Broadband spectrometer and measurement method thereof

Abstract

The invention discloses a broadband spectrometer and a measurement method thereof. The broadband spectrometer comprises a rotatably switchable beam splitter module, an adjustable fixed mirror module, a movable mirror module, a movable mirror reflector and a rotatably switchable detector module. A measuring light source is arranged on a measuring light incident path of the beam splitter module; the moving mirror module and the moving mirror reflector are sequentially arranged on a measuring light primary transmission path of the beam splitter module; the adjustable fixed mirror module is arranged on a primary reflection path of the measuring light; and the detector module is arranged on a measuring light secondary reflection light path and is used for detecting the measuring light secondary reflection light and the measuring light secondary transmission light. The invention further discloses a measuring method. According to the modulation type spectrometer cooperation control method, the light path collimation can be improved, and the light path error caused by the nonlinear motion of the moving mirror is reduced; efficient measurement in a broadband range can be realized, and the equipment cost is reduced; and the stability and the precision of the spectrometer system are improved, and the method is suitable for online measurement in a complex environment.

Description

Technical Field

[0001] The present invention relates to the field of optical spectrum measurement, and particularly to a wide-band spectrometer and a measurement method thereof. Background Art

[0002] Due to its high resolution and sensitivity, wide-band spectrometers have been widely used in fields such as chemical analysis, biomedicine, and environmental monitoring. However, the existing wide-band spectrometers have the following problems: 1. Insufficient collimation of the optical path: During the machining and assembly of the moving mirror, there are inevitably precision errors, which may lead to non-linear motion, thus destroying the collimation of the optical path and affecting the quality of the interference light and the accuracy of the measurement.

[0003] 2. Limited measurement band range for a single band: Traditional spectrometers usually can only cover a relatively narrow band range. If wide-band measurement is required, multiple spectrometer devices need to be used, increasing equipment investment and complexity. In addition, in the measurement of different bands, specific materials and detectors usually need to be selected. For example: Near-infrared band (900 - 2300 nm): Quartz material is usually used, which has good transmission performance, and the corresponding detector is mainly an InGaAs detector. Mid-infrared band (2.5 - 14 μm): CaF2 material is often adopted, which is suitable for efficient transmission in this band, and the corresponding detector is an MCT (mercury cadmium telluride) detector or an InSb detector. Far-infrared band (above 14 μm): KBr or ZnSe materials are mostly used to meet the transmission requirements of far-infrared, and the corresponding detector is generally a pyroelectric detector or a silicon-based microbolometer.

[0004] Therefore, how to improve the collimation of the optical path and achieve wide-band measurement is a key problem in the current technological development. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the present invention provides a wide-band spectrometer and a measurement method thereof.

[0006] To achieve the above invention objective, the technical solution adopted by the present invention is as follows: Provided is a wide-band spectrometer, which includes a beam splitter module that can be rotated and switched, an adjustable fixed mirror module, a moving mirror module, a moving mirror reflector, and a detector module that can be rotated and switched; a measurement light source is provided on the measurement light incident path of the beam splitter module, and the measurement light of the measurement light source forms a first transmitted light of the measurement light and a first reflected light of the measurement light after passing through the beam splitter module; the moving mirror module and the moving mirror reflector are sequentially arranged on the first transmitted path of the measurement light of the beam splitter module, and the moving mirror module and the moving mirror reflector cooperate to reflect the first transmitted light of the measurement light back to the beam splitter module, and the first transmitted light of the measurement light forms a second reflected light of the measurement light after passing through the beam splitter module; the adjustable fixed mirror module is arranged on the first reflected path of the measurement light, and the adjustable fixed mirror module is used to reflect the first reflected light of the measurement light back to the beam splitter module, and the first reflected light of the measurement light forms a second transmitted light of the measurement light after passing through the beam splitter module; the detector module is arranged on the path of the second reflected light of the measurement light, and the detector module is used to measure the interference information generated by the second reflected light of the measurement light and the second transmitted light of the measurement light; an adjustable fixed mirror module is arranged on the second reflected path of the measurement light of the beam splitter module; further included are a DSP chip, a conditioning signal module, and an STM32 microcontroller, and both the STM32 microcontroller and the conditioning signal module are electrically connected to the DSP chip.

[0007] Further, a laser calibration subsystem is further included, and the laser calibration subsystem includes a laser source, a first laser reflector, a second laser reflector, a third laser reflector, and a quadrant detector. The second laser reflector is arranged on the measurement light incident path, the third laser reflector is arranged on the path of the second reflected light of the measurement light, the third laser reflector is located between the beam splitter module and the detector module, and the quadrant detector is arranged on the laser emission path of the third laser reflector.

