Device and Method for Measuring Micro-Displacement of Strip by Differential Optical Flux Bridge Method

Abstract

The present invention discloses a device and method for measuring the micro-displacement of a strip by the differential optical flux bridge method. The strip to be measured is placed between the first and second lenses. The light beam emitted by the light source is converged into a parallel light beam by the first lens and then converged by the second lens and incident on the photoresistor of the bridge photoelectric measurement circuit. A part of the light beam emitted from the first lens is blocked by the strip, and the other part is directly incident on the second lens. The bridge photoelectric measurement circuit outputs a voltage to characterize the micro-displacement after passing through a conversion amplifier, and accurately obtains the relationship between the voltage and the micro-displacement. The present invention realizes the conversion of the change of the micro-displacement by using the method of differential optical flux, measures the differential optical flux through a direct current bridge photoelectric conversion circuit, and then outputs a voltage after passing through a conversion amplifier, accurately measures the micro-displacement of the strip, and greatly improves the measurement accuracy of the micro-displacement.

Description

Technical Field

[0001] The present invention relates to a device and method for measuring the micro-displacement of an object, and in particular to a device and method for measuring the micro-displacement of a strip by a differential optical flux bridge method. Background Art

[0002] There are many methods for measuring small deformations in physical experiments, mainly including the optical lever method, the micrometer method, the single-slit diffraction method, the optical interference method, the sensor method, etc. An accurate displacement measurement system has increasingly become the research content in various fields. Therefore, it is of great significance to increase the methods for measuring small displacements. The existing displacement measurement methods are roughly divided into three categories: mechanical measurement methods, electrical measurement methods, optical measurement methods, etc. Summary of the Invention

[0003] In order to solve the problems existing in the background art, the present invention provides a device and method for measuring the micro-displacement of a strip by a differential optical flux bridge method, which is an experimental instrument system for measuring the micro-displacement of a strip integrating optics, electricity, mechanics and computer technology.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention mainly includes a light source, a lens group, an object to be measured, and a bridge optoelectronic measurement circuit; the lens group includes a first lens and a second lens, the object to be measured is a strip, the strip is placed between the first lens and the second lens, the light beam emitted by the light source is converged into a parallel beam by the first lens and then converged by the second lens and incident on the photoresistor of the bridge optoelectronic measurement circuit. A part of the light beam emitted from the first lens is blocked by the strip, and the other part is directly incident on the second lens. The output end of the bridge optoelectronic measurement circuit is connected to an external computer through a conversion amplifier.

[0006] The described bridge optoelectronic measurement circuit includes a first photosensitive resistor R1, a second photosensitive resistor R2, resistors R3, R4, R5, R7, R8, and a conversion amplifier. The light beam emitted from the second lens irradiates on the first photosensitive resistor R1, and the second photosensitive resistor R2 is completely blocked by a light shield. A bridge circuit is formed by the first photosensitive resistor R1, the second photosensitive resistor R2, resistors R3, and R4. After the first photosensitive resistor R1 and resistor R3 are connected in series, they are respectively connected to the power supply voltage and ground. After the second photosensitive resistor R2 and resistor R4 are connected in series, they are respectively connected to the power supply voltage and ground. A connection is led out between the first photosensitive resistor R1 and resistor R2, and after passing through resistor R5, it is connected to the inverting input terminal of the amplifier. A connection is led out between the second photosensitive resistor R2 and resistor R4, and after passing through resistor R6, it is connected to the non-inverting input terminal of the amplifier. The non-inverting input terminal of the conversion amplifier is grounded after passing through resistor R6, and the inverting input terminal of the amplifier is connected to the output terminal through resistor R8. The output voltage of the output terminal of the amplifier is sent to the Arduino board, the relationship formula between the derived voltage and the micro-displacement is obtained, and finally the Arduino board is connected to a computer. In this way, the first photosensitive resistor is used as a measurement element, and the other second photosensitive resistor is used as a temperature compensation element and will be covered by a light shield. The two photosensitive resistors R1, R2 and the other two fixed-value resistors R3, R4 form a bridge circuit.

