Optical system for a triangulation device, a triangulation device and a method of use

Abstract

The application is suitable for the field of spectral detection technology, and provides a kind of optical system of triangulation device, ranging device and use method, the optical system includes laser emitting device, imaging lens and position sensor;The ratio obtained by dividing the pixel size of the position sensor by the focal length of the imaging lens is multiplied by the imaging displacement of the position sensor, and the product is 0.7~3.6;The ratio obtained by dividing the focal length of the imaging lens by the detection distance is 0.04~0.3;The pixel size is 7.8 microns~25 microns, the application can have a smaller pixel displacement amount under a higher theoretical resolution, thereby improving the calculation accuracy of the triangulation device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser triangulation ranging, and particularly relates to an optical system of a triangulation ranging device, a ranging device and a use method. BACKGROUND

[0002] The optical system of the triangulation ranging device is a system for measuring distance by using the principles of laser emission, diffuse reflection and reception. The principle is that the laser emits laser light, the laser light is diffusely reflected after irradiating the target object, the diffusely reflected light is focused on the position sensor through the imaging lens, and the distance between the object and the laser can be calculated by using the similar principle of triangle according to the laser incidence angle and the position offset of the reflected light on the position sensor. This method has the advantages of high precision and non-contact measurement, and is suitable for various application scenarios.

[0003] In the related art, the smaller the theoretical resolution value of the triangulation ranging device is under the condition that the algorithm is fixed, the higher the system accuracy is.

[0004] The pixel displacement (also referred to as the number of pixel waveforms) is an important factor affecting the imaging quality. In a static scene, when the pixel displacement exceeds the limit of the resolution of the optical system (such as the diffraction limit defined by the Rayleigh criterion), the image blurs. In a dynamic scene such as high-speed photography or target tracking, too large pixel displacement may cause motion blur. Therefore, the pixel displacement is limited to vary within a small range, which is beneficial to maintaining high imaging quality and high calculation accuracy. Otherwise, the imaging quality may be reduced, thereby affecting the calculation accuracy.

[0005] However, in the related art, the calculation accuracy of the triangulation ranging device is poor. In the related art, in order to ensure high theoretical resolution, the imaging lens focal length is often increased to increase the imaging displacement. At this time, the magnification of the optical system is large, which leads to a large pixel displacement, thereby reducing the image quality and affecting the calculation accuracy. SUMMARY

[0006] The embodiments of the application provide an optical system of a triangulation ranging device, a ranging device and a use method to improve the calculation accuracy of the triangulation ranging device.

[0007] In a first aspect, the embodiments of the application provide an optical system of a triangulation ranging device, which includes a laser emission device, an imaging lens and a position sensor; the product of the ratio of the pixel size of the position sensor divided by the focal length of the imaging lens and the imaging displacement of the position sensor is 0.7-3.6; the ratio of the focal length of the imaging lens divided by the detection distance is 0.04-0.3; and the pixel size is 7.8 microns-25 microns.

[0008] Further, the imaging lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence in the reflection direction of the laser; the first lens has positive refractive power; the second lens has negative refractive power; the third lens has positive refractive power; and the fourth lens has positive refractive power.

[0009] Further, the first lens has an Abbe number of 28-55; and / or, the second lens has a refractive index of 1.6-1.9; and / or, the third lens has a refractive index of 1.6-1.8.

[0010] Further, the optical system further comprises a reflector; the reflector is configured to reflect the laser emitted from the imaging lens to a position sensor.

[0011] Further, the detection distance is 250-1200 mm, and / or, the pixel displacement of the position sensor is 4-7.5 px; and / or, the position sensor is a charge coupled device; and / or, the emission lens of the laser emission device is an aspheric lens.

[0012] Further, the angle between the reflector and the vertical direction is 5-80°; and / or, the angle between the reflector and the vertical direction is 15-60°.

[0013] In a second aspect, the embodiments of the present application provide a triangulation device, comprising the optical system.

[0014] Further, the number of position sensors is multiple; the position sensors comprise a first position sensor and a second position sensor; in a first use state, the optical system of the triangulation device comprises a laser emission device, an imaging lens and the first position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emission device is adjusted to be a first angle;

[0015] In a second use state, the optical system of the triangulation device comprises a laser emission device, an imaging lens and the second position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emission device is adjusted to be a second angle;

[0016] The first angle and the second angle are the same or different.

[0017] Further, the triangulation device further comprises:

[0018] A light barrier is arranged between the laser emission device and the imaging lens to block the laser emitted by the laser emission device from entering the position sensor.

[0019] In a third aspect, the embodiments of the present application provide a method for using the triangulation device, comprising:

[0020] switching from the first use state to the second use state:

[0021] disassembling the first position sensor;

[0022] adjusting the included angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device to a second included angle;

[0023] adjusting the position of the second position sensor according to the second included angle and installing the second position sensor;

[0024] switching from the second use state to the first use state:

[0025] disassembling the second position sensor;

[0026] adjusting the included angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device to a first included angle;

[0027] adjusting the position of the first position sensor according to the first included angle and installing the first position sensor.

