Linear array scan imaging spectrometer system based on optical waveguide device

Abstract

The application belongs to the technical field of hyperspectral imaging instruments, and particularly relates to a linear array swing scanning imaging spectral system based on an optical waveguide device. The application comprises a telescope, a rotating table, a translation table, an optical fiber, an optical fiber adjusting frame and a spectrometer, wherein the telescope and the optical fiber adjusting frame are arranged on the rotating table, the rotating table is arranged on the translation table, the optical fiber adjusting frame fixes the optical fiber, the end face of the optical fiber is located at the imaging focal plane of the telescope, and the optical fiber is connected with the spectrometer; the rotating table and the translation table drive the telescope to perform point-by-point scanning on a target to be measured, and the optical fiber sends the received light signals to the spectrometer for analysis and measurement of spectral information. The application adopts a common optical fiber spectrometer, optimizes the structure of the linear array swing scanning imaging spectral system, and greatly reduces the assembly and adjustment difficulty and the volume and weight of the linear array swing scanning imaging spectral system.

Description

Technical Field

[0001] The present invention belongs to the technical field of hyperspectral imaging instruments, and in particular relates to a linear array swing scanning imaging spectrum system based on an optical waveguide device. Background Art

[0002] Spectral measurement and analysis technology is a fundamental technology in studying the composition and structure of materials. Spectral imaging technology combined with imaging function can simultaneously obtain spatial and spectral information of the target. It has become an important research direction in the field of optical measurement technology. It has been widely and deeply applied and studied in many fields such as agricultural development, environmental testing and food safety.

[0003] Spectral imaging instruments are classified into two types based on their imaging principles: swing-scanning and push-scanning. Swing-scanning imaging spectrometers utilize the translation of a mobile device to acquire the horizontal field of view, and mechanical scanning imaging to acquire the field of view perpendicular to the translation track. They use linear or planar array detectors to receive spectral data in each band. Push-scanning imaging spectrometers acquire the horizontal field of view solely through the translation of the mobile device, and employ large planar array detectors to collect spectral information across the track.

[0004] Generally speaking, given the same performance, the main advantage of push-broom imaging spectrometers is that they require no swinging motion, resulting in a relatively simple structure. Furthermore, the ability to simultaneously acquire pixels perpendicular to the field of view reduces the difficulty of image stitching. However, the field of view of a push-broom imaging spectrometer is limited by the size of the array detector. Due to the high cost of large array detectors, push-broom imaging spectrometers are not easily able to detect a large field of view. Furthermore, instrument calibration of push-broom imaging spectrometers is difficult, and spectral curvature can occur. In contrast, swing-broom imaging spectrometers have a relatively complex structure, and both swinging motion control and image stitching processing are more complex. However, due to their advantages of a large field of view and low cost, they have great potential for application in airborne imaging spectroscopy remote sensing.

[0005] Based on the type of detector used, pendulum scanning imaging spectrometers can be categorized into linear array and area array. The basic principle of a linear array is that radiation from each ground pixel sequentially enters the instrument's dispersive section. The dispersive section then splits the radiation from each pixel into specific spectral intervals, which are then received by the linear array detector. The number of pixels in a linear array detector is equal to the number of spectral bands that each pixel can split. Due to its unique imaging method, the advantages of linear array pendulum scanning spectrometers include: reduced optical system design difficulty; the imaging field of view is not limited by the size of the linear array detector, making large field of view detection easy and requiring less detectors; simple instrument calibration; and good spectral consistency. However, linear array pendulum scanning spectrometers also have disadvantages: the moving parts (scanning system) are bulky and heavy, making design, assembly, and control difficult. Area array pendulum scanning uses a similar imaging principle to linear arrays, but the use of area array CCD detectors is more expensive and requires calibration and uniformity correction. Summary of the Invention

