Light and small infrared imaging spectrometer suitable for unmanned aerial vehicle

Abstract

The invention discloses a light and small infrared imaging spectrometer suitable for an unmanned aerial vehicle, and relates to the technical field of infrared imaging spectrums. The spectrometer is sequentially and optically connected with a front optical system, a slit, a PGP light splitting assembly, a rear optical system and a background suppression type detector in the infrared light propagation direction. The front optical system collects target infrared light and collimates the target infrared light; the slit limits the line view field range, and the spatial resolution of spectral imaging is guaranteed; the PGP light splitting assembly performs high-precision light splitting imaging on the light beams; the rear optical system is used for imaging spectral information after light splitting to a detector; the surface of the background suppression type detector is plated with a gradual filter, and the background suppression type detector is used for receiving spectral signals and suppressing normal-temperature background radiation. Through the collaborative design of high-precision spectral imaging of the PGP and narrow-band filtering of the background suppression type detector, a low-temperature refrigeration device is not needed, the system has the characteristics of light weight and low power consumption, the portability and environmental adaptability are improved, and the system is suitable for scenes such as unmanned aerial vehicle carrying and field detection.

Description

Technical Field

[0001] This invention relates to the field of infrared imaging spectroscopy technology, and specifically to a lightweight infrared imaging spectrometer that does not require cryogenic cooling and is suitable for use with drones. Background Technology

[0002] Infrared imaging spectrometers combine imaging and spectral analysis capabilities and are widely used in fields such as resource exploration and environmental monitoring. Grating-based infrared imaging spectrometers are currently the mainstream type of infrared imaging spectrometer. However, a major problem plaguing grating-based infrared imaging spectrometers is strong background radiation. Low-temperature optics are required to suppress this background radiation; a common practice is to place the spectrometer and other back-end optical components in a cold chamber for cryogenic cooling.

[0003] While cryogenic refrigeration devices can reduce background radiation interference, they have significant drawbacks: First, they consume a lot of power (usually tens to hundreds of watts), requiring a large-capacity power supply module; second, they are bulky and heavy, failing to meet the lightweight requirements for drones and field portability; and third, the cold box has high maintenance costs and long maintenance cycles, making it impossible to meet the need for plug-and-play emergency response.

[0004] Therefore, developing an infrared imaging spectrometer that integrates a highly efficient stray light suppression structure, requires no cryogenic cooling, and balances low power consumption and high precision has become an urgent problem for the industry. Summary of the Invention

[0005] To address the problems of high power consumption, heavy weight, and high cost caused by the reliance on cryogenic cooling in existing infrared imaging spectrometers, this invention adds a gradient filter to the detector surface to form a background-suppressing detector, achieving background suppression and high-precision detection while reducing power consumption and weight. The specific technical solution is as follows:

[0006] A lightweight infrared imaging spectrometer suitable for unmanned aerial vehicles includes a front optical system, a slit, a PGP beam splitter, a rear optical system, and a background suppression detector, which are optically connected sequentially along the infrared light propagation direction.

[0007] The front optical system is used to collect infrared light from the target scene, collimate the collected infrared light, and output a parallel infrared beam.

[0008] The slit is used to receive the parallel infrared beam, define the linear field of view, and provide a stable spatial dimensional constraint for subsequent beam splitting imaging.

[0009] The PGP beam splitter is used to receive the beam after it has been filtered by the slit, perform high-precision dispersive beam splitting on it, and obtain a beam splitting beam containing target spectral information.

[0010] The rear optical system is used to receive the split beam, focus and image it, and project the split spectral information onto the detection surface of the background suppression detector.

[0011] The detection surface of the background suppression detector is coated with a gradient filter, and the gradient filter is in close contact with the detection surface of the background suppression detector, so that the temperature of the filter is consistent with the temperature of the detector, which is used to receive spectral imaging signals and suppress background radiation interference under normal temperature conditions.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. Stable operation at room temperature: The high-precision spectral splitting characteristics of the PGP spectral splitter, together with the gradient filter on the detector surface, and the built-in filter module of the detector to suppress background radiation, eliminate the need for a cooling device and solve the problem of reliance on cooling in traditional equipment.

[0014] 2. Low power consumption and lightweight: Eliminates the need for cooling and supporting systems, making it suitable for scenarios such as drones and handheld detection.

[0015] 3. High-precision spectral performance: The PGP component achieves high spectral resolution and spectral purity superior to existing room-temperature equipment.

[0016] 4. High reliability: No high-maintenance components such as refrigeration boxes, resulting in low maintenance costs. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 This is a structural diagram of the lightweight infrared imaging spectrometer system applicable to UAVs according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0020] This invention provides a lightweight infrared imaging spectrometer suitable for unmanned aerial vehicles, such as... Figure 1As shown, it includes a front optical system 1, a slit 2, a PGP beam splitter 3, a rear optical system 4, and a background suppression detector 5, which are optically connected sequentially along the infrared light propagation direction.

[0021] The front optical system 1 is used to collect infrared light from the target scene, collimate the collected infrared light, and output a parallel infrared beam.

[0022] The slit 2 is used to receive the parallel infrared beam, define the line field of view, and provide a stable spatial dimension constraint for subsequent beam splitting imaging.

