Dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring tube image visualization

Abstract

The present invention discloses a dual-optical-path spinning drop interfacial tensiometer imaging system with a visual image of the entire measuring tube. The key technical solution is that the system comprises a panoramic optical path and a measuring optical path. The panoramic optical path includes a panoramic lens and a panoramic digital camera, which are mounted on the panoramic digital camera and correspond to the panoramic LED backlight. The measuring optical path includes a measuring lens and a measuring digital camera, which are mounted on the measuring digital camera and correspond to the measuring LED backlight. The measuring optical path is arranged on a translation mechanism, and the measuring sample tube is placed within the rotation mechanism and rotates with the rotation mechanism. The translation mechanism and the rotation mechanism are controlled by a control system and a computer. This imaging system solves the problem of single-optical-path spinning drop interfacial tensiometer imaging systems, which cannot accurately measure tension or identify the position of the spinning drop in the measuring tube when the spinning drop length exceeds the visual range because the image of the entire spinning drop and the entire measuring tube cannot be observed.

Description

Technical Field

[0001] The invention belongs to the technical field of optical detection, and relates to a dual-light-path rotating drop interfacial tension meter imaging system with visible full-measuring tube images. Background Art

[0002] When using the spinning drop method to measure interfacial tension, it is generally necessary to take photos of the spinning drop for a long time. The position of the spinning drop is affected by many factors such as gravity, the physical state of the spinning drop, purity, density, ambient temperature, and the rotation speed of the mechanism. The position of the spinning drop is difficult to maintain stable during the entire measurement process, so its position needs to be captured in real time.

[0003] Traditional spinning drop interfacial tensiometers are single-optical imaging systems, consisting solely of a measurement imaging system. While meeting the requirements for tension measurement accuracy, the resolution of the measurement imaging system is limited by factors such as the magnification of the current measurement lens, the working distance of the measurement lens, the size of the measurement camera target, and the pixel density on the measurement camera target. Consequently, the horizontal length of its field of view is significantly shorter than the length of the measurement sample tube. When the length of the spinning drop exceeds the horizontal field of view of the measurement imaging system, the system cannot capture the entire spinning drop and the entire measurement tube, making accurate tension measurement and identification of the spinning drop's position within the tube impossible.

[0004] Traditional spinning drop tensiometers require the operator to manually operate the image-finding mechanism to move the spinning drop into the field of view of the measurement imaging system. Because the position of the spinning drop changes in real time, this requires frequent manual operation, resulting in high labor intensity and low production efficiency. Summary of the Invention

[0005] The object of the present invention is to provide a dual-light-path rotating drop interfacial tension meter imaging system with visual image of the entire measuring tube, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a dual-optical path rotating drop interfacial tension meter imaging system with visual image of the entire measuring tube, wherein the imaging system includes a panoramic optical path and a measuring optical path;

[0007] The panoramic optical path is used for capturing rotating drops and measuring tension in the full measuring tube range with a large field of view;

[0008] The measuring optical path is used for high-precision tension measurement in a small field of view;

[0009] The panoramic optical path is capable of capturing images or videos of the entire measuring tube;

[0010] The measuring optical path can realize high-resolution imaging of a small field of view where the rotating droplet is located.

[0011] Preferably, the panoramic optical path includes a panoramic lens and a panoramic digital camera, the panoramic lens is mounted on the panoramic digital camera, and the panoramic optical path corresponds to the panoramic LED backlight source; the measurement optical path includes a measurement lens and a measurement digital camera, the measurement lens is mounted on the measurement digital camera, and the measurement lens corresponds to the measurement LED backlight source.

[0012] Preferably, the panoramic LED backlight source and the measurement LED backlight source are placed in the panoramic optical path and the measurement optical path, respectively. Light emitted by the panoramic LED backlight source passes through the measurement sample tube and the panoramic lens, forming an image of the entire measurement tube and the rotating droplet on the target surface of the panoramic camera. Light emitted by the measurement LED backlight source passes through the measurement sample tube and the measurement lens, forming an image of the rotating droplet on the target surface of the measurement camera. The measurement sample tube is placed in a rotating mechanism, rotating with the rotating mechanism. The measurement optical path is arranged on a translation mechanism, moving with the translation mechanism. The translation mechanism and the rotation mechanism are respectively controlled by a control system and a computer.

