Spectrometric device and method of Littrow configuration

Abstract

This application belongs to the field of spectral measurement technology, specifically disclosing a spectral measurement device and method with a Littrow structure. In this method, the radius of curvature of a liquid glass lens is synchronously adjusted according to different wavelengths corresponding to the angle of a blazed grating, collimating and focusing a linear beam to form collimated light incident on the grooved surface of the blazed grating. The blazed grating diffracts the collimated light, forming diffracted light arranged according to wavelength, and reflects this diffracted light onto the liquid glass lens. The liquid glass lens then focuses the reflected diffracted light, arranging the diffracted light of different wavelengths along the dispersion direction. A motor drives the grating to rotate, transmitting the light of the target wavelength to the detector in the paraxial region. The detector converts the received spectral signal of the target wavelength into an electrical signal. A control module synchronously acquires the electrical signal and records the rotation position of the blazed grating, achieving a correspondence between the spectrum and the wavelength position. This application overcomes the problem of mismatch between the detector position and the ideal image point position.

Description

Technical Field

[0001] This application belongs to the field of spectral measurement technology, and more specifically, relates to a spectral measurement device and method with a Littrow structure. Background Technology

[0002] A spectrometer is an optical instrument that uses phenomena such as the dispersion and absorption of light to obtain spectral information of substances. As a core tool for analyzing the spectral information of substances, it has been widely used in many fields such as chemistry, physics, environmental monitoring, food safety, materials science, and astronomy. Its basic working principle is to introduce incident light through a slit, decompose it into light of different wavelengths by dispersive elements such as collimating lenses and gratings, and finally record the intensity of each wavelength of light by a detector to obtain spectral information.

[0003] The Littrow structure is a special optical path configuration in grating spectrometers, which has many outstanding technical advantages, including: (1) simple structure, requiring only one grating and one focusing lens or mirror, and the entrance slit and exit slit are located on the same side of the optical system, effectively compressing the equipment volume, improving the equipment integration, and having high portability; (2) high grating diffraction efficiency, the incident angle of the blazed grating is equal to the diffraction angle, which can greatly improve the energy utilization rate of diffracted light and reduce light energy loss; (3) small aberration, allowing the detector to receive only paraxial light, effectively avoiding off-axis aberration; (4) strong mechanical stability, suitable for complex and harsh industrial environments.

[0004] However, the Littrow structure has inherent limitations. Theoretically, this structure requires the incident and outgoing light to be collinear, which means the lens, grating, and slit are placed along the same central axis. This collinear arrangement means that, with fixed lens parameters, positional chromatic aberration at the target wavelength reaching the detector plane cannot be avoided, resulting in a strong correlation between spectral resolution and wavelength, making it impossible to achieve high spectral resolution across the entire spectrum. Furthermore, during broadband measurements, the dispersed light of different wavelengths, after being focused by the lens, produces a significant field curvature effect, causing the system's image plane to be arc-shaped, making it difficult to match with traditional planar fixed detectors. These problems lead to severe defocusing and off-axis errors at the detector end for each target wavelength, reducing the system's spectral resolution, signal-to-noise ratio, and effective luminous flux. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a spectral measurement device and method with a Littrow structure, aiming to solve the problem that in the Littrow structure of existing spectrometers, the positional chromatic aberration of the target wavelength reaching the detector plane cannot be avoided, resulting in a strong correlation between spectral resolution and wavelength, and making it impossible to achieve high spectral resolution across the entire spectral range.