[0028] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0029] The optical system of the triangulation device, the ranging device and the method for using the same according to the embodiments of the present application limit the product of the ratio obtained by dividing the pixel size of the position sensor in the optical system by the focal length of the imaging lens and the imaging displacement of the position sensor to 0.7-3.6, limit the ratio obtained by dividing the focal length of the imaging lens by the detection distance to 0.04-0.3, and limit the pixel size to 7.8 microns-25 microns, so that the present application can maintain a high theoretical resolution and have a small pixel displacement amount in the case of a large detection distance span, thereby improving the calculation accuracy of the triangulation device. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0031] Figure 1 is a schematic diagram of the direct triangulation principle of the optical system of the triangulation device.

[0032] Figure 2 is a schematic diagram of the relationship between object displacement and image displacement.

[0033] Figure 3 is a schematic diagram of the relationship between object shift and pixel.

[0034] Figure 4 is a schematic diagram of the pixel centroid spacing between the pixel waveform at A' and the pixel waveform at B'.

[0035] Figure 5 is a schematic diagram of the structure of the optical system of the triangulation device in Case 1.

[0036] Figure 6 is a schematic diagram of the structure of the optical system of the triangulation device in Case 2.

[0037] Figure 7 is a schematic diagram of the structure of the optical system of the triangulation device in Case 3.

[0038] Figure 8 is a schematic diagram of the structure of the optical system of the triangulation device in Case 4.

[0039] Figure 9 is a graph of the object-image displacement curve of the optical system of Case 1.

[0040] Figure 10 is a graph of the relationship between object shift and pixel of the optical system of Case 1.

[0041] Figure 11 is an imaging point column diagram of the optical system of Case 1; wherein, Figure 11 (a) in the diagram is an imaging point column diagram of the optical system at a detection distance of 300 mm; Figure 11 (b) in the diagram is an imaging point column diagram of the optical system at a detection distance of 400 mm; Figure 11 (c) in the diagram is an imaging point column diagram of the optical system at a detection distance of 500 mm; 0.655 represents a wavelength of 0.655 um, 0.663 represents a wavelength of 0.663 um, and 0.67 represents a wavelength of 0.67 um.

[0042] Figure 12 is an imaging MTF diagram of the optical system of Case 1, wherein the wavelength range of the diffracted light is 0.655 um to 0.670 um.

[0043] Figure 13 is a graph of the object-image displacement curve of the optical system of Case 2.

[0044] Figure 14 is a graph of the relationship between object shift and pixel of the optical system of Case 2.

[0045] Figure 15 is an imaging point column diagram of the optical system of Case 2; wherein, Figure 15(a) is a diagram of the imaging points of the optical system at a detection distance of 250 mm; Figure 15 (b) is a diagram of the imaging points of the optical system at a detection distance of 500 mm; Figure 15 (c) is a diagram of the imaging points of the optical system at a detection distance of 1200mm.

[0046] Figure 16 The image shows the MTF plot of the optical system in Case 2, where the wavelength range of the diffracted light is 0.655 μm to 0.670 μm.

[0047] Figure 17 This is the object-image displacement curve of the optical system in Case 3.

[0048] Figure 18 This is a graph showing the relationship between object movement and pixels in the optical system of Case 3.

[0049] Figure 19 This is the imaging point diagram of the optical system in Case 3; where, Figure 19 (a) is a diagram of the imaging points of the optical system at a detection distance of 300 mm; Figure 19 (b) is a diagram showing the imaging points of the optical system at a detection distance of 400 mm; Figure 19 (c) is a diagram of the imaging points of the optical system at a detection distance of 500mm.

[0050] Figure 20 The image MTF diagram of the optical system in Case 3 shows that the wavelength range of the diffracted light is from 0.655 μm to 0.670 μm.

[0051] Figure 21 This is the object-image displacement curve of the optical system in Case 4.

[0052] Figure 22 This is a graph showing the relationship between object movement and pixels in the optical system of Case 4.

[0053] Figure 23 This is the imaging point diagram of the optical system in Case 4; where, Figure 23 (a) is a diagram of the imaging points of the optical system at a detection distance of 300 mm; Figure 23 (b) is a diagram showing the imaging points of the optical system at a detection distance of 400 mm; Figure 23 (c) is a diagram of the imaging points of the optical system at a detection distance of 500mm.

[0054] Figure 24 The image MTF diagram of the optical system in Case 4 shows that the wavelength range of the diffracted light is from 0.655 μm to 0.670 μm. Detailed Implementation

[0055] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0056] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0057] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0059] Before introducing the embodiments of this application, the direct triangulation principle of the optical system of the triangulation distance measuring device in the related art is described as follows.

[0060] The optical system of a triangulation rangefinder is a system that measures distance using the principles of laser emission, diffuse reflection, and reception. The principle is as follows: the laser emits a laser beam, which, upon striking the target object, undergoes diffuse reflection. This reflected light is focused onto a position sensor through an imaging lens. Based on the laser's incident angle and the positional offset of the reflected light on the position sensor, the distance between the object and the laser can be calculated using the principle of triangle similarity.

[0061] In the optical system of a triangulation rangefinder, when the laser beam is incident perpendicularly onto the surface of the object being measured, that is, when the angle between the incident light and the normal to the surface of the object being measured is 0°, the incident method is called direct incidence, which is the most commonly used method.