[0013] Preferably, the panoramic lens is a large-field panoramic lens, and the end of the panoramic lens away from the panoramic digital camera is connected to the panoramic optical path extinction tube. The end of the panoramic optical path extinction tube is provided with a 45° inclined surface, and a panoramic optical path folding mirror is installed on the inclined surface. The panoramic optical path folding mirror is facing the panoramic LED backlight source.

[0014] Preferably, the measuring lens is a high-magnification measuring lens, the measuring lens is mounted on a measuring light path bracket, the measuring light path bracket is fixed on a translation mechanism, the end of the measuring lens away from the measuring digital camera is connected to a measuring light path deflecting device, a measuring light path deflecting mirror is provided at a corner of the measuring light path deflecting device, and the measuring light path deflecting mirror is directly facing the measuring LED backlight source.

[0015] Preferably, the translation mechanism includes a translation mechanism slider, a translation mechanism guide rail, a translation mechanism motor, a translation mechanism coupling and a translation mechanism screw; the measuring optical path bracket is installed on the translation mechanism slider, the translation mechanism slider slides on the translation mechanism guide rail, a translation mechanism screw is provided at the lower end of the translation mechanism guide rail, the translation mechanism screw is connected to the translation mechanism coupling, and the translation mechanism coupling is connected to the translation mechanism motor.

[0016] Preferably, a rotating mechanism is connected to the side of the measurement sample tube, both ends of the measurement sample tube are sealed, and the middle section is a hollow high-purity quartz glass tube.

[0017] Preferably, the rotating mechanism is composed of a high-speed motor, a precision bearing, and a rotating shaft. The precision bearing is sleeved on the rotating shaft, and the high-speed motor drives the rotating shaft to rotate.

[0018] Preferably, the panoramic LED backlight source includes a panoramic light source circuit board, a panoramic light source LED and a panoramic light source soft light panel. The panoramic light source circuit board controls the switching and brightness of the panoramic light source LED. A panoramic light source soft light panel is also provided on the side of the panoramic light source LED102.

[0019] Preferably, the measurement LED backlight source includes a measurement light source circuit board, a measurement light source LED and a measurement light source soft light plate, and the measurement light source circuit board controls the switch and brightness of the measurement light source LED; a measurement light source soft light plate is also provided at the upper end position of the measurement light source LED, and the measurement light source soft light plate is fixed on the measurement light source circuit board.

[0020] Technical effects and advantages of the present invention:

[0021] The dual-optical path spinning drop interfacial tensiometer imaging system has a panoramic optical path for complete spinning drop image observation and tension measurement within the entire measuring tube, and a measuring optical path for high-precision tension measurement in a small field of view. This system realizes the imaging function of the spinning drop being observable within the entire measuring tube, providing an imaging basis for the spinning drop interfacial tensiometer using this system to automatically identify the spinning drop position and automatically calculate the tension within the entire measuring tube.

[0022] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a stereoscopic image of the dual-optical-path spinning drop interfacial tension instrument imaging system;

[0024] Figure 2 Schematic diagram of the panoramic optical path structure of the present invention;

[0025] Figure 3 Schematic diagram of the installation of the measuring optical path of the present invention;

[0026] Figure 4 Schematic diagram of the structure of the measuring optical path of the present invention;

[0027] Figure 5 This is a schematic structural diagram of the panoramic LED backlight source of the present invention;

[0028] Figure 6 A schematic structural diagram of the LED backlight source measurement system of the present invention.

[0029] In the figure: 1. Panoramic LED backlight; 2. Panoramic lens; 3. Panoramic digital camera; 4. Measurement LED backlight; 5. Measurement lens; 6. Measurement digital camera; 7. Translation mechanism; 8. Measurement sample tube; 9.

