Micro-interference imaging spectroscopic device and implementation method based on external pushbroom

Abstract

This invention provides a microscopic interferometric imaging spectroscopic device and its implementation method based on an external pushbroom. The observation target, located in the illumination field of view, is imaged by an infinity-conjugate microscope objective. Parallel light is then incident on a transverse shearing interferometer module. Two parallel light beams obtained from the transverse shearing interferometer module pass through a Fourier lens group within the imaging lens, generating interference fringes on a planar array camera. Based on a spatial interferometric microscopic imaging optical path with no moving parts, linear pushbroom microscopic imaging is achieved by displacing the sample via an electric stage, obtaining a continuous time-distributed sequence of interference images. The light intensity corresponding to the observation target in each image is extracted from the interference image sequence and recombined to form the interference information of the observation target. Then, a computing unit performs a Fourier transform on this interference information to invert the spectral information of the observation target. The internal components of the interferometer module of this device remain stationary, ensuring the long-term stability and reliability of the hyperspectral microscopic imaging device.

Description

Technical Field

[0001] This invention relates to the field of microscopic hyperspectral imaging technology, specifically to a microscopic interferometric imaging spectroscopic device and its implementation method based on an external push-broom. Background Technology

[0002] Hyperspectral microinterferometry is an advanced analytical technique that combines hyperspectral imaging and interferometric imaging spectroscopy, providing rich spectral and spatial information. By utilizing the high spectral resolution, it is possible to continuously measure the interferograms generated by light in a narrow wavelength band. Then, by combining the Fourier transform relationship between the interferogram and the reconstructed spectrum, a Fourier integral transform is performed on the interferogram to calculate the spectral information of the object under test, thereby enabling a more detailed analysis of the spectral characteristics of the observed target.

[0003] Traditional micro-interferometric imaging devices often employ either time-of-flight Fourier transform interferometry (TOF) spectrometers or rotating TOF interferometric imaging spectrometers. TOF spectrometers are typically based on a Michelson interferometer, using a moving mirror to alter the optical path difference and generate different interference fringe patterns. Rotating TOF interferometric imaging spectrometers adjust the optical path difference by rotating a transverse shear beam splitter to generate interference fringe patterns. Both types of micro-interferometric imaging devices have moving parts. The mechanical vibrations generated during device movement can affect the acquisition of the interference image of the observed target, easily causing data errors and reducing measurement accuracy. Furthermore, adding a servo system to control the moving parts to suppress mechanical vibrations increases the complexity of the micro-interferometric imaging device, leading to higher assembly and adjustment difficulties and increased maintenance costs. These two drawbacks limit the large-scale application of micro-interferometric imaging devices.

[0004] Chinese Patent 102322956A, Chinese Patent 102759402B, and the design method of ROSI high-sensitivity interferometric imaging instrument proposed by Yuan Yan et al. [J]. Acta Photonica Sinica, 2007, (02): 279-281. are all rotational Fourier transform interferometric imaging spectroscopy techniques. They have high requirements for the assembly and adjustment of the transverse shearing interferometer module, and mechanical vibration will be generated during the movement, resulting in poor system stability and reliability.

[0005] To address the shortcomings of current micro-interference imaging spectrometers, this invention proposes a micro-interference imaging spectrometer based on an external pushbroom. It employs a fixed transverse shearing interference module design to ensure no displacement of internal components during the micro-interference imaging spectroscopy process, resulting in extremely high system stability and reliability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a micro-interference imaging spectroscopic device and its implementation method based on an external pushbroom.

[0007] The micro-interference imaging spectroscopic device based on an external pushbroom provided by the present invention includes: a light source, a condenser lens, an electric stage, a microscope objective, a transverse shearing beam splitter, a first plane mirror, a second plane mirror, an electric plane mirror, an imaging lens, an area array camera, and a computing unit.

[0008] The condenser lens converts the light beam emitted from the light source into a parallel beam, which uniformly illuminates the sample on the motorized stage. The microscope objective converts the radiation beam from the sample into a parallel beam, which enters the transverse shearing beam splitter of the Sagnac interferometer. The transverse shearing beam splitter transversely shears the incident beam into two parallel coherent beams, one reflected and one transmitted.