[0006] In view of this, the present invention aims to provide a linear array swing scanning imaging spectroscopy system based on optical waveguide devices to solve the problem that the existing linear array swing scanning imaging spectroscopy system is difficult to assemble and adjust due to its complex system, large volume and weight, making it unable to be widely used in the field of imaging spectroscopy. The present invention adopts a common optical fiber spectrometer to optimize the structure of the linear array swing scanning imaging spectroscopy system, which greatly reduces the difficulty of assembly and adjustment and the volume and weight of the linear array swing scanning imaging spectroscopy system.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0008] A linear array scanning imaging spectroscopy system based on optical waveguide devices includes: a telescope objective lens, a turntable, a translation stage, an optical fiber, an optical fiber adjustment frame and a spectrometer, wherein:

[0009] The telescope objective lens and the optical fiber adjustment frame are arranged on a turntable, the turntable is arranged on a translation stage, the optical fiber adjustment frame fixes the optical fiber, the end face of the optical fiber is located at the focus of the telescope objective lens, and the optical fiber is connected to the spectrometer;

[0010] The turntable and translation stage drive the telescope objective to scan the target point by point, and the optical fiber sends the received light signal to the spectrometer for spectral information analysis and measurement.

[0011] Furthermore, the telephoto objective lens includes an off-axis parabolic mirror.

[0012] Furthermore, the optical fiber adjustment frame also includes an adjustment displacement stage, on which the optical fiber is fixedly arranged. The adjustment displacement stage drives the optical fiber to move relative to the telescope objective lens so that the end face of the optical fiber is located at the imaging focal plane of the telescope objective lens.

[0013] Further, the spectrometer comprises a linear array detector.

[0014] Compared with the prior art, the application can achieve the following beneficial effects:

[0015] (1) The linear array scanning imaging spectrometer system based on the optical waveguide device directly swings the telescope objective lens, omits the front scanning mirror in the conventional linear array scanning imaging spectrometer system, simplifies the linear array scanning imaging spectrometer system, and reduces the volume and mass of the linear array scanning imaging spectrometer system.

[0016] (2) The linear array scanning imaging spectrometer system based on the optical waveguide device optimizes aberration of the telescope objective lens only for the near-axis central field of view, reduces the complexity of the telescope objective lens, adopts a single off-axis mirror instead of the conventional transmissive achromatic objective lens, and can realize a light and small type, low-cost linear array scanning telescope objective lens system, and reduces the complexity and weight of the system. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application and are incorporated herein for illustrative purposes. The illustrative embodiments of the present application and their description serve to explain the present application. In the drawings:

[0018] Figure 1 FIG. 1 is a structural schematic diagram of a linear array scanning imaging spectrometer system based on an optical waveguide device according to an embodiment of the present application;

[0019] FIG. 2(a) is a sectional view of a fiber adjusting frame according to an embodiment of the present application;

[0020] FIG. 2(b) is a side view of the fiber adjusting frame according to an embodiment of the present application

[0021] Figure 3 FIG. 3 is a schematic diagram of a target to be measured obtained by scanning according to an embodiment of the present application.

[0022] Legend of reference signs:

[0023] 1, light source; 2, target to be measured; 3, rotary table; 4, translation table; 5, telephoto objective; 6, optical fiber adjusting rack; 7, optical fiber; 8, spectrometer; 9, packaging shell; 10, adjusting displacement table; 11, adjusting rod; 12, reflecting mirror. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not constitute a limitation on the present application.

[0025] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0027] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0028] The present application will be described in detail below with reference to the drawings and embodiments.

[0029] As Figure 1As shown, the linear array scanning imaging spectroscopy system based on optical waveguide devices provided by the present invention includes: a telescope objective lens 5, a turntable 3, a translation stage 4 (a one-dimensional translation stage, a two-dimensional translation stage, or a multi-dimensional translation stage, set as required), an optical fiber 7 (the optical fiber 7 is adjusted according to user requirements), an optical fiber adjustment frame 6, and a spectrometer 8 (the spectrometer 8 includes a linear array detector), wherein:

[0030] The telephoto objective lens 5 and the optical fiber adjustment frame 6 are arranged on the turntable 3, the turntable 3 is arranged on the translation stage 4, the optical fiber adjustment frame 6 fixes the optical fiber 7, the end face of the optical fiber 7 is located at the focus of the telephoto objective lens 5, and the optical fiber 7 is connected to the spectrometer 8;

[0031] The light source 1 is irradiated on the target 2 to be measured, the turntable 3 and the translation stage 4 drive the telescope objective lens 5 to scan the target 2 point by point, and the optical fiber 7 sends the received light signal to the spectrometer 8 for spectral information analysis and measurement.