[0006] The first aspect of this application relates to a spectral measurement device with a Littrow structure, comprising: an incident optical fiber, an incident slit, a liquid glass lens, a blazed grating, a motor, a detector, and a control module; wherein the incident optical fiber, the incident slit, the liquid glass lens, and the blazed grating are arranged sequentially; the detector is located in the propagation direction of the diffracted light after being focused by the liquid glass lens; the motor is connected to the blazed grating; and the control module is connected to the motor and the detector. The incident fiber is used to output the incident beam, forming incident light rays that propagate at a certain angle to the optical axis of the liquid glass lens; the incident slit is used to constrain the spatial distribution of the incident light rays, forming a line beam; the radius of curvature of the liquid glass lens is synchronously adjusted according to the different wavelengths corresponding to the angle of the blazed grating, used to collimate the line beam, forming collimated light incident on the grooved surface of the blazed grating; at the same time, it is used to focus the reflected diffracted light, so that the diffracted light of different wavelengths is arranged along the dispersion direction; Blazed gratings are used to diffract collimated light, forming diffracted light arranged according to wavelength, and reflecting the diffracted light onto a liquid glass lens; The motor is used to drive the grating to rotate, so that the light of the target wavelength can be transmitted to the detector in the paraxial region; The detector is used to receive spectral signals at the target wavelength and convert the spectral signals into electrical signals; The control module is used to control the motor's start / stop, speed, and rotation angle; it is also used to control the current of the electromagnetic drive coil and adjust the curvature of the liquid glass lens; and it is used to synchronously acquire the electrical signals output by the detector, record the rotation position of the blazed grating, and realize the correspondence between the spectrum and the wavelength position.

[0007] In some implementations, the detector is a single-point detector or a concave detector; when the detector is a single-point detector, it is used to detect light of the target wavelength in the paraxial region after being focused by a liquid glass lens; when the detector is a concave detector, the curved detection surface matches the curvature of the dispersed light after being focused by the liquid glass lens, so that light of different wavelengths is focused on the detection surface, and is used to detect light of the target wavelength in the paraxial region.

[0008] In some embodiments, the concave detector includes a concave linear CCD sensor and a signal conditioning circuit. The concave linear CCD sensor is of the indium gallium arsenide type, with a radius of curvature of 28 mm and a spectral response covering 800 nm to 2600 nm.

[0009] In some embodiments, the effective aperture of the liquid glass lens is greater than 50 mm, and an electromagnetic drive coil is disposed outside the liquid glass lens. The electromagnetic drive coil is used to adjust the deformation of the thin film surface of the liquid glass lens according to the change of current so that the ideal image point of the focus reaches the detector. The curvature adjustment range is 50 mm to 200 mm. The interior of the liquid glass lens is filled with optical silicone oil with a refractive index of 1.45.

[0010] In some implementations, the motor is used to drive the rotary table, and the motor step angle is... The maximum safe operating speed is .

[0011] In some embodiments, the entrance slit is made of stainless steel with a thickness of less than 0.05 mm, and the slit width is 20 mm. ~50 .

[0012] In some implementations, the blazed grating is a straight-lined reflection diffraction grating with a line count of 600~1200 lines / mm.

[0013] The second aspect of this application relates to a method for spectral measurement of a Littrow structure, comprising the following steps: The incident light beam is propagated to the entrance slit at a certain angle to the optical axis of the liquid glass lens, converted into a line beam, and then refracted into collimated light by the liquid glass lens. Collimated light is incident on the grooved surface of a blazed grating, diffracting light of different wavelengths and reflecting it in order of wavelength; The diffracted light is focused by a liquid glass lens to form a dispersive spectrum. A rotating motor drives a blazed grating to rotate, enabling the detector to detect the target wavelength of light in the paraxial region. The spectral signal of the target wavelength is then converted into an electrical signal through photoelectric conversion. By controlling the current of the electromagnetic drive coil to adjust the curvature of the liquid glass lens, positional chromatic aberration of the target wavelength reaching the detector surface is eliminated. The control module synchronously acquires the electrical signals output by the detector and records the rotation position of the blazed grating to achieve the correspondence between the spectrum and the wavelength position.

[0014] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: Traditional fixed-curvature lenses struggle to focus diffracted light from different target wavelengths onto the same axial position when scanning different target wavelengths using a grating. This easily leads to defocusing errors on the detector plane, while field curvature causes image plane mismatch, resulting in off-axis errors. Consequently, spectral resolution deteriorates and luminous flux decreases. This application addresses this issue by using a motor to rotate a blazed grating, changing the target wavelength and synchronously adjusting the radius of curvature of the liquid glass lens according to the target wavelength. This allows different target wavelengths to be imaged at a fixed detector position, reducing defocusing and off-axis errors and improving spectral resolution and system luminous flux.