[0009] The Sagnac interferometer has three plane mirrors, which are defined as the first plane mirror, the second plane mirror, and the motorized plane mirror. The first plane mirror is placed in the reflected light path of the transverse beam splitter, the second plane mirror is located in the transmitted light path of the transverse beam splitter, and the motorized plane mirror is connected to the computing unit and is placed after the transmitted light path of the transverse beam splitter and in front of the second plane mirror.

[0010] The imaging lens is a Fourier lens group, placed after the outgoing light of the Sagnac interferometer, and is used to perform interference imaging of the two beams transmitted and reflected in the Sagnac interferometer.

[0011] An area array camera is placed on the focal plane of the imaging lens to receive the interference fringe image formed on the focal plane;

[0012] The computing unit is connected to the area array camera, and performs data processing and Fourier transform on the interferometric image sequence received by the area array camera to obtain the spectral information of the observed target.

[0013] Preferably, the beam-splitting surface of the transverse shear beam splitter forms a 45-degree angle with the parallel beam.

[0014] Preferably, the first plane mirror forms an angle of 22.5 degrees with the direction of incident light, and the second plane mirror forms an angle of 67.5 degrees with the direction of incident light.

[0015] Preferably, the second plane mirror and the first plane mirror are at an angle of 45 degrees, and the center of the second plane mirror and the center of the transverse shear beam splitter are at the same height.

[0016] Preferably, the computing unit is connected to the electric stage, and the computing unit controls the electric stage to drive the sample to perform linear sweeping to obtain an interference image sequence;

[0017] The light intensity corresponding to the observed target in each image of the interferometric image sequence is extracted, and the interferometric information of the observed target is recombined. Then, the Fourier transform of the interferometric information is performed by the computing unit to obtain the spectral information of the observed target.

[0018] In the process of realizing micro-interference imaging spectroscopy, the positions of the first plane mirror, the second plane mirror, and the transverse shearing beam splitter are fixed. The electric stage with a high-precision grating ruler with closed-loop feedback control is automatically controlled by the computing unit to perform linear motion sweeping, thereby obtaining a continuous time-series of interference images.

[0019] Preferably, the reflected beam split by the transverse beam splitter first reaches the first plane mirror, then reaches the second plane mirror after reflection, then reaches the transverse beam splitter after reflection, and finally reaches the imaging lens after reflection by the transverse beam splitter.

[0020] The transmitted beam split by the transverse beam splitter first reaches the second plane mirror, then is reflected to the first plane mirror, then reflected again to the transverse beam splitter, and finally reaches the imaging lens through the transmission of the transverse beam splitter.

[0021] These two beams of light are coherent beams obtained by the transverse shearing of the incident beam by the transverse shearing beam splitter, and finally form an interference fringe image on the focal plane where the area array camera is located.

[0022] Preferably, during the first imaging, the computing unit controls the motorized plane mirror to be inserted into the optical path and switches to the normal imaging mode. The reflected light path after passing through the transverse beam splitter is shielded after reaching the motorized plane mirror. The transmitted light path after passing through the transverse beam splitter is directly reflected back to the transverse beam splitter after reaching the motorized plane mirror. After being reflected by the transverse beam splitter, it enters the imaging lens and is directly imaged on the area array camera for microscopic focusing and auxiliary positioning of the observed target. After focusing and positioning are completed, the motorized plane mirror is removed and the system switches to the interferometric imaging mode to obtain the interferometric image of the observed target.

[0023] The microscopic interferometric imaging spectroscopy method based on an external pushbroom provided by the present invention includes the following steps:

[0024] Step 1: The condenser lens converts the light beam emitted from the light source into a parallel beam, which uniformly illuminates the sample on the motorized stage. The radiation beam from the sample is formed into a parallel beam through the infinity conjugate microscope objective and enters the transverse shearing beam splitter.

[0025] Step 2: The transverse beam splitter transversely splits each incoming beam of light to obtain two parallel coherent beams. The Fourier lens group in the imaging lens converges the two coherent beams onto the area array camera to generate corresponding interference fringes.

[0026] Step 3: Insert a plane mirror into one of the beams of light after horizontal shearing, switch to normal imaging mode, and perform microscopic focusing and auxiliary positioning of the observed target;

[0027] Step 4: Remove the plane mirror, restore to the interferometric imaging mode, obtain the interferometric image of the observed target, the computing unit controls the electric stage to drive the sample to perform linear sweeping, obtain the interferometric image sequence with continuous time distribution, and the area array camera transmits the acquired interferometric image sequence to the computing unit.