[0062] See Figure 1As shown in the figure, the laser emitted by the laser 01 is directly irradiated on the measured object through the transmitting lens 02, and the diffuse reflection light generated by the measured object is propagated to the position sensor 09 through the imaging lens 08. The position sensor 09 can be a photoelectric detector such as a charge coupled device (CCD). The following position sensor 09 is described by taking the charge coupled device (CCD) as an example.

[0063] The dashed line OM passing through the point M is the distance reference line 04, the solid line 05 passing through the point A is the upper detection limit of the measured object, the solid line 07 passing through the point B is the lower detection limit of the measured object, the dashed line 06 passing through the point N is the reference position, the moving distance of AN is y2, and the moving distance of NB is y1. The sum of y1 and y2 is the detection distance.

[0064] The detection distance in the present application refers to the distance between the closest position of the measured object to the distance reference line and the farthest position of the measured object to the distance reference line when the measured object is detected in the optical system of the triangulation distance measuring device. For example, the closest position of the measured object to the distance reference line is 300 mm, and the farthest position of the measured object to the distance reference line is 500 mm. That is, the detection distance is 300 mm-500 mm.

[0065] The fixed detection distance refers to the distance between the closest position of the measured object to the distance reference line and the farthest position of the measured object to the distance reference line. The detection distance can be a certain point value or a fixed detection range, which is not limited here.

[0066] The relationship between the moving distance y1 of the measured object and the imaging displacement x1 of the reflected light spot on the position sensor 09 through the imaging lens 08 satisfies:

[0067] .

[0068] The relationship between the moving distance y2 of the measured object and the imaging displacement x2 of the reflected light spot on the position sensor 09 through the imaging lens satisfies:

[0069] .

[0070] wherein, and are vectors.

[0071] Referring to Figure 1 As shown in the figure, the imaging lens optical axis 010 and the incident light optical axis 03 intersect at the point N, and the included angle is θ; the imaging lens optical axis 010 and the position sensor 09 intersect at the point N', and the included angle is β; N and N' are the imaging points, and the distance from the point N to the main plane O' of the imaging lens is the object distance , and the distance from O' to N' is the image distance The focal length of the imaging lens is f. The reflected light of point A intersects with the position sensor 09 at A' through the imaging lens, and the reflected light of point B intersects with the position sensor 09 at B' through the imaging lens.

[0072] The imaging surface on the position sensor, the surface of the measured object, and the main plane of the imaging lens satisfy the optical state of intersecting at a common point, that is, the Scheimpflug law. It is easy to derive from the Scheimpflug law that: .

[0073] The greater the distance from the reference line OM and the focal length f of the imaging lens 08, the greater the volume of the sensing head of the position sensor, and the higher the measurement accuracy. The greater the angle θ between the optical axis of the imaging lens and the optical axis of the incident light, the greater the width of the sensing head of the position sensor, and the higher the measurement accuracy.

[0074] However, in the case of detecting a fixed distance, the greater the focal length of the imaging lens, the greater the size of the image shift x (that is, the sum of the imaging displacement x1 and the imaging displacement x2), and the smaller the theoretical resolution value (that is, the higher the theoretical resolution). However, in this case, the pixel displacement is relatively large. Conversely, the smaller the focal length of the imaging lens, the smaller the size of the image shift (that is, the sum of the imaging displacement x1 and the imaging displacement x2), and the greater the theoretical resolution value (that is, the lower the theoretical resolution). However, in this case, the pixel displacement is relatively small.

[0075] As can be seen from the above, in the case of detecting a fixed distance, it is difficult in the related art to make the pixel displacement relatively small while meeting a relatively high theoretical resolution, thereby failing to guarantee the system accuracy and stability.

[0076] The specific description is as follows.

[0077] In the case of detecting a fixed distance, the focal length f of the imaging lens and the pixel size P of the CCD jointly determine the theoretical resolution and the pixel displacement I (also called the number of pixel waveforms); the pixel size P of the CCD is in units of um, the unit of Δs is mm, and the calculation formula of the pixel displacement I is as follows:

[0078] Pixel displacement I = (Δs x 1000) / P;

[0079] Wherein, Δs is the moving distance of the light spot center on the CCD corresponding to the emitting light spot passing through the imaging lens at a certain single detection distance, which can also be simply denoted as the single-point light spot moving distance, and is expressed in mm. It can also be understood that the imaging lens has a magnification, and the size of the light spot corresponding to the emitting light spot passing through the imaging lens on the CCD is moved within the range of the object shift in the entire detection distance (that is, Figure 2 ), and the total light spot center moving distance corresponding to the imaging lens on the CCD is denoted as X (that is, Figure 2 ), which is expressed in mm.

[0080] Referring to Figure 2 As shown in the figure, the image shift x / mm can be obtained by converting the pixel displacement amount Figure 3 As shown in the figure. (Assuming that the CCD pixel size is 12.5um, and the image shift centroid travel is 5mm; then 5mm x 1000 / 12.5um = 400 pixels). Assuming that the software processing can distinguish 0.03 pixels, then the image shift can identify 12.5 x 0.03 = 0.375um, and the object image displacement curve is the steepest at the detection distance B position, that is, the theoretical resolution is the largest, so when the B' point identifies 0.375um of image shift in the A' direction, the corresponding object shift distance is the theoretical resolution.

