Laser displacement sensor measuring device and method based on diffusion lens constraint model

Abstract

The invention discloses a laser displacement sensor measuring device and method based on a diffusion lens constraint model, and the method comprises the steps: carrying out the analysis of a condition that a sensor does not respond or is abnormal in response through building a bidirectional reflection distribution model of a laser displacement sensor facing a mirror reflection surface; and establishing a diffusion lens constraint model and calculating model selection parameters of the diffusion lens. According to the device and the method, the problem that the laser displacement sensor has no response or has abnormal response when facing a mirror reflection surface can be solved, and meanwhile, the device and the method have certain anti-interference capability in a scene in which multiple sensors are simultaneously applied.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric measurement, and in particular relates to a laser displacement sensor measurement device and method based on a diffusion lens constraint model. Background Art

[0002] Laser displacement sensor is a sensor that uses laser technology to measure the position or displacement of a target object. It uses a laser transmitter to emit a laser beam, which is irradiated to the target surface and reflected back to the sensor. By measuring the propagation time or phase change of the laser beam, the distance between the target and the sensor can be calculated. Laser displacement sensors are widely used in manufacturing, robotics, construction engineering and other fields to measure and monitor the displacement, vibration, shape and other parameters of an object. Although laser displacement sensors perform well in many applications, when the target is a reflective surface dominated by mirror reflection, laser displacement sensors often have no response or abnormal response. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a laser displacement sensor measurement device and method based on a diffusion lens constraint model, by establishing a bidirectional reflection distribution model of the laser displacement sensor facing a mirror reflection surface, analyzing the situation where the sensor has no response or abnormal response, establishing a diffusion lens constraint model and calculating the selection parameters of the diffusion lens. The device and method can solve the problem of no response or abnormal response of the laser displacement sensor when facing a mirror reflection surface, and at the same time have a certain anti-interference ability in the scene where multiple sensors are used simultaneously.

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

[0005] A laser displacement sensor measuring device based on a diffusion lens constraint model comprises a guide rail, a first linear polarizing plate, a second linear polarizing plate, a lens slot, a diffusion lens, a laser displacement sensor and a housing;

[0006] The guide rail is composed of two horizontal rods and one vertical rod, the horizontal rod and the vertical rod are fixed by screws, and the position of the vertical rod can be adjusted according to screw holes of different lengths;

[0007] The diffusion lens and the linear polarizer are combined into a group of polarized diffusion lenses, which are placed in the housing and mounted on the guide rail through a lens slot; the linear polarizer is placed parallel to the polarized diffusion lens and mounted on the guide rail through a lens slot;

[0008] Before using the laser displacement sensor for detection, adjust the position of the polarization diffusion lens so that it is located in front of the transmitting end of the laser displacement sensor and fixed, and adjust the second linear polarizer so that it is located in front of the receiving end of the laser displacement sensor and fixed.

[0009] A laser displacement sensor measurement method based on a diffusion lens constraint model comprises the following steps:

[0010] Step 1: Install the housing according to the size of the laser displacement sensor, fix the polarization diffusion lens through one lens slot, fix the second linear polarizer through another lens slot, adjust the positions of the two lens slots, and fix them in the screw holes of the guide rails with screws;

[0011] Step 2: Establish a bidirectional reflection distribution model BRDF of the laser displacement sensor facing the diffuse reflection surface, and model and analyze the normal response of the laser displacement sensor;

[0012] Step 3: Establish a bidirectional reflection distribution model dominated by mirror reflection for the laser displacement sensor, and conduct modeling analysis for the situation where the laser displacement sensor has no response or abnormal response;

[0013] Step 4: Establish a diffusion lens constraint model through the optical path analysis diagram, use the diffusion lens constraint model to input the laser displacement sensor fixed parameters and measurement distance, and output the parameter values ​​of the diffusion lens;

[0014] Step 5: The linear polarizer 1 installed in front of the transmitting end of the laser displacement sensor is used to make the emitted laser beam have polarization characteristics, and the linear polarizer 2 installed in front of the receiving end is rotated to make the intensity of the laser reflected back to the receiving end of the laser displacement sensor through the linear polarizer 2 maximum. The angle increment of the linear polarizer 2 relative to the linear polarizer 1 is △θ;

