A common optical path large aperture time modulation interference spectroscopy imaging device and method

Abstract

The present invention belongs to the field of optical technology and discloses a common-path, large-aperture, time-modulated interferometric spectroscopy imaging device and method. The device comprises a triangular common-path interferometer, an asymmetric structure equipped with a moving mirror scanning mechanism for generating a time-varying optical path difference. The device operates in a staring observation mode. This invention retains the common-path and large-aperture advantages of conventional spatiotemporal joint modulation interferometric spectroscopy imaging technology while achieving high spectral resolution. It exhibits advantages such as high stability, high throughput, and a high signal-to-noise ratio.

Description

Technical Field

[0001] The present invention belongs to the field of optical technology, and more specifically, relates to a common optical path large aperture time modulation interference spectroscopy imaging device and method. Background Art

[0002] Interferometric spectroscopy (imaging), based on the principles of interferometric spectroscopy, is an important technique within optical detection and spectroscopy (imaging). Three main types of interferometric spectroscopy (imaging) have emerged: time-modulated (dynamic) Michelson interferometers, spatially modulated (static) lateral shearing interferometers, and combined time-space modulation (static) lateral shearing interferometers. Numerous interferometric spectrometers have emerged based on these techniques, but each often has its own limitations. Time-modulated interferometric spectrometers utilize the motion of a moving mirror in a Michelson interferometer to generate a varying optical path difference. Spectral information is obtained by Fourier transforming the interference fringes at varying optical path differences. This technique offers high optical throughput and signal-to-noise ratio. In particular, the spectral resolution achieved by the large optical path difference generated by the linear motion of the moving mirror far exceeds that of any other currently available spectral detection technology. However, the speed and attitude control required during the moving mirror's motion necessitate high interferometer calibration accuracy, resulting in poor optomechanical stability and limited application to mobile platforms such as vehicles, aircraft, ships, mobile robots, and satellites. All time-modulated interferometric spectrometers (imaging instruments) operate in staring observation mode, which requires the scanning integration of the moving mirror inside the instrument to obtain interference patterns at different times. The spatial modulation type relies on a lateral shearing interferometer with a common optical path. It has high stability, good real-time performance, and a simple structure, but the spectral resolution is limited by the number and size of detector units and has a low resolution. The structure of the spatiotemporal joint modulation type is similar to the spatial modulation type. It has high stability and can have higher detection sensitivity than spatial modulation interferometers and dispersive spectrometers, but it has very high requirements for platform stability, and the spectral resolution is similar to that of the spatial modulation type but lower. Spatial modulation and spatiotemporal joint modulation types operate in line scanning or window scanning mode.

[0003] Large-aperture static interferometers (imaging) are the primary form of spatiotemporal joint modulation interferometers (imaging). They utilize a common-path spectrometer based on the Sagnac triangular lateral shearing interferometer. Due to the lack of slits, the aperture is large, and due to the lack of moving mirrors within the interferometer, the instrument is "static." It relies on the platform's scanning field of view to obtain different optical path differences for the same target under different fields of view. However, the low spectral resolution limits the application of this type of spectrometer. Achieving high spectral resolution while retaining the advantages of traditional spatiotemporal joint modulation interferometer spectroscopy (imaging) in terms of common path and large aperture is a challenge in this field. Summary of the Invention

[0004] The present invention provides a common optical path large-aperture time-modulated interferometric spectroscopy imaging device and method to solve the problem in the prior art that large-aperture interferometric spectroscopy imaging devices and methods cannot retain the advantages of spatiotemporal joint modulation interferometric spectroscopy (imaging) technology while obtaining high spectral resolution.

[0005] The present invention provides a common optical path large aperture time modulation interference spectroscopy imaging device, comprising: a triangular common optical path interferometer, the triangular common optical path interferometer having an asymmetric structure, and a moving mirror scanning mechanism for generating an optical path difference that varies with time, wherein the common optical path large aperture time modulation interference spectroscopy imaging device operates in a staring observation mode.

[0006] Preferably, the triangular common optical path interferometer includes a beam splitter, a first plane reflector, a second plane reflector, a first optical path adjustment component and a second optical path adjustment component; the first optical path adjustment component and the second optical path adjustment component are combined to form the moving mirror scanning mechanism, the first optical path adjustment component and the second optical path adjustment component are respectively placed in the two arms of the interferometer, the two arms respectively generate the first optical path and the second optical path, the first optical path and the second optical path are combined to form an optical path difference that varies periodically near zero optical path difference; the target light enters the triangular common optical path interferometer as parallel light, and the beam splitter divides the parallel light into a first transmitted light beam and a second optical path adjustment component. a first reflected light beam; the first reflected light beam passes through the first plane reflector, the first optical path adjustment component, and the second plane reflector in sequence, and then returns to the beam splitter again, and is divided into a second transmitted light beam and a second reflected light beam by the beam splitter; the first transmitted light beam passes through the second plane reflector, the second optical path adjustment component, and the first plane reflector in sequence, and then returns to the beam splitter again, and is divided into a third transmitted light beam and a third reflected light beam by the beam splitter; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction.

