Single-time ultrafast multi-mode time sequence phase imaging device

Abstract

The invention provides a single-time ultrafast multi-mode time sequence phase imaging device, and relates to the technical field of ultrafast optical imaging and computational optical imaging, and the imaging device comprises a light source system which is used for generating a linearly polarized femtosecond laser pulse; the chirp laser pulse generation system generates a chirp laser pulse based on the femtosecond laser pulse; the pulse shaping system is used for generating a time sequence multi-wavelength sub-pulse based on the chirp laser pulse; and the coherent modulation imaging system performs coherent modulation imaging based on the time sequence multi-wavelength sub-pulses, and realizes single-time ultrafast multi-modal time sequence phase imaging by using a wavelength and modulation coding combined constraint inversion algorithm. After femtosecond laser pulses are converted into chirped pulses, coaxial time sequence multi-wavelength sub-pulses with harmonious time resolution and harmonious sub-pulse number are generated by using a pulse shaping technology.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrafast optical imaging and computational optical imaging, and in particular to a single-shot ultrafast multi-modal time-series phase imaging device. Background Art

[0002] Ultrafast optical imaging has always attracted much attention as an important optical detection method used to detect the evolution of ultrafast events. Current ultrafast imaging can be roughly divided into two categories, intensity imaging and complex amplitude imaging. The current photography frequency of intensity imaging can reach the terahertz level, but it is impossible to obtain phase information, such as laser-induced plasma and the interaction between ultrashort pulses and matter. In order to fully record these phenomena, complex amplitude recording methods are needed. Complex amplitude recording mainly includes holographic recording and coherent diffraction imaging. Spatial femtosecond holography uses different multiplexing recording methods to obtain certain instantaneous scenes of ultrafast processes, but the system is large and complex and cannot describe the entire process; frequency domain femtosecond holography can perform complex amplitude recording of the entire process of ultrafast events, but it is limited by the slit and cannot obtain complete spatial information.

[0003] With the development of computational imaging, coherent diffraction imaging has also begun to emerge, and the wavefront distribution of an object can be obtained using only one diffraction spot. At present, among the methods for realizing ultrafast single-shot multi-frame phase imaging based on coherent modulation imaging, there are methods that control the time delay between incident pulses by integrating the illumination system on a silicon photonic chip. The time resolution of the system is achieved by reducing the spatial resolution. When high time and spatial resolution is required, the applicability is greatly reduced; there are also methods that control the time delay between incident pulses by fiber coupling, and pass the sub-pulses through optical fibers of different lengths to detect the measured events in sequence with small angle differences, thus realizing quantitative ultrafast complex amplitude imaging without reducing the spatial resolution. However, its time resolution is affected by the optical fiber and can only be achieved at the picosecond level. These methods have a common problem: since the incident pulses are incident on the object at different angles, this inevitably leads to the situation where the beams are on different axes, which causes parallax problems in phase imaging, and further affects the accuracy of ultrafast phase measurement. In addition, the time delay and pulse width between the incident pulses are difficult to tune, that is, the time resolution cannot be adjusted, which brings challenges to the detection of ultrafast events with different time resolution requirements. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a single ultrafast multimodal time-series phase imaging device, which uses ultrafast multimodal phase imaging technology assisted by computational imaging to capture the spatiotemporal characteristics and phase information of non-repeatable atomic time transient events. The present invention adopts a parallel sub-pulse string imaging device to generate multiple coaxially transmitted sub-pulse strings with a certain delay in a single operation and record multiple time-series images; at the same time, for multimodal diffraction images, a wavelength and modulation coding joint constrained anti-diffraction algorithm is developed, and the amplitude and phase information of the event can be obtained with a single ordinary intensity sensor, which provides a powerful research tool for revealing scientific problems such as the development laws of atomic time transient processes and can promote innovative research in basic science and major scientific projects.