[0007] The described strip is an opaque object, and specifically, a steel plate with a rectangular cross-section can be used.

[0008] The described strip moves closer to / away from the optical axis in a direction perpendicular to the optical axis.

[0009] The light source, the lens group, and the photosensitive resistor R1 of the bridge optoelectronic measurement circuit are arranged on the same optical axis.

[0010] The photosensitive resistor R2 is a light-shielded photosensitive resistor. The photosensitive resistor is sensitive to light. The stronger the light, the smaller the resistance, and the resistance is the largest when there is no light at all.

[0011] II. A method for measuring the micro-displacement of a strip by the differential light flux bridge method:

[0012] The light beam emitted by the light source is converged into a parallel beam by the first lens, and then converged by the second lens and incident on the photoresistor R1 of the bridge photoelectric measurement circuit. A part of the light beam emitted by the first lens is blocked by the strip, and the other part is directly incident on the second lens. The output current signal of the bridge photoelectric measurement circuit is converted into a voltage signal by a conversion amplifier; in the path where the parallel light beam emitted by the first lens reaches the second lens, a part of the light is blocked by the strip, so that the light flux incident on the photoresistor from the second lens is reduced, which in turn affects the illumination intensity of the first photoresistor R1, causing the finally output voltage signal to change; during the micro-displacement process of the strip along the direction perpendicular to the light beam, the voltage signal is collected in real time, and the change of the voltage signal is analyzed and processed to obtain the measurement result of the micro-displacement of the strip.

[0013] Before the experimental measurement, move the strip to completely block the light beam emitted by the first lens, and pre-adjust the bridge balance. The pre-adjustment of the bridge balance is specifically achieved by adjusting the resistance R3 parameter in the bridge photoelectric measurement circuit, so that the voltage U0 at the output end of the amplifier is zero.

[0014] The change of the voltage signal is analyzed and processed to obtain the measurement result of the micro-displacement of the strip. Specifically, the following formula is used to inversely calculate the micro-displacement of the strip:

[0015] U=-ae X / b +c

[0016] Where U represents the voltage value output by the bridge photoelectric measurement circuit after passing through the conversion amplifier, X represents the radial change distance of the cross-section of the strip from the maximum light flux to the minimum light flux, and a, b, and c respectively represent the first, second, and third fitting parameters.

[0017] The present invention realizes the conversion of the change of the micro-displacement by using the method of differential light flux, and measures the differential light flux through a direct current bridge and a photoelectric conversion circuit. Because the photoelectric sensor is used to accurately measure the micro-displacement of the strip, the ratio of the change of the light passing amount to the micro-displacement amount is increased, and the measurement accuracy of the micro-displacement is greatly improved. Finally, the relationship between the voltage and the micro-displacement is accurately obtained by using the Arduino board and the Arduino IDE software, and a calculation conversion formula is established to realize the calculation and measurement of the micro-displacement of the strip.

[0018] The beneficial effects of the present invention are:

[0019] The present invention constructs an experimental device for measuring the micro-displacement of the strip by the differential light flux method, and measures the differential light flux through a direct current bridge and a photoelectric conversion circuit, improving the measurement accuracy and obtaining good results.

[0020] The present invention measures the micro-displacement by converting it into differential optical flux, improving the measurement accuracy of the micro-displacement, and uses a DC bridge circuit to measure the electrical signal, and accurately obtains the measurement of the micro-displacement through analysis and processing.

