An optical device for taking and measuring atomic spectra

Abstract

The utility model provides a kind of optical device for shooting and measuring atomic spectrum, including hydrogen lamp for generating hydrogen atomic spectrum;Mercury lamp for generating reference spectrum, image acquisition equipment and computer equipment installed with image analysis software, image acquisition equipment is used to transmit the spectrum image captured to computer equipment;Image analysis software is used to process the spectrum image transmitted from image acquisition equipment, to measure the wavelength of atomic spectrum;It is sequentially provided with collimating slit one, neutral filter and beam splitter along the propagation direction of the light path of mercury lamp, hydrogen lamp is correspondingly arranged above beam splitter, collimating slit two is correspondingly arranged below beam splitter, transmission grating is correspondingly arranged below collimating slit two, the camera of image acquisition equipment is aligned with transmission grating, for capturing the spectrum image dispersed after transmission grating.This device can accurately measure the wavelength of hydrogen atomic spectrum, and determine its characteristics, provide reliable data support for scientific research and practical application.

Description

Technical Field

[0001] This invention belongs to the field of spectral analysis technology, specifically relating to an optical device for capturing and measuring atomic spectra. Background Technology

[0002] Spectroscopic analysis is an important method for studying atomic structure. In 1885, Balmer summarized the results of measurements of the hydrogen spectrum and proposed the famous Balmer formula, which provided a solid experimental foundation for the establishment of quantum theory. The Rydberg constant, obtained through the Balmer formula, became the standard for verifying the reliability of atomic theory and the basis for measuring other fundamental physical constants.

[0003] The spectrum emitted by a hydrogen lamp is a typical atomic line spectrum, produced by energy level transitions in hydrogen atoms. It presents as discrete bright lines, reflecting the quantization of atomic energy levels. The hydrogen atom is a single-electron atom; when an electron transitions from a higher energy level n2 to a lower energy level n1, it emits a photon, with energy satisfying the specified threshold.

[0004] ,

[0005] The spectrum emitted by a mercury lamp is a line spectrum, mainly consisting of spectral lines of specific wavelengths. These spectral lines are often used as standard spectral lines in optical experiments. Commonly used spectral analysis models are mainly used to interpret spectral data and extract material characteristic information, such as the Bragg equation and the Lorentz-Gaussian fitting model.

[0006] Traditional hydrogen atom spectroscopy experiments require a spectrometer, grating, hydrogen lamp, voltage regulator, neon lamp transformer, mercury lamp (or sodium lamp, helium-neon laser tube), etc. A spectrometer is a precise optical instrument for measuring angles and can measure important optical parameters such as grating constant and wavelength. It is a crucial component of spectral analysis instruments such as chromatographs. While there are many models of spectrometers, their basic structure is similar, mainly consisting of four parts: a collimator, an autocollimating telescope, a sample platform, and a reading device. Due to its precision and complex structure, a spectrometer requires strict adherence to prescribed adjustments during use. These adjustments include visual coarse adjustment, observing from the side to ensure the telescope and collimator optical axes are aligned and coaxial; focusing the telescope to infinity; aligning the telescope's optical axis perpendicular to the spectrometer's central axis; and adjusting the collimator to emit parallel light with its optical axis perpendicular to the spectrometer's central axis. Therefore, operation is complex and demands a high level of experimental skill from the user.

[0007] Another existing multifunctional grating spectrometer consists of a grating polychromator, a CCD receiving unit, an electronic signal processing unit, an A / D acquisition unit, and a computer. Although it integrates multiple technologies such as optics, precision mechanics, electronics, and computer science, it is mainly operated and used by professional laboratories and technicians.

[0008] Technical difficulties associated with conventional experimental instruments: Operating common spectrometers requires a high level of technical skill and places high demands on the user's experimental abilities. When observing atomic spectra, it is necessary to first align the telescope's crosshairs with the center of the zeroth-order spectral line, read the orientation of the incident light from the scale, and then measure the orientations of a pair of corresponding spectral lines on either side of the zeroth-order spectral line, calculating the angles between them and the incident light. If the difference between these angles is no more than 2 minutes, then the parallel rays are considered perpendicular to the incident grating plane, meaning the grating plane is perpendicular to the optical axis of the collimator.