[0005] To achieve the above object, the present invention provides the following technical solutions: Based on the above purpose, the present invention provides a single-shot ultrafast multi-modal time-series phase imaging device, which includes: A light source system for generating linearly polarized femtosecond laser pulses; A chirped laser pulse generating system, which generates chirped laser pulses based on the femtosecond laser pulses output by the light source system; A pulse shaping system, which generates coaxial time-series multi-wavelength sub-pulses with adjustable time resolution and adjustable number of sub-pulses based on the generated chirped laser pulse; The coherent modulation imaging system performs coherent modulation imaging based on the time series multi-wavelength sub-pulses generated by the pulse shaping system, and utilizes the wavelength and modulation coding combined constrained anti-derivative algorithm to achieve single-shot ultrafast multi-modal time-series phase imaging.

[0006] As a further solution of the present invention, the femtosecond laser pulses generated by the light source system are used as the laser source of the imaging system.

[0007] As a further solution of the present invention, the light source system adopts a titanium sapphire femtosecond laser, which outputs femtosecond laser pulses with a central wavelength of 800nm, a pulse width of 30-100 femtoseconds, and a spectrum width of 30-80 nanometers.

[0008] As a further solution of the present invention, the chirped laser pulse generating system broadens the femtosecond laser pulse through a disperser to generate a picosecond chirped laser pulse with adjustable generation time delay.

[0009] As a further solution of the present invention, the pulse shaping system includes two gratings with the same parameters, two lenses with the same parameters and a multi-slit with adjustable width; the two lenses are combined to form a 4f system, the two gratings are respectively placed on the front and rear focal planes of the 4f system, and the multi-slit is placed on the confocal plane of the 4f system.

[0010] As a further solution of the present invention, when the pulse shaping system generates a time-series multi-wavelength sub-pulse, the chirped laser pulse generated by the chirped laser pulse generating system is emitted to the first grating, and passes through the first lens, multiple slits, the second lens and the second grating in sequence to generate a coaxial time-series multi-wavelength sub-pulse with adjustable time resolution and adjustable sub-pulse number.

[0011] As a further solution of the present invention, the coherent modulation imaging system includes a phase plate and a detector. The coherent modulation imaging system loads ultrafast event information onto a time series multi-wavelength sub-pulse generated by a pulse shaping system. After the time series multi-wavelength sub-pulse is modulated by the phase plate, the diffraction pattern is recorded by the detector, and the event is reconstructed using a wavelength and modulation coding joint constrained anti-diffraction algorithm to obtain the phase information of the atomic time transient event.

[0012] Compared with the prior art, the single-shot ultrafast multi-modal time-series phase imaging device proposed in the present invention has the following beneficial effects: 1. The ultrafast single-shot multi-amplitude phase imaging device of the present invention realizes accurate measurement of phase imaging and adjustable high time resolution by converting femtosecond laser pulses into chirped pulses, and then using pulse shaping technology to generate coaxial time resolution adjustable and sub-pulse number adjustable time series multi-wavelength sub-pulses. In this way, the pulse width and the time interval between sub-pulses can be effectively regulated, thereby controlling the time resolution of imaging to adapt to ultrafast imaging events with different time resolutions. In addition, these sub-pulses perform phase detection in the coaxial direction, avoiding the phase measurement error caused by parallax in the case of different axes.

[0013] 2. In addition, the highest time resolution can theoretically reach the femtosecond level, and the time resolution can be coordinated with the chirp and sub-pulse width according to the detection event requirements. No complex interference device is required. With the assistance of computational imaging, a single record can obtain the phase information of 4-8 non-repeatable atomic time transient events with a time resolution of hundreds of femtoseconds. The structure is simple and the system is stable.

[0014] These and other aspects of the present application will be more concise and understandable in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the exemplary embodiments or related technical descriptions. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings: Figure 1 The present invention is a schematic structural diagram of a single-shot ultrafast multi-modal time-series phase imaging device according to an embodiment of the present invention.