[0007] Preferably, one of the first optical path adjustment component and the second optical path adjustment component is a moving mirror, and the other optical path adjustment component is a fixed mirror; the optical path adjustment component serving as a moving mirror includes an optical path adjustment device and a motor, and the optical path adjustment device moves under the drive of the motor; the optical path adjustment component serving as a fixed mirror only includes an optical path adjustment device.

[0008] Preferably, the optical path adjustment device in the optical path adjustment assembly serving as a moving mirror adopts a first prism, and the optical path adjustment device in the optical path adjustment assembly serving as a fixed mirror adopts a second prism, and the exit surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface; the first prism rotates under the drive of the motor, and the rotation axis of the motor is perpendicular to the propagation direction of the light beam; the posture of the second prism has a certain angle of inclination relative to the vertical incident surface of the light beam, which is used to compensate for the zero-position dispersion effect and increase the zero optical path difference position.

[0009] Preferably, the first prism consists of a prism pair, and the two prisms in the prism pair rotate in opposite directions.

[0010] Preferably, the first optical path adjustment component and the second optical path adjustment component are both moving mirrors; the first optical path adjustment component includes a first optical path adjustment device and a first motor, and the second optical path adjustment component includes a second optical path adjustment device and a second motor; the first optical path adjustment device moves under the drive of the first motor, and the second optical path adjustment device moves under the drive of the second motor.

[0011] Preferably, the common-path large-aperture time-modulated interference spectroscopy imaging device also includes: a converging component, a detection and acquisition module and a signal processing module; the target surface of the detection and acquisition module is located on the back focal plane of the converging component, and the signal processing module is connected to the detection and acquisition module; the converging component is used to form interference with the light beam emitted by the triangular common-path interferometer and image it onto the detection and acquisition module; the detection and acquisition module is used to sample and collect the interference fringe signals at different times, and convert them into electrical signals to obtain detection information; the signal processing module is used to perform spectral restoration based on the detection information to obtain spectral information.

[0012] Preferably, the common optical path large aperture time-modulated interference spectroscopy imaging device also includes: a front-end component; the front-end component includes a converging lens, an aperture and a collimating lens arranged in sequence along the optical path; the target light becomes parallel light after passing through the front-end component and is incident on the triangular common optical path interferometer.

[0013] On the other hand, the present invention provides a common optical path large aperture time modulation interference spectroscopy imaging method, which is implemented using the above-mentioned common optical path large aperture time modulation interference spectroscopy imaging device. By setting a moving mirror scanning mechanism for generating an optical path difference that varies with time in a triangular common optical path interferometer, the common optical path large aperture time modulation interference spectroscopy imaging device is enabled to operate in a staring observation mode.

[0014] Preferably, the common optical path large aperture time modulation interference spectroscopy imaging method comprises the following steps:

[0015] Step 1: The target light is converted into parallel light after passing through the front component and is incident on the triangular common optical path interferometer;

[0016] Step 2: Splitting the parallel light into a first transmitted light beam and a first reflected light beam through a beam splitter; the first reflected light beam sequentially passes through a first plane reflector, a first optical path adjustment component, and a second plane reflector, and then returns to the beam splitter again, and is split into a second transmitted light beam and a second reflected light beam through the beam splitter; the first transmitted light beam sequentially passes through a second plane reflector, a second optical path adjustment component, and the first plane reflector, and then returns to the beam splitter again, and is split into a third transmitted light beam and a third reflected light beam through the beam splitter; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction;

[0017] Step 3: The light beams emitted from the triangular common optical path interferometer are interfered by a converging component and imaged onto a detection and acquisition module;

[0018] Step 4: The detection and acquisition module samples and collects interference fringe signals at different times, and converts them into electrical signals to obtain detection information;

[0019] Step 5: Perform spectrum restoration based on the detection information through a signal processing module to obtain spectrum information.

[0020] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0021] The common-path, large-aperture, time-modulated interferometric spectroscopy imaging device provided by the present invention includes a triangular common-path interferometer. The triangular common-path interferometer has an asymmetric structure and is equipped with a moving mirror scanning mechanism for generating a time-varying optical path difference. The common-path, large-aperture, time-modulated interferometric spectroscopy imaging device operates in a staring observation mode. The present invention utilizes common-path spectroscopic technology based on a Sagnac triangular lateral shearing interferometer. This technology offers a large aperture due to the absence of a slit and high stability due to its common-path technology. Furthermore, the interferometer is equipped with a moving mirror scanning mechanism, which generates a time-varying optical path difference through its movement, thereby achieving high spectral resolution.