[0015] Step 6: When multiple laser displacement sensors are installed and used at the same time, adjust the angle between the linear polarizer 1 of the polarization diffusion lens of one of the two adjacent laser displacement sensors and the guide rail to θ1, and the angle between the linear polarizer 2 and the guide rail to θ1+△θ; the angle between the linear polarizer 1 of the polarization diffusion lens of the other laser displacement sensor and the guide rail is θ2, θ2=θ1+π / 2, and the angle between the linear polarizer 2 and the guide rail is θ2+△θ, so that multiple laser displacement sensors have anti-interference ability when installed and used at the same time.

[0016] Furthermore, the bidirectional reflection distribution model BRDF describes the reflection distribution characteristics of a point on the surface for incident light. After determining the incident direction l and the outgoing direction v, the BRDF value f(l,v) measures the characteristics of the object surface reflecting the light, and is defined as the ratio of the outgoing radiance L0(v) to the incident irradiance E(l), as shown in the following formula:

[0017]

[0018] Where, E represents irradiance, which refers to the energy received per unit area and per unit time, dE(l) represents the differential irradiance from the incident direction l; L represents emittance, which refers to the energy received per unit vertical area, unit solid angle, and unit time, and dL0(v) represents the differential emittance reflected from the object surface in the direction v;

[0019] According to the Cook-Torrance bidirectional reflection distribution model, the BRDF value f(l,v) is:

[0020] f(l,v)=k d f lambert +k s f cook-torrance

[0021] where k d Indicates the proportion of diffuse reflection energy, k s Indicates the ratio of the energy of the mirror reflection part, f lambert Represents the BRDF value of the diffuse reflection part, f cook-torrance The BRDF value representing the specular reflection part.

[0022] Furthermore, the step 2 is specifically as follows:

[0023] Assuming that the target object surface has only diffuse reflection effect, k d =1,k s =0, then the BRDF value is:

[0024] f(l,v)=f lambert

[0025] Assuming that diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value is written as:

[0026]

[0027] The differential radiance received by the laser displacement sensor is:

[0028]

[0029] The energy EN received by the laser displacement sensor d It is expressed as:

[0030]

[0031] Where Ω0 represents the area where the laser displacement sensor light receiving element receives the signal;

[0032] The response threshold T0 of the laser displacement sensor setting is expressed as:

[0033] T0=λEN d ,λ∈(0,1)

[0034] When the measured surface is a diffuse reflection surface, the energy EN received by the laser displacement sensor light receiving element d If it is greater than the response threshold T0, the laser displacement sensor can respond normally.

[0035] Furthermore, the step 3 is specifically as follows:

[0036] Assuming that the mirror reflection effect on the surface of the target object is greater than the diffuse reflection effect, let k d =α,k s =β, then the BRDF value is:

[0037] f(l,v)=αf lambert +βf cook-torrance

[0038] Among them, α, β∈[0,1], α+β=1 and α<<β;

[0039] Assuming that the diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value of the diffuse reflection part is written as:

[0040]

[0041] The differential radiance of the diffuse reflection part received by the laser displacement sensor is:

[0042]

[0043] The diffuse reflection energy EN′ received by the laser displacement sensor d It is expressed as:

[0044]

[0045] Since α, β∈[0,1], α+β=1 and α<<β, the energy EN′ of the diffuse reflection part received by the laser displacement sensor light receiving element d It is much smaller than the response threshold T0. At this time, the laser displacement sensor cannot make a normal response based on the diffuse reflection part.

[0046] According to the Cook-Torrance bidirectional reflection distribution model, the BRDF value of the specular reflection part is written as:

[0047]

[0048] where θ l is the angle between the incident direction l and the macro normal direction n, θ vis the angle between the outgoing direction v and n, h is the direction of the microplane normal; F(v,h) represents the Fresnel equation, which describes the ratio of light reflected from the surface of an object at different incident light angles, F(v,h)∈[0,1]; D(h) represents the normal distribution function, D(h)∈[0,1]; G(l,v) represents the geometric function, which describes the self-occlusion property of the microplane, G(l,v)∈[0,1];

[0049] The differential radiance of the specular reflection part is:

[0050]

[0051] Energy EN of the mirror reflection emission area S It is expressed as:

[0052]

[0053] Where Ω S Indicates the emission area of ​​the specular reflection part.