[0008] Further, the beam splitter module includes a beam splitter body, a beam splitter motor, and a plurality of beam splitter sheets. The beam splitter motor is electrically connected to the DSP chip, the output end of the beam splitter motor is fixedly connected to the beam splitter body, the plurality of beam splitter sheets are uniformly arranged in the circumferential direction of the beam splitter body, through holes for installing the beam splitter sheets are provided on the beam splitter body, and the beam splitter motor is a stepper motor, a synchronous motor, or a servo motor.

[0009] Further, the fixed mirror module includes a mounting seat, an optical lens, and a plurality of piezoelectric ceramic actuators. One ends of the plurality of piezoelectric ceramic actuators are fixedly connected to the mounting seat, and the other ends are fixedly connected to the optical lens, and the piezoelectric ceramic actuators are electrically connected to the DSP chip.

[0010] Further, the detector module includes a detector motor and a detector. The output end of the detector motor is fixedly connected to the detector, the detector motor is electrically connected to the DSP chip, and the detector motor is a stepper motor, a synchronous motor, or a servo motor.

[0011] Further, the moving mirror module includes a solid angle mirror and a moving mirror motion motor that drives the solid angle mirror to move horizontally. The output end of the moving mirror motion motor is fixedly connected to the solid angle mirror. The moving mirror motion motor is electrically connected to the DSP chip, and the moving mirror motion motor is a linear voice coil motor.

[0012] Further, the first laser mirror is parallel to the second laser mirror, and the second laser mirror is located on the rotation axis of the beam splitter module.

[0013] Further, the fixed mirror module and the detector module are both at 45 degrees to the beam splitter module, and the fixed mirror module and the detector module are both parallel to the horizontal plane.

[0014] A measurement method for a wide-band spectrometer includes the following steps: S1: Select a measurement band, and determine the corresponding beam splitter and detector according to the measurement band; S2: According to the determined beam splitter and detector, rotate and switch the beam splitter motor and the detector module to the corresponding positions, and perform static optical path calibration; specifically: If the beam splitter module and the detector module are both in corresponding positions, then step S3 is executed; If there is one position of the beam splitter module and the detector module that is not corresponding, then control the beam splitter motor and the detector motor to switch the beam splitter module and the detector module to the corresponding positions respectively. The beam splitter motor drives the beam splitter module to rotate an angle , is the number of times of rotating 90 degrees, , and is an integer; further, if after the rotation and switching of the beam splitter module or the detector module are completed, the center of the laser beam is not at the center of the quadrant detector, it means that the beam splitter module has not been switched to the ideal position. The current obtained by the quadrant detector carries the first offset phase information. The conditioning signal module conditions the first offset phase information, and the conditioned first offset phase information is fed back to the DSP chip. The DSP chip calculates and processes the first offset phase information to obtain the fine-tuning angle of the beam splitter motor or the detector motor. The beam splitter motor or the detector motor drives the beam splitter module or the detector module to perform rotational fine-tuning according to the fine-tuning angle, so that the center of the laser beam coincides with the center of the quadrant detector, and the beam splitter on the beam splitter module or the detector on the detector module is switched to the corresponding position, completing the switching of the beam splitter module or the detector module, and continue to execute step S3; S3: After completing the static optical path calibration, perform dynamic optical path calibration; specifically: After the determined beam splitter and detector are adjusted and switched to the corresponding positions, the moving mirror motor drives the solid angle mirror to move back and forth. During the movement of the solid angle mirror, the current obtained by the four-quadrant detector detecting the laser carries the second offset phase information. The conditioning signal module conditions the second offset phase information, and the conditioned second offset phase information is transmitted to the DSP chip for calculation and processing to obtain an offset signal, and the offset signal is transmitted to the piezoelectric ceramic actuator. The piezoelectric ceramic actuator dynamically adjusts the angular offset of the fixed mirror according to the offset signal to fit the angular offset of the solid angle mirror, so as to collimate the optical path; S4: Collect the interference signal through the detector module and transmit it to the DSP chip, and output the spectral map data of the measurement band.

[0015] The specific method for the DSP chip in step S2 to calculate the fine-tuning angles of the beam splitter motor and the detector motor is as follows: S21: Calculate the offset of the light spot relative to the center of the detection surface according to the area of the light spot projected by the laser beam on the four-quadrant detector; Specifically, when the light spot irradiates the four-quadrant detector, 、 The axis offset is proportional to the light spot area, and the addition and subtraction algorithm model is used to calculate 、 The offset of each axis. The specific addition and subtraction algorithm model is as follows:

[0016]

[0017] In the formula, Represents the offset of the light spot relative to the center of the detection surface in Axis direction, Represents the offset of the light spot relative to the center of the detection surface in Axis direction, 、 、 And Respectively represent the currents in the four quadrants of the four-quadrant detector; 、 、 、 Are the light spot areas on the four quadrants of the four-quadrant detector respectively; S22: Calculate the fine-tuning angle Of the beam splitter motor according to the offset of the light spot relative to the center of the detection surface. The specific calculation formula is as follows: ; In the formula, Is the optical path length from the beam splitter to the detector.