[0022] This invention, which proposes for the first time the integration of a common optical path with time-modulated interferometry (imaging), is of great significance. It overcomes the problem of poor stability, offering the advantages of high stability and strong anti-interference capabilities, while also maintaining the advantages of high throughput, high signal-to-noise ratio, and low stray light. In other words, this invention retains the advantages of spatiotemporal combined interferometry (imaging) while achieving high spectral resolution.

[0023] In traditional common-path interferometers, the optical path lengths of the two arms are always fixed or identical, resulting in a fixed optical path length difference between the two arms, making it impossible to implement a time-modulated operating mode. The present invention provides at least one "dynamic" optical path adjustment component as a moving mirror in the common-path interferometer. The movement of the moving mirror at different times produces different optical path length differences, thereby obtaining a time-integrated interference pattern and inverting the target's spectral information. This invention can implement a time-modulated interferometric spectrometer (imaging) operating mode, overcoming the limitations of previous common-path interferometers on spectral information acquisition.

[0024] Furthermore, because traditional time-modulated interferometry (imaging) instruments require a varying optical path difference to acquire interference patterns at different times, the two arms of their core interferometer component are relatively independent, creating a non-common optical path interferometer. While non-common optical path and common optical path interferometers are different types of interferometers, the present invention utilizes a common optical path interferometer core component, breaking through the limitations of traditional non-common optical path interferometers and implementing time-modulated interferometry (imaging) technology based on a common optical path interferometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an optical principle diagram of a common optical path large aperture time-modulated interference spectroscopy imaging device for implementing interference spectroscopy provided in Example 1 of the present invention;

[0026] Figure 2 This is an optical principle diagram of a common optical path large aperture time modulation interference spectroscopy imaging device for implementing interference spectroscopy provided in Example 2 of the present invention;

[0027] Figure 3 This is a schematic diagram of a common optical path large aperture time-modulated interferometric spectroscopy imaging device provided in Example 3 of the present invention.

[0028] Among them, 1-incident light beam, 2-beam splitter, 3-first plane reflector, 4-second plane reflector, 5-first optical path adjustment device, 6-second optical path adjustment device, 7-motor, 8-front assembly, 9-convergence assembly, 10-detection and acquisition module, 11-signal processing module;

[0029] 81 - Converging lens, 82 - Aperture, 83 - Collimating lens. DETAILED DESCRIPTION

[0030] All current time-modulated interferometry (imaging) technologies suffer from a major limitation: poor stability, environmental adaptability, and low interference resistance. This is due to the nature of current time-modulated interferometry techniques: they all employ non-common-path interferometry (exemplified by Michelson interferometry) rather than common-path interferometry (exemplified by Sagnac interferometry). The primary advantage of non-common-path interferometry lies in its ability to achieve a relatively short optical path. The interferometer's two arms, separated by its beam splitter, are separated, and the light beams travel through each arm independently. The optical path difference in each arm can be varied depending on the arm length, thus generating the desired optical path difference. However, the resulting interferometer often exhibits differences in interference fringes due to thermodynamic deformation and environmental changes acting on the two independent arms, resulting in unstable interference fringes. With common-path interferometry, the beams in both arms of the interferometer travel along the same path, or even completely overlap. Therefore, thermodynamic deformations caused by external factors, such as vibration and temperature fluctuations, act simultaneously on both beams, canceling each other out. This results in highly stable interference fringes and a more reliable interferometer.

[0031] Previous common-path interference spectrometry technology cannot be used in time-modulated interference spectrometers (imaging instruments). The reason is that for staring observations of targets in the same field of view, the two beams of light separated by the interferometer beam splitter travel along the same path and cannot produce a changing optical path difference. As a result, it is impossible to obtain interference patterns at different optical path differences, and further, it is impossible to perform Fourier transform to obtain a spectrum.

[0032] To preserve the advantages of spatiotemporal combined modulation interferometry (imaging) while achieving high spectral resolution, the present invention proposes a common-path, large-aperture, time-modulated interferometry (TSM) imaging device and method. This device utilizes common-path spectroscopic technology based on a Sagnac triangular lateral shearing interferometer, and incorporates a moving mirror scanning mechanism within the interferometer to produce a variable optical path difference. The device operates in a staring observation mode, as opposed to the field-of-view scanning observation mode of spatiotemporal combined modulation interferometry (TSM). This device overcomes the problem of poor stability, offering the advantages of high stability and strong anti-interference capabilities, while maintaining the advantages of high throughput, high signal-to-noise ratio, and low stray light.

[0033] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0034] Example 1:

[0035] Example 1 provides a common-path large-aperture time-modulated interference spectroscopy imaging device, which mainly includes: a triangular common-path interferometer, the triangular common-path interferometer is an asymmetric structure, and the triangular common-path interferometer is provided with a moving mirror scanning mechanism for generating an optical path difference that varies with time. The common-path large-aperture time-modulated interference spectroscopy imaging device operates in a staring observation mode.