[0021] The present invention uses a photoelectric sensor to measure the micro-displacement of a strip (a material with a rectangular cross-section), so as to further increase the ratio of the change in the optical throughput to the micro-displacement amount, and further reduce the measurement error. Description of the Drawings

[0022] Figure 1 is a schematic diagram of the experimental instrument system;

[0023] Figure 2 is a general schematic diagram of the system circuit;

[0024] Figure 3 is a D-X relationship curve graph of the data set of the embodiment. Detailed Implementation Manner

[0025] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0026] As Figure 1 shown, the device for specific implementation mainly includes a light source, a lens group, a to-be-measured object, and a bridge optoelectronic measurement circuit; the lens group includes a first lens and a second lens, the to-be-measured object is a strip, and the strip is an opaque object, specifically a rectangular steel plate can be used. The strip is placed between the first lens and the second lens. The light beam emitted by the light source is converged into a parallel beam by the first lens, and then converged by the second lens and incident on the light-receiving photoresistor of the bridge optoelectronic measurement circuit. A part of the light beam emitted by the first lens is blocked by the strip, and the other part is directly incident on the second lens. The output end of the bridge optoelectronic measurement circuit is connected to an external computer.

[0027] As Figure 2As shown in the figure, the bridge optoelectronic measurement circuit includes a first photosensitive resistor (as the light-receiving photosensitive resistor), a second photosensitive resistor (as the light-blocking photosensitive resistor), a resistor R3 (adjustable resistor), a resistor R4, a resistor R8, and a conversion amplifier. The light beam emitted from the first lens irradiates onto the first photosensitive resistor, and the second photosensitive resistor is completely blocked by the light-shielding cover. A bridge circuit is formed by the first photosensitive resistor, the second photosensitive resistor, the resistor R3, and the resistor R4. After the first photosensitive resistor and the resistor R3 are connected in series, they are respectively connected to the power supply voltage and the ground. After the second photosensitive resistor and the resistor R4 are connected in series, they are respectively connected to the power supply voltage and the ground. A connection is led out between the first photosensitive resistor and the resistor R3 and connected to the negative input terminal of the amplifier after passing through the resistor R5. A connection is led out between the second photosensitive resistor and the resistor R4 and connected to the positive input terminal of the amplifier after passing through the resistor R6. The positive input terminal of the amplifier is grounded after passing through the resistor R7. The negative input terminal of the amplifier is connected to the output terminal through the resistor R8, and the output terminal of the amplifier outputs a voltage and sends it to the computer. In this way, the first photosensitive resistor serves as the measurement element, and the other second photosensitive resistor serves as the temperature compensation element and will be covered with a light-shielding cover. The two photosensitive resistors and R3, R4 form a bridge circuit.

[0028] The light source, the lens group, and the photosensitive resistors of the bridge optoelectronic measurement circuit are arranged on the same optical axis.

[0029] The photosensitive resistor is a light-receiving photosensitive resistor. The light-receiving photosensitive resistor is sensitive to light irradiation. The stronger the light irradiation, the smaller the resistance, and the resistance is the largest when there is no light irradiation at all.

[0030] The photosensitive resistor is a light-blocking photosensitive resistor. The light-blocking photosensitive resistor is sensitive to light irradiation. The stronger the light irradiation, the smaller the resistance, and the resistance is the largest when there is no light irradiation at all.

[0031] The working process of the embodiment of the present invention is as follows:

[0032] The light beam emitted by the light source, after being converged into a parallel light beam by the first lens, is then converged by the second lens and incident on the photosensitive resistor of the bridge optoelectronic measurement circuit. A part of the light beam emitted from the first lens is blocked by the strip, and the other part is directly incident on the second lens, and the output current signal of the bridge optoelectronic measurement circuit; in the path where the parallel light beam emitted from the first lens reaches the second lens, a part of the light is blocked by the strip, so that the light flux incident on the photosensitive resistor from the second lens is reduced, which in turn affects the light intensity irradiated on the first photosensitive resistor, causing the voltage signal to change.

[0033] During the process of the strip moving closer to / away from the optical axis in a direction perpendicular to the optical axis, the detection voltage signal is collected in real time, and the change of the voltage signal is analyzed and processed to obtain the measurement result of the micro-displacement of the strip.