[0015] Based on this, this application uses a concave linear CCD as the detector, matching its curved detection surface with the arc-shaped image surface formed by field curvature, so that light of different wavelengths can fall more accurately on the detection surface, thereby compensating for field curvature aberration, reducing spot widening caused by off-axis, and improving light throughput, signal-to-noise ratio and spectral resolution.

[0016] This application provides a spectral measurement device with a Littrow structure, which uses a liquid glass lens instead of a plano-convex lens. The radius of curvature of the liquid glass lens can be synchronously adjusted according to different wavelengths corresponding to the blazed grating angle, so that the focused image point can be detected by the detector. This achieves the optimal curvature for different wavelengths. After introducing variable curvature adjustment, the root mean square (RMS) radius of the system point plot is significantly reduced from a large initial value to a smaller range. At the same time, it effectively suppresses major aberrations such as spherical aberration, allowing light rays of different apertures to converge more accurately on the image plane and improving the energy concentration of the light spot.

[0017] This application sets an incident tilt angle to form incident light rays that propagate at a certain angle to the optical axis of the liquid glass lens, so that they no longer propagate collinearly along the central optical axis. This improves the matching relationship between grating size, lens aperture and optical path spatial geometry, reduces light cut-off phenomenon and improves the optical collection efficiency of the system. At the same time, the incident tilt angle cannot be too large to limit off-axis aberrations such as astigmatism and coma, thereby improving optical resolution.

[0018] This application, by using a motor to drive the grating rotation, enables the detector to detect the entire spectrum within the working range of the blazed grating, covering 0.8... ~2.6 The wide spectral range, and the wide spectral bands are acquired by the same optical system, avoids the problems of inconsistent response and discontinuous dispersion caused by splicing multiple spectrometers, making system calibration simpler and more stable.

[0019] This application, through systematic optimization based on Seidel aberration analysis, identifies spherical aberration as the main source of phase difference and corrects it from two levels: system structural parameters and optical materials. This effectively improves the spot quality and spectral line shape, enhances the system's luminous flux, signal-to-noise ratio, and spectral resolution, and makes the improved Littrow spectrometer more suitable for high-precision measurement scenarios and more stable in engineering. Attached Figure Description

[0020] Figure 1 This is a structural diagram of a spectral measurement device with a Littrow structure provided in an embodiment of this application.

[0021] Figure 2 This is a structural diagram of another Littrow structure spectral measurement device provided in the embodiments of this application.

[0022] Figure 3This is a schematic diagram of the optical path of an electromagnetically driven liquid glass lens provided in an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the optical path of a concave detector provided in an embodiment of this application.

[0024] Figure 5 This is a schematic diagram of the structure of the electromagnetically driven liquid glass lens provided in the embodiments of this application.

[0025] Figure 6 This is a flowchart of the spectral measurement method provided in this application.

[0026] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the incident optical fiber; 2 is the incident slit; 3 is the liquid glass lens; 4 is the blazed grating; 5 is the detector; 6 is the concave detector. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0029] In this application, the terms “first” and “second” are used to distinguish different objects, rather than to describe a specific order of objects.

[0030] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0031] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0032] The embodiments of this application are described below with reference to the accompanying drawings.