[0036] For details, see Figure 1 The triangular common optical path interferometer includes a beam splitter 2, a first plane mirror 3, a second plane mirror 4, a first optical path adjustment component and a second optical path adjustment component; the first optical path adjustment component and the second optical path adjustment component are combined to form the moving mirror scanning mechanism, the first optical path adjustment component and the second optical path adjustment component are respectively placed in the two arms of the interferometer, and the two arms respectively generate the first optical path and the second optical path, and the first optical path and the second optical path are combined to form an optical path difference that changes periodically near zero optical path difference.

[0037] The target light (i.e., the incident light beam 1) enters the triangular common-path interferometer as parallel light, and the beam splitter 2 splits the parallel light into a first transmitted light beam and a first reflected light beam; the first reflected light beam passes through the first plane mirror 3, the first optical path adjustment component, and the second plane mirror 4 in sequence and then returns to the beam splitter 2 again, and is split into a second transmitted light beam and a second reflected light beam by the beam splitter 2; the first transmitted light beam passes through the second plane mirror 4, the second optical path adjustment component, and the first plane mirror 3 in sequence and then returns to the beam splitter 2 again, and is split into a third transmitted light beam and a third reflected light beam by the beam splitter 2; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction.

[0038] Among them, one of the first optical path adjustment component and the second optical path adjustment component is a moving mirror, and the other optical path adjustment component is a fixed mirror; the optical path adjustment component serving as a moving mirror includes an optical path adjustment device and a motor, and the optical path adjustment device moves under the drive of the motor; the optical path adjustment component serving as a fixed mirror only includes the optical path adjustment device.

[0039] The following description will be made by taking the optical path adjustment device as a prism and the movement mode of the movable mirror as rotation as an example.

[0040] See also Figure 1The first optical distance adjusting device 5 is a fixed mirror, the second optical distance adjusting device 6 is a moving mirror, and the second optical distance adjusting device 6 moves under the drive of the motor 7. The optical path adjustment device (i.e., the second optical path adjustment device 6) in the optical path adjustment assembly serving as a moving mirror adopts a first prism, and the optical path adjustment device (i.e., the first optical path adjustment device 5) in the optical path adjustment assembly serving as a fixed mirror adopts a second prism. The two prisms are used to change the optical path. The incident surface and the exit surface of the light beam of the prism are strictly parallel (within 5 inches), so that the exit surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface. The first prism rotates under the drive of the motor 7. The rotation axis of the motor 7 is perpendicular to the propagation direction of the light beam. Rotating perpendicular to the paper is a preferred embodiment so as to keep the direction of the exiting light beam consistent with that of the incident light. The posture of the second prism is fixed, and the posture of the second prism has a certain angle of inclination relative to the vertical incident surface of the light beam so as to compensate for the zero-position dispersion effect and increase the zero optical path difference position (doubled compared to the vertical incidence). When there is a certain amount of shaking in the rotation axis of the motor 7, the first prism will deviate from the ideal posture to a certain extent, and the light beam emitted from the first prism will have a certain spatial position offset, but due to The incident surface and the exit surface of the first prism are parallel, so that the propagation direction of the emitted light beam is not deflected, that is, the self-compensation of the attitude error caused by the shaking of the axis system when the moving mirror rotates is achieved, and the immunity of the interferometer shaking error and the permanent alignment of the two interfering light beams are achieved. If the first prism is specifically composed of a pair of prisms arranged together, and the attitudes of the two prisms in the prism pair can be kept relatively variable (that is, the rotation directions of the motor are opposite, respectively +θ angle and -θ angle), then the propagation direction of the light beam after passing through this prism pair will always remain consistent, and the space If the optical paths of the first and second prisms always overlap, a very high degree of interference modulation can be achieved. The changing optical path is generated by the rotation of the first prism, and combined with the fixed optical path of the second prism, a periodic optical path difference is formed near zero optical path difference, from -L to 0 and then from 0 to +L, passing through the position of zero optical path difference, where L is the maximum optical path difference. Thus, interference patterns corresponding to different optical path differences at different times can be obtained. The interference pattern is then subjected to a spectral restoration algorithm such as Fourier transform to obtain the target's spectrum. This is the working mode of the time-modulated interferometric spectrometer (imaging) instrument.

[0041] It should be noted that the function of the first plane reflector 3 and the second plane reflector 4 is to form a triangular interferometer for reflecting the light beam and adjusting the distribution of the light beam in space. The first plane reflector 3 and the second plane reflector 4 can be replaced by a single plane reflector or by a combination of multiple plane mirrors. Since the function of the first optical path adjustment device 5 and the second optical path adjustment device 6 is to generate an optical path difference that varies with time, that is, the function of the optical path adjustment device is to generate an interference pattern from zero optical path difference to maximum optical path difference that varies with time, and obtain the target's spectrum through a spectral restoration algorithm such as Fourier transform, thereby realizing the time-modulated interference spectrometer (imaging) working mode, the combination of the first prism and the second prism can also be replaced by a single prism, or the first prism and the second prism are both specifically implemented by a prism combination. In addition, the first prism and the second prism can also be replaced by other optical path adjustment structures such as prisms of other structures and reflector combinations. In addition to rotation, the movement of the prism can also be swinging, linear motion, etc. Correspondingly, the shaft of the motor 7 may be in periodic rotation, periodic swing or other periodic motion modes.