[0028] Step 5: The computing unit extracts the light intensity corresponding to the observed target in each image from the image sequence, recombines them into the interference information of the observed target, and then performs Fourier transform calculation on the interference information to obtain the spectral information of the observed target.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) This invention uses an external push-broom mode to acquire interferometric image sequences and adopts a fixed transverse shearing interferometric module design, which effectively avoids the mechanical vibration problem caused by the rotation of the transverse shearing interferometric module or the displacement of the moving mirror in traditional imaging methods, and greatly improves the stability and reliability of the system.

[0031] 2) The device of the present invention achieves the switching between ordinary imaging mode and interferometric imaging mode by inserting and removing a plane mirror in one of the optical paths of the transverse shearing interferometer, thereby improving the flexibility of the device. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the structure of a Sagnac-type micro-interference imaging spectrometer based on an external pushbroom. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0035] Example

[0036] This invention provides a Sagnac-type micro-interferometric imaging spectroscopic device based on an external pushbroom, such as... Figure 1As shown, the device includes a light source 1, a condenser lens 2, an electric stage 3, a microscope objective 4, a transverse shearing beam splitter 5, a first plane mirror 6, a second plane mirror 7, an electric plane mirror 8, an imaging lens 9, an area array camera 10, and a computing unit 11. The condenser lens 2 converts the light beam emitted from the light source 1 into a parallel beam, which uniformly illuminates the sample on the electric stage 3. The microscope objective 4 converts the radiation beam from the sample into a parallel beam, which enters the transverse shearing beam splitter 5 of the Sagnac interferometer. The beam splitting surface of the transverse shearing beam splitter 5 forms a 45-degree angle with the parallel beam.

[0037] The Sagnac interferometer has three plane mirrors, defined as a first plane mirror 6, a second plane mirror 7, and a motorized plane mirror 8. The first plane mirror 6 is placed in the reflected light path of the transverse beam splitter 5, forming a 22.5-degree angle with the incident light direction. The second plane mirror 7 is located in the transmitted light path of the transverse beam splitter 5, forming a 67.5-degree angle with the incident light direction. The angle between the second plane mirror 7 and the first plane mirror 6 is 45 degrees, and the centers of the second plane mirror 6 and the transverse beam splitter 5 are at the same height. The motorized plane mirror 8 is connected to the computing unit 11 and is placed after the transmitted light path of the transverse beam splitter 5 and in front of the second plane mirror 7. When the computing unit 11 controls the motorized plane mirror 8 to be inserted into the light path, it switches to the normal imaging mode, facilitating microscopic focusing and auxiliary positioning of the observed target. When the motorized plane mirror 8 is removed from the light path, it switches back to the interferometric imaging mode, obtaining the interferometric image of the observed target.

[0038] Imaging lens 9 is a Fourier lens group, placed after the outgoing light of the Sagnac interferometer, and is used to perform interference imaging of the two beams transmitted and reflected in the Sagnac interferometer.

[0039] The area array camera 10 is placed on the focal plane of the imaging lens 9 to receive the interference fringe image formed on the focal plane;

[0040] The computing unit 11 is connected to the area array camera 10, and performs data processing and Fourier transform on the interferometric image sequence received by the area array camera 10 to obtain the spectral information of the observed target.

[0041] The computing unit 11 is connected to the electric stage 3. In this invention, the computing unit 11 controls the electric stage 3 to drive the sample to perform linear sweeping and obtain an interference image sequence.

[0042] In the process of realizing micro-interference imaging spectrum, the positions of the first plane mirror 6, the second plane mirror 7, and the transverse shearing beam splitter 5 are fixed. The electric stage 3 with a high-precision grating ruler with closed-loop feedback control is automatically controlled by the computing unit 11 to perform linear motion sweeping, so as to obtain a continuous time interference image sequence.