[0033] like Figure 1 and Figure 2As shown, a spectral measurement device with a Littrow structure provided in an embodiment of this application includes: an incident optical fiber 1, an incident slit 2, a liquid glass lens 3, a blazed grating 4, a detector 5, a motor, and a control module; The incident fiber 1, the incident slit 2, the liquid glass lens 3, and the blazed grating 4 are arranged in sequence; the detector is located in the propagation direction of the diffracted light after being focused by the liquid glass lens 3; the motor is connected to the blazed grating; the control module is connected to the motor and the detector; The incident fiber 1 is used to output the incident beam, forming an incident ray that propagates at a certain angle to the optical axis of the liquid glass lens 3; the incident slit 2 is used to constrain the spatial distribution of the incident ray, so that the incident light forms a linear distribution to improve the optical resolution. The liquid glass lens 3 has its radius of curvature adjusted synchronously according to the different wavelengths corresponding to the grating angle, so as to reduce aberrations along the optical axis. It is used to collimate and focus the linear beam so that the collimated and focused principal ray is incident on the grooved surface of the blazed grating 4 at a preset angle. At the same time, the liquid glass lens 3 is used to focus the reflected diffracted light so that the diffracted light of different wavelengths is arranged along the dispersion direction. The blazed grating 4 is used to diffract the collimated light to form diffracted light arranged according to wavelength. That is, the periodic grooves on the surface of the grating disperse the light of different wavelengths at a specific angle and make the diffracted light return to the direction of the liquid glass lens 3 at a certain angle, and be focused twice to form a dispersive beam of different wavelengths. The light of different wavelengths spreads along the dispersion direction. The motor is used to drive the grating to rotate, so that the light of the target wavelength is transmitted to the detector in the paraxial region, thereby reducing aberrations in the direction perpendicular to the optical axis; the detector 5 is used to receive the spectral signal of the target wavelength and convert the spectral signal into an electrical signal for subsequent spectral acquisition. The control module is used to control the motor's start / stop, speed, and rotation angle; it is also used to control the current of the electromagnetic drive coil and adjust the curvature of the liquid glass lens; and it is used to synchronously acquire the electrical signals output by the detector and record the rotation position of the blazed grating to achieve the correspondence between the spectrum and the wavelength position.

[0034] In this embodiment, the motor type is a rotary table, the step angle is 1.8°, the total number of open-loop steps is 768,000 steps, and the maximum safe operating speed is 15° / s, ensuring that the blazed grating 4 is accurately positioned and achieves high-speed scanning during the scanning process.

[0035] The detector can be a single-point detector or a concave detector 6; when the detector is a single-point detector, it is used to detect light of the target wavelength passing through the optical axis; when the detector is a concave detector, it is used to detect light of the target wavelength in the paraxial region.

[0036] More specifically, combined Figure 3The application method of concave detector 6 is explained as follows: The detector is a self-developed photodetector, composed of a concave linear CCD sensor and a signal conditioning circuit. The concave linear CCD sensor is an indium gallium arsenide (IGaAs) type. Since the scattered light's focal points are arranged in an arc after passing through the liquid glass lens, the radius of curvature of its concave detection surface matches the arc shape of the scattered light. In this embodiment, the radius of curvature, calculated and optimized using Zemax optical path simulation and parameter fitting, is designed to be 28mm, and the effective length of the photosensitive surface is 36mm, which can completely cover the focal range of the scattered light. The CCD has 1024 pixels and a single pixel size of [missing information]. Its spectral response covers 800nm~2600nm, covering the target wavelength band of the spectrometer. It has a fast response speed, high sensitivity, and can stably output spectral signals, ensuring high resolution and high signal-to-noise ratio of spectral acquisition during the scanning process.

[0037] In this embodiment, the control module is an integrated circuit based on an STM32 microcontroller, which can realize motor start / stop, speed control, angle control and detector synchronous sampling; during the scanning process, the STM32 microcontroller records the grating position and sampling signal, completes wavelength-angle mapping, and thus obtains an accurate spectral curve.

[0038] In this embodiment, the entrance slit 2 is made of stainless steel. The entrance slit is processed on a stainless steel sheet with a thickness of 0.05 mm using laser processing technology, and the slit width is 50 mm. The height is 6.5mm, and the overall dimensions of the incident slit are... To reduce surface reflection, the incident slit is oxidized and blackened to further optimize its optical performance.

[0039] like Figure 4 As shown, the effective aperture of the electromagnetically driven liquid glass lens is 50.8 mm. The liquid glass lens is equipped with an electromagnetic drive coil, which can adjust the surface deformation of the film according to the change of current, thereby changing the curvature. The curvature adjustment range is 50 mm to 200 mm. The lens is filled with optical silicone oil, with a refractive index of 1.45 and an Abbe number of 52.