[0042] The present invention is implemented based on a triangular Sagnac interferometer, which can be composed of a semi-transparent and semi-reflective beam splitter, two plane mirrors and a pair of prisms, and its variable optical path difference is generated by a rotating prism combination pair. The target light enters the triangular interferometer as parallel light, and is then divided into a first transmitted light beam and a first reflected light beam by the semi-transparent and semi-reflective beam splitter in the interferometer; the first transmitted light beam and the first reflected light beam pass through a fixed and variable optical path adjustment component respectively, and then return to the beam splitter again; the transmitted light beam and the reflected light beam returned to the beam splitter are transmitted and reflected by the beam splitter again, forming four lights, of which every two lights are converged to generate interference, one interference light beam returns to the incident direction of the light source, and the other interference light beam propagates in another direction ( Figure 1 vertical light source incident direction).

[0043] The triangular interferometer can be a hollow structure composed of separate components. The semi-transparent and semi-reflective beam splitter can be a cubic beam splitter or a flat plate beam splitter. The triangular interferometer can also be a solid structure composed of a prism coated with a reflective film and a semi-transparent and semi-reflective beam splitter film. The triangular interferometer must be an asymmetric structure, that is, the two reflecting surfaces of the interferometer are not strictly symmetrical about the beam splitting surface axis, but one of the surfaces produces a certain degree of translation. The amount of translation depends on design requirements such as the optical path difference, the diameter of the beam, and the required physical space dimensions of the structure. The light beam incident on this triangular interferometer is separated by the interferometer beam splitter and passes through the same components in the interferometer, thus forming a common optical path interferometer.

[0044] Example 2:

[0045] Example 2 provides a common optical path large-aperture time-modulated interference spectroscopy imaging device. The difference from Example 1 is that the first optical path adjustment component and the second optical path adjustment component in Example 2 are both moving mirrors; the first optical path adjustment component includes a first optical path adjustment device and a first motor, and the second optical path adjustment component includes a second optical path adjustment device and a second motor; the first optical path adjustment device moves under the drive of the first motor, and the second optical path adjustment device moves under the drive of the second motor.

[0046] For example, the first motor and the second motor are two different motors, and the rotation directions and rotation speeds of the first optical distance adjustment device and the second optical distance adjustment device may be different.

[0047] For example, see Figure 2 The first motor and the second motor are the same motor, denoted as electrode 7. The first optical path adjustment device 5 and the second optical path adjustment device 6 both use prisms. The two prisms are connected together for movement. By setting the materials, sizes (such as length) or rotation postures of the two prisms differently, an optical path difference that changes with time is generated.

[0048] Example 3:

[0049] Example 3 provides a common optical path large aperture time modulation interference spectroscopy imaging device, see Figure 3 In addition to the triangular common optical path interferometer provided in Example 1 or Example 2, the present invention further comprises: a pre-assembly 8, a converging assembly 9, a detection and acquisition module 10, and a signal processing module 11. The target surface of the detection and acquisition module 10 is located on the back focal plane of the converging assembly 9, and the signal processing module 11 is connected to the detection and acquisition module 10.

[0050] The target light becomes parallel light after passing through the front assembly 8 and is incident on the triangular common optical path interferometer. Specifically, the front assembly 8 includes a converging lens 81, an aperture 82 and a collimating lens 83 arranged in sequence along the optical path. The target light is converged by the converging lens 81. The aperture 82 filters and limits the shape of the image surface of the converging lens 81 and prevents stray light. The collimating lens 83 is used for collimation, so that the light passing through the front optical system 8 becomes parallel light. The front optical system 8 can adopt various forms such as refraction, catadioptric reflection and total reflection, and its purpose is to convert the target radiation into parallel light. In addition, according to design requirements, the front optical system 8 can also remove the collimating lens 83 to become a converging optical path, or the front optical system 8 can be directly omitted to reduce the volume and weight of the instrument.

[0051] The converging assembly 9 is used to interfere the light beams emitted by the triangular common optical path interferometer and image them onto the detection and acquisition module 10. Specifically, when the first optical path adjustment device 5 is a fixed mirror and the second optical path adjustment device 6 is a moving mirror, the second reflected light beam and the third transmitted light beam are converged to generate interference and are received by the detector of the detection and acquisition module 10. The converging assembly 9 can be a single lens or a lens combination, and the lens combination facilitates the elimination of aberrations. The converging assembly 9 can be refractive or reflective.

