pump light, the idler light is spatially separated from the signal light and pump light, reducing background noise that may be introduced by the signal light and pump light. The idler light is then imaged onto a CCD camera on a detector through a second lens 12 to obtain information about the target object.

[0040] As an embodiment, the second high-reflection mirror 6 is HR@1064nm, the third high-reflection mirror 7 is HR@532nm, the third lens 9 is an optical lens with f=150mm, and the beam combiner 10 is AR@1064nm&HR@532nm.

[0041] The CCD camera is placed on the image plane of the imaging system and is used to obtain the spatial intensity information of the target object. By regulating and changing the topological charge of the pump light, the spatial information of different characteristics of the amplitude / phase target object is modulated and detected and recorded by the camera CCD, thereby achieving the effect of identifying and extracting different spatial characteristic patterns of the target object.

[0042] As a preferred embodiment, the nonlinear crystal 11 is an OPA crystal. Figure 2 As shown, the center distances among the target object 8, the third lens 9, the nonlinear crystal 11, the second lens 12 and the CCD camera are all the focal length f.

[0043] Through vortex pumped optical parametric amplification imaging, the idler light recorded by the CCD camera is edge-enhanced object detail information. Further, by setting spiral phase plates of different orders, the topological charge of the vortex pump light can be controlled and changed, thereby modulating the spatial information of different characteristics of the amplitude / phase target object, achieving the effect of identifying and extracting different spatial characteristic patterns of the target object. The implementation case effect diagram is shown below. Figure 3 As shown in the figure, when the topological charge l = 1, the linear structural features of the target object can be identified and the edge structure details can be extracted; when the topological charge l = 2, the 90° right-angle structural features of the target object can be identified and the edge structure details can be extracted; when the topological charge l = 3, the structural features of the target object with an acute angle less than 90° can be identified and the edge structure details can be extracted. In other words, the system can achieve the effect of identifying different spatial characteristic structures of the target object and extracting edge structure details by using spiral phase plates with different topological charges.

[0044] It should be noted that for the aforementioned embodiments, for simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, because according to the present invention, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope to be protected by the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making any creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also fall within the scope to be protected by the present invention.

Claims

1. An optical parametric amplification pattern recognition system based on vortex pumping, characterized in that: include: A light source system, which outputs the required signal light and an ultrashort pulse pump light source; A vortex ultrashort pulse pump light generation system includes a retarder, spiral phase plates of different orders, a first high-reflection mirror, and a first lens. The ultrashort pulse pump light source passes through the retarder and enters the spiral phase plates of different orders. The pump light source passes through the spiral phase plates of different orders. The first high-reflection mirror reflects the light beams passing through the spiral phase plates of different orders to the first lens. The first lens images the spiral phase plate into the nonlinear crystal of the optical parametric amplification imaging system, which is used to perform vortex phase filtering on the signal light carrying object information. An optical parametric amplification (OPA) imaging system comprises an imaging system, a nonlinear crystal, and a camera. The imaging system is a 4f system and comprises a third lens and a second lens. A target object is placed in the object plane of the imaging system, and the nonlinear crystal is placed in the Fourier spectrum plane of the imaging system, acting as a nonlinear medium for optical parametric amplification. Idle light is generated by rotating the angle of the nonlinear crystal. Idle light is generated by adjusting the phase matching angle, and then imaged onto the camera through the second lens to obtain information about the target object. By regulating and changing the topological charge of the pump light, spatial information of different characteristics of the amplitude / phase target object is modulated and detected and recorded by the camera, thereby achieving the effect of identifying and extracting different spatial characteristic patterns of the target object.

2. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The center distances between the target object, the third lens, the nonlinear crystal, the second lens and the camera are all focal lengths f.

3. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The spiral phase plate has a structure with a stepped surface. The optical path of the light wave passing through the spiral phase plate also presents a stepped spiral change. By changing the period of change of the spiral phase, the topological charge of the vortex light beam is changed. Different topological charges will identify and extract different characteristic information of the object.

4. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: A beam combiner is provided between the third lens and the nonlinear crystal. The first lens images the spiral phase plate and reflects it through the beam combiner into the nonlinear crystal of the optical parametric amplification imaging system for vortex phase filtering of the illumination signal light carrying object information.

5. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The nonlinear crystal is an OPA crystal.

6. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The camera is a CCD camera.

7. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: By adjusting the polarization and time synchronization of the signal light and the pump light source and adjusting the phase matching angle to meet the phase matching conditions for optical parametric amplification, idler light is generated.

8. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The light source system is a picosecond laser system with 10 Hz, 20 ps, ​​30 mJ, and dual-wavelength output of 1064 nm and 532 nm, wherein 1064 nm is used as the illumination signal light to carry object information, and 532 nm is used as the pump light for optical parametric amplification.

9. The optical parametric amplification pattern recognition system based on vortex pumping according to claim 1, characterized in that: The retarder includes two parallel high-reflection mirrors.

10. An optical parametric amplification pattern recognition system based on vortex pumping according to any one of claims 1 to 9, characterized in that: The illumination signal light output by the light source system passes through the second high-reflection mirror and the third high-reflection mirror in sequence and then passes through the imaging system to achieve spatial frequency modulation and analysis.

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