[0018] The beneficial effects of the present invention are as follows: The modulation-type spectrometer and its control method of the present invention can improve the collimation of the optical path and reduce the optical path error caused by the non-linear movement of the moving mirror; achieve efficient measurement in a wide wavelength range, reduce equipment costs; improve the stability and accuracy of the spectrometer system, and are applicable to on-line measurement in complex environments.

[0019] In the present invention, the user selects the target wavelength band according to the characteristics of the measurement sample, and the system roughly adjusts the positions of the beam splitter and the detector. The voice coil motor completes the precise movement of the beam splitter and the detector, and positions them to the target wavelength band area. The detector and the DSP chip cooperate to adjust the positions of the moving mirror and the fixed mirror in real time to ensure the collimation of the optical path.

[0020] In the present invention, the detector collects the interference signal and transmits it to the signal processing module, and outputs the spectral information of the target wavelength band. If it is necessary to switch the measurement wavelength band, the beam splitter and detector conversion module quickly adapts to the new measurement requirements, without the need to replace the equipment, simplifying the operation process.

[0021] This embodiment of the present invention can effectively improve the measurement efficiency and stability of the system, and is applicable to the spectral measurement requirements in a variety of complex environments.

[0022] In order to achieve wide-band measurement, the present invention designs a rotatable and switchable beam splitter module and a rotatable and switchable detector module; the beam splitter conversion module is driven by a voice coil motor, and quickly switches to the appropriate beam splitter according to the target wavelength band requirements to achieve efficient measurement in different spectral wavelength bands; the detector conversion module adapts to the optical signals of different wavelength bands, and the detector conversion module can quickly replace the appropriate detector component to ensure the sensitivity and accuracy of spectral measurement.

[0023] In the present invention, the target wavelength band is selected according to the sample characteristics, and the positions of the beam splitter and the detector are roughly adjusted. The voice coil motor is used to complete the precise movement of the beam splitter and the detector to achieve efficient measurement of spectra in different wavelength bands.

[0024] In the present invention, the detector receives the interference optical signal and generates a micro-current signal, which is transmitted to the DSP chip with the function of distinguishing the offset position after signal conditioning. The DSP chip is used to calculate the deviation position of the optical path, and send the adjustment information to the piezoelectric ceramic sheet of the voice coil motor and the piezoelectric ceramic actuator; the piezoelectric ceramic actuator is installed on the fixed mirror and is used to adjust the reflection angle of the fixed mirror to fit the reflection angle of the moving mirror to ensure the collimation of the optical path.

[0025] Different beam splitter sheets are provided on the beam splitter of the present invention, and the beam splitter is rotated and switched to achieve the rapid switching of spectral measurements in different wavelength bands; a detector is provided on the detector module, and the detector is rotated and switched to adapt to the detection requirements of different wavelength bands. Description of the Drawings

[0026] Figure 1Schematic diagram of the overall structure of the broadband spectrometer of the present invention; Figure 2 Schematic diagram of the beam splitter module; Figure 3 Front view of the fixed mirror module; Figure 4 Top view of the fixed mirror module; Figure 5 Schematic diagram of the detector module; Figure 6 Schematic diagram of the structural principle of the detector module; Figure 7 Flow chart of the moving mirror movement of the spectrometer; Figure 8 Schematic diagram of the detector electrical signal flow; Explanation of the main component symbols in the figure is as follows: 1. First laser mirror; 2. Second laser mirror; 3. Beam splitter module; 31. Beam splitter body; 32. Beam splitter motor; 33. Beam splitter plate; 4. Fixed mirror module; 41. Mounting seat; 42. Optical lens; 43. Piezoelectric ceramic actuator; 5. Moving mirror module; 6. Moving mirror movement motor; 7. Moving mirror; 8. Third laser mirror; 9. Detector module; 91. Detector motor; 92. Detector; 10. Quadrant detector. Specific embodiments

