A method for precise wavelength calibration based on a MEMS Fabry-Perot cavity chip

Abstract

The present application mainly relates to the technical field of near-infrared spectroscopy. In order to solve the problem that the conventional wavelength calibration method of MEMS Fabry-Perot cavity chip has low precision, and it is usually necessary to repeatedly calibrate a single wavelength to ensure the measurement precision, which is time-consuming and laborious, the present application provides an accurate wavelength calibration method based on MEMS Fabry-Perot cavity, first, the wavelength of each wavelength point is calculated according to the wavelength range and the number of wavelength points of the MEMS Fabry-Perot cavity chip, the wavelength point to be calibrated is determined, the wavelength point λ m is set, a large range of voltage intervals is scanned, and the corresponding calibration voltage v1 is roughly obtained λ m , then the fine scanning voltage range is selected according to the calibration voltage v1, the voltage interval is narrowed to obtain the calibration voltage v2, the calibration voltage v2 is fixed, a small range of wavelength intervals is scanned, and the corresponding calibration wavelength λ p of v2 is calculated and obtained, and finally the voltage v2 is fine-tuned to obtain the voltage corresponding to the wavelength point λ m . The method described in the present application is mainly suitable for wavelength calibration of a miniature near-infrared spectroscopy system.

Description

Technical Field

[0001] This invention relates primarily to the field of near-infrared spectroscopy, and in particular to a precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip. Background Technology

[0002] With the development of microelectromechanical systems (MEMS) technology, miniaturization of near-infrared spectrometers has become a key focus in recent years. Currently, the most common miniaturized near-infrared spectrometers are based on Fabry-Perot (MPS) interferometric tunable filter chips. The optical principle of MEMS MPS chips is based on the Fabry-Perot interferometry principle. These spectrometers, fabricated using semiconductor integrated circuit technology, are driven by different voltages to obtain different narrowband spectra. Before integrating MEMS MPS chips into a miniaturized spectroscopic system, their wavelengths need to be calibrated. This is essential for the implementation of the detection algorithm in the miniaturized spectroscopic system. Currently, conventional wavelength calibration methods for MEMS MPS chips have low accuracy. To improve calibration accuracy, a common method is to repeatedly calibrate a single wavelength to ensure measurement precision. This method is time-consuming and labor-intensive, severely hindering the application and industrialization of MEMS MPS chips. Therefore, achieving precise wavelength calibration of MEMS MPS chips has become an urgent problem to be solved. Summary of the Invention

[0003] The technical problem to be solved by this invention:

[0004] This paper presents a precise wavelength calibration method based on MEMS Fabry-Perot cavity chips, which solves the problem that conventional wavelength calibration methods for MEMS Fabry-Perot cavity chips have low accuracy and usually require repeated calibration of a single wavelength to ensure measurement accuracy, which is time-consuming and labor-intensive.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip includes the following steps:

[0007] Step 1: Select the wavelength point of the voltage to be calibrated Perform a coarse scan to obtain wavelength points. Corresponding coarse calibration voltage ;

[0008] Step 2: Based on the rough calibration voltage The voltage range for fine scanning is determined by the scanning voltage interval step size set in the coarse scan, and the fine calibration voltage is obtained. ;

[0009] Step 3: Calculate the fine calibration voltage Corresponding wavelength point ;

[0010] Step 4: Based on wavelength points and calibration voltage Perform manual fine-tuning to obtain wavelength points. Final calibration voltage ;

[0011] Step 5: Verify the final calibration voltage Is it a wavelength point? The accurate calibration voltage.

[0012] Furthermore, prior to step 1, the method further includes: determining the wavelength range of the MEMS Fabry-Perot cavity. The wavelength difference between two adjacent wavelength points is calculated using the number of wavelength points. The wavelengths at all wavelength points of the MEMS Fabry-Perot cavity were calculated. ,in The first in MEMS Fabry-Perot cavity chip Each wavelength point.

[0013] Furthermore, step 1 specifically includes setting the scan start voltage, end voltage, and scan interval voltage step size. And set the start wavelength and end wavelength to the wavelength points of the voltage to be calibrated in the oscilloscope. The voltage corresponding to the point of maximum light intensity in the scanning result is the wavelength point. Rough calibration voltage .

[0014] Furthermore, step 2 includes: setting the scan start voltage to... The end voltage is set to The scanning interval voltage step size is set to And set the start wavelength and end wavelength of the oscilloscope to the wavelength point to be calibrated. The voltage corresponding to the point of maximum light intensity in the scanning result is the wavelength point. Fine calibration voltage .

