Laser displacement sensor adopting Fresnel lens

Abstract

The utility model relates to the technical field of laser displacement sensors, in particular to a laser displacement sensor adopting a Fresnel lens, which comprises a laser, a light spot position detector, an emitting optical surface, a receiving optical surface left partition and a receiving optical surface right partition. The optical function of the receiving optical surface left subarea is divided into detection of an ultra-short-distance detected object, the receiving optical surface right subarea adopts a Fresnel optical surface, and the optical function of the receiving optical surface right subarea is divided into detection of a middle-distance detected object and a long-distance detected object. According to the utility model, the optical design technique is different from the rest, and the pain point of a blind area which cannot be detected at an ultra-short distance in the industry is solved by partitioning and combining the receiving optical surfaces, so that the optical probe is unique in appearance, more professional in optical design technique, stronger in function and larger in detection range.

Description

Technical Field

[0001] This utility model relates to the field of laser displacement sensor technology, and in particular to a laser displacement sensor using Fresnel lenses. Background Technology

[0002] A laser displacement sensor is a sensor that uses laser technology for measurement. It consists of a laser, a laser detector, and a measurement circuit. Laser sensors are a new type of measuring instrument that can accurately and non-contactly measure changes in the position and displacement of the measured object. They can measure precise geometric measurements such as displacement, thickness, vibration, distance, and diameter. Lasers have the excellent characteristic of good straightness, and laser displacement sensors have higher accuracy than known ultrasonic sensors. Traditional laser displacement sensors cannot detect objects if the distance between them and the object being detected is very close. This very close distance or area is a blind zone, and the distance to the object being detected cannot be detected in the blind zone. This invention solves the defect of not being able to detect the object being detected in the blind zone at very close distances. Utility Model Content

[0003] The purpose of this invention is to solve the problem in the prior art that the blind zone at very close distances cannot detect the object being detected, and to propose a Fresnel lens laser displacement sensor.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A laser displacement sensor using Fresnel lenses includes a laser, a spot position detector, an emitting optical surface, a left section of a receiving optical surface, and a right section of a receiving optical surface. The left section of the receiving optical surface uses a Fresnel optical surface, and its optical function is to detect objects at very close range. The right section of the receiving optical surface uses a Fresnel optical surface, and its optical function is to detect objects at medium and long distances.

[0006] Preferably, the incident light spot is perpendicular to the surface of the object being measured, and there is only one accurate focusing position.

[0007] Preferably, the left and right sections of the receiving optical surface receive scattered light from the incident light point and image it onto the soft surface of the light point position detector.

[0008] Preferably, the position of the scattered light on the soft-sensitive surface of the light spot position detector is processed by analog and digital circuits, analyzed by a microprocessor, and the corresponding output value is calculated. Within the analog quantity window set by the user, a standard data signal is output proportionally. When using a switch output, it is turned on within the set window and turned off outside the window. In addition, the detection windows for analog quantity and switch output can be set independently.

[0009] Compared with the prior art, the present invention has the following advantages:

[0010] This utility model employs a unique optical design approach. By dividing and combining the receiving optical surface, it addresses the pain point of blind spots that cannot be detected at extremely close range. In contrast, laser displacement sensors on the European, American, and Chinese markets use aspherical lenses for both the receiving and transmitting lenses, which are not Fresnel lenses, let alone partitioned Fresnel lenses. Therefore, this utility model not only has a distinctive appearance but also a more professional optical design approach, stronger functionality, and a wider detection range. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a Fresnel lens laser displacement sensor proposed in this utility model;

[0012] Figure 2 This is a front view schematic diagram of a Fresnel lens laser displacement sensor proposed in this utility model;

[0013] Figure 3 This is a rear-view schematic diagram of a Fresnel lens laser displacement sensor proposed in this utility model;

[0014] Figure 4 This is a schematic diagram of a laser detection process using a Fresnel lens laser displacement sensor proposed in this utility model;

[0015] Figure 5 This is an engineering schematic diagram of a Fresnel lens laser displacement sensor proposed in this utility model;

[0016] Figure 6 This is a schematic diagram of the light spot in the AB region of the receiving sensor when the distance between the object being measured and the laser displacement sensor is 2.5 mm, according to a Fresnel lens laser displacement sensor proposed in this utility model.

[0017] Figure 7 This invention presents a schematic diagram of the light spot in the AB region of the receiving sensor when the distance between the object being measured and the laser displacement sensor is 3 mm.

[0018] In the diagram: 1. Emitting optical surface; 2. Left section of receiving optical surface; 3. Right section of receiving optical surface. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0020] Reference Figures 1-7 A laser displacement sensor employing Fresnel lenses includes a laser, a spot position detector, an emitting optical surface 1, a left receiving optical surface 2, and a right receiving optical surface 3. The left receiving optical surface 2 uses Fresnel optical surfaces and its optical function is to detect objects at very close range. The right receiving optical surface 3 uses Fresnel optical surfaces and its optical function is to detect objects at medium and long distances. This invention addresses the industry's pain point of blind spots in ultra-close-range detection by dividing and combining the receiving optical surfaces. In contrast, laser displacement sensors on the European, American, and Chinese markets use aspherical lenses for both the receiving and emitting lenses, which are not Fresnel lenses, nor are they divided and combined Fresnel lenses. Therefore, this invention not only has a unique appearance but also a more professional optical design, stronger functionality, and a wider detection range.