[0027] The specific embodiments of the present invention will be described below to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0028] As Figure 1 and 2As shown in the figure, the broadband spectrometer includes a beam splitter module 3, an adjustable fixed mirror module 4, a moving mirror module 5, a moving mirror 7, and a rotatable and switchable detector module 9. A measurement light source is provided on the measurement light incident path of the beam splitter module 3. The measurement light of the measurement light source forms a first transmitted light of the measurement light and a first reflected light of the measurement light after passing through the beam splitter module 3. The moving mirror module 5 and the moving mirror 7 are sequentially arranged on the first transmitted path of the measurement light of the beam splitter module 3. The moving mirror module 5 and the moving mirror 7 cooperate to reflect the first transmitted light of the measurement light back to the beam splitter module 3. The first transmitted light of the measurement light forms a second reflected light of the measurement light after passing through the beam splitter module 3. The adjustable fixed mirror module 4 is arranged on the first reflected path of the measurement light. The adjustable fixed mirror module 4 is used to reflect the first reflected light of the measurement light back to the beam splitter module 3. The first reflected light of the measurement light forms a second transmitted light of the measurement light after passing through the beam splitter module 3. The detector module 9 is arranged on the path of the second reflected light of the measurement light. The detector module 9 is used to measure the interference information generated by the second reflected light of the measurement light and the second transmitted light of the measurement light. Both the fixed mirror module 4 and the detector module 9 are at a 45-degree angle to the beam splitter module 3. Both the fixed mirror module 4 and the detector module 9 are parallel to the horizontal plane. It also includes a DSP chip, a conditioning signal module, and an STM32 microcontroller. Both the STM32 microcontroller and the conditioning signal module are electrically connected to the DSP chip.

[0029] It also includes a laser calibration subsystem. The laser calibration subsystem includes a laser source, a first laser mirror 1, a second laser mirror 2, a third laser mirror 8, and a quadrant detector 10. The second laser mirror 2 is arranged on the measurement light incident path. The third laser mirror 8 is arranged on the path of the second reflected light of the measurement light. The third laser mirror 8 is located between the beam splitter module 3 and the detector module 9. The first laser mirror 1 is parallel to the second laser mirror 2. The second laser mirror 2 is located on the rotation axis of the beam splitter module 3. The quadrant detector 10 is arranged on the laser emission path of the third laser mirror 8. The quadrant detector only needs to be adjusted by 90° through a rotating motor. Since it is only a detector for receiving optical signals, it does not affect the collimation of the optical path.

[0030] The beam splitter module 3 includes a beam splitter body 31, a beam splitter motor 32, and a plurality of beam splitter plates 33. The beam splitter motor 32 is electrically connected to the DSP chip. The output end of the beam splitter motor 32 is fixedly connected to the beam splitter body 31. The plurality of beam splitter plates 33 are evenly distributed in the circumferential direction of the beam splitter body 31. Through holes for installing the beam splitter plates 33 are provided on the beam splitter body 31. The beam splitter motor 32 is a stepper motor, a synchronous motor, or a servo motor. After the fractional plates on the beam splitter module are switched to the accurate positions, the collimation of the optical path is ensured. Collimation means that the laser is parallel to the measurement light.

[0031] As Figure 3 and 4As shown, the fixed mirror module 4 includes a mounting base 41, an optical lens 42, and several piezoelectric ceramic actuators 43. In this embodiment, it is preferably set that there are four piezoelectric ceramic actuators 43, and the four piezoelectric ceramic actuators 43 are partially arranged on the mounting base 41. One end of several piezoelectric ceramic actuators 43 is fixedly connected to the mounting base 41, and the other end is fixedly connected to the optical lens 42. The piezoelectric ceramic actuators 43 are electrically connected to the DSP chip. To improve the collimation of the optical path, the influence of the non-linear movement of the fixed mirror module 4 is corrected by the feedback signal of the detector 92: the detector 92 receives the interference light signal and outputs a micro-current signal to the DSP chip. The DSP chip analyzes the data of the optical path deviation information and transmits the adjustment signal to the voice coil motor and the piezoelectric ceramic sheet of the piezoelectric ceramic actuator 43. The optical lens 42 is mounted on several piezoelectric ceramic actuators 43, and the reflection angle of the optical lens 42 is adjusted in real time according to the deviation signal to fit the change of the angle during the movement of the moving mirror, ensuring the collimation of the optical path.

[0032] As Figure 5 and 6 shown, the detector module 9 includes a detector motor 91 and a detector 92. The output end of the detector motor 91 is fixedly connected to the detector 92. The detector motor 91 is electrically connected to the DSP chip. The detector motor 91 is a stepper motor, a synchronous motor, or a servo motor.

[0033] The moving mirror module 5 includes a solid angle mirror and a moving mirror movement motor 6 that drives the solid angle mirror to move horizontally. The output end of the moving mirror movement motor 6 is fixedly connected to the solid angle mirror. The moving mirror movement motor 6 is electrically connected to the DSP chip. The moving mirror movement motor 6 is a linear voice coil motor. During the acceleration and deceleration movement of the moving mirror module 5, affected by its friction and external disturbances, the moving mirror lens 5 may be tilted. Therefore, a solid angle mirror is selected as the moving mirror, which has higher stability and always reflects light parallel to the incident light. Therefore, it only needs to keep the incident light parallel to the laser. When the light has a slight deviation, that is, the optical path is not collimated, the laser light will not reach the center of the quadrant detector.