[0009] For measuring the wavelength of atomic spectra, a spectrometer cannot directly read the wavelength; instead, it requires indirect measurement and calculation. The specific process utilizes the grating equation:

[0010] ,

[0011] Measure and record the positions of the +1 and -1 order diffraction spectra. Repeat the measurement three times and take the average value.

[0012] ;

[0013] Therefore, a low-cost, easy-to-operate optical device is needed to meet the needs of teaching and basic experiments. Utility Model Content

[0014] This invention provides an optical device for capturing and measuring atomic spectra, aiming to solve the problem of complex operation of existing instruments for hydrogen atom spectroscopy experiments.

[0015] To achieve the above objectives, the specific solution of this utility model is as follows:

[0016] An optical device for capturing and measuring atomic spectra, comprising:

[0017] A hydrogen lamp used to generate the hydrogen atom spectrum;

[0018] A mercury lamp used to generate a reference spectrum;

[0019] Image acquisition devices used to capture spectral images dispersed by transmission gratings;

[0020] A computer device equipped with image analysis software; an image acquisition device is used to transmit captured spectral images to the computer device; the image analysis software is used to process the spectral images transmitted from the image acquisition device to measure the wavelength of atomic spectra.

[0021] A collimating slit one, a neutral density filter, and a beam splitter are arranged sequentially along the light propagation direction of the mercury lamp. A hydrogen lamp is positioned above the beam splitter, and a collimating slit two is positioned below the beam splitter. A transmission grating is positioned below the collimating slit two. The camera of the image acquisition device is aligned with the transmission grating to capture the spectral image dispersed by the transmission grating.

[0022] Furthermore, the beam splitter includes a dielectric film mirror or a cubic beam splitter.

[0023] Furthermore, the size of the transmission grating is 12.7 mm, 25 mm, or 50 mm, and the number of lines is 600 lines per millimeter.

[0024] Furthermore, the neutral filter is a reflective filter or an absorptive filter.

[0025] Furthermore, the width adjustment range of the first collimation slit and the second collimation slit is set to 0.01 to 2 mm, respectively.

[0026] Furthermore, the image analysis software is Tracker software.

[0027] Advantages of this utility model

[0028] 1. Precise Measurement and Error Calibration: The optical device of this invention for capturing and measuring atomic spectra uses both hydrogen and mercury lamps, eliminating the need to capture separate spectra for each. Only a single captured spectral image needs to be analyzed and measured. Using the mercury lamp spectrum as a reference standard, the hydrogen atom spectrum measurement is calibrated and error checked. This method ensures precise measurement and reliable error analysis of the hydrogen atom spectrum under consistent experimental conditions, providing strong support for the accuracy of experimental data.

[0029] 2. Breakthrough Measurement of Violet Spectral Lines: The Balmer spectral lines of hydrogen atoms in this novel device encompass four light rays: red, blue-green, blue, and violet. In traditional measurements, the violet spectral line is difficult to observe and measure effectively due to its dimness and proximity to the edge of the visible spectrum. This device cleverly utilizes the long-exposure function of the image acquisition device's camera to successfully capture four visible spectral lines, including the brightest spectral line and the dim violet line. This provides the possibility for comprehensive analysis of the hydrogen atom Balmer spectral lines and overcomes the difficulties encountered by conventional measurement methods in measuring violet spectral lines.

[0030] 3. Efficient and convenient spectral wavelength analysis: The Tracker image analysis software is used to perform spectral wavelength analysis on the captured images. This software is easy to operate, requiring no complex measurement procedures or tedious mathematical calculations, and can quickly produce experimental measurement results, greatly improving the efficiency of spectral measurement, reducing the requirements for professional skills, and making spectral measurement easier to learn and popularize.

[0031] 4. High-precision Rydberg constant measurement and wide applicability: The optical device of this invention successfully measured the Rydberg constant of the hydrogen atom and calibrated the mercury lamp spectrum. Experimental results show that it can determine the Rydberg constant with a relative error of less than 0.5%, meeting the accuracy requirements of basic physics experiments. The design combines simple optical components with open-source software, breaking the dependence of traditional spectral measurements on professional laboratory conditions. It has many advantages, including low cost, affordability, simple and quick operation, obvious experimental phenomena, and accurate and efficient data processing. As a scientific and educational experimental device, it is easy to promote and apply on a large scale. It is not only suitable for relevant professionals in universities, but also easy for ordinary teenagers to use and operate, greatly expanding the application scope of spectral measurement in the field of education and helping to stimulate teenagers' interest in science and their spirit of exploration.