[0034] Before the specific experimental measurement, adjust the parallelism of the first convex lens and the second convex lens. First, install the light source, the first convex lens, the second convex lens, and the image screen on the optical bench in sequence. First, bring them closer, adjust their height and left-right positions so that the centers of each component are approximately at the same height on a straight line, and make the planes of the lens and the image screen parallel to each other. Then move the first convex lens between the light source and the image screen to obtain a circular image with changing size on the image screen. To determine whether the light emitted by the light source can be converged into a parallel light beam after passing through the first convex lens, place a circular disc of the same size as the convex lens at the position of the circular image. When the circular image completely coincides with the circular disc, parallel light is obtained. At this time, fix the positions of the light source and the first convex lens unchanged. Finally, move the image screen behind the second convex lens and move the position of the image screen until a bright spot is obtained on the image screen. This point is the convergence point of the light beam after passing through the second convex lens. Then place the first photosensitive resistor at the bright spot.

[0035] In the specific implementation, a strip (size 200mm×150mm×100mm) is used as the strip. In the specific implementation, a photosensitive resistor (GL5516), several Dupont wires (for connecting components), a breadboard (for arranging components), two lenses (Φ40mm, f = 92mm), an LED lamp (used as a light source), a transformer (for converting 220V AC into 10V low voltage), and an I-V conversion amplifier (model OPA277, LM353) are selected.

[0036] Use the mobile phone scale app to measure the position of the strip, that is, align the 0 scale line with the mark, and move the measurement position on the mobile phone to see the measured displacement value. Move the strip so that it just stops blocking the light to just completely block the light, each time moving about 2 - 5mm, and read the corresponding binary count value or the directly displayed voltage value.

[0037] If the strip moves away from the optical axis center during the micro-displacement process, the shading area is the smallest, the illumination of the photosensitive resistor is the largest, the resistance value is the smallest, the bridge is unbalanced, and the maximum output voltage U0 of the amplifier is If the strip moves closer to the optical axis center during the micro-displacement process, the shading area increases, the illumination of the photosensitive resistor weakens, the resistance value becomes larger, the bridge is unbalanced, and the output voltage U0 of the amplifier is positive, between 0 and Between.

[0038] The experimental data are shown in Table 3 below.

[0039] Table 3

[0040]

[0041] The obtained D-X fitting relationship curve is as Figure 3 Shown, according to Figure 3 The curve graph, derive the mathematical formula of the relationship between D and X in the range of 0 - 1000:

[0042] D = -0.93254e X / 0.53946 +928.50917 (3)

[0043] Convert the binary count into a voltage value according to the relevant A / D conversion formula, and obtain Table 4 as follows:

[0044] Table 4

[0045]

[0046] According to the conversion formula, retain 2 significant figures after the decimal point to obtain:

[0047] U = -4.54×10 -3 e X / 0.54 +4.53 (4)

[0048] Let X = 0 be the maximum luminous flux. a, b, and c are obtained through multiple experimental data and curve fitting. After calculation, a = 4.54×10 -3 , b = 0.54, c = 4.53. Thus, obtain:

[0049] Therefore, the mathematical approximation formula for the relationship between U and X can also be obtained:

[0050]

[0051] As long as the voltage value is obtained, the micro-displacement of the strip is measured.

[0052] In an actual scenario, the offset displacement can be calculated according to the voltage magnitude output by the I-V conversion amplifier.

Claims

1. A device for measuring the micro-displacement of a strip by a differential optical flux bridge method, characterized in that: It mainly includes a light source, a lens group, an object to be measured, and a bridge optoelectronic measurement circuit; the lens group includes a first lens and a second lens, the object to be measured is a strip, the strip is placed between the first lens and the second lens, the light beam emitted by the light source, after being converged into a parallel beam by the first lens, is then converged by the second lens and incident on the photoresistor of the bridge optoelectronic measurement circuit. A part of the light beam emitted by the first lens is blocked by the strip, and the other part is directly incident on the second lens. The output end of the bridge optoelectronic measurement circuit is connected to an external computer through a conversion amplifier; The strip is an opaque object; The strip moves closer to / away from the optical axis in a direction perpendicular to the optical axis.