[0034] The beam splitter motor 32, the piezoelectric ceramic actuator 43, the moving mirror movement motor 6, and the detector motor 91 are all electrically connected to the DSP chip. The control end of the DSP chip is electrically connected to the beam splitter motor 32, the piezoelectric ceramic actuator 43, the detector motor 91, and the moving mirror movement motor through a digital-to-analog converter. The signal feedback end of the DSP chip is sequentially connected to an analog-to-digital converter and a conditioning signal module and then electrically connected to the beam splitter motor 32, the piezoelectric ceramic actuator 43, the detector motor 91, and the moving mirror movement motor.

[0035] The incident light may be deflected due to external factors. Since the solid angle mirror has the characteristic that the incident light and the reflected light are parallel, when the light is transmitted to the moving mirror 7, it will carry a deviation angle, resulting in the light not being able to return along the original path. In another embodiment, four piezoelectric ceramic actuators 43 can also be provided behind the moving mirror 7 to adjust the angle of the first plane mirror 7, thereby calibrating the deviation angle and enabling the light to return along the original path.

[0036] Working principle of the measurement optical path: The beam splitter 3 switches to the corresponding spectroscopic mode according to the measurement wavelength selected by the user, and the measurement light of the measurement light source is incident on the beam splitter 3. After the measurement light is incident on the beam splitter 3, it is divided into two parts: transmitted light and reflected light. Specifically: Transmitted light path: The transmitted light directly passes through the beam splitter 3 and finally enters the detector 9 to participate in the generation of the interference signal. Reflected light path: The reflected light is reflected by the moving mirror module 5 to the moving mirror 7, and then the light beam returns to the beam splitter 3 along the original path. After being reflected by the beam splitter 3 again, the light beam reaches the fixed mirror module 4 and finally passes through the beam splitter 3 to converge with the transmitted light to form an interference light signal. Figure 1 In the figure, the black optical path represents the measurement light source path, the green optical path represents the first transmitted light path of the measurement light, the blue optical path represents the first reflected light path of the measurement light, the purple represents the second transmitted light and the second reflected light path of the measurement light, and the red optical path represents the laser projection and reflection path. Through a reasonable layout of optical elements, the generation of the interference signal is ensured to be adapted to the position of the detector, meeting the requirements of measurement spectral analysis.

[0037] Laser optical path calibration principle: Laser is used as the light source for real-time optical path calibration. The laser emitted by the laser passes through the first laser mirror 1 and the second laser mirror 2 in sequence and reaches the beam splitter 3. The laser beam is divided into two parts. Specifically: Transmitted light path: After the laser is transmitted, it directly forms a reference light signal. Reflected light path: After the laser is reflected, it passes through the moving mirror module 5 and the moving mirror 7 in sequence and returns to the beam splitter 3 to form interference light. This light is reflected by the third laser mirror 8 to the detector 92 and outputs through an electrical signal to provide the deviation information required for optical path calibration. The feedback signal is processed by the DSP chip to dynamically adjust the actions of the beam splitter motor 32, the piezoelectric ceramic actuator 43, the detector motor 91, and the moving mirror movement motor, realizing high-precision control of optical path calibration.