[0023] The PGP beam splitter 3 is used to receive the beam after it has been filtered by the slit, perform high-precision dispersive beam splitting on it, and obtain a beam splitting beam containing target spectral information.

[0024] The rear optical system 4 is used to receive the split beam, focus and image it, and project the split spectral information onto the detection surface of the background suppression detector.

[0025] The detection surface of the background suppression detector 5 is coated with a gradient filter, and the gradient filter is in close contact with the detection surface of the background suppression detector, so that the temperature of the filter is consistent with the temperature of the detector, which is used to receive spectral imaging signals and suppress background radiation interference under normal temperature conditions.

[0026] The front optical system includes an objective lens group and a collimating lens group arranged in sequence; the collimating lens group converts the infrared light collected by the objective lens group into a parallel infrared beam.

[0027] The slit is an adjustable metal slit, which allows for precise control of the line field of view by adjusting its width.

[0028] The PGP beam splitter includes a front prism, a grating, and a rear prism arranged sequentially along the optical axis; the front prism and the rear prism are symmetrically arranged to compensate for polarization effects and correct nonlinear dispersion.

[0029] The bandwidth of a linear graded filter needs to be determined based on multiple factors, including current process limitations (minimum bandwidth), optical system design resolution, and sensitivity requirements. By establishing a cost function that constrains multiple factors, the final bandwidth of the linear graded filter can be determined.

[0030] The total spectral range of a linear graded filter must match the total spectral range of the grating. Specific Implementation

[0032] This invention provides a lightweight infrared imaging spectrometer suitable for unmanned aerial vehicles (UAVs). Along the infrared light propagation direction, it sequentially connects a front optical system, a slit, a PGP beam splitter, a rear optical system, and a background suppression detector. All components are integrated within a lightweight alloy shell. The specific structure is as follows:

[0033] The front optical system consists of an objective lens group and a collimating lens group. The objective lens group uses germanium lenses to collect infrared light; the collimating lens group converts divergent light into a parallel beam to ensure beam splitting accuracy.

[0034] Slit: An adjustable slit that can be adjusted according to detection requirements. Its core function is to define the linear field of view, providing stable spatial dimensional constraints for subsequent spectroscopic imaging and ensuring accurate matching of spectral and spatial information.

[0035] PGP beam splitter assembly: The front prism, grating, and rear prism are symmetrically and coaxially arranged. The front prism performs initial coarse beam splitting and compensates for the polarization effect of the grating.

[0036] Rear optical system: includes imaging lens group. The imaging lens group adopts an aberration-correcting design to accurately project the split spectrum onto the detector's detection surface.

[0037] Background suppression detector: Focal plane array detector with a graded filter coated on the detection surface. The graded filter is matched with the dispersion direction of the PGP, selectively transmitting the target wavelength and significantly reducing the amount of panchromatic background radiation entering a single pixel in the back optical path.

Claims

1. A lightweight infrared imaging spectrometer suitable for unmanned aerial vehicles (UAVs), characterized in that, It includes a front optical system, a slit, a PGP beam splitter, a rear optical system, and a background suppression detector, which are sequentially optically connected along the infrared light propagation direction. The front optical system is used to collect infrared light from the target scene, collimate the collected infrared light, and output a parallel infrared beam. The slit is used to receive the parallel infrared beam, define the linear field of view, and provide a stable spatial dimensional constraint for subsequent beam splitting imaging. The PGP beam splitter is used to receive the beam after it has been filtered by the slit, perform high-precision dispersive beam splitting on it, and obtain a beam splitting beam containing target spectral information. The rear optical system is used to receive the split beam, focus and image it, and project the split spectral information onto the detection surface of the background suppression detector. The detection surface of the background suppression detector is coated with a gradient filter, and the gradient filter is in close contact with the detection surface of the background suppression detector, so that the temperature of the filter is consistent with the temperature of the detector, which is used to receive spectral imaging signals and suppress background radiation interference under normal temperature conditions.

2. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, The front optical system includes an objective lens group and a collimating lens group arranged in sequence; the collimating lens group converts the infrared light collected by the objective lens group into a parallel infrared beam.

3. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, The slit is an adjustable metal slit, which allows for precise control of the line field of view by adjusting its width.

4. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, The PGP beam splitter includes a front prism, a grating, and a rear prism arranged sequentially along the optical axis; the front prism and the rear prism are symmetrically arranged to compensate for polarization effects and correct nonlinear dispersion.

5. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, The bandwidth of a linear graded filter is determined based on the minimum bandwidth, the optical system design resolution, and the sensitivity requirements. The final bandwidth of the linear graded filter is determined by establishing a cost function with multiple constraints.

6. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, The total spectral range of a linear graded filter must match the total spectral range of the grating.

7. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 2, characterized in that, The objective lens group uses germanium lenses to collect infrared light.

8. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 3, characterized in that, The slit is an adjustable slit.

9. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 1, characterized in that, Background suppression detectors employ focal plane array detectors.

10. The lightweight infrared imaging spectrometer suitable for UAVs according to claim 5, characterized in that, The gradient filter matches the dispersion direction of the PGP beam splitter, selectively transmitting the target wavelength and reducing the amount of panchromatic background radiation entering the single pixel in the rear optical path.

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