[0081] The pixel displacement amount I can also be referred to as the number of pixel waveforms. Referring to Figure 1 As shown in the figure, the laser emits a light beam, and assuming that the transmission spot size to point A is 100um, and after the magnification of the imaging lens, the spot size on the CCD is 62.5um, then the pixel displacement amount I = 62.5 / 12.5 = 5. Therefore, the pixel displacement amount is closely related to the transmission spot size, and the smaller the transmission spot size, the smaller the pixel displacement amount.

[0082] The triangulation device can read the pixel displacement amount at each position on the CCD through the oscilloscope, calculate the image shift through the pixel centroid spacing, and thus calculate the object shift. Because the magnification of the imaging lens corresponding to different detection distances is not the same, and the transmission spot size at different positions is also not the same, generally speaking, the full-range pixel displacement amount is not consistent, and generally conforms to "the pixel displacement amount is more at near distance detection, and the pixel displacement amount is less at far distance detection". Referring to Figure 1 and Figure 4 As shown in the figure, the image shift can be calculated according to the spacing a between the pixel centroid of the pixel waveform 011 at A' and the pixel centroid of the pixel waveform 012 at B', and thus the object shift can be calculated.

[0083] The smaller the theoretical resolution value, that is, the higher the theoretical resolution, the higher the accuracy; the higher the pixel waveform, the better for the algorithm, and the higher the accuracy; the fewer the number of pixel waveforms, the better for the algorithm, and the higher the accuracy, and the fewer the number, which is beneficial to the detection stability and the improvement of the repeatability.

[0084] As can be seen from the above, under the premise of fixed detection distance and high theoretical resolution, the system focal length is often large, and at this time the pixel displacement amount is difficult to be small, resulting in that it is difficult to improve and guarantee the system accuracy and stability on the algorithm.

[0085] To solve the problem that the pixel displacement is difficult to keep small under the premise of fixed detection distance and keeping high theoretical resolution, resulting in the contradiction between theoretical resolution and algorithm stability, and to realize high-precision distance detection under the constraint of limited pixel displacement and improve the calculation accuracy of the triangulation distance measuring device, the optical system of the triangulation distance measuring device provided in the embodiments of the present application includes a laser emitting device, an imaging lens and a position sensor; the product of the ratio of the pixel size of the position sensor divided by the focal length of the imaging lens and the imaging displacement of the position sensor is 0.7-3.6; the ratio of the focal length of the imaging lens divided by the detection distance is 0.04-0.3; and the pixel size is 7.8 microns-25 microns.

[0086] The embodiments of the present application aim at the core contradiction that the pixel displacement is too large when the detection distance is fixed and the theoretical resolution is kept high, and by limiting the proportional relationship of the pixel size, the focal length of the imaging lens and the detection distance (such as the focal length / detection distance is 0.04-0.3), the theoretical resolution of the system is kept at a reasonable level under the constraint of limited pixel displacement, and the interference of the large displacement on the algorithm stability is avoided, and the balance between the two is achieved.

[0087] The pixel size is limited to 7.8 microns-25 microns, and in combination with the ratio of the focal length of the imaging lens and the detection distance, the imaging displacement of the target object on the position sensor is ensured to be in the range that can be accurately identified.

[0088] The product of the pixel size / focal length and the imaging displacement is limited to 0.7-3.6, which further optimizes the signal-to-noise ratio and quantization accuracy of the imaging signal, reduces the measurement error caused by improper parameter matching, and ultimately improves the calculation accuracy of the triangulation distance measuring device.

[0089] The various parameters of the embodiments of the present application are designed around the scenario of fixed detection distance, and the ratio of the focal length and the detection distance (0.04-0.3) ensures that the optical magnification of the system at this distance is reasonable, which can capture target details (high resolution) and output reliable results through stable algorithms, and is suitable for scenarios such as industrial measurement and three-dimensional modeling that require high-precision detection at fixed distances.

[0090] Therefore, the embodiments of the present application limit the product of the ratio of the pixel size of the position sensor divided by the focal length of the imaging lens and the imaging displacement of the position sensor to 0.7-3.6, limit the ratio of the focal length of the imaging lens divided by the detection distance to 0.04-0.3, and limit the pixel size to 7.8 microns-25 microns, so that the present application can reduce the variation range of the pixel displacement under high theoretical resolution, thereby improving the calculation accuracy of the triangulation distance measuring device.

[0091] Optionally, the optical system comprises a laser emitting device, an imaging lens 08 and a position sensor 09. Optionally, the laser emitting device comprises a laser 01 and an emitting lens 02. The imaging lens can realize the optical conversion function, focusing the light spot reflected by the measured object on the position sensor to form a clear image point. The imaging lens has good aberration correction function, so as to ensure the detection accuracy and stability of the sensor.