[0038] A measurement method for a wide-band spectrometer includes the following steps: Figure 7 It is a flow chart of the movement of the moving mirror of the spectrometer: S1: Select the measurement band and determine the corresponding beam splitter and detector according to the measurement band; The selectable wavelength bands in this embodiment are 900 - 2300 nm, 2.5 - 14 μm, and above 14 μm. When the wavelength band is 900 - 2300 nm, the beam splitter module and the detector module can be respectively selected as a quartz material beam splitter and an InGaAs detector. When the wavelength band is 2.5 - 14 μm, the beam splitter module and the detector module can be respectively selected as a CaF2 material beam splitter and an MCT (mercury cadmium telluride) detector / InSb detector. When the wavelength band is above 14 μm, the beam splitter module and the detector module can be respectively selected as a ZnSe material beam splitter and a pyroelectric detector. S2: According to the determined beam splitter and detector, rotate and switch the beam splitter motor and the detector module to the corresponding positions, and perform static optical path calibration. Specifically: If both the beam splitter module and the detector module are in the corresponding positions, then execute step S3; If there is one position of the beam splitter module and the detector module that is not corresponding, then control the beam splitter motor and the detector motor to respectively switch the beam splitter module and the detector module to the corresponding positions. The beam splitter motor drives the beam splitter module to rotate an angle , which is the number of times of rotating 90 degrees, , and it is an integer. Further, if after the rotation and switching of the beam splitter module or the detector module are completed, the center of the laser beam is not at the center of the quadrant detector, it means that the beam splitter module has not been switched to the ideal position. For example, Figure 8 , the current obtained by the quadrant detector carries the first offset phase information. The conditioning signal module conditions the first offset phase information, and the conditioned first offset phase information is fed back to the DSP chip. The DSP chip calculates and processes the first offset phase information to obtain the fine-tuning angle of the beam splitter motor or the detector motor. The beam splitter motor or the detector motor drives the beam splitter module or the detector module to rotate and fine-tune according to the fine-tuning angle, so that the center of the laser beam coincides with the center of the quadrant detector, and the beam splitter on the beam splitter module or the detector on the detector module is switched to the corresponding position, completing the switching of the beam splitter module or the detector module, and then continue to execute step S3; The specific method for the DSP chip to calculate the fine-tuning angles of the beam splitter motor and the detector motor is as follows. The switching methods of the beam splitter module and the detector module are the same. The calculation method takes the switching method of the beam splitter module as an example: S21: Calculate the offset of the light spot relative to the center of the detection surface according to the area of the light spot projected by the laser beam on the quadrant detector; Specifically, when the light spot irradiates on the quadrant detector, , the offsets on the , The offset of each axis. The specific addition and subtraction algorithm model is as follows:

[0039]

[0040] In the formula, represents the offset of the light spot relative to the center of the detection surface in the axis direction, represents the offset of the light spot relative to the center of the detection surface in the axis direction, , , and respectively represent the currents of the four quadrants in the quadrant detector; , , , are respectively the light spot areas of the four quadrants on the quadrant detector; S22: In actual operation, the optical path length is usually a known physical parameter and can be determined by direct measurement. Thus, the relationship between the offset and the angle can be expressed more accurately. According to the relationship between the offset and the angle, the fine-tuning angle formula of the beam splitter motor can be calculated. The relationship between the offset and the beam splitter angle satisfies the following formula: ; ; Where: is the optical path length from the beam splitter to the detector, is the coupling coefficient of the beam splitter angle to the vertical offset; Calculate the fine-tuning angle of the beam splitter motor according to the offset of the light spot relative to the center of the detection surface. The specific calculation formula is as follows: ; In the formula, is the optical path length from the beam splitter to the detector; S3: After completing the static calibration of the optical path, perform the dynamic calibration of the optical path; specifically: After the determined beam splitter and detector are adjusted and switched to the corresponding positions, the moving mirror motor drives the solid angle mirror to move reciprocally. During the movement of the solid angle mirror, the current obtained by the quadrant detector detecting the laser carries the second offset phase information. The conditioning signal module conditions the second offset phase information, and the conditioned second offset phase information is sent to the DSP chip for calculation and processing to obtain the offset signal, and the offset signal is transmitted to the piezoelectric ceramic actuator. The piezoelectric ceramic actuator dynamically adjusts the angle offset of the fixed mirror according to the offset signal to fit the angle offset of the solid angle mirror and make the optical path collimated; S31: Calculate the offset of the light spot relative to the center of the detection surface according to the area of the light spot projected by the laser on the quadrant detector, same as step S21; S32: Calculate the fine-tuning angle of the fixed mirror module based on the DSP chip , and the specific calculation formula is as follows: ; In the formula, is the optical path length from the fixed mirror to the detector; According to the relationship between the offset and the fixed mirror angle, the initial fine-tuning angle calculation formula of the fixed mirror module can be obtained, where the relationship between the offset and the fixed mirror angle satisfies the following formula: ; ; Among them: is the coupling coefficient of the fixed mirror angle to the horizontal direction offset; Combining the formula here, the fine-tuning angle machine loss formula of the fixed mirror module can be obtained; S4: Collect the interference signal through the detector module and transmit it to the DSP chip to output the spectral map data of the measurement band.