[0016] Figure 2 The present invention is a schematic structural diagram of a pulse shaping system in a single-shot ultrafast multi-modal time-series phase imaging device according to an embodiment of the present invention.

[0017] Figure 3 The present invention is a schematic structural diagram of a coherent modulation imaging system in a single-shot ultrafast multi-modal temporal phase imaging device according to an embodiment of the present invention.

[0018] Reference numerals: 11-light source system, 12-chirped laser pulse generation system, 13-pulse shaping system, 131-grating, 132-lens, 133-multi-slit, 14-coherent modulation imaging system, 141-event, 142-phase plate, 143-detector. DETAILED DESCRIPTION

[0019] Below, the present application is further described in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are intended to distinguish two non-identical entities or non-identical parameters with the same name. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, other steps or units inherent to a process, method, system, product or device that includes a series of steps or units.

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0024] Since the incident pulses are incident on the object at different angles, this inevitably leads to the situation that the beams are not in the same axis, which causes parallax problems in phase imaging, and further affects the accuracy of ultrafast phase measurement. In addition, the time delay and pulse width between the incident pulses are difficult to achieve coordination, that is, the time resolution cannot be adjusted, which brings challenges to the detection of ultrafast events facing different time resolution requirements. The present invention proposes a single ultrafast multi-modal time-series phase imaging device, which aims to capture the spatiotemporal characteristics and phase information of atomic time transient events that cannot be repeated. Through ultrafast multi-modal phase imaging technology, assisted by computational imaging means, by adopting a parallel sub-pulse string imaging device, multiple coaxially transmitted and delayed sub-pulse strings can be generated in a single operation, and multiple time-series images can be recorded; at the same time, for multi-modal diffraction images, a wavelength and modulation coding joint constrained anti-diffraction algorithm is developed, and only a single ordinary intensity sensor is needed to obtain the amplitude and phase information of the event, which provides a powerful research tool for revealing the development law of atomic time transient processes and other scientific problems, and can promote innovative research in basic science and major scientific projects.

[0025] See also Figure 1 As shown, an embodiment of the present invention provides a single-shot ultrafast multi-modal temporal phase imaging device, which includes a light source system 11, a chirped laser pulse generation system 12, a pulse shaping system 13, and a coherent modulation imaging system 14. The light source system 11 is used to generate linearly polarized femtosecond laser pulses; the chirped laser pulse generation system 12 generates chirped laser pulses based on the femtosecond laser pulses output by the light source system 11; the pulse shaping system 13 generates coaxial time-series multi-wavelength sub-pulses with adjustable time resolution and adjustable number of sub-pulses based on the generated chirped laser pulses; the coherent modulation imaging system 14 performs coherent modulation imaging based on the time-series multi-wavelength sub-pulses generated by the pulse shaping system 13, and uses the wavelength and modulation coding combined constrained anti-derivative algorithm to achieve single-shot ultrafast multi-modal temporal phase imaging.

[0026] Specifically, in the present embodiment, the femtosecond laser pulse generated by the light source system 11 is transmitted to the chirped laser pulse generating system 12. After receiving the femtosecond laser pulse, the chirped laser pulse generating system 12 widens the femtosecond laser pulse by its own dispersion characteristics, so that the femtosecond laser pulse is widened into a picosecond chirped laser pulse. The chirped laser pulse generated by the chirped laser pulse generating system 12 is input to the pulse shaping system 13. The pulse shaping system 13 converts the chirped laser pulse generated by the chirped laser pulse generating system 12 into a coaxial time series multi-wavelength sub-pulse with adjustable time resolution and adjustable number of sub-pulses, and inputs the chirped laser pulse into the coherent modulation imaging system 14. The coherent modulation imaging system 14 loads the ultrafast event information on the coaxial time series multi-wavelength sub-pulse with adjustable time resolution and adjustable number of sub-pulses generated by the pulse shaping system 13, and then reconstructs the phase information of the event at different times through the wavelength and modulation coding joint constrained anti-derivative algorithm.