[0092] Optionally, the emitting lens of the laser emitting device is an aspheric lens. The emitting lens adopts an aspheric lens instead of a spherical lens, which can better focus or collimate the divergent Gaussian beam emitted by the laser, ensuring the detection accuracy and stability.

[0093] Optionally, the position sensor 09 is a charge coupled device (CCD).

[0094] Taking the CCD as an example. The focal length f of the imaging lens, the CCD pixel size P and the image shift x satisfy: 0.7≤(P / f)×X≤3.6; the ratio of the focal length f of the imaging system to the detection distance y satisfies: 0.04≤f / y≤0.3; 7.8um≤CCD pixel size P≤25um. Exemplarily, the value of (P / f)×X can be 0.7, 1.0, 1.2, 1.5, 1.8, 2.2, 2.4, 3.0, 3.2 or 3.6; here, only examples are given without limitation. Exemplarily, the value of f / y can be 0.04, 0.08, 0.1, 0.12, 0.15, 0.18, 0.22, 0.24, 0.26 or 0.3; here, only examples are given without limitation. Exemplarily, the value of CCD pixel size P can be 7.8um, 8um, 10um, 12um, 14um, 16um, 18um, 20um, 22um or 25um; here, only examples are given without limitation.

[0095] Optionally, the detection distance is 250mm-1200mm, and the detection distance can also be 300mm-500mm, 600mm-800mm; here, only examples are given without limitation.

[0096] Optionally, the pixel displacement of the position sensor is 4-7.5px (pixels); exemplarily, the pixel displacement of the position sensor is 4, 5, 6, 7 or 7.5px.

[0097] In order to improve the imaging quality, the imaging lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in the reflection direction of the laser in sequence; the focal power of the first lens is positive; the focal power of the second lens is negative; the focal power of the third lens is positive; and the focal power of the fourth lens is positive.

[0098] The imaging lens adopts a four-lens combination design of "positive focal power-negative focal power-positive focal power-positive focal power", the first lens serves as a front-end lens and can preliminarily converge laser reflected light; the second lens and the first lens form a "positive-negative combination", which can effectively offset the spherical aberration and chromatic aberration (especially axial chromatic aberration) generated by the first lens, while reducing the field curvature and distortion of the system and improving the imaging quality of the edge field of view; the third lens and the fourth lens further converge light rays to ensure the total focal power of the system after the second lens corrects part of the aberration, and through the synergistic effect of the double positive lenses, the remaining aberration (such as coma and magnification chromatic aberration) can be finely corrected, and the focusing ability of light rays with different incident angles can be enhanced to ensure that the laser reflected light forms a clear and sharp image point on the position sensor. The focal power combination of the four lenses can reduce the imaging errors caused by environmental factors such as laser wavelength fluctuation and temperature change through optimization of aberration correction: for example, the inhibitory effect of the negative focal power lens on chromatic aberration can reduce the impact of slight changes in laser wavelength on focusing accuracy; and the structure of the multiple lenses in cooperation also improves the mechanical stability of the system, which indirectly ensures the consistency of the measurement accuracy.

[0099] Therefore, the imaging lens adopts a four-piece spherical structure, which realizes good aberration correction function and high lens resolution through the matching of lens focal power and material, and helps the system to maintain high measurement accuracy.

[0100] Optionally, an imaging lens diaphragm is arranged between the second lens and the third lens.

[0101] Optionally, a receiving window mirror is arranged in front of the first lens. Illustratively, the receiving window mirror adopts a band-pass filter. In this way, high transmittance can be provided for light in a specific wavelength range, while the interference of out-of-band stray light is strongly suppressed, ensuring detection accuracy and stability.

[0102] Optionally, the Abbe number of the first lens is 28-55, the refractive index of the second lens is 1.6-1.9, and the refractive index of the third lens is 1.6-1.8. Illustratively, the Abbe number of the first lens is 28, 30, 35, 40, 45 or 55, the refractive index of the second lens is 1.6, 1.7, 1.8 or 1.9, and the refractive index of the third lens is 1.6, 1.7, 1.8 or 1.9. This is only an example and is not limited.

[0103] The first lens with an Abbe number of 28-55 can ensure the front-end light collection efficiency and basic dispersion control; the second lens with a refractive index of 1.6-1.9 can strengthen aberration cancellation and system compactness; the third lens with a refractive index of 1.6-1.8 can play a role in linking intermediate correction and light convergence; and finally, the fourth lens realizes closed-loop optimization of total focal power and imaging accuracy.

[0104] Further, the optical system further comprises a mirror; the mirror is used for reflecting the laser emitted from the imaging lens to a position sensor.

[0105] The optical system adds the mirror to reduce the volume of the sensing head of the position sensor, so as to make the whole optical system smaller.

[0106] The addition of the mirror realizes the miniaturization of the system by optimizing the spatial layout, and enhances the environmental adaptability and application flexibility of the system without sacrificing the ranging accuracy by improving the stability of the optical path and matching the core optical parameters, which forms synergy with the lens parameter design and optical power combination described above, and improves the comprehensive performance of the triangulation ranging device.

[0107] Further, the angle between the mirror and the vertical direction is 5°-80°; optionally, the angle between the mirror and the vertical direction is 15°-60°.