[0040] Combination Figure 5 The use of the electromagnetically driven liquid glass lens is explained as follows: In this embodiment, the curvature adjustment of the liquid glass lens 3 is linked to the scanning mechanism of the blazed grating 4 for control.

[0041] For the m-th order diffraction, the target wavelength λ and the grating working angle θ satisfy mλ = 2dsinθ. When the grating rotates, the equivalent object distance of the diffracted return beams corresponding to different target wavelengths relative to the liquid glass lens changes. Therefore, to ensure that light of different wavelengths is imaged at the same single-point detector position, the lens focal length should change accordingly. Based on the imaging relationship, the liquid glass lens, in order to ensure that the target wavelength is imaged at the fixed single-point detector position 5... For imaging, the required equivalent optical power must meet the following conditions. ,in The equivalent object distance of the diffraction return beam corresponding to the target wavelength relative to the liquid glass lens. This is the fixed distance from the liquid glass lens to the detector. This is also determined by the thin lens imaging formula. The control module adjusts the voltage of the liquid glass lens accordingly to change the radius of curvature, so that the liquid glass lens provides an equivalent optical power that matches the target wavelength, thereby achieving better imaging results for different target wavelengths at a fixed detector position.

[0042] Taking an 800nm ​​target wavelength as an example, the target curvature of the liquid glass lens is 78.016 mm for the front surface and -39.186 mm for the rear surface. When the system scans to this target wavelength, the control module drives the liquid glass lens to reach the corresponding target curvature state, so that the target wavelength is imaged at the fixed detector position. After introducing variable curvature adjustment, the root mean square (RMS) radius of the system's dot plot is significantly reduced from an initial large number to a smaller range, reducing the defocusing error of different target wavelengths at the fixed detector position, weakening the field curvature mismatch caused by the change in image plane position with wavelength and the resulting spot broadening, thereby improving the spot energy concentration and spectral measurement accuracy.

[0043] According to the Zemax simulation results of the optical path before and after curvature optimization, the root mean square (RMS) radius of the system point array is relatively large at 646.288 in the unoptimized case. However, after using liquid glass lenses for optimal curvature matching, the RMS radius is significantly reduced to 3.672, the system imaging quality is significantly improved, and aberrations such as spherical aberration are effectively suppressed.

[0044] In this embodiment, the blazed grating is selected as a ruled reflection diffraction grating with a size of [size missing]. The blaze wavelength is 750nm, the number of lines is 600 lines / mm, and the blaze angle is [missing information]. The diffraction efficiency at the blaze wavelength is 60%~80%.

[0045] like Figure 6 As shown, the imaging method using the improved Littrow spectrometer provided in this embodiment includes the following steps: Step S1: Incident light introduction and collimation External light is coupled into the incident fiber 1 at a preset angle through the fiber optic coupling. The incident light is confined into a linear beam by the incident slit 2. The liquid glass lens 3 then collimates the diverging linear beam into collimated light. Step S2: Grating Diffraction and Dispersion Formation A collimated beam is irradiated onto a blazed grating 4 at a specific incident angle. The blazed grating 4 diffracts light of different wavelengths and returns them in order of wavelength. Step S3: Secondary Focusing and Spectral Output The diffracted light is focused by the liquid glass lens 3 to form a dispersive spectrum; after the system is powered on, it is initialized and started based on the control module and enters the standby state; when the scanning command is received, the control module generates a drive pulse sequence for the stepper motor, which drives the rotary table (stepper motor) to rotate at a preset step angle to realize the scanning motion of the grating; During the rotation of the stepper motor, the control circuit reads the motor step count in real time. By the correspondence between the step count and the rotation angle, and the functional relationship between the angle and the wavelength, the rotation angle of the grating is converted into the wavelength of the spectrum to be measured, and the correlation between the wavelength and the grating position is established. Step S4: Spectral signal acquisition and conditioning During grating scanning synchronization, the detector receives light of the target wavelength passing through the optical axis or paraxial region, and performs photoelectric conversion on the received target wavelength spectral signal to generate an electrical signal; when the detector is a concave detector, the signal conditioning circuit amplifies, filters and processes the electrical signal to output a stable and collectable spectral signal. Step S5: Feedback Processing and Curvature Adjustment The control module outputs current to control the current of the electromagnetic drive coil used to change the curvature of the liquid glass lens, and adjusts it in a closed loop to the current value with the highest signal-to-noise ratio at the target wavelength.