[0027] In this embodiment, the femtosecond laser pulses generated by the light source system 11 are used as the laser source of the imaging system. The light source system 11 may use a titanium sapphire femtosecond laser, and the output femtosecond laser pulses have a central wavelength of 800nm, a pulse width of 30-100 femtoseconds, and a corresponding spectrum width of 30-80 nanometers.

[0028] In this embodiment, the chirped laser pulse refers to a laser pulse whose instantaneous frequency varies with time. The chirped laser pulse generating system 12 widens the femtosecond laser pulse through a disperser to generate a picosecond chirped laser pulse with adjustable generation time delay. It should be noted that in a specific implementation, the femtosecond laser pulse can also be widened to a pulse width of other magnitudes according to actual needs.

[0029] In this embodiment, see Figure 1 and Figure 2 As shown, the pulse shaping system 13 includes two gratings 131 with the same parameters, two lenses 132 with the same parameters and a multi-slit 133 with adjustable width; the two lenses 132 are combined to form a 4f system, the two gratings 131 are respectively placed on the front and rear focal planes of the 4f system, and the multi-slit 133 is placed on the confocal plane of the 4f system.

[0030] When the pulse shaping system 13 generates a time-series multi-wavelength sub-pulse, the chirped laser pulse generated by the chirped laser pulse generating system 12 is emitted to the first grating, and passes through the first lens, the multi-slit, the second lens and the second grating in sequence to generate a coaxial time-series multi-wavelength sub-pulse with adjustable time resolution and adjustable sub-pulse number.

[0031] It should be noted that, in this embodiment, the pulse shaping system 13 composed of the grating 131, the lens 132 and the multiple slits 133 is fixed in the existing technology, such as fixed by the shell structure; in the specific implementation, the slit width and the number of slits can be adjusted according to actual needs.

[0032] In this embodiment, the coherent modulation imaging system 14 loads the ultrafast event information into a coaxial time-series multi-wavelength sub-pulse with adjustable time resolution and adjustable number of sub-pulses, and reconstructs the event information using a wavelength and modulation coding joint constrained anti-derivative algorithm. Figure 1 and Figure 3 As shown, the coherent modulation imaging system 14 includes a phase plate 142 and a detector 143. The coherent modulation imaging system 14 loads the information of the ultrafast event 141 onto the time series multi-wavelength sub-pulses generated by the pulse shaping system 13. After the time series multi-wavelength sub-pulses are modulated by the phase plate 142, the diffraction pattern is recorded by the detector 143, and the event 141 is reconstructed using the wavelength and modulation coding joint constrained anti-diffraction algorithm to obtain the phase information of the atomic time transient event 141.

[0033] It should be noted that, in specific implementation, phase plates with different distributions can be designed according to actual needs.

[0034] The ultrafast single-shot multi-amplitude phase imaging device of the present invention realizes accurate measurement of phase imaging and adjustable high time resolution. After the femtosecond laser pulse is converted into a chirped pulse, the pulse shaping technology is used to generate a time series of multi-wavelength sub-pulses with adjustable coaxial time resolution and adjustable number of sub-pulses. In this way, the pulse width and the time interval between sub-pulses can be effectively regulated, thereby controlling the time resolution of imaging to adapt to ultrafast imaging events with different time resolutions. In addition, these sub-pulses perform phase detection in the coaxial direction, avoiding the phase measurement error caused by parallax in the case of different axes.

[0035] In addition, the highest time resolution can theoretically reach the femtosecond level, and the time resolution can be coordinated with the chirp and sub-pulse width according to the detection event requirements. No complex interference device is required. With the assistance of computational imaging, a single recording can obtain the phase information of 4-8 non-repeatable atomic time transient events with a time resolution of hundreds of femtoseconds. The structure is simple and the system is stable.