[0108] Exemplarily, the angle between the mirror and the vertical direction can be 5°, 10°, 15°, 20°, 30°, 45°, 60°, 70° or 80°, etc., which are only examples and are not limited.

[0109] In a second aspect, the embodiments of the present application provide a triangulation ranging device, comprising the optical system described above.

[0110] Further, the number of position sensors is multiple; the position sensors comprise a first position sensor and a second position sensor; in a first use state, the optical system of the triangulation ranging device comprises a laser emitting device, an imaging lens and the first position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device is adjusted to be a first angle;

[0111] In a second use state, the optical system of the triangulation ranging device comprises a laser emitting device, an imaging lens and the second position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device is adjusted to be a second angle;

[0112] The first angle and the second angle are the same or different.

[0113] The triangulation ranging device of the embodiments of the present application realizes multiple measurement modes by arranging multiple position sensors, and in each measurement mode, only the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device needs to be adjusted according to the requirement of detecting distance in each measurement mode, and the corresponding specification of the position sensor is installed at the position corresponding to the angle.

[0114] In this way, the cost of the triangulation ranging device can be reduced, and the switching and use of multiple measurement modes can be realized as much as possible in a limited internal volume space.

[0115] Further, the triangulation ranging device further comprises:

[0116] The light barrier is arranged between the laser emitting device and the imaging lens to block the laser emitted by the laser emitting device from entering the position sensor.

[0117] The light barrier can avoid unnecessary light from hitting the effective light sensing surface of the CCD, avoid interference with the received signal, and ensure detection accuracy and stability.

[0118] The above is described through specific implementation cases.

[0119] Case 1

[0120] The triangulation ranging device comprises Figure 1 The optical system of the triangulation ranging device shown in the figure is different in that the optical system further comprises a mirror; the position sensor is a CCD; specifically, referring to Figure 5 The optical system comprises a CCD, a CCD front packaging glass 1, a mirror 2, an imaging lens 08, and a receiving window mirror 4; the reflected light generated after the laser emitted by the laser of the optical system irradiates the surface of the measured object enters the CCD through the receiving window mirror 4, the imaging lens 08, the mirror 2, and the CCD front packaging glass 1 in sequence.

[0121] The imaging lens 08 comprises a first lens 5, a second lens 6, a third lens 7, and a fourth lens 8; an imaging lens diaphragm 3 is arranged between the second lens 6 and the third lens 7; the angle between the mirror and the vertical direction Z is a, and the angle a is adjusted according to the spatial distribution state; in the case of ensuring a small volume and not causing light interference, the angle can be adjusted arbitrarily. Exemplarily, the mutual positions, setting angles, and optical paths of the CCD front packaging glass 1, the mirror 2, the imaging lens diaphragm 3, each lens in the imaging lens 08, and the receiving window mirror 4 are shown in Figure 5 .

[0122] The main parameters of the optical system are as follows: the detection distance is 300-500 mm, the reference distance MN is 400 mm, the included angle θ between the optical axis of the imaging lens and the emitted light is 10.2°, the slow axis size of the emitted light spot (the position of the emitted light spot is adjusted by adjusting the position of the laser emitter so that the emitted light spot is focused at different positions) is 320 um at the position of the detection distance of 300 mm, 340 um at the position of the detection distance of 400 mm, and 465 um at the position of the detection distance of 500 mm, the CCD pixel size P is 12.5 um, the focal length f of the imaging lens is 42 mm, the image shift x is 4.6 mm, the pixel displacement I is about 5.5 px, the theoretical resolution of 0.03 sub-pixels is 18 um at the detection distance of 400 mm, and the theoretical resolution of 0.03 sub-pixels is 27 um at the detection distance of 500 mm, the linear accuracy is ±0.05% F.S., and the repeatability is 2 um.

[0123] The parameters of the optical system in the triangulation device are input into optical design and simulation software such as Zemax software, and the optical effect of the above optical system is analyzed. The parameters of the optical system in the triangulation device are shown in Table 1.

[0124] Table 1

[0125]

[0126] Table 1 (continued)

[0127]

[0128] Case 2

[0129] The triangulation device comprises Figure 1 The optical system of the triangulation device shown in the drawing, wherein the optical system further comprises a mirror; the position sensor is a CCD; specifically, referring to Figure 6 The optical system comprises a CCD, a CCD front packaging glass 1, a mirror 2, an imaging lens 08, and a receiving window mirror 4; the reflected light generated after the laser emitted by the laser of the optical system irradiates the surface of the measured object enters the CCD through the receiving window mirror 4, the imaging lens 08, the mirror 2, and the CCD front packaging glass 1 in sequence.