[0030] Rotating mechanism; 10. Control system and computer;

[0031] 101. Panoramic light source circuit board; 102. Panoramic light source LED; 103. Panoramic light source soft light panel;

[0032] 201. Panoramic optical path deflecting mirror; 202. Panoramic optical path extinction tube;

[0033] 401. Measure the light source circuit board; 402. Measure the light source LED; 403. Measure the light source soft board;

[0034] 501. Measuring optical path deflecting mirror; 502. Measuring optical path bracket;

[0035] 701. Translation mechanism slider; 702. Translation mechanism guide rail; 703. Translation mechanism motor; 704.

[0036] Translation mechanism coupling; 705. Translation mechanism screw. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] The present invention provides Figure 1-6 The image of a dual-light path spinning drop interfacial tension meter with full measurement tube image visualization is shown.

[0039] The imaging system of this invention utilizes two optical paths: a panoramic optical path for observing the complete rotating droplet image and measuring tension within the entire measuring tube; and a measuring optical path for high-precision tension measurement within a narrow field of view. The panoramic optical path can capture images or videos of the entire measuring tube and the rotating droplet, ensuring that the image of the rotating droplet remains within the visible range. The measuring optical path enables high-resolution imaging within the narrow field of view within which the rotating droplet resides.

[0040] The present invention comprises a panoramic LED backlight source 1, a large-field panoramic lens 2, a panoramic digital camera 3, a measuring LED backlight source 4, a measuring lens 5, a measuring digital camera 6, a translation mechanism 7, a rotation mechanism 9, a measuring sample tube 8, a control system and a computer 10.

[0041] The panoramic optical path is located at the upper end of the measurement optical path. Specifically, it is mounted on a fixed frame, the bottom end of which is connected to the base. A translation mechanism 7 is provided at the lower end of the measurement optical path, and the measurement optical path moves with the translation mechanism 7. A rotation mechanism 9 is provided on the side of the translation mechanism 7, and a measurement sample tube 8 is placed within the rotation mechanism 9. The measurement sample tube 8 rotates with the rotation mechanism 9. The translation mechanism 7 and the rotation mechanism 9 are controlled by a control system and a computer 10, respectively.

[0042] Specifically, the panoramic optical path is composed of a panoramic LED backlight source 1, a large-field panoramic lens 2, and a panoramic digital camera 3. The front end of the panoramic digital camera 3 is provided with a large-field panoramic lens 2. The other end of the large-field panoramic lens 2 is connected to a panoramic optical path extinction tube 202. The end of the panoramic optical path extinction tube 202 is provided with a 45° inclined surface, and a panoramic optical path folding mirror 201 is installed on the inclined surface. Specifically, the panoramic optical path extinction tube 202 is configured to be retractable and divided into an inner tube and an outer tube, and the inner tube is nested inside the outer tube. The outermost end of the outer tube is connected to a triangular folding device, and a 45° inclined surface is provided at the folding point of the folding device. The inclined surface is fixedly connected to the panoramic optical path folding mirror 201 for refraction of light. The panoramic optical path deflecting mirror 201 is facing the panoramic LED backlight source 1, and the panoramic LED backlight source 1 is placed below the measuring sample tube 8. The light emitted by the panoramic LED backlight source 1 passes through the measuring sample tube 8 and the panoramic digital camera 3, so that the measuring sample tube 8 and the rotating droplet are imaged on the target surface of the panoramic digital camera 3.

[0043] The panoramic LED backlight source 1 includes a panoramic light source circuit board 101, a panoramic light source LED 102, and a panoramic light source soft light panel 103. The panoramic light source circuit board 101 controls the light source size of the panoramic light source LED 102 to open and close. In order to make the taken photos clearer, a panoramic light source soft light panel 103 is also provided on the side of the panoramic light source LED 102.