[0052] The detection and acquisition module 10 is used to sample and collect interference fringe signals at different times, converting them into electrical signals to obtain detection information. After obtaining the electrical signals, the detection and acquisition module 10 can also perform signal processing such as amplification and filtering. The detection and acquisition module 10 provides raw measurement data for inverting relevant parameters such as the target light spectrum and image. Depending on the detection light source, the detection and acquisition module 10 can be a CCD or other photoelectric conversion device.

[0053] The signal processing module 11 is configured to perform spectral restoration based on the detection information to obtain spectral information. Specifically, the signal processing module 11 performs data processing and analysis on the interference signal acquired by the detection and acquisition module 10, including preprocessing of the raw interference pattern data, error correction, spectral responsivity calibration correction, radiometry calibration correction, and Fourier transform, completing the spectral restoration process and obtaining the spectrum and / or high-resolution spectral image of the target (i.e., the incident light beam 1).

[0054] The spectral application range of the present invention is applicable from ultraviolet to far infrared and THz, and is mainly limited by the spectral application range of the beam splitter and prism, reflector film layer, converging component and detection and acquisition module, that is, different beam splitter substrate materials and their film layers, prism materials and their film layers and reflector film layers, detection spectral response, etc. correspond to different bands.

[0055] In addition, other forms of spectrometers / spectrometers (imaging instruments) can be derived based on the principles of the present invention. For example, by adding a polarization device to the optical path, a time-modulated polarization spectrometer and a polarization spectrometer (imaging instrument) can be formed.

[0056] Example 4:

[0057] Example 4 provides a common optical path large aperture time modulation interference spectroscopy imaging method, which is implemented using the common optical path large aperture time modulation interference spectroscopy imaging device as described in the above embodiments. By setting a moving mirror scanning mechanism for generating an optical path difference that varies with time in a triangular common optical path interferometer, the common optical path large aperture time modulation interference spectroscopy imaging device operates in a staring observation mode.

[0058] A specific method corresponding to the device of Example 3 is provided below.

[0059] A common optical path large aperture time modulation interference spectroscopy imaging method comprises the following steps:

[0060] Step 1: The target light is converted into parallel light after passing through the front component and is incident on the triangular common optical path interferometer;

[0061] Step 2: Splitting the parallel light into a first transmitted light beam and a first reflected light beam through a beam splitter; the first reflected light beam sequentially passes through a first plane reflector, a first optical path adjustment component, and a second plane reflector, and then returns to the beam splitter again, and is split into a second transmitted light beam and a second reflected light beam through the beam splitter; the first transmitted light beam sequentially passes through a second plane reflector, a second optical path adjustment component, and the first plane reflector, and then returns to the beam splitter again, and is split into a third transmitted light beam and a third reflected light beam through the beam splitter; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction;

[0062] Step 3: The light beams emitted from the triangular common optical path interferometer are interfered by a converging component and imaged onto a detection and acquisition module;

[0063] Step 4: The detection and acquisition module samples and collects interference fringe signals at different times, and converts them into electrical signals to obtain detection information;

[0064] Step 5: Perform spectrum restoration based on the detection information through a signal processing module to obtain spectrum information.

[0065] The embodiments of the present invention provide a common optical path large aperture time-modulated interferometric spectroscopy imaging device and method, which have at least the following technical effects:

[0066] (1) It can realize the time modulation type interference spectrometer (imaging) working mode. In the traditional common optical path interferometer, the optical path of the two arms of the interferometer is always fixed or the same, resulting in a fixed optical path difference between the two arms, thus making it impossible to realize the time modulation working mode. However, the present invention can generate different optical path differences by the movement of the moving mirror at different times in the common optical path interferometer, and then obtain the time integral interference pattern, thereby inverting the spectral information of the target. The working mode of the present invention breaks through the previous common optical path interferometer's limited ability to obtain spectral information.

[0067] (2) Common optical path interferometer core components can be used. Traditional time-modulated interferometer (imaging) instruments need to achieve a variable optical path difference to obtain interference patterns at different times. The two arms of the core interferometer component are relatively independent, that is, non-common optical path interferometers. Non-common optical path and common optical path interferometers are different types of interferometers. The present invention breaks through the limitations of traditional non-common optical path interferometers and realizes time-modulated interferometer (imaging) technology based on common optical path interferometers.

[0068] (3) High stability. This interference spectrometer technology is based on common optical path technology, and the common optical path interference spectrometer (imaging) has high stability. The interferometer of non-common optical path technology used in traditional time-modulated interference spectrometer (imaging) is easily disturbed by external thermodynamic changes, causing changes in optical path difference, and then causing the movement of interference fringes and phase instability, which will bring about large instrument errors and make high-precision measurements inaccurate. After using common optical path spectrometer technology, external thermodynamic changes act on the two arms of the interferometer at the same time, so the optical path difference generated can offset each other, and the interference fringes formed are also more stable. The corresponding interferometer and spectrometer (imaging) have high stability.