[0015] Furthermore, step 3 specifically includes:

[0016] The wavelength to be obtained is nm nm nm The light intensity value at a wavelength of nm, if the wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is ;

[0017] like The final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The light intensity values ​​at the corresponding two wavelength points in the spectral image The corresponding two wavelength points; where the light intensity value The wavelength of one of the two corresponding wavelength points is nm, another setting is denoted as nm, light intensity value One of the corresponding wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is: ;

[0018] like The final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The light intensity values ​​at the corresponding two wavelength points in the spectral image The corresponding two wavelength points, where the light intensity value One of the corresponding two wavelength points is nm, another setting is nm, light intensity value One of the corresponding two wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is: .

[0019] Furthermore, step 5 specifically includes: based on the characteristic wavelength point selected in step 3... nm nm or nm nm and wavelength point Final calibration voltage The calibration results were verified using spectral images;

[0020] If the characteristic wavelength point selected in step 3 is nm nm, then find the points corresponding to the wavelength in the spectral image respectively. nm and The wavelength points with the same nm light intensity value, and the above 4 wavelength points and wavelength points Calculate the average value of the wavelength, and if the calculation result is consistent with the wavelength point... If the wavelengths are the same, then the final calibration voltage will be... Wavelength point The accurate calibration voltage; if the characteristic wavelength point selected in step 3 is nm nm, then find the points corresponding to the wavelength in the spectral image respectively. nm and The wavelength points with the same nm light intensity value, and the above 4 wavelength points and wavelength points Calculate the average value of the wavelength, and if the calculation result is consistent with the wavelength point... If the wavelengths are the same, then the final calibration voltage will be... Wavelength point The accurate calibration voltage.

[0021] The beneficial effects of this invention are:

[0022] The present invention discloses a precise calibration method based on MEMS Fabry-Perot cavity. After obtaining a coarse calibration voltage for the wavelength to be calibrated, the scanning voltage step size is reduced to obtain a more accurate fine calibration voltage. The wavelength under the fine calibration voltage is calculated. The error between this wavelength and the wavelength of the voltage to be calibrated is small. The small errors are manually adjusted to obtain the calibration voltage of the wavelength to be calibrated. This method can significantly improve the wavelength voltage calibration accuracy of MEMS Fabry-Perot cavity chips and improve operational efficiency. Attached Figure Description

[0023] Figure 1 This is a flowchart of a precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip, as described in this invention.

[0024] Figure 2 This is a schematic diagram of the coarse scanning spectrum in an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the refined scanning spectrum in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the wavelength range at the calibration voltage of 26.55V described in this embodiment of the invention.

[0027] Figure 5 This is a schematic diagram of the spectral image of the calibration voltage of 26.537V in an embodiment of the present invention. Detailed Implementation

[0028] like Figure 1As shown, the precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip described in this invention first calculates the wavelength of each wavelength point according to the wavelength range and number of wavelength points of the MEMS Fabry-Perot cavity chip, and then determines the wavelength points that need to be calibrated. A wide range of voltage intervals is set for scanning to roughly obtain... Corresponding calibration voltage Then, according to the calibrated voltage By selecting a refined scanning voltage range and narrowing the voltage interval, the calibration voltage can be obtained more precisely. Fixed calibration voltage Scanning is performed within a small range of wavelength intervals, and the results are calculated. Corresponding calibration wavelength Finally, regarding the voltage Fine-tuning is performed to obtain the wavelength point. The corresponding voltage.

[0029] Example:

[0030] Based on the working principle of the MEMS Fabry-Perot cavity chip in a miniaturized near-infrared spectrometer, its free spectral width is limited, with a wavelength range within 400 nm and a maximum of 41 wavelength points. This optimal operating condition is further optimized. Conversely, a higher number of wavelength points results in more accurate spectral data, a wider wavelength range, and broader practical applications. Therefore, a wavelength range of 400 nm and 41 wavelength points were selected. The wavelength range of the MEMS Fabry-Perot cavity chip in the miniaturized near-infrared spectrometer is set as follows: With 41 wavelength points, the wavelength range between two adjacent wavelength points of this MEMS Fabry-Perot cavity chip can be calculated as follows: Furthermore, the wavelengths of all the wavelength points to be calibrated in the MEMS Fabry-Perot cavity chip of the miniaturized near-infrared spectrometer in this embodiment can be calculated as follows: , , ..., .