[0036] In summary, the ultrafast single-shot multi-frame phase imaging device of the present invention realizes coaxial single-shot multi-frame coherent modulation imaging, avoids the phase measurement error caused by different parallaxes in the background of different axes, and improves the accuracy and stability of phase measurement. The time resolution can be coordinated with the chirp amount and sub-pulse width according to the ultrafast event detection requirements, and the structure is simple and the system is stable. By adjusting the chirp amount and sub-pulse width, the system can achieve optimal performance under different time resolution requirements. The present invention has a simple structure and a stable system, which helps to overcome the challenges that may be encountered in ultrafast event detection under different time resolutions, and improves the accuracy and reliability of data acquisition and analysis.

[0037] The ultrafast single-shot multi-frame phase imaging device of the present invention can be used to study ultrafast optical processes, such as the propagation of laser pulses in matter, optical nonlinear effects, non-repeatable atomic time transient events, etc. By providing a tunable time resolution of hundreds of femtoseconds, the present invention can help researchers deeply analyze the time evolution and phase changes of optical processes.

[0038] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0039] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A single-shot ultrafast multi-modal time-series phase imaging device, characterized in that: The imaging device comprises: A light source system (11) for generating linearly polarized femtosecond laser pulses; A chirped laser pulse generating system (12) generates chirped laser pulses based on the femtosecond laser pulses output by the light source system (11); A pulse shaping system (13) generates coaxial time-series multi-wavelength sub-pulses with adjustable time resolution and adjustable number of sub-pulses based on the generated chirped laser pulses; A coherent modulation imaging system (14) performs coherent modulation imaging based on the time-series multi-wavelength sub-pulses generated by the pulse shaping system (13), and utilizes a wavelength and modulation coding combined constrained anti-derivative algorithm to achieve single-shot ultrafast multi-modal time-series phase imaging.

2. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 1, characterized in that: The femtosecond laser pulses generated by the light source system (11) serve as the laser source of the imaging system.

3. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 2, characterized in that: The light source system (11) adopts a titanium sapphire femtosecond laser, which outputs femtosecond laser pulses with a central wavelength of 800nm, a pulse width of 30-100 femtoseconds, and a spectrum width of 30-80 nanometers.

4. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 1, characterized in that: The chirped laser pulse generating system (12) widens the femtosecond laser pulse through a disperser to generate a picosecond chirped laser pulse with adjustable generation time delay.

5. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 1, characterized in that: The pulse shaping system (13) comprises two gratings (131) with the same parameters, two lenses (132) with the same parameters, and a multi-slit (133) with adjustable width; the two lenses (132) are combined to form a 4f system, the two gratings (131) are respectively placed on the front and rear focal planes of the 4f system, and the multi-slit (133) is placed on the confocal plane of the 4f system.

6. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 5, characterized in that: When the pulse shaping system (13) generates time-series multi-wavelength sub-pulses, the chirped laser pulses generated by the chirped laser pulse generating system (12) are emitted to the first grating, and sequentially pass through the first lens, the multi-slit, the second lens and the second grating to generate coaxial time-series multi-wavelength sub-pulses with adjustable time resolution and adjustable number of sub-pulses.

7. The single-shot ultrafast multi-modal temporal phase imaging device according to claim 6, characterized in that: The coherent modulation imaging system (14) comprises a phase plate (142) and a detector (143). The coherent modulation imaging system (14) loads information of an ultrafast event (141) onto a time series multi-wavelength sub-pulse generated by a pulse shaping system (13). After the time series multi-wavelength sub-pulse is modulated by the phase plate (142), a diffraction pattern is recorded by the detector (143), and the event (141) is reconstructed using a wavelength and modulation coding joint constrained anti-diffraction algorithm to obtain phase information of the atomic time transient event (141).

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