[0043] The working principle of the Sagnac-type micro-interference imaging spectrometer based on an external pushbroom according to the present invention is as follows:

[0044] A beam of light emitted from light source 1 is converged into a parallel beam by condenser lens 2, uniformly illuminating the sample on motorized stage 3. Microscope objective 4 converts the radiated beam into a parallel beam at infinity, which then enters the transverse shearing beam splitter 5 of the Sagnac interferometer. The transverse shearing beam splitter 5 transversely splits the incident beam into two parallel coherent beams: one reflected and one transmitted. The Fourier lens group of imaging lens 9 converges the two coherent beams onto area array camera 10, generating corresponding interference fringe images. Subsequently, the computing unit 11 controls the motorized plane mirror 8 to be inserted into the transmission light path, switching to normal imaging mode for microscopic focusing and auxiliary positioning of the observed target. After focusing and positioning are completed, the motorized plane mirror 8 is removed, returning to interferometric imaging mode. The computing unit 11 controls the motorized stage 3 to move the sample in a straight line, receiving the interference image sequence on area array camera 10. Finally, the computing unit 11 performs Fourier transform data processing on the interference image sequence to invert and obtain the spectral reconstruction information of the observed target.

[0045] The reflected beam split by the transverse beam splitter 5 first reaches the first plane mirror 6, then reaches the second plane mirror 7 after reflection, then reaches the transverse beam splitter 5 after reflection, and finally reaches the imaging lens 9 after reflection by the transverse beam splitter 5.

[0046] The transmitted beam split by the transverse beam splitter 5 first reaches the second plane mirror 7, then reaches the first plane mirror 6 after reflection, then reaches the transverse beam splitter 5 after reflection, and finally reaches the imaging lens 9 through the transmission of the transverse beam splitter 5. These two beams are coherent beams obtained by the transverse beam splitter 5 transversely cutting the incident beam, and finally form an interference fringe image on the focal plane of the area array camera 10.

[0047] During the first imaging, the computing unit 11 controls the motorized plane mirror 8 to be inserted into the optical path and switches to the normal imaging mode. The reflected light path after passing through the transverse beam splitter 5 is shielded after reaching the motorized plane mirror 8; the transmitted light path after passing through the transverse beam splitter 5 is directly reflected back to the transverse beam splitter 5 after reaching the motorized plane mirror 8, and after being reflected by the transverse beam splitter 5, it enters the imaging lens 9 and is directly imaged on the area array camera 10 for microscopic focusing and auxiliary positioning of the observed target. After the focusing and positioning are completed, the motorized plane mirror 8 is removed, and the system switches to the interferometric imaging mode to obtain the interferometric image of the observed target.

[0048] The computing unit 11 controls the electric stage 3 to move the sample and achieve linear push-broom microscopy imaging, obtaining a continuous time-distributed sequence of interferometric images. The light intensity corresponding to the observed target in each image is extracted from the interferometric image sequence, and the interferometric information of the observed target is recombined. The computing unit 11 then performs a Fourier transform on this interferometric information to invert and obtain the spectral information of the observed target.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0050] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A microscopic interferometric imaging spectroscopic device based on an external pushbroom, characterized in that, include: The light source (1), condenser lens (2), motorized stage (3), microscope objective (4), transverse shearing beam splitter (5), first plane mirror (6), second plane mirror (7), motorized plane mirror (8), imaging lens (9), area array camera (10), and computing unit (11). The condenser lens (2) converts the light beam emitted from the light source (1) into a parallel beam, which uniformly illuminates the sample on the electric stage (3). The microscope objective (4) converts the radiation beam of the sample into a parallel beam, which enters the transverse shearing beam splitter (5) of the Sagnac interferometer. The transverse shearing beam splitter (5) transversely shears the incident beam into two parallel coherent beams, one reflected and one transmitted. The Sagnac interferometer module has three plane mirrors, defined as a first plane mirror (6), a second plane mirror (7), and an electric plane mirror (8). The first plane mirror (6) is placed in the reflected light path of the transverse beam splitter (5), and the second plane mirror (7) is located in the transmitted light path of the transverse beam splitter (5). The electric plane mirror (8) is connected to the computing unit (11), and is placed after the transmitted light path of the transverse beam splitter (5) and in front of the second plane mirror (7). The imaging lens (9) is a Fourier lens group, which is placed after the outgoing light of the Sagnac interferometer to perform interference imaging of the two beams transmitted and reflected in the Sagnac interferometer. The area array camera (10) is placed on the focal plane of the imaging lens (9) to receive the interference fringe image formed on the focal plane; The computing unit (11) is connected to the area array camera (10) to perform data processing and Fourier transform on the interferometric image sequence received by the area array camera (10) and invert the spectral information of the observed target. In the process of realizing micro-interference imaging spectrum, the positions of the first plane mirror (6), the second plane mirror (7), and the transverse shear beam splitter (5) are fixed. The electric stage (3) with a high-precision grating ruler with closed-loop feedback control is automatically controlled by the computing unit (11) to perform linear motion sweeping, so as to obtain a continuous time interference image sequence.

2. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The beam splitting surface of the transverse shear beam splitter (5) is at a 45-degree angle to the parallel beam.

3. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The first plane mirror (6) forms an angle of 22.5 degrees with the direction of the incident light.

4. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The second plane mirror (7) forms a 67.5-degree angle with the direction of the incident light.

5. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The angle between the second plane mirror (7) and the first plane mirror (6) is 45 degrees.

6. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The centers of the second plane mirror (7) and the first plane mirror (6) are at the same height as the center of the transverse shear beam splitter (5).

7. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The computing unit (11) is connected to the electric stage (3). The computing unit (11) controls the electric stage (3) to drive the sample to perform linear sweeping and obtain the interference image sequence. The light intensity corresponding to the observed target in each image is extracted from the interferometric image sequence, and the interferometric information of the observed target is recombined. Then, the Fourier transform of the interferometric information is calculated by the computing unit (11) to obtain the spectral information of the observed target.

8. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, The reflected beam split by the transverse beam splitter (5) first reaches the first plane mirror (6), then reaches the second plane mirror (7) after reflection, then reaches the transverse beam splitter (5) after reflection, and finally reaches the imaging lens (9) through the reflection of the transverse beam splitter (5). The transmitted beam split by the transverse beam splitter (5) first reaches the second plane mirror (7), then reaches the first plane mirror (6) after reflection, then reaches the transverse beam splitter (5) after reflection, and finally reaches the imaging lens (9) through the transmission of the transverse beam splitter (5). These two beams of light are coherent beams obtained by the transverse shearing beam splitter (5) to transversely shear the incident beam, and finally form an interference fringe image on the focal plane where the area array camera (10) is located.

9. The microscopic interferometric imaging spectroscopic device based on an external pushbroom according to claim 1, characterized in that, During the first imaging, the computing unit (11) controls the electric plane mirror (8) to be inserted into the optical path and switches to the normal imaging mode. The reflected light path after passing through the transverse beam splitter (5) is shielded after reaching the electric plane mirror (8). The transmitted light path after passing through the transverse beam splitter (5) is directly reflected back to the transverse beam splitter (5) after reaching the electric plane mirror (8). After being reflected by the transverse beam splitter (5), it enters the imaging lens (9) and is directly imaged on the area array camera (10) to perform microscopic focusing and auxiliary positioning of the observed target. After the focusing and positioning are completed, the electric plane mirror (8) is removed and the interferometric imaging mode is switched to obtain the interferometric image of the observed target.

10. A method for achieving microscopic interferometric imaging spectroscopy based on an external pushbroom, characterized in that, The micro-interference imaging spectroscopic apparatus based on an external pushbroom, as described in any one of claims 1 to 9, comprises the following steps: Step 1: The condenser lens converts the light beam emitted from the light source into a parallel beam, which uniformly illuminates the sample on the motorized stage. The radiation beam from the sample is formed into a parallel beam through the infinity conjugate microscope objective and enters the transverse shearing beam splitter. Step 2: The transverse beam splitter transversely splits each incoming beam of light to obtain two parallel coherent beams. The Fourier lens group in the imaging lens converges the two coherent beams onto the area array camera to generate corresponding interference fringes. Step 3: Insert an electric plane mirror into the transversely sheared transmission optical path, switch to normal imaging mode, and perform microscopic focusing and auxiliary positioning of the observed target; Step 4: Remove the motorized plane mirror, restore to the interferometric imaging mode, obtain the interferometric image of the observed target, the computing unit controls the motorized stage to drive the sample to perform linear sweeping, obtain the interferometric image sequence with continuous time distribution, and the area array camera transmits the acquired interferometric image sequence to the computing unit. Step 5: The computing unit extracts the light intensity corresponding to the observed target in each image from the image sequence, recombines them into the interference information of the observed target, and then performs Fourier transform calculation on the interference information to obtain the spectral information of the observed target.

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