[0032] 5. Flexible Light Source Replacement and Expanded Application Range: The optical device of this invention is designed with flexibility in mind, allowing for the flexible replacement of the light source. This enables the measurement of various atomic spectra, such as incandescent lamp spectra, halogen lamp spectra, LED lamp spectra, and fluorescent lamp spectra. This feature greatly expands the application range of the experimental device, extending it beyond hydrogen atom spectrum measurement to include spectral analysis of other types of light sources, meeting diverse experimental needs and enhancing the device's versatility and practicality.

[0033] In summary, the optical device of this invention, with its precise measurement capabilities, innovative method for measuring violet spectral lines, efficient and convenient analytical means, high-precision measurement results, and wide applicability and flexibility, demonstrates enormous application potential and promotional value, bringing new breakthroughs and convenience to the field of atomic spectroscopy measurement. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the optical device of this invention for capturing and measuring atomic spectra.

[0035] Figure 2 for Figure 1 The diffraction spectrum image of the reference spectrum of the mercury lamp obtained by the image acquisition equipment.

[0036] Figure 3 for Figure 1 The diffraction spectrum image of a hydrogen lamp obtained by the image acquisition equipment.

[0037] Figure 4 for Figure 1 A diagram of the Tracker software interface configured on the image acquisition device.

[0038] Figure 5 The transmission spectrum analysis curve of the hydrogen lamp obtained by Tracker software.

[0039] Figure 6 The graph shows the mercury lamp spectrum analysis obtained from the Tracker software.

[0040] In the picture:

[0041] 1. Hydrogen lamp; 2. Beam splitter; 3. Transmission grating; 4. Neutral density filter; 5. Mercury lamp; 6. Collimation slit one; 7. Collimation slit two; 8. Image acquisition equipment. Detailed Implementation

[0042] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. It should be noted that the specific embodiments are not intended to limit the scope of the present invention.

[0043] like Figures 1 to 6 As shown in the illustration, this specific embodiment provides an optical device for capturing and measuring atomic spectra, comprising:

[0044] A hydrogen lamp 1 is used to generate the hydrogen atom spectrum. The hydrogen lamp 1 is a high-pressure gas discharge light source containing hydrogen gas, which emits pink light during discharge. The hydrogen lamp 1 emits light containing the hydrogen atom spectrum. This light passes sequentially through a beam splitter 2, a collimating slit 7, and a transmission grating 3. The transmission grating 3 disperses the light into diffraction spectra of different wavelengths, forming the diffraction spectrum of the hydrogen atom spectrum. An image of the diffraction spectrum is captured by an image acquisition device 8, as shown in the image. Figure 3 As shown. Although the light emitted by hydrogen lamp 1 also passes through beam splitter 2, collimating slit 2 7 and transmission grating 3, and is similar to the light emitted by mercury lamp 5, the spectrum of hydrogen lamp 1 is mainly used for measurement.

[0045] A mercury lamp 5 is used to generate a reference spectrum; the mercury lamp 5 generates a reference spectrum for calibrating the hydrogen atom spectrum; along the light propagation direction of the mercury lamp 5, a collimating slit 6, a neutral density filter 4, and a beam splitter 2 are sequentially arranged; the transmission grating 3 also disperses the light from the mercury lamp 5 into diffraction spectra of different wavelengths, forming the diffraction spectrum of the reference spectrum. This diffraction spectrum of the reference spectrum is mixed with the diffraction spectrum of the hydrogen atom spectrum to form a mixed spectrum image, which is captured by the image acquisition device 8. Figure 2 As shown. The mercury lamp 5 emits light of multiple wavelengths, including specific wavelengths used for calibration, such as 435.8 nm and 546.1 nm. The mercury lamp 5 is based on the arc discharge phenomenon of ionization discharge of metallic mercury vapor in a strong electric field. When the low-voltage mercury lamp 5 with a rated voltage of 220 volts is emitting light normally, it emits bluish-violet light, mainly including 5 monochromatic lights.