[0069] (4) High light flux. Since there is no slit in the large-aperture common optical path time-modulated interferometry (imaging) system to limit the target imaging area and spectral resolution, the system has a large aperture and high light flux.

[0070] (5) Wide range of applications. Due to the adoption of the common optical path splitting method, the stability of the time-modulated interferometer is greatly improved, and the anti-interference ability is enhanced. Therefore, it can be used on vehicle-mounted motion platforms, airborne platforms, ship-mounted platforms, mobile robots, satellite-mounted platforms, etc., which are basically inapplicable to traditional applications. Therefore, the application occasions are more and the application fields will be wider.

[0071] (6) Simple structure and easy to miniaturize. The common optical path time-modulated interference spectrometer proposed in the present invention has a core interferometer consisting only of a flat beam splitter, a plane mirror, and a prism. The beam splitter compensation plate in the traditional time-modulated interference spectrometer (imaging) is removed. As a result, the entire structure is very compact and can be miniaturized without sacrificing light flux. It is suitable for handheld use and can be easily carried on various platforms.

[0072] (7) It can realize the sampling of the change of optical path difference from -L to +L (L is the maximum optical path difference). The optical path difference between the two arms of the traditional common optical path interferometer is fixed, while the present invention sets an optical path adjustment device in both arms of the interferometer, and the posture of the optical path adjustment device in the movable arm can be rotated and changed, so that the optical path difference can be changed from -L to 0 and then from 0 to +L. Passing the position of zero optical path difference, the interferometer can obtain the corresponding change interference pattern. This process is a prerequisite for achieving the target spectrum restoration and realizing the time modulation interference spectrometer (imaging) instrument.

[0073] (8) It can realize self-compensation for the shaking error of the rotating axis of the moving mirror and realize permanent alignment of the interferometer. By strictly controlling the design and processing technology of the optical path adjustment device, the incident surface and the exit surface of the light beam passing through the optical path adjustment device are strictly parallel. Then, even if the optical path adjustment device is tilted to a certain extent due to the shaking of the rotating axis, the exit light beam still remains parallel to the incident light beam, and the propagation direction of the light beam is not deflected; that is, this scheme can realize self-compensation for the posture error caused by the shaking of the axis system when the moving mirror rotates, thereby realizing immunity to the shaking error of the interferometer and permanent alignment of the two interference beams.

[0074] (9) A very high interference modulation index can be achieved. A pair of optical path adjustment devices with the same relative postures are set in the interferometer's movable arm, and the incident surface of the light beam of each optical path adjustment device is strictly parallel to the exit surface. According to the principle of optical path reversibility, even if the light beam incident on the previous optical path adjustment device is offset in space due to the change in the posture of the optical path adjustment device, it will be compensated by the next optical path adjustment device. As a result, the light beam not only maintains the same ideal propagation direction as when the posture does not change, but also the spatial position when returning to the beam splitter is also consistent with the ideal when the posture does not change, so that the interference light beams completely overlap in space, thereby avoiding the image plane interference problem caused by the non-overlapping of the light beams in space (the interference modulation index decreases due to the error of the converging lens group). Therefore, a very high interference modulation index can be achieved.

[0075] (10) Suitable for high-speed measurement. Since the prism that produces the optical path difference adopts a 360° continuous rotation mode, the acceleration and deceleration process in the traditional linear or swinging process is avoided during the measurement process, which improves the time utilization and thus the measurement frequency is increased. At the same time, the prism material that produces the optical path difference can produce more than 8 zero crossing points in a 360° cycle, that is, the prism can produce more than 8 interference patterns and spectra when it rotates one circle, thus making ultra-high-speed spectral measurement possible. The realization of this function will not only improve the anti-environmental interference ability of the interference spectrometer (imaging) instrument, but also enable the interference spectrometer (imaging) instrument to be further expanded to the field of high-speed spectral measurement, such as flying targets, flames or even chemical reactions.

[0076] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A common optical path large aperture time modulation interference spectroscopy imaging device, characterized in that: include: A triangular common optical path interferometer, wherein the triangular common optical path interferometer has an asymmetric structure and is provided with a moving mirror scanning mechanism for generating an optical path difference that varies with time, and the common optical path large aperture time modulation interference spectroscopy imaging device operates in a staring observation mode; The triangular common optical path interferometer includes a beam splitter, a first plane reflector, a second plane reflector, a first optical path adjustment component, and a second optical path adjustment component; the first optical path adjustment component and the second optical path adjustment component are combined to form the moving mirror scanning mechanism, the first optical path adjustment component and the second optical path adjustment component are respectively placed in the two arms of the interferometer, and the two arms respectively generate a first optical path and a second optical path, and the first optical path and the second optical path are combined to form an optical path difference that periodically changes near zero optical path difference; One of the first optical path adjustment component and the second optical path adjustment component is a moving mirror, and the other optical path adjustment component is a fixed mirror; or, both the first optical path adjustment component and the second optical path adjustment component are moving mirrors.

2. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 1, characterized in that: The target light enters the triangular common-path interferometer as parallel light, and the beam splitter splits the parallel light into a first transmitted light beam and a first reflected light beam; the first reflected light beam passes through the first plane reflector, the first optical path adjustment component, and the second plane reflector in sequence, and then returns to the beam splitter again, and is split into a second transmitted light beam and a second reflected light beam by the beam splitter; the first transmitted light beam passes through the second plane reflector, the second optical path adjustment component, and the first plane reflector in sequence, and then returns to the beam splitter again, and is split into a third transmitted light beam and a third reflected light beam by the beam splitter; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction.

3. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 2, characterized in that: When one of the first optical path adjustment component and the second optical path adjustment component is a moving mirror and the other optical path adjustment component is a fixed mirror; the optical path adjustment component serving as the moving mirror includes an optical path adjustment device and a motor, and the optical path adjustment device moves under the drive of the motor; the optical path adjustment component serving as the fixed mirror only includes the optical path adjustment device.

4. The common optical path large aperture time-modulated interferometric spectroscopy imaging device according to claim 3, characterized in that: The optical path adjustment device in the optical path adjustment component serving as a moving mirror adopts a first prism, and the optical path adjustment device in the optical path adjustment component serving as a fixed mirror adopts a second prism. The exit surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface; the first prism rotates under the drive of the motor, and the rotation axis of the motor is perpendicular to the propagation direction of the light beam; the posture of the second prism has a certain angle of inclination relative to the vertical incident surface of the light beam, which is used to compensate for the zero-position dispersion effect and increase the zero-crossing optical path difference position.

5. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 4, characterized in that: The first prism is composed of a prism pair, and the two prisms in the prism pair rotate in opposite directions.

6. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 2, characterized in that: When the first optical path adjustment component and the second optical path adjustment component are both moving mirrors; the first optical path adjustment component includes a first optical path adjustment device and a first motor, and the second optical path adjustment component includes a second optical path adjustment device and a second motor; the first optical path adjustment device moves under the drive of the first motor, and the second optical path adjustment device moves under the drive of the second motor.

7. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 2, characterized in that: Also includes: A converging component, a detection and acquisition module, and a signal processing module; the target surface of the detection and acquisition module is located on the back focal plane of the converging component, and the signal processing module is connected to the detection and acquisition module; the converging component is used to form interference on the light beams emitted by the triangular common optical path interferometer and image them onto the detection and acquisition module; the detection and acquisition module is used to sample and collect interference fringe signals at different times and convert them into electrical signals to obtain detection information; the signal processing module is used to perform spectral restoration based on the detection information to obtain spectral information.

8. The common optical path large aperture time modulation interference spectroscopy imaging device according to claim 2, characterized in that: Also includes: A front assembly; the front assembly includes a converging lens, an aperture and a collimating lens arranged in sequence along the optical path; the target light becomes parallel light after passing through the front assembly and is incident on the triangular common optical path interferometer.

9. A common optical path large aperture time modulation interference spectroscopy imaging method, characterized in that: The method is implemented by using a common-path large-aperture time-modulated interference spectroscopy imaging device as described in any one of claims 1 to 8, wherein a moving mirror scanning mechanism for generating an optical path difference that varies with time is provided in a triangular common-path interferometer, so that the common-path large-aperture time-modulated interference spectroscopy imaging device operates in a staring observation mode.

10. The common optical path large aperture time modulation interference spectroscopy imaging method according to claim 9, characterized in that: The following steps are involved: Step 1: The target light is converted into parallel light after passing through the front component and is incident on the triangular common optical path interferometer; Step 2: Splitting the parallel light into a first transmitted light beam and a first reflected light beam through a beam splitter; the first reflected light beam sequentially passes through a first plane reflector, a first optical path adjustment component, and a second plane reflector, and then returns to the beam splitter again, and is split into a second transmitted light beam and a second reflected light beam through the beam splitter; the first transmitted light beam sequentially passes through a second plane reflector, a second optical path adjustment component, and the first plane reflector, and then returns to the beam splitter again, and is split into a third transmitted light beam and a third reflected light beam through the beam splitter; the second reflected light beam and the third transmitted light beam are emitted along a first direction, and the second transmitted light beam and the third reflected light beam are emitted along a second direction; Step 3: The light beams emitted from the triangular common optical path interferometer are interfered by a converging component and imaged onto a detection and acquisition module; Step 4: The detection and acquisition module samples and collects interference fringe signals at different times, and converts them into electrical signals to obtain detection information; Step 5: Perform spectrum restoration based on the detection information through a signal processing module to obtain spectrum information.

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