[0046] Step S6: Data processing and scanning completed The control module synchronously acquires the conditioned spectral signal or the electrical signal output by the detector, and combines it with the wavelength information corresponding to the grating position to generate wavelength-intensity spectral data; it determines whether the scan is complete. If it is complete, it controls the motor to return and ends the scanning process; if it is not complete, it continues to drive the motor to scan and acquire signals until the entire process is completed.

[0047] In summary, this application has the following advantages compared with the prior art: In practical engineering applications, especially under working conditions with a certain numerical aperture and wide spectral range, the traditional Littrow structure still inevitably introduces certain aberrations.

[0048] This application employs a liquid glass lens in conjunction with a single-point detector. Traditional fixed-curvature lenses, when scanning different target wavelengths with a grating, suffer from positional chromatic aberration, making it difficult to accurately image the diffracted light of each target wavelength at the same fixed detector position. This results in defocusing errors, leading to decreased spectral resolution and reduced luminous flux. This application addresses this by using a motor to rotate a blazed grating, changing the target wavelength and synchronously adjusting the curvature radius of the liquid glass lens accordingly. This ensures that different target wavelengths can be imaged at the fixed detector position, thereby reducing defocusing errors and optimizing spectral resolution and system luminous flux.

[0049] Based on this, this application also provides another implementation method, namely, using a concave linear CCD as a detector, matching its curved detection surface with the arc-shaped image surface formed by field curvature, so that light of different wavelengths can fall more accurately on the detection surface, thereby compensating for field curvature aberration, reducing spot broadening caused by off-axis, and improving spectral resolution, luminous flux and signal-to-noise ratio.

[0050] This paper addresses the field curvature problem in traditional Littrow structures during imaging. In conventional spectral measurement devices, after the dispersion of light rays by a grating, the focal points of different wavelengths are focused by a plano-convex lens in an arc-shaped distribution along the dispersion direction. This makes it difficult to effectively match with traditional planar detectors, easily leading to defocusing of some wavelengths, thus reducing luminous flux and signal-to-noise ratio, and affecting spectral resolution. Therefore, this application introduces a concave linear CCD at the detector end, matching the curvature of the detector receiving surface with the actual image plane shape. This ensures that light rays of different wavelengths can be accurately focused on the detector surface. Through this structural design, the field curvature aberration of the system is effectively compensated, the spot broadening caused by off-axis projection is reduced, and the spectral line shape is sharper, thereby significantly improving the spectral resolution, luminous flux, and signal-to-noise ratio of the system.

[0051] Aberration analysis and optical path optimization were performed on the existing Littrow spectrometer optical system using Seidel plots obtained with Zemax software. By setting the incident tilt angle, this application ensures that the principal rays no longer propagate collinearly along the system's central optical axis, thereby improving the matching relationship between grating size, lens aperture, and optical path spatial geometry, reducing light cutoff, and increasing the system's optical collection efficiency. Simultaneously, the incident tilt angle cannot be too large to limit off-axis aberrations such as astigmatism and coma, thus improving optical resolution.

[0052] This application covers 0.8 ~2.6 The wide spectral range, and the wide spectral bands are acquired by the same optical system, avoids the problems of inconsistent response and discontinuous dispersion caused by splicing multiple spectrometers, making system calibration simpler and more stable.

[0053] This application utilizes systematic optimization based on Seidel aberration analysis to correct both system structural parameters and optical materials, effectively improving spot quality and spectral line shape, enhancing the system's luminous flux, signal-to-noise ratio, and spectral resolution. This results in a more suitable and stable Littrow spectrometer for high-precision measurement scenarios.