2. The device for measuring the micro-displacement of the strip by the differential optical flux bridge method according to claim 1, wherein: The bridge optoelectronic measurement circuit includes a first photoresistor R1, a second photoresistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R8 and a conversion amplifier. The light beam emitted from the second lens is incident on the first photoresistor R1, the second photoresistor R2 is completely blocked by a light shield, and a bridge circuit is formed by the first photoresistor R1, the second photoresistor R2, the resistor R3, and the resistor R4. After the first photoresistor R1 and the resistor R3 are connected in series, they are respectively connected to the power supply voltage and the ground. After the second photoresistor R2 and the resistor R4 are connected in series, they are respectively connected to the power supply voltage and the ground. A connection is led out between the first photoresistor R1 and the resistor R2 and connected to the inverting input terminal of the amplifier after passing through the resistor R5. A connection is led out between the second photoresistor R2 and the resistor R4 and connected to the non-inverting input terminal of the amplifier after passing through the resistor R6. The non-inverting input terminal of the conversion amplifier is grounded after passing through the resistor R6, the inverting input terminal of the amplifier is connected to the output terminal through the resistor R8, the output voltage of the output terminal of the amplifier is sent to the Arduino board, and finally the Arduino board is connected to the computer.

3. The device for measuring the micro-displacement of a strip by the differential optical flux bridge method according to claim 1, wherein: The light source, the lens group, and the photoresistor R1 of the bridge optoelectronic measurement circuit are arranged on the same optical axis.

4. The device for measuring the micro-displacement of a strip by the differential optical flux bridge method according to claim 2, characterized in that: The photoresistor R2 is a light-shielding photoresistor.

5. A method for measuring the micro-displacement of a strip by a differential optical flux bridge method applied to the device according to any one of claims 1-4, characterized in that: The light beam emitted by the light source, after being converged into a parallel beam by the first lens, is then converged by the second lens and incident on the photoresistor R1 of the bridge optoelectronic measurement circuit. A part of the light beam emitted by the first lens is blocked by the strip, and the other part is directly incident on the second lens. The output current signal of the bridge optoelectronic measurement circuit is output as a voltage signal after passing through the conversion amplifier; in the path where the parallel beam emitted by the first lens reaches the second lens, a part of the light is blocked by the strip, so that the light flux incident on the photoresistor from the second lens is reduced, which in turn affects the illumination intensity of the light incident on the first photoresistor R1, resulting in a change in the finally output voltage signal; during the micro-displacement process of the strip in a direction perpendicular to the light beam, the detection voltage signal is collected in real time, and the change of the voltage signal is analyzed and processed to obtain the measurement result of the micro-displacement of the strip.

6. A method for measuring the micro-displacement of a strip by a differential optical flux bridge method according to claim 5, characterized in that: Before the experimental measurement, move the strip to completely block the light beam emitted by the first lens, and through pre-adjusting the bridge balance, make the voltage U0 at the output end of the amplifier zero.

7. A method for measuring the micro-displacement of a strip by a differential optical flux bridge method according to claim 5, characterized in that: Analyze and process the change of the voltage signal to obtain the measurement result of the micro-displacement of the strip. Specifically, the following formula is used to inversely calculate the micro-displacement of the strip: U = -ae X / b + c Wherein, U represents the voltage value output by the bridge optoelectronic measurement circuit after passing through the conversion amplifier, X represents the radial change distance of the cross-section of the strip from the maximum light flux to the minimum light flux, and a, b, and c respectively represent the first, second, and third fitting parameters.

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