[0130] The imaging lens 08 comprises a first lens 5, a second lens 6, a third lens 7, and a fourth lens 8; the imaging lens diaphragm 3 is arranged between the second lens 6 and the third lens 7; the included angle a between the mirror and the vertical direction Z is adjusted according to the included angle θ between the optical axis of the imaging lens and the emitted light. The mutual positions, setting angles, and optical paths of the CCD front packaging glass 1, the mirror 2, the imaging lens diaphragm 3, each lens in the imaging lens 08, and the receiving window mirror 4 are shown in the drawing. Figure 6 The imaging lens 08 comprises a first lens 5, a second lens 6, a third lens 7, and a fourth lens 8; the imaging lens diaphragm 3 is arranged between the second lens 6 and the third lens 7; the included angle a between the mirror and the vertical direction Z is adjusted according to the included angle θ between the optical axis of the imaging lens and the emitted light. The mutual positions, setting angles, and optical paths of the CCD front packaging glass 1, the mirror 2, the imaging lens diaphragm 3, each lens in the imaging lens 08, and the receiving window mirror 4 are shown in the drawing.

[0131] The main parameters of the optical system are as follows: the detection distance is 250-1200 mm, the reference distance MN is 500 mm, the angle θ between the optical axis of the imaging lens and the emitted light is 8.19°, the slow axis size of the emitted light spot (the position of the emitted light spot is adjusted to focus at different positions) is 400 um at the position of the detection distance of 250 mm, 625 um at the position of the detection distance of 5000 mm, and 1820 um at the position of the detection distance of 1200 mm, the CCD pixel size P is 14 um, the imaging lens focal length f is 42 mm, the image shift x is 10.8 mm, the pixel displacement I is about 7.5 px, the 0.03 sub-pixel theoretical resolution is 31.2 um at the position of the detection distance of 500 mm, the 0.03 sub-pixel theoretical resolution is 175 um at the position of the detection distance of 1200 mm, the linear accuracy is ±0.05% F.S., and the repeatability is 2 um.

[0132] The parameters of the optical system in the triangulation device are input into the Zemax software to analyze the optical effect of the optical system. The parameters of the optical system in the triangulation device are shown in Table 2.

[0133] Table 2

[0134]

[0135] Continuation of Table 2

[0136]

[0137] Case 3

[0138] The triangulation device comprises Figure 1 The optical system of the triangulation device shown in the drawing, wherein the optical system further comprises a mirror; the position sensor is a CCD; specifically, referring to Figure 7 As shown in the drawing, the optical system comprises a CCD, a CCD front packaging glass 1, a mirror 2, an imaging lens 08, and a receiving window mirror 4; the reflected light generated after the laser emitted by the laser of the optical system irradiates the surface of the measured object enters the CCD through the receiving window mirror 4, the imaging lens 08, the mirror 2, and the CCD front packaging glass 1 in sequence.

[0139] The imaging lens 08 comprises a first lens 5, a second lens 6, a third lens 7 and a fourth lens 8; the imaging lens diaphragm 3 is arranged between the second lens 6 and the third lens 7; the included angle between the mirror and the vertical direction Z is a, and the included angle a is adjusted according to the included angle θ between the imaging lens optical axis and the emitted light. The mutual positions, setting angles and optical paths of the CCD front packaging glass 1, the mirror 2, the imaging lens diaphragm 3, the imaging lens 08 and the receiving window mirror 4 are shown in Figure 7

[0140] The main parameters of the optical system are as follows: the detection distance is 300-500 mm, the reference distance MN is 400 mm; the included angle θ between the imaging lens optical axis and the emitted light is 10.2°; the slow axis size of the emitted light spot (the position of the emitted light spot is adjusted by adjusting the position of the emitting end laser so as to focus the emitted light spot at different positions) is 320 um at the position of 300 mm of the detection distance; the slow axis size of the emitted light spot is 340 um at the position of 400 mm of the detection distance; the slow axis size of the emitted light spot is 465 um at the position of 500 mm of the detection distance; the CCD pixel size P is 7.8 um; the imaging lens focal length f is 22.2 mm; the image shift x is 2.07 mm; the pixel displacement I is about 4 px; the 0.03 sub-pixel theoretical resolution is 24.5 um at the position of 400 mm of the detection distance; the 0.03 sub-pixel theoretical resolution is 37.0 um at the position of 500 mm of the detection distance, and the linearity accuracy is ±0.05% F.S.; the repeatability accuracy is 2 um.

[0141] The parameters of the optical system in the triangulation device are input into the Zemax software to analyze the optical effect of the above optical system. The parameters of the optical system in the triangulation device are shown in Table 3.

[0142] Table 3

[0143]

[0144] Table 3 (continued)

[0145]

[0146] Case 4

[0147] The triangulation device comprises Figure 1 The optical system of the triangulation device shown in the drawing, and the difference lies in that the optical system further comprises a mirror; the position sensor is a CCD; specifically, referring to Figure 8 The optical system comprises a CCD, a CCD front packaging glass 1, a mirror 2, an imaging lens 08 and a receiving window mirror 4; the reflected light generated after the laser emitted by the laser of the optical system irradiates the surface of the measured object enters the CCD through the receiving window mirror 4, the imaging lens 08, the mirror 2 and the CCD front packaging glass 1 in sequence.​

[0148] The imaging lens 08 comprises a first lens 5, a second lens 6, a third lens 7 and a fourth lens 8; the imaging lens diaphragm 3 is arranged between the second lens 6 and the third lens 7; the angle between the mirror and the vertical direction Z is a, and the angle a is adjusted according to the angle θ between the imaging lens optical axis and the emitted light. The mutual positions, setting angles and optical paths of the CCD front package glass 1, the mirror 2, the imaging lens diaphragm 3, the imaging lens 08 and the receiving window mirror 4 are shown in Figure 8 .