[0054] when When the laser displacement sensor's light-receiving element cannot receive the energy reflected by the mirror, that is, EN S = 0, at this time, the laser displacement sensor light receiving element can only receive the diffuse reflection part of the energy, and the diffuse reflection part of the energy EN′ d It is far smaller than the response threshold T0, causing the laser displacement sensor to fail to respond.

[0055] Adding a diffusion lens in front of the transmitting end allows the mirror reflection emission area to cover the response area of ​​the laser displacement sensor light receiving element, that is, Ω0∈Ω S At this time, the energy of the diffuse reflection part received by the laser displacement sensor light receiving element is:

[0056]

[0057] The energy of the mirror reflection part received by the laser displacement sensor light receiving element is:

[0058]

[0059] At this time, the total energy of diffuse reflection and specular reflection received by the laser displacement sensor light receiving element is The total energy is greater than the response threshold T0, and the laser displacement sensor can respond normally.

[0060] Furthermore, the step 4 is specifically as follows:

[0061] The geometric analysis diagram of the diffusion lens constraint model is established. L0 represents the distance from the center of the laser diode to the farthest end of the light receiving element, and L sensor Indicates the length of the light receiving element, Lresponse It indicates the distance from the center of the laser diode to point P2 on the laser displacement sensor housing when the reflected light enters the farthest end of the light-receiving element after the laser beam is diffused by the diffusion lens. L1 indicates the diameter of the laser beam emitted by the laser diode. L2 indicates the distance from point P1 to point P2 on the laser displacement sensor housing. f0 indicates the focal length of the diffusion lens. W1 indicates the thickness of the diffusion lens. α indicates the deflection angle of the laser after passing through the diffusion lens. d indicates the measurement distance.

[0062] When the mirror reflected light can completely cover the light-receiving element of the laser displacement sensor, a response constraint model is established:

[0063] L response ≥L0

[0064] From the geometric constraints we know:

[0065] L response <L1+2L2

[0066] Depend on We get L2 = dtanα;

[0067] again get

[0068] L response <L1+2L2 and The diffusion lens constraint model is:

[0069]

[0070] It is deduced that:

[0071]

[0072] That is, the diffusion lens constraint model is:

[0073] f0<S1d+S2

[0074] in is a known intrinsic parameter of the laser displacement sensor.

[0075] According to the diffusion lens constraint model, the inherent parameters S1, S2 of the laser displacement sensor and the value of the measured distance d are input, and the focal length parameter f0 of the diffusion lens to be selected is output.

[0076] The beneficial effects of the present invention are as follows:

[0077] The present invention can solve the problem of no response or abnormal response of the laser displacement sensor when facing a mirror reflective surface, and at the same time has a certain interference resistance capability in the scenario where multiple sensors are used simultaneously, thereby broadening the application scope of the laser displacement sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic diagram of the device of the present invention;

[0079] Figure 2 It is a schematic diagram of a bidirectional reflection distribution model of a laser displacement sensor according to an embodiment of the present invention facing a diffuse reflection surface;

[0080] Figure 3 It is a schematic diagram of a bidirectional reflection distribution model when the laser displacement sensor according to an embodiment of the present invention faces a reflective surface dominated by mirror reflection;

[0081] Figure 4 A schematic diagram of an improved method using a polarization diffusion lens according to an embodiment of the present invention;

[0082] Figure 5 A schematic diagram of geometric analysis of a polarization diffusion lens constraint model according to an embodiment of the present invention;

[0083] Figure 6 This is a schematic diagram of a polarization diffusion lens constraint model according to an embodiment of the present invention;

[0084] Figure 7 The figure is a schematic diagram of polarized light beam encoding based on a polarization diffusion lens according to an embodiment of the present invention.