[0031] In this embodiment, a wavelength of 2000nm is selected to specifically illustrate the method of the present invention. The fixed calibration wavelength is set to 2000nm, meaning that both the start and end wavelengths are set to 2000nm in the oscilloscope. The pause interval between the two scan points is set to 1 second. Setting it to 1 second ensures good scanning stability and accuracy. Meanwhile, since the operating voltage of the MEMS Fabry-Perot cavity chip is... Therefore, during the coarse scanning process, the voltage applied to the MEMS Fabry-Perot cavity chip is set to... The starting voltage was set to 10V, and the ending voltage was set to 35V. Too small a scanning voltage interval would significantly affect scanning efficiency, while too large a scanning voltage interval would affect scanning accuracy. Therefore, 1V was selected as the scanning voltage interval. After scanning, the spectral graph is as follows: Figure 2 As shown, the horizontal axis represents the voltage applied to the MEMS Fabry-Perot cavity chip, and the vertical axis represents the light intensity value collected by the MEMS Fabry-Perot cavity chip. The voltage value corresponding to the maximum near-infrared light intensity point is 27V, which is the rough calibration voltage corresponding to the wavelength point of 2000nm. .

[0032] In this embodiment, the voltage interval for coarse scanning is... That is, within the voltage range There may be near-infrared light intensity points with larger values ​​in the range, therefore the scanning voltage range in the fine scanning is selected as [value missing]. To balance accuracy and scanning efficiency, the voltage interval for fine scanning was reduced to 0.05V. Specifically, the starting voltage was set to 26V, the ending voltage to 28V, and the interval step size to 0.05V in the oscilloscope. After scanning, the spectral pattern is as follows: Figure 3 As shown, the horizontal axis represents the voltage applied to the MEMS Fabry-Perot cavity chip, and the vertical axis represents the light intensity value collected by the MEMS Fabry-Perot cavity chip. The voltage value corresponding to the maximum near-infrared light intensity is 26.55V, which is the fine calibration voltage corresponding to a wavelength of 2000nm. .

[0033] In this embodiment, the calibration voltage is a fixed value. The calibration wavelength range is set below. In this embodiment, the five-point average method is used to calculate the calibration wavelength. The specific principle of the five-point average method is as follows: the actual calibration wavelength is obtained by averaging five characteristic wavelength points in the spectrum under a fixed calibration voltage. To ensure the accuracy and precision of the calculation, the five candidate characteristic wavelength points used in this embodiment are the wavelength point with the maximum light intensity, the wavelength point extending 1 nm from the wavelength point with the maximum light intensity, and the wavelength points extending 2 nm from the wavelength point with the maximum light intensity. The wavelength point with the maximum light intensity is selected. The wavelengths at points plus or minus 1 nm and 2 nm to the left and right of the wavelength are the wavelengths. nm nm nm nm point, if wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is ;

[0034] like The five final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The light intensity values ​​at the corresponding two wavelength points in the spectral image The two corresponding wavelength points. The light intensity value... The wavelength of one of the two corresponding wavelength points is nm, another setting is denoted as nm, light intensity value One of the corresponding wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is:

[0035] like The five final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The corresponding two wavelength points and the light intensity values ​​in the spectral image The two corresponding wavelength points. The light intensity value... One of the corresponding two wavelength points is nm, another setting is nm, light intensity value One of the corresponding two wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is: .

[0036] In this embodiment, the five candidate feature wavelength points can be calculated as follows: nm nm nm nm nm; the starting wavelength was set to 1998 nm and the ending wavelength to 2002 nm. To improve scanning accuracy, the interval step size was set to 0.1 nm and the interval time to 1 second. After scanning, the spectral pattern is as follows: Figure 4As shown, the horizontal axis represents the wavelength value of the MEMS Fabry-Perot cavity chip for near-infrared spectroscopy, and the vertical axis represents the light intensity value collected by the MEMS Fabry-Perot cavity chip. The light intensity value at a wavelength of 1998 nm is greater than the light intensity value at a wavelength of 2002 nm, i.e. Therefore, based on the five-point mean method for selecting feature points, the wavelengths of the five final selected feature wavelength points are as follows: nm nm nm nm nm can be further calculated using the five-point average method to obtain the calibration voltage. The corresponding calibration wavelength is: .