[0041] In order to better ensure the accuracy of the angle rotation of the beam splitter motor 32, the detector motor 91, and the moving mirror movement motor, as well as the accuracy of the adjustment angle of the four piezoelectric ceramic actuators 43, the PID control strategy can be further combined to achieve the precise control of the adjustment angles of the beam splitter motor 32, the detector motor 91, the moving mirror movement motor, and the ceramic actuator 43; The specific method of combining the PID control strategy is as follows: A1: Set the expected inclination angles and that need to be adjusted for the fixed mirror module and the beam splitter module, and use the quadrant detector to collect the actual inclination angle of the current fixed mirror module and the actual inclination angle of the beam splitter module; A2: Calculate the deviation between the actual inclination angle of the fixed mirror module and the expected inclination angle , and the deviation between the actual inclination angle of the beam splitter module and the expected inclination angle ; According to the inclination angle deviations and , introduce the deviation change rates and as input variables and input them into the two-dimensional model controller; A3: The two-dimensional model controller performs simulation control processing on the input variables according to the preset model rules and outputs the proportional coefficient for adjusting the fixed mirror module , integral coefficient , differential coefficient , and the proportionality coefficient for adjusting the beam splitter module , integral coefficient , differential coefficient ; These coefficients are respectively matched with the control parameters of the piezoelectric ceramic after the fixed mirror module and the angle control parameters of the rotating motor; A4: The proportionality coefficient obtained from the output of the two-dimensional model controller , integral coefficient , differential coefficient , finely adjust the piezoelectric ceramic of the fixed mirror module to ensure that the surface of the fixed mirror module is perpendicular to the incident light; At the same time, use the , , output by the controller to finely adjust the rotating motor to ensure that the beam splitter module forms a 45° angle with the incident light; A5: The proportional, integral, and differential coefficients updated in real time by the controller are used to adjust the control parameters of the fixed mirror module and the beam splitter module, so that the system tilt angle gradually approaches the expected tilt angle and ; A6: Repeat steps S2 to S5, and continuously optimize the tilt angle adjustment parameters using the real-time feedback signal of the quadrant detector until the actual tilt angle of the fixed mirror module is adjusted to the expected tilt angle , and the actual tilt angle of the beam splitter module is adjusted to the expected tilt angle , completing the precise calibration process of the fixed mirror module and the beam splitter module.

Claims

1. A wideband spectrometer, characterized in that: It comprises a rotatable and switchable beam splitter module (3), an adjustable fixed mirror module (4), a moving mirror module (5), a moving mirror reflector (7) and a rotatable and switchable detector module (9); A measuring light source is provided on the measuring light incident path of the beam splitter module (3), and the measuring light of the measuring light source passes through the beam splitter module (3) to form a first transmitted light of the measuring light and a first reflected light of the measuring light; The moving mirror module (5) and the moving mirror reflector (7) are sequentially arranged on a primary transmission path of the measuring light of the beam splitter module (3); the moving mirror module (5) and the moving mirror reflector (7) cooperate to reflect the primary transmission light of the measuring light back to the beam splitter module (3); the primary transmission light of the measuring light passes through the beam splitter module (3) to form secondary reflection light of the measuring light; The adjustable fixed mirror module (4) is arranged on the primary reflection path of the measuring light, and the adjustable fixed mirror module (4) is used to reflect the primary reflected light of the measuring light back to the beam splitter module (3), and the primary reflected light of the measuring light passes through the beam splitter module (3) to form secondary transmitted light of the measuring light; The detector module (9) is arranged on the secondary reflected light path of the measuring light, and the detector module (9) is used to measure interference information generated by the secondary reflected light of the measuring light and the secondary transmitted light of the measuring light; It also includes a DSP chip, a signal conditioning module and an STM32 microcontroller, wherein the STM32 microcontroller and the signal conditioning module are both electrically connected to the DSP chip.

2. The broadband spectrometer according to claim 1, characterized in that: The invention also comprises a laser calibration subsystem, the laser calibration subsystem comprising a laser source, a first laser reflection mirror (1), a second laser reflection mirror (2), a third laser reflection mirror (8) and a four-quadrant detector (10), wherein the second laser reflection mirror (2) is arranged on the incident path of the measuring light, the third laser reflection mirror (8) is arranged on the secondary reflected light path of the measuring light, the third laser reflection mirror (8) is located between the beam splitter module (3) and the detector module (9), and the four-quadrant detector (10) is arranged on the laser emission path of the third laser reflection mirror (8).

3. The broadband spectrometer according to claim 1, characterized in that: The beam splitter module (3) comprises a beam splitter body (31), a beam splitter motor (32) and a plurality of beam splitter plates (33); the beam splitter motor (32) is electrically connected to a DSP chip; an output end of the beam splitter motor (32) is fixedly connected to the beam splitter body (31); the plurality of beam splitter plates (33) are evenly arranged in a circumferential direction of the beam splitter body (31); a through hole for mounting the beam splitter plates (33) is provided on the beam splitter body (31); and the beam splitter motor (32) is a stepping motor, a synchronous motor or a steering gear.

4. The broadband spectrometer according to claim 1, characterized in that: The fixed mirror module (4) comprises a mounting seat (41), an optical lens (42) and a plurality of piezoelectric ceramic actuators (43); one end of the plurality of piezoelectric ceramic actuators (43) is fixedly connected to the mounting seat (41) and the other end is fixedly connected to the optical lens (42); and the piezoelectric ceramic actuators (43) are electrically connected to a DSP chip.