[0085] In the figure: 1 guide rail, 2 linear polarizing plate 1, 3 linear polarizing plate 2, 4 lens slot, 5 diffusion lens, 6 laser displacement sensor, 7 housing, 8 sensor transmitting end, 9 sensor receiving end, 10 mirror reflection surface. DETAILED DESCRIPTION

[0086] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0087] The present invention establishes a bidirectional reflection distribution model of a laser displacement sensor facing a mirror reflective surface, analyzes the situation where the sensor has no response or abnormal response, establishes a diffusion lens constraint model and calculates the selection parameters of the diffusion lens, and provides a laser displacement sensor measurement device and method based on the diffusion lens constraint model. The device and method can solve the problem of the laser displacement sensor having no response or abnormal response when facing a mirror reflective surface, and at the same time have a certain anti-interference ability in the scenario where multiple sensors are used simultaneously.

[0088] The purpose of the present invention is to provide a laser displacement sensor measurement device and method based on a diffusion lens constraint model to solve the problem of no response or abnormal response in the prior art when the measured target is a mirror reflection surface.

[0089] A laser displacement sensor measuring device based on a diffusion lens constraint model comprises a shell, and a guide rail, a diffusion lens, a first linear polarizing plate, a second linear polarizing plate and a lens slot installed in the shell.

[0090] A group of diffuser lens and linear polarizer is placed in the shell as a whole, facing the side of the shell, and installed on the guide rail through the lens slot. Linear polarizer 2 is placed parallel to the lens and polarizer diffuser lens, and installed on the guide rail inside the shell through the lens slot. The guide rail consists of two horizontal rods and a vertical rod. The horizontal rod and the vertical rod are fixed by screws, and the position of the vertical rod can be adjusted according to the screw holes with different lengths.

[0091] A laser displacement sensor measurement method based on a diffusion lens constraint model comprises the following steps:

[0092] S1. Install a suitable external housing according to the size of the laser displacement sensor, fix the polarization diffusion lens through one lens slot, fix the second linear polarizer through another lens slot, adjust the two lens slots to a suitable position, and fix them in the screw holes of the guide rails with screws;

[0093] S2. Establish a bidirectional reflection distribution model of the laser displacement sensor facing the diffuse reflection surface, and conduct modeling analysis on the normal response of the laser displacement sensor;

[0094] S3. Establish a bidirectional reflection distribution model dominated by mirror reflection for the laser displacement sensor, and conduct modeling analysis for the situation where the laser displacement sensor has no response or abnormal response;

[0095] S4, establishing a diffusion lens constraint model through an optical path analysis diagram, using the model to input fixed parameters and a measurement distance of a laser displacement sensor, and outputting parameter values ​​of the installed diffusion lens;

[0096] S5, the linear polarizer 1 installed in front of the transmitting end is used to make the emitted laser beam have polarization characteristics, and the linear polarizer 2 installed in front of the receiving end is rotated to make the intensity of the laser reflected back to the receiving end of the laser displacement sensor through the linear polarizer 2 maximum, and the angle increment of the linear polarizer 2 relative to the linear polarizer 1 is △θ;

[0097] S6. When multiple sensors are installed and used at the same time, adjust the angle between the linear polarizer of the polarization diffusion lens in the adjacent laser displacement sensor 1 and the guide rail to θ1, the angle between the linear polarizer 2 and the guide rail to θ1+△θ, the angle between the linear polarizer of the polarization diffusion lens in the laser displacement sensor 2 and the guide rail to θ2, and the angle between the linear polarizer 2 and the guide rail to θ2+△θ, so that this method has a certain anti-interference ability in the scenario where multiple sensors are used simultaneously.

[0098] Example:

[0099] like Figure 1 As shown, a laser displacement sensor measurement method and device based on a diffusion lens constraint model includes a housing and a guide rail installed in the housing, a diffusion lens, a linear polarizer 1, a linear polarizer 2 and a lens slot. The diffusion lens and the linear polarizer are combined into a polarized diffusion lens and placed in the housing as a whole, and are mounted on the guide rail through the lens slot. The linear polarizer 2 is placed parallel to the polarized diffusion lens and is mounted on the guide rail through the lens slot. The guide rail consists of two horizontal rods and a vertical rod, and the horizontal rod and the vertical rod are fixed by screws. The position of the vertical rod can be adjusted according to the screw holes with different lengths.