[0037] The calibration wavelength of 1999.8 nm, calculated using the five-point averaging method, differs slightly from the initial calibration wavelength of 2000 nm. The difference is minor; by fine-tuning the calibration voltage, the adjusted voltage becomes the initial calibration wavelength. The corresponding calibration voltage. In this embodiment, when the voltage is finely adjusted to 26.573V, the corresponding calibration wavelength is 2000nm.

[0038] When the voltage is finely adjusted to 26.537V, the spectral image is as follows. Figure 5 As shown, wavelengths with the same intensity value as the wavelength of 1998 nm (2001.9 nm) and wavelengths with the same intensity value as the wavelength of 1999 nm (2001 nm) were selected for verification. This indicates that the wavelength corresponding to a voltage of 26.537V is indeed a wavelength of 2000nm.

Claims

1. A precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip, characterized in that, Includes the following steps: Step 1: Select the wavelength point of the voltage to be calibrated Perform a coarse scan to obtain wavelength points. Corresponding coarse calibration voltage ; Step 2: Based on the rough calibration voltage The voltage range for fine scanning is determined by the scanning voltage interval step size set in the coarse scan, and the fine calibration voltage is obtained. ; Step 3: Calculate the fine calibration voltage Corresponding wavelength point ; Specifically, it includes: The wavelength to be obtained is nm nm nm The light intensity value at a wavelength of nm, if the wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is , wavelength is The wavelength point light intensity value corresponding to nm is ; like The final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The light intensity values ​​at the corresponding two wavelength points in the spectral image The corresponding two wavelength points; where the light intensity value The wavelength of one of the two corresponding wavelength points is nm, another setting is nm, light intensity value One of the corresponding wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is: ; like The final selected characteristic wavelength points are as follows: Light intensity values ​​in spectral images The light intensity values ​​at the corresponding two wavelength points in the spectral image The corresponding two wavelength points, where the light intensity value One of the corresponding two wavelength points is nm, another setting is nm, light intensity value One of the corresponding two wavelength points is nm, another setting is nm is obtained by calculating the five-point mean method above. Corresponding calibration wavelength The final calculation formula is: ; Step 4: Based on wavelength points and fine calibration voltage Perform manual fine-tuning to obtain wavelength points. Final calibration voltage ; Step 5: Verify the final calibration voltage Is it a wavelength point? The accurate calibration voltage specifically includes: based on the characteristic wavelength point selected in step 3... nm nm or nm nm and wavelength point Final calibration voltage The calibration results were verified using spectral images; If the characteristic wavelength point selected in step 3 is nm nm, then find the points corresponding to the wavelength in the spectral image respectively. nm and The wavelength points with the same nm light intensity value, and the above 4 wavelength points and wavelength points Calculate the average value of the wavelength, and if the calculation result is consistent with the wavelength point... If the wavelengths are the same, then the final calibration voltage will be... Wavelength point The accurate calibration voltage; if the characteristic wavelength point selected in step 3 is nm nm, then find the points corresponding to the wavelength in the spectral image respectively. nm and The wavelength points with the same nm light intensity value, and the above 4 wavelength points and wavelength points Calculate the average value of the wavelength, and if the calculation result is consistent with the wavelength point... If the wavelengths are the same, then the final calibration voltage will be... Wavelength point The accurate calibration voltage.

2. The precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip according to claim 1, characterized in that, Before step 1, the method further includes: determining the wavelength range of the MEMS Fabry-Perot cavity. The wavelength difference between two adjacent wavelength points is calculated using the number of wavelength points. The wavelengths at all wavelength points of the MEMS Fabry-Perot cavity were calculated. ,in The first in MEMS Fabry-Perot cavity chip Each wavelength point.

3. The precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip according to claim 1, characterized in that, Step 1 specifically includes setting the scan start voltage, end voltage, and scan interval voltage step size. And set the start wavelength and end wavelength to the wavelength points of the voltage to be calibrated in the oscilloscope. The voltage corresponding to the point of maximum light intensity in the scanning result is the wavelength point. Rough calibration voltage .

4. The precise wavelength calibration method based on a MEMS Fabry-Perot cavity chip according to claim 2, characterized in that, Step 2 includes: setting the scan start voltage to... The end voltage is set to The scanning interval voltage step size is set to ,in Less than And set the start wavelength and end wavelength of the oscilloscope to the wavelength point to be calibrated. The voltage corresponding to the point of maximum light intensity in the scanning result is the wavelength point. Fine calibration voltage .

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