5. The broadband spectrometer according to claim 1, characterized in that: The detector module (9) comprises a detector motor (91) and a detector (92); the output end of the detector motor (91) is fixedly connected to the detector (92); the detector motor (91) is electrically connected to a DSP chip; and the detector motor (91) is a stepping motor, a synchronous motor or a steering gear.

6. The broadband spectrometer according to claim 1, characterized in that: The moving mirror module (5) comprises a three-dimensional corner mirror and a moving mirror motion motor (6) for driving the three-dimensional corner mirror to move horizontally, the output end of the moving mirror motion motor (6) is fixedly connected to the three-dimensional corner mirror, the moving mirror motion motor (6) is electrically connected to the DSP chip, and the moving mirror motion motor (6) is a linear voice coil motor.

7. The broadband spectrometer according to claim 1, characterized in that: The first laser reflection mirror (1) is parallel to the second laser reflection mirror (2), and the second laser reflection mirror (2) is located on the rotation axis of the beam splitter module (3).

8. The broadband spectrometer according to claim 1, characterized in that: The fixed mirror module (4) and the detector module (9) are both at 45 degrees to the beam splitter module (3), and the fixed mirror module (4) and the detector module (9) are both parallel to a horizontal plane.

9. A measurement method for the wide-band spectrometer according to any one of claims 1 to 8, characterized in that: The steps include: S1: Select the measurement band and determine the corresponding beam splitter and detector according to the measurement band; S2: According to the determined beam splitter and detector, the beam splitter motor and detector module are rotated and switched to the corresponding positions, and the optical path is statically calibrated; specifically: If the beam splitter module and the detector module are in corresponding positions, step S3 is executed; If there is a position where the beam splitter module and the detector module are not corresponding, the beam splitter motor and the detector motor are controlled to switch the beam splitter module and the detector module to the corresponding position respectively, and the beam splitter motor drives the beam splitter module to rotate by an angle , is the number of 90 degree rotations, , and is an integer; further, if after the rotation and switching of the beam splitter module or the detector module is completed, the center of its laser light is not in the center of the four-quadrant detector, it means that the beam splitter module has not been switched to the ideal position, and the current obtained by the four-quadrant detector carries the first offset phase information. The conditioning signal module conditions the first offset phase information, and the conditioned first offset phase information is fed back to the DSP chip. The DSP chip calculates and processes the first offset phase information to obtain the fine-tuning angle of the beam splitter motor or the detector motor. The beam splitter motor or the detector motor drives the beam splitter module or the detector module to rotate and fine-tune according to the fine-tuning angle, so that the center of the laser light coincides with the center of the four-quadrant detector, so that the beam splitter on the beam splitter module or the detector on the detector module is switched to the corresponding position, the switching of the beam splitter module or the detector module is completed, and step S3 is continued; S3: After completing the static calibration of the optical path, perform dynamic calibration of the optical path; specifically: When the determined beam splitter and detector are adjusted and switched to the corresponding positions, the moving mirror motion motor drives the stereo corner mirror to reciprocate. During the movement of the stereo corner mirror, the current obtained by the four-quadrant detector detecting the laser carries the second offset phase information. The conditioning signal module conditions the second offset phase information. The conditioned second offset phase information is transmitted to the DSP chip for calculation and processing to obtain an offset signal, and the offset signal is transmitted to the piezoelectric ceramic actuator. The piezoelectric ceramic actuator dynamically adjusts the angle offset of the fixed mirror according to the offset signal to fit the angle offset of the stereo corner mirror, so as to collimate the optical path. S4: The interference signal is collected through the detector module and transmitted to the DSP chip, and the spectrum data of the measurement band is output.

10. The measurement method of the wide-band spectrometer according to claim 9, characterized in that: The specific method for the DSP chip in step S2 to calculate the fine-tuning angles of the beam splitter motor and the detector motor is as follows: S21: Calculate the offset of the light spot relative to the center of the detection surface according to the light spot area projected by the laser light on the four-quadrant detector; Specifically, when the light spot is irradiated onto the four-quadrant detector, , The axis offset is proportional to the spot area and is calculated using the addition and subtraction algorithm model , The offset of each axis, the specific addition and subtraction algorithm model is as follows: In the formula, Indicates that the light spot is relative to the center of the detection surface The offset in the axis direction, Indicates that the light spot is relative to the center of the detection surface The offset in the axis direction, , , and Respectively represent the currents in the four quadrants of the four-quadrant detector; , , , They are the spot areas on the four quadrants of the four-quadrant detector respectively; S22: Calculate the fine-tuning angle of the beam splitter motor based on the offset of the light spot relative to the center of the detection surface , the specific calculation formula is as follows: ； In the formula, is the optical path length from the beam splitter to the detector.

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