[0021] The principle of the triangular displacement measurement system is as follows: a beam of light is emitted from the light source to the surface of the object being measured, and the position of the reflected light point is observed through imaging in another direction, thereby calculating the displacement of the object point; when the laser displacement sensor adopts the triangular measurement method, the highest linearity reaches 1µm, the resolution reaches 0.1µm, and it can even achieve a high resolution of 0.01%, a high linearity of 0.1%, and a high response of 9.4KHz.

[0022] When the light emitted by the laser is focused by the emitting optical surface 1 and incident on the surface of the object being measured, the movement of the object or changes in its surface cause the incident light spot to move along the incident optical axis. At the same time, the left partition 2 and the right partition 3 of the receiving optical surface receive the scattered light from the incident light spot and image it on the soft surface of the light spot position detector (such as PSD or CCD). However, since the laser beam of the sensor is perpendicular to the surface being measured, there is only one accurate focusing position, and the images at other positions are in a state of defocus to varying degrees.

[0023] Because defocusing will cause image point blurring, thus reducing the measurement accuracy of the system, in order to improve accuracy, as shown in the attached... Figure 4 As shown, θ1 and θ2 must satisfy tgθ1=Utgθ2, where U is the lateral magnification. At this time, the measured points within a certain depth of field can be positively imaged on the detector, thus ensuring accuracy.

[0024] If the object being measured is very close to the laser displacement sensor, such as 2mm, the light energy, after being focused by the receiving lens, cannot be focused on the two active areas of the Silicon PIN Photo Diode. In this case, the Silicon PIN Photo Diode cannot receive light energy and therefore cannot generate current. This is because the current of the Silicon PIN Photo Diode is directly proportional to the light intensity. Conversely, when the light intensity received by the Silicon PIN Photo Diode increases, the number of electron-hole pairs generated per unit time increases, and the photocurrent also increases accordingly. Conversely, when the light intensity decreases, the photocurrent will decrease accordingly.

[0025] And as attached Figure 6 As shown, attached Figure 6 The left side represents region A, and the right side represents region B. When the object being measured is 2.5 mm away from the laser displacement sensor, light energy is received through the silicon pin photodiode, causing the light spot to be located in region A. Simultaneously, the irradiance is calculated to be 1656 W / m². 2 ;

[0026] And as attached Figure 7 As shown, attached Figure 7 The left side represents region A, and the right side represents region B. When the object being measured is 3mm away from the laser displacement sensor, light energy is received through the silicon pin photodiode, causing the light spot to be located in region A. Simultaneously, the irradiance is calculated to be 4254W / m². 2 ; and then through attachment Figure 6 and attached Figure 7 The comparison shows that the irradiance received at 3mm is significantly higher, many times higher than that at 2.5mm.

[0027] The functional principle of this utility model can be explained through the following operation methods:

[0028] The laser displacement sensor performs detection based on the triangular displacement measurement system as shown below:

[0029] The laser beam, through a lens, directs a visible red laser beam onto the surface of the object being measured. The laser beam scattered by the object's surface passes through the receiver lens and is received by the internal CCD linear camera. Depending on the distance, the CCD linear camera can "see" the light spot at different angles. Based on this angle and the known distance between the laser and the camera, the digital signal processor can calculate the distance between the sensor and the object being measured.

[0030] Meanwhile, the beam's position at the receiving element is processed by analog and digital circuits, analyzed by a microprocessor, and the corresponding output value is calculated. Within the user-defined analog output window, a standard data signal is output proportionally. If a switch output is used, it is turned on within the set window and turned off outside the window. In addition, the detection windows for analog and switch outputs can be set independently.

[0031] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A laser displacement sensor employing Fresnel lenses, comprising a laser, a spot position detector, an emitting optical surface (1), a left section (2) of a receiving optical surface, and a right section (3) of a receiving optical surface, characterized in that, The left section (2) of the receiving optical surface adopts a Fresnel optical surface, and the optical function of the left section (2) of the receiving optical surface is to detect the object at ultra-close distance. The right section (3) of the receiving optical surface adopts a Fresnel optical surface, and the optical function of the right section (3) of the receiving optical surface is to detect the object at medium distance and long distance displacement.

2. A laser displacement sensor using Fresnel lenses according to claim 1, characterized in that, The left and right optical sections (2 and 3) of the receiving optical surface receive scattered light from the incident light point and image it onto the soft surface of the light point position detector.

3. A laser displacement sensor using Fresnel lenses according to claim 2, characterized in that, The position of the scattered light on the soft-sensitive surface of the light spot position detector is processed by analog and digital circuits, analyzed by a microprocessor, and the corresponding output value is calculated. Within the analog quantity window set by the user, a standard data signal is output proportionally. When using a switch output, it is turned on within the set window and turned off outside the window. In addition, the detection windows for analog quantity and switch output can be set independently.

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