[0044] Specifically, the measurement optical path consists of a measurement LED backlight 4, a measurement lens 5, and a measurement digital camera 6. The measurement lens 5 is located at the front end of the measurement digital camera 6. In this embodiment, a high-magnification measurement lens is used. The measurement lens 5 is mounted on a measurement optical path bracket 502, which is fixed to the translation mechanism 7. The other end of the measurement lens 5 is connected to a measurement optical path deflection device. A measurement optical path deflection mirror 501 is installed at a corner of the measurement optical path deflection device, facing the measurement LED backlight 4. The measurement LED backlight 4 is placed below the measurement sample tube 8 to allow light emitted by the measurement LED backlight 4 to pass through the measurement sample tube 8 and the measurement lens 5, forming an image of the rotating droplet on the target surface of the measurement digital camera 6. The measurement LED backlight source 4 includes a measurement light source circuit board 401, a measurement light source LED 402, and a measurement light source soft plate 403; the measurement light source circuit board 401 controls the light source size and on / off of the measurement light source LED 402; in order to make the taken photos clearer and avoid the influence of strong light, a measurement light source soft plate 403 is also provided at the upper end of the measurement light source LED 402, and the measurement light source soft plate 403 is bolted to the measurement light source circuit board 401.

[0045] Specifically, a translation mechanism 7 is further provided at the lower end of the measurement optical path, and the translation mechanism 7 includes a translation mechanism slider 701, a translation mechanism guide rail 702, a translation mechanism motor 703, a translation mechanism coupling 704 and a translation mechanism screw 705; the measurement optical path bracket 502 is installed on the translation mechanism slider 701, and the translation mechanism slider 701 slides on the translation mechanism guide rail 702. A translation mechanism screw 705 is provided at the lower end of the translation mechanism guide rail 702, and the translation mechanism screw 705 is connected to the translation mechanism coupling 704. The translation mechanism coupling 704 is connected to the translation mechanism motor 703, and the translation mechanism motor 703 drives the movement of the translation mechanism slider 701, so that it drives the measuring lens 5 and the measuring digital camera 6 to move to the rotating drop position.

[0046] Specifically, the measurement sample tube 8 is placed above the panoramic LED backlight source 1 and the measurement LED backlight source 4. The measurement sample tube 8 is placed in a rotating mechanism 9, which includes a rotating motor, precision bearings, a rotating shaft, and a coupling. The precision bearing is sleeved on the rotating shaft. One end of the rotating shaft is connected to the rotating motor, and the other end is connected to the coupling. The coupling includes an outer rotor and an inner rotor. The outer rotor is connected to the output shaft of the drive motor, and the inner rotor is directly connected to the rotating body. The rotating body includes a stainless steel sealed cabin with symmetrically positioned observation windows. The bearings of the rotating mechanism 9 are fixed to the cabin. A seal is provided at the connection between one end of the cabin and the coupling. The other end of the cabin encloses a rotating transmission device. The rotating transmission device includes a measurement sample tube 8 containing a sample. The measurement sample tube 8 is held by the rotating body. The rotating motor is connected to a control system and a computer 10. The rotation speed of the rotating motor is controlled by a program, and the computer is responsible for calculating the tension value of the rotating drop. During the test, the measurement sample tube 8 is first placed in the rotating transmission device, and the rotating mechanism 9 rotates at high speed, thereby driving the measurement sample tube 8 placed therein to rotate at high speed. After the speed runs steadily for a certain period of time, subsequent framing measurements are performed.

[0047] The following are the functions and effects of each component:

[0048] Panoramic LED backlight 1

[0049] It is used to provide a light source for the panoramic light path, including a panoramic light source circuit board 101 and a panoramic light source soft light board 103. When the panoramic imaging light path is working, the control system drives the panoramic light source LED 102.

[0050] Wide field of view panoramic lens 2

[0051] It is used for the panoramic imaging optical path, and the field of view covers the entire range of the measuring sample tube 8. During the test, no matter where the rotating drop is in the measuring sample tube 8, its position can be covered.

[0052] Panoramic digital camera 3

[0053] Used for panoramic imaging optical path image acquisition. The acquired images are not only used to capture the image position of the rotating droplet within the entire range of the measurement sample tube 8, but can also be used for rotating droplet size conversion calculations and tension value calculation based on physical quantities such as rotation speed and temperature;

[0054] The diagonal length of the camera imaging chip target surface ranges from 1 / 3 inch to 2 inches.