[0046] Image acquisition device 8 is used to capture spectral images dispersed by transmission grating 3; the image acquisition device includes, but is not limited to, mobile phones, professional cameras or industrial cameras; the image acquisition device is a mobile phone with a high-resolution camera, the camera resolution is not less than 12 million pixels and the aperture is f / 1.8; the image acquisition device is a professional camera, the camera resolution is not less than 24 million pixels and the aperture is f / 2.8; the image acquisition device is an industrial camera, the industrial camera resolution is not less than 5 million pixels and the aperture is f / 1.4.

[0047] The camera of the image acquisition device 8 is aligned with the transmission grating 3 to capture the spectral image dispersed by the transmission grating. The image acquisition device 8 is used to transmit the captured spectral image to a computer device.

[0048] A computer device equipped with image analysis software, specifically Tracker software, is used to process spectral images transmitted from an image acquisition device to measure the wavelengths of atomic spectra. This implementation uses Tracker software, specifically the Chinese version v6.2.0. The image analysis software can analyze the captured spectral images to measure the wavelengths of atomic spectra, such as... Figure 4 As shown. Due to the beam splitter 2, the camera of the image acquisition device 8 can simultaneously capture the spectra of the mercury lamp 5 and the hydrogen lamp 1. The spectrum of the mercury lamp 5 is used for calibration, while the spectrum of the hydrogen lamp 1 is used for measurement. Figure 5 and Figure 6 As shown, by comparing the known wavelength spectral lines of mercury lamp 5 with the spectral lines of hydrogen lamp 1, the wavelength of the hydrogen atom spectrum can be accurately measured, thereby enabling the imaging and measurement of atomic spectra.

[0049] Along the light propagation direction of the mercury lamp 5, a collimating slit 6, a neutral density filter 4, and a beam splitter 2 are arranged in sequence. The hydrogen lamp 1 is positioned above the beam splitter 2. A collimating slit 7 is positioned below the beam splitter 2. A transmission grating 4 is positioned below the collimating slit 7. The camera of the image acquisition device 8 is aligned with the transmission grating 4 to capture the spectral image dispersed by the transmission grating.

[0050] The function of the collimating slit 6 is to convert the divergent light emitted by the mercury lamp 5 into a more parallel light beam, thereby improving the directionality of the light.

[0051] The neutral density filter 4 can be either a reflective filter or an absorptive filter. The absorptive neutral density filter used in this experiment is made of neutral gray glass. The surface finish of the neutral filter 4 is 60-40, its thickness is 1.33±0.5mm, its transmittance is 79%, and its effective aperture is greater than 90%. The function of the neutral filter 4 is to adjust the light intensity and prevent excessively strong light from damaging subsequent optical components or imaging equipment, such as the camera in an image acquisition device.

[0052] The beam splitter 2 includes a dielectric film reflector or a cubic beam splitter 2. The mercury lamp 5 and the hydrogen lamp 1 are placed in different positions, and light emitted from different sources is unlikely to propagate along the same optical path. The beam splitter 2 decomposes the light emitted from the mercury lamp 5 into multiple beams, allowing some of the light from the mercury lamp 5 and some of the light from the hydrogen lamp 1 to propagate in the same direction. The function of the beam splitter 2 is to guide the light from the mercury lamp 5 to different optical paths; one part continues to propagate to the transmission grating 3, while the other part is guided to the path of the hydrogen lamp 1. The split beams then pass through the collimating slit 7 again, further ensuring the parallelism of the light rays, which is crucial for accurate spectral analysis. The hydrogen lamp 1 is positioned above the beam splitter 2, and the collimating slit 7 is positioned below the beam splitter 2, with the transmission grating 3 positioned below the collimating slit 7.

[0053] Collimating slit 7 further collimates the light from beam splitter 2. Collimating slit 6 and collimating slit 7 serve as key apertures at the optical path entrance, limiting the incident light range and adjusting the light to be parallel. The width of the collimating slits can be adjusted within the range of 0.01 to 2 mm. The optical device in this embodiment uses slit sizes of 0.2, 0.5, and 1.0 mm, which can be selected according to actual measurement requirements to obtain optimal spectral resolution and signal strength.