[0032] The telephoto objective lens 5 is an off-axis parabolic mirror, a double cemented achromatic objective lens or a triple separated achromatic objective lens.

[0033] As shown in Figures 2 (a) and 2 (b), the optical fiber adjustment frame 6 also includes an adjustment displacement stage 10, on which the optical fiber 7 is fixedly mounted. The adjustment rod 11 is adjusted so that the adjustment displacement stage 10 drives the optical fiber 7 to move relative to the telephoto objective lens 5, thereby positioning the end face of the optical fiber 7 at the imaging focal plane of the telephoto objective lens 5. The adjustment displacement stage 10 and the adjustment rod 11 are both encapsulated in a packaging shell 9, which also includes a reflector 12 for reflecting the scanning light from the telephoto objective lens 5 into the optical fiber 7.

[0034] exist Figure 1 Within the dashed box, the linear array scanning imaging spectroscopy system includes a front telescope objective 5 and a rear spectral spectrometer module (spectrometer 8). The spectrometer module can be designed to perform spectrometry for any wavelength band. First, the telescope objective 5 only needs to be optimized for the paraxial field of view to reduce the number of lenses used and the weight of the system. Second, combined with the flexible optical fiber 7 for image transmission, the lightweight telescope objective 5 can be directly swung and scanned without the need for the entire spectrometer 8 or the addition of a scanning plane mirror. This reduces the load on the turntable 3, thereby reducing the weight, volume, and power consumption requirements of the turntable 3. Finally, the optical fiber 7 is coupled to the imaging focal plane of the telescope objective 5. Each sweep position corresponds to a single point in the object-side field of view. Spatial information of the target 2 to be measured is obtained through point-by-point scanning and splicing.

[0035] Example 1

[0036] In order to further illustrate the role of the linear array swing scanning imaging spectroscopy system based on optical waveguide devices of the present invention, the actual detection effect of the present invention is verified through the following examples.

[0037] The linear array swing-scanning imaging spectroscopy system is designed with an object distance of 1 meter. The telescope objective lens 5 uses an off-axis parabolic mirror with a primary focal length of 50 mm. The optical fiber 7 uses a multimode fiber 7 with a core diameter of 200 μm. This results in a spatial resolution of 3.94 mm. A turntable 3 is used for pitch scanning, with a maximum swing speed of 50° / s and a sweeping field of view of 60°. A translation stage 4 is used for azimuth scanning, with a maximum travel of 200 mm. Spectrometer 8 uses a short-wave infrared fiber 7, with a spectral range of 0.9-2.5 μm, a spectral resolution of 12.5 nm, and an F-number of 4. The corresponding slit size of spectrometer 8 is 0.05 × 0.25 mm, and the optical system efficiency of spectrometer 8 is 0.48. Given these design parameters, the specific movement speeds of the corresponding translation stage 4 and turntable 3 can be determined based on the system's sweeping field of view and integration time. According to estimates, under the lighting conditions of a 500W halogen lamp in the laboratory, when the reflectivity of the target 2 is 0.3 and the integration time is 20ms, the signal-to-noise ratio of the linear array scanning imaging spectroscopy system at a wavelength of 2.4μm is calculated to be approximately 91, which can meet the usage requirements.