[0100] Before using the laser displacement sensor and external device for detection, adjust the two lens slots to the appropriate position according to the size of the laser displacement sensor, so that the polarization diffusion lens is located in front of the emitting end of the laser displacement sensor and fixed on the guide rail, and the linear polarizer 2 is located in front of the receiving end of the laser displacement sensor and fixed on the guide rail.

[0101] The bidirectional reflectance distribution function model (BRDF) describes the reflection distribution characteristics of a point on the surface for incident light. After determining the incident direction l and the outgoing direction v, the BRDF value f(l,v) measures the reflection characteristics of the object surface and light, and is defined as the ratio of the outgoing radiance L0(v) to the incident irradiance E(l), as shown in the following formula:

[0102]

[0103] Where E is the irradiance, which refers to the energy received per unit area and per unit time; dE(l) is the differential irradiance from the incident direction l; L is the radiance, which refers to the energy received per unit vertical area, unit solid angle and per unit time; dL0(v) is the differential radiance reflected from the object surface in the direction v.

[0104] According to the Cook-Torrance bidirectional reflection model, the BRDF value f(l,v) is:

[0105] f(l,v)=k d f lambert +k s f cook-torrance

[0106] where k d Indicates the proportion of diffuse reflection energy, k s Indicates the ratio of the energy of the mirror reflection part, f lambert Represents the BRDF value of the diffuse reflection part, f cook-torrance The BRDF value representing the specular reflection part.

[0107] like Figure 2As shown in the figure, assuming that the target object surface has only diffuse reflection effect, then k d =1,k s =0, then the BRDF value is:

[0108] f(l,v)=f lambert

[0109] Assuming that diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value can be written as:

[0110]

[0111] The differential radiance received by the laser displacement sensor is:

[0112]

[0113] The energy EN received by the laser displacement sensor d It is expressed as:

[0114]

[0115] Where Ω0 represents the area where the laser displacement sensor light receiving element receives the signal.

[0116] The response threshold T0 of the laser displacement sensor setting can be expressed as:

[0117] T0=λEN d ,λ∈(0,1)

[0118] From the above formula, we can know that when the measured surface is a diffuse reflection surface, the energy EN received by the laser displacement sensor light receiving element is d If it is greater than the response threshold T0, the laser displacement sensor can respond normally.

[0119] like Figure 3 As shown in the figure, assuming that the target object surface mainly has a mirror reflection effect, let k d =α,k s =β, then the BRDF value is:

[0120] f(l,v)=αf lambert +βf cook-torrance

[0121] Among them, α, β∈[0,1], α+β=1 and α<<β.

[0122] Assuming that the diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value of the diffuse reflection part can be written as:

[0123]

[0124] The differential radiance of the diffuse reflection part received by the laser displacement sensor is:

[0125]

[0126] The diffuse reflection energy EN′ received by the laser displacement sensor d It is expressed as:

[0127]

[0128] Where Ω0 represents the area where the laser displacement sensor light receiving element receives the signal.

[0129] Since α, β∈[0,1], α+β=1 and α<<β, the energy EN′ of the diffuse reflection part received by the laser displacement sensor light receiving element d It is far smaller than the response threshold T0. At this time, the laser displacement sensor cannot make a normal response based on the diffuse reflection part.

[0130] According to the Cook-Torrance bidirectional reflection model, the BRDF value of the specular reflection part can be written as:

[0131]

[0132] where θ l is the angle between the incident direction l and the macro normal direction n, θ v is the angle between the outgoing directions v and n, h is the direction of the microplane normal; F(v,h) represents the Fresnel equation, which describes the ratio of light reflected from the surface of an object at different incident light angles, F(v,h)∈[0,1]; D(h) represents the normal distribution function, which describes the distribution of normals of tiny mirrors at a microscopic angle. The normal distribution of rough surfaces is relatively uniform, and the normal distribution of smooth surfaces is relatively concentrated, D(h)∈[0,1]; G(l,v) represents the geometric function, which describes the self-occlusion property of microplanes, G(l,v)∈[0,1].