[0054] The transmission grating 3 has a size of 12.7 mm, 25 mm, or 50 mm. In this embodiment, the transmission grating 3 is 25 mm in size, with 600 lines per millimeter. The function of the transmission grating 3 is to disperse light into spectral lines of different wavelengths for capture by the camera of the image acquisition device 8. The transmission grating 3 utilizes the principle of light diffraction to cause light waves to disperse. It consists of a large number of parallel slits or grooves of equal width and spacing. When the incident light wave contains composite light of several different wavelengths, after diffraction by the grating, the bright fringes of different wavelengths of light of the same order are arranged in a certain order to form colored spectral lines. The light emitted by the hydrogen lamp 1 also passes through the beam splitter 2, collimating slit 7, and transmission grating 3, similar to the light from the mercury lamp 5, but the spectrum of the hydrogen lamp 1 is mainly used for measurement.

[0055] Working principle:

[0056] Simultaneously, hydrogen lamp 1 and mercury lamp 5 are turned on. Hydrogen lamp 1 emits light containing the hydrogen atom spectrum, which passes sequentially through beam splitter 2, collimating slit 7, and transmission grating 3, forming a diffraction spectrum of the hydrogen atom spectrum. Light emitted from mercury lamp 5 passes sequentially through collimating slit 6, neutral density filter 4, beam splitter 2, collimating slit 7, and transmission grating 3, forming a diffraction spectrum of the reference spectrum. Beam splitter 2 decomposes the light from mercury lamp 5 into multiple beams. A portion continues to propagate to transmission grating 3, while another portion is guided to the path of hydrogen lamp 1, ensuring that both beams propagate in the same direction. Transmission grating 3 utilizes the principle of light diffraction to disperse the light into spectral lines of different wavelengths. The diffraction spectrum of the hydrogen atom spectrum mixes with the diffraction spectrum of the reference spectrum to form a mixed spectral image, which is captured by an image acquisition device. The camera of the image acquisition device is aimed at transmission grating 3, and its Tracker software processes the captured spectral image. The camera of the image acquisition device simultaneously captures spectral images of the mercury lamp 5 and the hydrogen lamp 1, including the diffraction spectrum of the hydrogen atom spectrum and the diffraction spectrum of the reference spectrum.

[0057] The captured spectral images were analyzed using Tracker software. By comparing the known wavelength spectral lines of mercury lamp 5 (such as 435.8 nm and 546.1 nm) with the diffraction spectral lines of hydrogen lamp 1, Tracker software could accurately measure the wavelength of the hydrogen atom spectrum. This combination of calibration and measurement ensured the accuracy and reliability of hydrogen atom spectral measurements, thus enabling efficient imaging and measurement of atomic spectra.

[0058] The following section performs spectral calibration and analysis on the spectral images captured by the optical device used for capturing and measuring atomic spectra in the above specific embodiments:

[0059] I. Spectral Calibration:

[0060] 1. Open the Tracker software and drag and drop the captured image to import it, or import it through the "File → Open" toolbar at the top of the Tracker software page.

[0061] 2. Repeatedly adjust the image position, selecting the start and end points of the spectral region marked in the image, and choosing an area with continuous light and high brightness.

[0062] 3. Click "Show / Hide Axes" to establish a Cartesian coordinate system in this area, with the right direction as positive. Drag and rotate the axes according to the selected area to ensure that the axes pass through the entire calibration area. You can choose to hide the axes according to the experimental requirements.

[0063] 4. Click "New → Calibration Point" in the toolbar. The Tracker software determines the length value based on the coordinates between two points. Hold down the Shift key and move the mouse to determine the left and right endpoints. Then you can read and record the coordinates of the two points in the toolbar above.

[0064] 5. After calibrating the endpoints, you can perform spectral analysis. In the Tracker software, find and click "Create → Line Type → Line Type A" in the toolbar at the top. Locate the area to be analyzed and drag the mouse to confirm. If the line type cannot completely cover the vertical axis length of the spectral lines in the selected area, you can customize the tiling value in the Tracker software toolbar at the top.

[0065] 6. The right toolbar of the Tracker software displays the curve image of the spectrum and the coordinate data of the image.

[0066] II. Diffraction Spectrum Analysis of Hydrogen Lamp 1

[0067] 1. For example Figure 5 As shown, the diffraction spectrum analysis curve of hydrogen lamp 1 was obtained experimentally. When analyzing the spectrum using Tracker software, the horizontal and vertical coordinate data of the spectral image can be measured, i.e., the wavelength and corresponding intensity of the visible light spectrum. Figure 5 The diffraction spectrum analysis curve of hydrogen lamp 1 shown below contains the measured peak values ​​and their corresponding light intensities:

[0068] The first peak value has an abscissa of 436.731nm and a ordinate corresponding to a light intensity of 177.485, which corresponds to blue light.