[0054] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A spectral measurement device of Littrow configuration, characterized in that include: The system comprises an incident optical fiber, an incident slit, a liquid glass lens, a blazed grating, a motor, a detector, and a control module; wherein the incident optical fiber, the incident slit, the liquid glass lens, and the blazed grating are arranged in sequence; the detector is located in the propagation direction of the diffracted light after being focused by the liquid glass lens; the motor is connected to the blazed grating; and the control module is connected to both the motor and the detector. The incident fiber is used to output the incident beam, forming incident light rays that propagate at a certain angle to the optical axis of the liquid glass lens; the incident slit is used to constrain the spatial distribution of the incident light rays, forming a line beam; the radius of curvature of the liquid glass lens is synchronously adjusted according to the different wavelengths corresponding to the angle of the blazed grating, used to collimate and focus the line beam, forming collimated light; at the same time, it is used to focus the reflected diffracted light, so that the diffracted light of different wavelengths is arranged along the dispersion direction; Blazed gratings are used to diffract collimated light, forming diffracted light arranged according to wavelength, and reflecting the diffracted light onto a liquid glass lens; The motor drives the grating to rotate, allowing light of the target wavelength to be transmitted to the detector in the paraxial region. The detector receives the spectral signal of the target wavelength and converts it into an electrical signal. The control module controls the motor's start / stop, speed, and rotation angle. It also controls the current of the electromagnetic drive coil and adjusts the curvature of the liquid glass lens. Simultaneously, it synchronously acquires the electrical signal output by the detector, records the rotation position of the blazed grating, and achieves the correspondence between the spectrum and the wavelength position.

2. The spectroscopic measurement device according to claim 1, characterized in that The detector can be a single-point detector or a concave detector. When the detector is a single-point detector, it is used to detect light of the target wavelength in the paraxial region after being focused by a liquid glass lens. When the detector is a concave detector, the curved detection surface matches the curvature of the dispersed light after being focused by the liquid glass lens, so that light of different wavelengths is focused on the detection surface, and is used to detect light of the target wavelength in the paraxial region.

3. The spectroscopic measurement device of claim 2, wherein, The concave detector includes a concave linear CCD sensor and a signal conditioning circuit. The concave linear CCD sensor is of the indium gallium arsenide type, with a radius of curvature of 28 mm and a spectral response covering 800 nm to 2600 nm.

4. Spectrometric apparatus according to any one of claims 1 to 3, characterized in that The effective aperture of the liquid glass lens is greater than 50mm, and an electromagnetic drive coil is configured on the outside of the liquid glass lens. The electromagnetic drive coil is used to adjust the deformation of the thin film surface of the liquid glass lens according to the change of current so that the ideal image point of the focus reaches the detector. The curvature adjustment range is 50mm~200mm. The interior of the liquid glass lens is filled with optical silicone oil with a refractive index of 1.

45.

5. The spectrographic measuring device according to claim 1, characterized in that The motor is used to drive the rotary table, and the motor step angle is... The maximum safe operating speed is .

6. The spectrographic measuring device according to claim 1, characterized in that The entrance slit is made of stainless steel with a thickness of less than 0.05 mm, and the slit width is 20 mm. ~50 .

7. The spectroscopic measurement apparatus according to claim 1 or 5, characterized by The blazed grating is a straight-lined reflection diffraction grating with a line count of 600~1200 lines / mm.

8. A spectral measurement method based on the spectral measurement device of claim 1, characterized in that, Includes the following steps: The incident light beam is propagated to the entrance slit at a certain angle to the optical axis of the liquid glass lens, converted into a line beam, and then refracted into collimated light by the liquid glass lens. Collimated light is incident on the grooved surface of a blazed grating, diffracting light of different wavelengths and reflecting it in order of wavelength; The diffracted light is focused by a liquid glass lens to form a dispersive spectrum. A rotating motor drives a blazed grating to rotate, enabling the detector to detect the target wavelength of light in the paraxial region. The spectral signal of the target wavelength is then converted into an electrical signal through photoelectric conversion. By controlling the current of the electromagnetic drive coil to adjust the curvature of the liquid glass lens, positional chromatic aberration of the target wavelength reaching the detector surface is eliminated. The control module synchronously acquires the electrical signals output by the detector and records the rotation position of the blazed grating to achieve the correspondence between the spectrum and the wavelength position.

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