[0133] The differential radiance of the specular reflection part is:

[0134]

[0135] Energy EN of the mirror reflection emission area S It is expressed as:

[0136]

[0137] Where Ω S Indicates the emission area of ​​the specular reflection part.

[0138] when When the laser displacement sensor's light-receiving element cannot receive the energy reflected by the mirror, that is, ENS = 0, at this time, the laser displacement sensor light receiving element can only receive the diffuse reflection part of the energy, and the diffuse reflection part of the energy EN′ d It is far smaller than the response threshold T0, causing the laser displacement sensor to fail to respond.

[0139] like Figure 4 As shown in the figure, in order to make the laser displacement sensor respond normally on the reflective surface dominated by mirror reflection, a diffusion lens is added in front of the transmitting end so that the mirror reflection emission area can cover the response area of ​​the laser displacement sensor light receiving element, that is, Ω0∈Ω S At this time, the energy of the diffuse reflection part received by the laser displacement sensor light receiving element is:

[0140]

[0141] The energy of the mirror reflection part received by the laser displacement sensor light receiving element is:

[0142]

[0143] At this time, the total energy of diffuse reflection and specular reflection received by the laser displacement sensor light receiving element is The total energy is greater than the response threshold T0, and the laser displacement sensor can respond normally.

[0144] like Figure 5 As shown in the figure, the geometric analysis diagram of the diffusion lens constraint model is established. In the figure, L0 represents the distance from the center of the laser diode to the farthest end of the light receiving element, and L sensor Indicates the length of the light receiving element, L response It represents the distance from the center of the laser diode to point P2 on the laser displacement sensor housing after the laser beam is diffused by the diffusion lens, when the reflected light can enter the farthest end of the light-receiving element. L1 represents the diameter of the laser beam emitted by the laser diode. L2 represents the distance from point P1 to point P2 on the laser displacement sensor housing. f0 represents the focal length of the diffusion lens. W1 represents the thickness of the diffusion lens. α represents the deflection angle of the laser after passing through the diffusion lens. d represents the measurement distance.

[0145] When the mirror reflected light can completely cover the light-receiving element of the laser displacement sensor, a response constraint model is established:

[0146] L response ≥L0

[0147] Depend on Figure 5 From the geometric constraints in, we can see that:

[0148] L response <L1+2L2

[0149] Depend on We get L2 = dtanα;

[0150] again get

[0151] L response <L1+2L2 and The response constraint model is:

[0152]

[0153] The above formula is derived as follows:

[0154]

[0155] That is, the diffusion lens constraint model is:

[0156] f0<S1d+S2

[0157] in is a known intrinsic parameter of the laser displacement sensor.

[0158] like Figure 6 As shown, according to the diffusion lens constraint model, the inherent parameters S1, S2 of the laser displacement sensor and the value of the measured distance d are input, and according to the diffusion lens constraint model, the focal length parameter f0 of the diffusion lens to be selected can be output.

[0159] like Figure 7 As shown, since a diffusion lens is installed in front of the emitting end of the laser displacement sensor, the reflection area of ​​the diffused laser is larger. In order to prevent the problem of mutual interference when multiple sensors are used in combination, the angle between the linear polarizer of the polarization diffusion lens in the laser displacement sensor 1 and the guide rail is adjusted to θ1, the angle between the linear polarizer 2 and the guide rail is adjusted to θ1+△θ, and the angle between the linear polarizer of the polarization diffusion lens in the laser displacement sensor 2 and the guide rail is θ2, wherein θ2=θ1+π / 2, and the angle between the linear polarizer 2 and the guide rail is θ2+△θ, so that the method has a certain anti-interference ability in the scenario where multiple sensors are used simultaneously.

Claims

1. A laser displacement sensor measurement device based on a diffusion lens constraint model, It is characterized in that It includes a guide rail, a linear polarizing plate 1, a linear polarizing plate 2, a lens slot, a diffusion lens, a laser displacement sensor and a housing; The guide rail is composed of two horizontal rods and one vertical rod, the horizontal rod and the vertical rod are fixed by screws, and the position of the vertical rod can be adjusted according to screw holes of different lengths; The diffusion lens and the linear polarizer are combined into a group of polarized diffusion lenses, which are placed in the housing and mounted on the guide rail through a lens slot; the linear polarizer is placed parallel to the polarized diffusion lens and mounted on the guide rail through a lens slot; Before using the laser displacement sensor for detection, adjust the position of the polarization diffusion lens so that it is located in front of the transmitting end of the laser displacement sensor and fixed, and adjust the second linear polarizer so that it is located in front of the receiving end of the laser displacement sensor and fixed.