[0038] This invention designs a coupling optical path structure combining a lightweight off-axis parabolic mirror and a multimode optical fiber. Light reflected from the target enters the coupling optical path's aperture, is reflected and converged by the off-axis parabolic mirror, and is coupled into the multimode optical fiber. The multimode optical fiber is mechanically secured to an adjustable translation stage (a one-dimensional translation stage). Controlling the stage's movement allows for rapid alignment of the multimode optical fiber's end face with the focal plane of the off-axis parabolic mirror, facilitating optical path alignment.

[0039] By controlling the coupled optical path to scan point by point through the turntable 3, the three-dimensional information acquisition of the spatial dimension and spectral dimension of the target 2 to be measured can be achieved. The linear array scanning imaging spectrum system is used to scan the target 2 to be measured (black and white checkerboard target) and the splicing effect is as follows: Figure 3 As shown in FIG, from the splicing results, it can be seen that the linear array swing scanning imaging spectroscopy system of the present invention has a simple structure, low difficulty in installation and adjustment, small size and weight, and low cost.

[0040] When designing the telephoto objective lens 5 and the optical fiber 7, the following issues should be noted:

[0041] 1. The telescope objective lens 5 of a conventional linear array swing scanning imaging spectroscopy system generally adopts an ordinary telescope objective lens 5. In order to ensure the field of view of the telescope objective lens 5, multiple lenses or reflectors are generally required. However, due to the particularity of the linear array swing scanning imaging spectroscopy system, in fact, only the central field of view of the telescope objective lens 5 affects the imaging spectrum detection quality of the system, and other fields of view have no effect. Therefore, the telescope objective lens 5 can be optimized only for the paraxial central field of view, so that many off-axis field of view aberration correction processes can be saved. In theory, only the paraxial chromatic aberration and spherical aberration need to be optimized to a certain extent. The specific implementation form of the telescope objective lens 5 can be flexibly selected according to the design indicators of the linear array swing scanning imaging spectroscopy system. Generally speaking, when using a transmissive optical system, the use of a double-cemented or triple-separated achromatic objective lens can well guarantee the imaging quality of the paraxial field of view.

[0042] 2. When designing optical fiber 7, due to limitations on the number of bends and bend diameter, its length must be appropriately considered when designing the linear array scanning imaging spectroscopy system. While ensuring sufficient bending space for optical fiber 7, it should also be kept short to avoid unnecessary weight increase. The optical waveguide device employed in the present invention can utilize different core diameters to adjust the spatial resolution of the linear array scanning imaging spectroscopy system. Whether the telescope objective lens 5 utilizes a transmissive or reflective optical system design approach is for detecting spatial targets. Therefore, changing the specifications of the telescope system and optical fiber 7 essentially involves changing the coupling optical path between them.

[0043] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0044] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A linear array scanning imaging spectroscopy system based on optical waveguide devices, characterized by: include: Telescope objective lens, turntable, translation stage, optical fiber, optical fiber adjustment frame and spectrometer, among which, The telescopic objective lens and the optical fiber adjustment frame are arranged on the turntable, the turntable is arranged on the translation stage, the optical fiber adjustment frame fixes the optical fiber, the end face of the optical fiber is located at the imaging focal plane of the telescopic objective lens, and the optical fiber is connected to the spectrometer; The turntable and the translation stage drive the telescopic objective lens to scan the target point by point. The telescopic objective lens is only optimized for the paraxial central field of view. The optical fiber sends the received light signal to the spectrometer for analysis and measurement of spectral information.

2. The linear array scanning imaging spectroscopy system based on optical waveguide devices according to claim 1, characterized in that: The telescopic objective lens includes an off-axis parabolic mirror.

3. The linear array scanning imaging spectroscopy system based on optical waveguide devices according to claim 1, characterized in that: The optical fiber adjustment frame also includes an adjustment displacement stage, on which the optical fiber is fixedly arranged. The adjustment displacement stage drives the optical fiber to move relative to the telescope objective lens so that the end face of the optical fiber is located at the imaging focal plane of the telescope objective lens.

4. The linear array scanning imaging spectroscopy system based on optical waveguide devices according to claim 1, characterized in that: The spectrometer includes a linear array detector.

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