[0055] Measuring LED backlight 4

[0056] It is used for filling light in the measurement optical path and is composed of a measurement light source circuit board 401 and a measurement light source soft light board 403. When the measurement imaging optical path is working, the control system drives the measurement light source LED 402.

[0057] Measuring lens 5

[0058] Used to measure the imaging optical path, the image of the high-speed rotating droplet in the measurement sample tube 8 is magnified. A higher magnification increases measurement accuracy. If the digital camera target surface is fixed, a higher magnification corresponds to a smaller field of view. To achieve micron-level measurement accuracy, the magnification of the measurement lens 5 is typically between 0.1x and 4.5x.

[0059] Measuring digital camera 6

[0060] It is used to measure the imaging optical path image acquisition. The acquired image is used for rotating droplet size conversion calculation, and then the tension value is calculated based on physical quantities such as rotation speed and temperature.

[0061] The diagonal length of the camera imaging chip target surface ranges from 1 / 3 inch to 2 inches.

[0062] Translation mechanism 7

[0063] Because the field of view of the measurement lens 5 is much smaller than the full length of the measurement sample tube 8, it's impossible to ensure that the rotating droplet remains within the measurement field of view during testing. Therefore, the digital camera 6 and the measurement lens 5 must be capable of left and right movement to accommodate varying positions of the rotating droplet. The translation mechanism 7 accomplishes this function. The translation mechanism 7 features high linearity and zero backlash, ensuring that the rotating droplet remains within the optical path depth of field and provides stable imaging before and after movement.

[0064] During operation, the control system first obtains the position of the rotating droplet through the panoramic imaging optical path, converts it into the driving steps of the translation mechanism motor 703, and then drives the translation mechanism motor 703 to drive the measuring lens 5 and the measuring digital camera 6 to move to the rotating droplet position.

[0065] Measuring sample tube 8

[0066] The measurement sample tube 8 is typically 30mm-60mm long (L), with an inner diameter (H) greater than 10 times H. The inner diameter (H) is typically set to φ2mm-φ6mm. Both ends are sealed, and the middle section is a hollow, high-purity quartz glass tube. During testing, the measurement sample tube 8 is inserted, sealed at both ends, and then mounted in the rotating mechanism 9.

[0067] Rotating mechanism 9

[0068] The rotating mechanism 9 consists of a high-speed motor, precision bearings, and a rotating shaft. The precision bearings are mounted on the rotating shaft, and the high-speed motor drives the rotating shaft. The rotating mechanism 9 drives the measurement sample tube 8 to rotate at a set speed, which is used for tension calculation.

[0069] Control system and computer 10

[0070] The control system and computer 10 first capture the position of the rotating droplet through the panoramic imaging optical path, and then drive the translation mechanism 7 according to the rotating droplet position information to translate the high-magnification measurement lens 5 to the rotating droplet position. A high-definition rotating droplet image is obtained by measuring the imaging optical path, and then the length and height of the rotating droplet are calculated, and finally the tension value calculation is completed.