2. A laser displacement sensor measurement method using the measuring device according to claim 1, It is characterized in that The steps include: Step 1: Install the housing according to the size of the laser displacement sensor, fix the polarization diffusion lens through one lens slot, fix the second linear polarizer through another lens slot, adjust the positions of the two lens slots, and fix them in the screw holes of the guide rails with screws; Step 2: Establish a bidirectional reflection distribution model BRDF of the laser displacement sensor facing the diffuse reflection surface, and model and analyze the normal response of the laser displacement sensor; Step 3: Establish a bidirectional reflection distribution model dominated by mirror reflection for the laser displacement sensor, and conduct modeling analysis for the situation where the laser displacement sensor has no response or abnormal response; Step 4: Establish a diffusion lens constraint model through the optical path analysis diagram, use the diffusion lens constraint model to input the laser displacement sensor fixed parameters and measurement distance, and output the parameter values ​​of the diffusion lens; Step 5: The linear polarizer 1 installed in front of the transmitting end of the laser displacement sensor is used to make the emitted laser beam have polarization characteristics, and the linear polarizer 2 installed in front of the receiving end is rotated to make the intensity of the laser reflected back to the receiving end of the laser displacement sensor through the linear polarizer 2 maximum. The angle increment of the linear polarizer 2 relative to the linear polarizer 1 is △θ; Step 6: When multiple laser displacement sensors are installed and used at the same time, adjust the angle between the linear polarizer of the polarization diffusion lens of one of the two adjacent laser displacement sensors and the guide rail to θ 1 , the angle between the second linear polarizer and the guide rail is θ 1 +△θ; the angle between the linear polarizer of the polarization diffusion lens of the other laser displacement sensor and the guide rail is θ 2 ,θ 2 =θ 1 +π / 2, the angle between the second linear polarizer and the guide rail is θ 2 +△θ, so that multiple laser displacement sensors have anti-interference ability when installed and used at the same time.

3. A laser displacement sensor measurement method according to claim 2, It is characterized in that The bidirectional reflection distribution model BRDF describes the reflection distribution characteristics of a point on the surface for incident light. After determining the incident direction l and the outgoing direction v, the BRDF value f(l,v) measures the reflection characteristics of the object surface and the light, which is defined as the outgoing radiance L 0 The ratio of (v) to the incident irradiance E(l) is as follows: Where E is the irradiance, which refers to the energy received per unit area and per unit time, dE(l) is the differential irradiance from the incident direction l; L is the radiance, which refers to the energy received per unit vertical area, unit solid angle, and unit time, dL 0 (v) represents the differential radiance reflected from the surface of the object in direction v; According to the Cook-Torrance bidirectional reflection distribution model, the BRDF value f(l,v) is: f(l,v)=k d f lambert +k s f cook-torrance where k d Indicates the proportion of diffuse reflection energy, k s Indicates the ratio of the energy of the mirror reflection part, f lambert Represents the BRDF value of the diffuse reflection part, f cook-torrance The BRDF value representing the specular reflection portion.

4. A laser displacement sensor measurement method according to claim 3, It is characterized in that The step 2 is specifically as follows: Assuming that the target object surface has only diffuse reflection effect, k d =1,k s =0, then the BRDF value is: f(l,v)=f lambert Assuming that diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value is written as: The differential radiance received by the laser displacement sensor is: The energy EN received by the laser displacement sensor d It is expressed as: Where Ω 0 Indicates the area where the laser displacement sensor light receiving element receives signals; The response threshold T of the laser displacement sensor is set 0 It is expressed as: T 0 =λEN d ,λ∈(0,1) When the measured surface is a diffuse reflection surface, the energy EN received by the laser displacement sensor light receiving element d Greater than the response threshold T 0 , the laser displacement sensor can respond normally.