[0069] The second peak value is 488.731 nm, corresponding to a light intensity of 88.591, which corresponds to cyan light.

[0070] The third peak value is 516.731 nm, corresponding to a light intensity of 143.692, and this wavelength corresponds to green light.

[0071] The fourth peak value is 552.731, corresponding to a light intensity of 87.350, and this wavelength corresponds to yellow light.

[0072] The fifth peak value is 672.731 nm, corresponding to a light intensity of 66.934, and this wavelength corresponds to red light.

[0073] 2. Calculate the Rydberg constant based on the standard spectral lines of the Balmer series and compare it with the standard value to calculate the relative error. For example:

[0074] The Rydberg constant of the standard hydrogen atom is .

[0075] When the wavelength is 436.731 nm, the calculated Berg constant is R ≈ 1.0905 × 10⁷ m⁻¹, and the relative error with the standard value is approximately:

[0076] ,

[0077] When the wavelength is 488.731 nm, the relative error between the calculated value R≈1.0936×10⁷ and the standard value is approximately:

[0078] ,

[0079] Errors may originate from wavelength deviations; the software-calibrated wavelength differs from the standard wavelength, which may be due to measurement errors or spectral broadening.

[0080] III. Diffraction Spectral Analysis of Reference Spectrum of Mercury Lamp 5

[0081] like Figure 6 As shown, the experimental results for the mercury lamp 5's spectral analysis curve are as follows. In the transmission diffraction spectral analysis curve, the measured peak values ​​and their corresponding light intensities are as follows:

[0082] The first peak value is 394.617nm, and the horizontal axis corresponds to a light intensity of 28.184, which corresponds to violet light.

[0083] The second peak value is 445.617 nm, corresponding to a light intensity of 29.315, and this wavelength corresponds to blue light;

[0084] The third peak value is 510.966 nm, corresponding to a light intensity of 140.337, and this wavelength corresponds to green light;

[0085] The fourth peak value is 567.966, corresponding to a light intensity of 81.759, and this wavelength corresponds to yellow light.

[0086] IV. Experimental Environment and Precautions

[0087] 1. Place the lens in a location close to the mercury lamp light source that allows for capturing the entire spectrum, and ensure a completely dark and quiet shooting environment to avoid the influence of stray light sources and sound sources on the experiment.

[0088] 2. The captured images will be affected by the distance, angle and lighting conditions of the shooting scene, and the spectral brightness is prone to change. Therefore, it is necessary to ensure the consistency of the shooting environment.

[0089] Through the above steps and parameter settings, the optical device of this embodiment can accurately measure the wavelength of the hydrogen atom spectrum and determine its characteristics, providing reliable data support for scientific research and practical applications.

Claims

1. An optical device for capturing and measuring atomic spectra, characterized in that, include: A hydrogen lamp used to generate the hydrogen atom spectrum; A mercury lamp used to generate a reference spectrum; Image acquisition devices used to capture spectral images dispersed by transmission gratings; A computer device equipped with image analysis software; an image acquisition device is used to transmit captured spectral images to the computer device; the image analysis software is used to process the spectral images transmitted from the image acquisition device to measure the wavelength of atomic spectra. A collimating slit one, a neutral density filter, and a beam splitter are arranged sequentially along the light propagation direction of the mercury lamp. A hydrogen lamp is positioned above the beam splitter, and a collimating slit two is positioned below the beam splitter. A transmission grating is positioned below the collimating slit two. The camera of the image acquisition device is aligned with the transmission grating to capture the spectral image dispersed by the transmission grating.

2. The optical device according to claim 1, characterized in that, The beam splitter includes a dielectric film mirror or a cubic beam splitter.

3. The optical device according to claim 1, characterized in that, The dimensions of the transmission grating are 12.7 mm, 25 mm, or 50 mm, and the number of lines is 600 lines per millimeter.

4. The optical device according to claim 1, characterized in that, The neutral density filter is either a reflective filter or an absorptive filter.

5. The optical device according to claim 1, characterized in that, The width adjustment range of the first and second collimating slits is set to 0.01 to 2 mm, respectively.

6. The optical device according to claim 1, characterized in that, The image analysis software is Tracker software.

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