[0071] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Dual-optical path spinning drop interfacial tension meter imaging system with full measurement tube image visualization, characterized by: The imaging system comprises a panoramic optical path and a measuring optical path; the panoramic optical path comprises a panoramic lens (2), a panoramic digital camera (3) and a panoramic LED backlight source (1); the panoramic lens (2) is mounted on the panoramic digital camera (3); the light emitted by the panoramic LED backlight source (1) passes through the measuring sample tube (8) and the panoramic digital camera (3), so that the measuring sample tube (8) and the rotating droplet are imaged on the target surface of the panoramic digital camera (3); the measuring optical path comprises a measuring lens (5), a measuring digital camera (6) and a measuring LED backlight source (4); the measuring lens (5) is mounted on the measuring digital camera (6); the light emitted by the measuring LED backlight source (4) passes through the measuring sample tube (8) and the measuring lens (5), The rotating droplet is imaged on the target surface of the measuring digital camera (6); the measuring sample tube (8) is arranged in the rotating mechanism (9), the measuring sample tube (8) rotates together with the rotating mechanism (9), the measuring optical path is arranged on the translation mechanism (7), the measuring optical path moves together with the translation mechanism (7), the translation mechanism (7) and the rotating mechanism (9) are respectively controlled by a control system and a computer (10); the control system and the computer (10) first capture the position of the rotating droplet through the panoramic optical path, and then drive the translation mechanism (7) according to the rotating droplet position information, so that the high-magnification measuring lens (5) is translated to the rotating droplet position, and a high-definition rotating droplet image is obtained through the measuring optical path, and then the length and height of the rotating droplet are calculated, and finally the tension value calculation is completed; The panoramic optical path is used for capturing rotating drops and measuring tension in the full measuring tube range with a large field of view; The measuring optical path is used for high-precision tension measurement in a small field of view; The panoramic optical path can capture images or videos of the complete measuring tube; The measuring optical path can realize high-resolution imaging of a small field of view where the rotating droplet is located.

2. The dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring-tube image visualization according to claim 1, characterized in that: The rotating mechanism (9) is composed of a high-speed motor, a precision bearing, and a rotating shaft. The precision bearing is sleeved on the rotating shaft, and the high-speed motor drives the rotating shaft to rotate.

3. The dual-optical path spinning drop interfacial tension meter imaging system with full-measuring tube image visualization according to claim 1, characterized in that: The measuring sample tube (8) is sealed at both ends, and the middle section is a hollow high-purity quartz glass tube.

4. The dual-optical path spinning drop interfacial tension meter imaging system with full-measuring tube image visualization according to claim 1, characterized in that: One end of the panoramic lens (2) away from the panoramic digital camera (3) is connected to a panoramic light path extinction cylinder (202); a 45° inclined surface is provided at the end of the panoramic light path extinction cylinder (202); a panoramic light path folding mirror (201) is mounted on the inclined surface; and the panoramic light path folding mirror (201) faces the panoramic LED backlight source (1).

5. The dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring-tube image visualization according to claim 1, characterized in that: The measuring lens (5) is mounted on a measuring light path bracket (502), the measuring light path bracket (502) is fixed on a translation mechanism (7), one end of the measuring lens (5) away from the measuring digital camera (6) is connected to a measuring light path deflecting device, a measuring light path deflecting mirror (501) is provided at a corner of the measuring light path deflecting device, and the measuring light path deflecting mirror (501) faces the measuring LED backlight source (4).

6. The dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring-tube image visualization according to claim 5, characterized in that: The translation mechanism (7) comprises a translation mechanism slider (701), a translation mechanism guide rail (702), a translation mechanism motor (703), a translation mechanism coupling (704) and a translation mechanism lead screw (705); the measuring optical path bracket (502) is mounted on the translation mechanism slider (701); the translation mechanism slider (701) slides on the translation mechanism guide rail (702); a translation mechanism lead screw (705) is provided at the lower end of the translation mechanism guide rail (702); the translation mechanism lead screw (705) is connected to the translation mechanism coupling (704); and the translation mechanism coupling (704) is connected to the translation mechanism motor (703).

7. The dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring-tube image visualization according to claim 1, characterized in that: The panoramic LED backlight source (1) comprises a panoramic light source circuit board (101), a panoramic light source LED (102) and a panoramic light source soft plate (103); the panoramic light source circuit board (101) controls the switching and brightness of the panoramic light source LED (102); and the panoramic light source soft plate (103) is further provided on the side of the panoramic light source LED (102).

8. The dual-optical-path spinning drop interfacial tension meter imaging system with full-measuring-tube image visualization according to claim 1, characterized in that: The measuring LED backlight source (4) comprises a measuring light source circuit board (401), a measuring light source LED (402) and a measuring light source soft plate (403); the measuring light source circuit board (401) controls the switch and brightness of the measuring light source LED (402); a measuring light source soft plate (403) is further provided at the upper end of the measuring light source LED (402); the measuring light source soft plate (403) is fixed on the measuring light source circuit board (401).

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