5. A laser displacement sensor measurement method according to claim 4, It is characterized in that The step 3 is specifically as follows: Assuming that the mirror reflection effect on the surface of the target object is greater than the diffuse reflection effect, let k d =α,k s =β, then the BRDF value is: f(l,v)=αf lambert +βf cook-torrance Among them, α, β∈[0,1], α+β=1 and α<<β; Assuming that the diffuse reflection is uniform and spreads across the entire hemisphere, the BRDF value of the diffuse reflection part is written as: The differential radiance of the diffuse reflection part received by the laser displacement sensor is: The diffuse reflection energy EN′ received by the laser displacement sensor d It is expressed as: Since α, β∈[0,1], α+β=1 and α<<β, the energy EN′ of the diffuse reflection part received by the laser displacement sensor light receiving element d Far less than the response threshold T 0 ,At this time, the laser displacement sensor cannot make a normal response according to the diffuse reflection part; According to the Cook-Torrance bidirectional reflection distribution model, the BRDF value of the specular reflection part is written as: where θ l is the angle between the incident direction l and the macro normal direction n, θ v is the angle between the outgoing direction v and n, h is the direction of the microplane normal; F(v,h) represents the Fresnel equation, which describes the ratio of light reflected from the surface of an object at different incident light angles, F(v,h)∈[0,1]; D(h) represents the normal distribution function, D(h)∈[0,1]; G(l,v) represents the geometric function, which describes the self-occlusion property of the microplane, G(l,v)∈[0,1]; The differential radiance of the specular reflection part is: Energy EN of the mirror reflection emission area S It is expressed as: Where Ω S Indicates the emission area of ​​the specular reflection part; when When the laser displacement sensor's light-receiving element cannot receive the energy reflected by the mirror, that is, EN S = 0, at this time, the laser displacement sensor light receiving element can only receive the diffuse reflection part of the energy, and the diffuse reflection part of the energy EN′ d Far less than the response threshold T 0 , causing the laser displacement sensor to fail to respond; Adding a diffusion lens in front of the transmitting end allows the mirror reflection emission area to cover the response area of ​​the laser displacement sensor light receiving element, that is, Ω 0 ∈Ω S At this time, the energy of the diffuse reflection part received by the laser displacement sensor light receiving element is: The energy of the mirror reflection part received by the laser displacement sensor light receiving element is: At this time, the total energy of diffuse reflection and specular reflection received by the laser displacement sensor light receiving element is The total energy is greater than the response threshold T 0 , the laser displacement sensor can respond normally.

6. A laser displacement sensor measurement method according to claim 5, It is characterized in that The step 4 is specifically as follows: Geometric analysis diagram for establishing the diffusion lens constraint model, L 0 Indicates the distance from the center of the laser diode to the farthest end of the light receiving element, L sensor Indicates the length of the light receiving element, L response It means that after the laser beam is diffused by the diffusion lens, when the reflected light enters the farthest end of the light receiving element, the distance from the center of the laser diode to the laser displacement sensor housing is P 2 The distance between the points, L 1 Indicates the diameter of the laser beam emitted by the laser diode, L 2 Indicates the P on the laser displacement sensor housing 1 Point to P 2 The distance between the points, f 0 represents the focal length of the diffusion lens, W 1 represents the thickness of the diffusion lens, α represents the deflection angle of the laser after passing through the diffusion lens, and d represents the measurement distance; When the mirror reflected light can completely cover the light-receiving element of the laser displacement sensor, a response constraint model is established: L response ≥L 0 From the geometric constraints we know: L response <L 1 +2L 2 Depend on Get L 2 = dtanα; again get L response <L 1 +2L 2 and The diffusion lens constraint model is: It is deduced that: That is, the diffusion lens constraint model is: f 0 <S 1 d+S 2 in is a known intrinsic parameter of the laser displacement sensor; According to the diffusion lens constraint model, the inherent parameters S of the laser displacement sensor are input. 1 ,S 2 And the value of the measured distance d, that is, the focal length parameter f of the diffusion lens to be selected is output 0 .

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