[0149] The main parameters of the optical system are as follows: the detection distance is 300-500 mm, the reference distance MN is 400 mm; the angle θ between the imaging lens optical axis and the emitted light is 10.2°; the slow axis size of the emitted light spot (the position of the emitted end laser is adjusted so that the emitted light spot is focused at different positions) is 320 um at the position of 300 mm of the detection distance; the slow axis size of the emitted light spot is 340 um at the position of 400 mm of the detection distance; the slow axis size of the emitted light spot is 465 um at the position of 500 mm of the detection distance; the CCD pixel size P is 25 um; the imaging lens focal length f is 59.6 mm; the image shift x is 8.35 mm; the pixel displacement I is about 6 px; the 0.03 sub-pixel theoretical resolution is 19.5 um at the position of 400 mm of the detection distance; the 0.03 sub-pixel theoretical resolution is 31.5 um at the position of 500 mm of the detection distance, the linear accuracy is ±0.05% F.S.; and the repeatability is 2 um.

[0150] The parameters of the optical system in the triangulation device are input into the Zemax software to analyze the optical effect of the above-mentioned optical system. The parameters of the optical system in the triangulation device are shown in Table 4.

[0151] Table 4

[0152]

[0153] Continuation of Table 4

[0154]

[0155] In the above cases, the left and right refer to the fluctuation range of the numerical value change not more than ±1.

[0156] In the above cases, the component names corresponding to each serial number are shown in Table 5.

[0157] Table 5

[0158]

[0159] Note: S1 surface in Table 5 is the surface on which light from the incident direction is projected, and S2 surface is the surface on which light from the incident direction is projected.

[0160] The simulation analysis of Case 1-4 is described with reference to Figures 9-24 as shown.

[0161] Case 1 is described with reference to Figures 9-12 as shown. It is described with reference to Figure 9 as shown, and the object shift y, i.e. the detection distance, is from 300 mm to 500 mm, and the corresponding image shift x is moved by 4.6 mm. It is described with reference to Figure 10 as shown, and the detection distance is from 300 mm to 500 mm, and a total of 364 pixels are used. The conversion relationship is 364 pixels x CCD pixel size 12.5 um = image shift x 4.6 mm; assuming that the software processing can distinguish 0.03 pixel points, the object shift corresponding to the 364th pixel to the 363.97th pixel is 27 um, i.e. the 0.03 sub-pixel theoretical resolution at 500 mm is 27 um.

[0162] The parameters of Case 1 in the light trace diagram of the software are shown in Table 6.

[0163] Table 6

[0164]

[0165] It is described with reference to Figure 10 and Table 6, the slow axis size of the emitted light spot is adjusted to 320 um at the detection distance of 300 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (2.9706-2.9019) x 1000 / 12.5 = 5.5; the slow axis size of the emitted light spot is adjusted to 340 um at the detection distance of 400 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (0.1312-0.0695) x 1000 / 12.5 = 4.9; the slow axis size of the emitted light spot is adjusted to 465 um at the detection distance of 500 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (1.6549-1.5894) x 1000 / 12.5 = 5.2. That is, when the detection distance changes in the range of 300 mm-500 mm, the change range of the pixel displacement amount is 4.9-5.5, thereby maintaining a high theoretical resolution and a small pixel displacement amount in the case of a large detection distance span, thereby improving the calculation accuracy of the triangulation device.

[0166] Figure 11 The parameters of Cases (a), (b) and (c) in the point diagram of the software are shown in Table 7.

[0167] Table 7

[0168]

[0169] Referring to Figure 11 and Table 7, the point diagram RMS radius is within 3.5 um in the detection distance of 300-500 mm, close to the Airy disk radius, indicating that the imaging quality is good and the aberration correction is good. Figure 12 Referring to

[0170] Case 2 Referring to Figures 13-16 Referring to Figure 13 Referring to Figure 14 Referring to

[0171] The parameters of Case 2 in the light path diagram of the software are shown in Table 8.

[0172] Table 8

[0173]

[0174] Referring to Table 8, the slow axis size of the emitted light spot is adjusted to 400 um at a detection distance of 250 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (7.5224-7.4217) x 1000 / 14 = 7.2; the slow axis size of the emitted light spot is adjusted to 625 um at a detection distance of 500 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (0.7446-0.6573) x 1000 / 14 = 6.2; the slow axis size of the emitted light spot is adjusted to 1820 um at a detection distance of 1200 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (3.4051-3.3034) x 1000 / 14 = 7.3. That is, when the detection distance changes in the range of 250 mm-1200 mm, the change range of the pixel displacement amount is 6.2-7.3, thereby maintaining a high theoretical resolution and a small pixel displacement amount in the case of a large detection distance span, thereby improving the calculation accuracy of the triangulation device.

[0175] Figure 15 The parameters of cases (a), (b) and (c) in the point column diagram of the software are shown in Table 9.

[0176] Table 9

[0177]

[0178] Referring to Figure 15 and Table 9, the point diagram RMS radius is within 6 um, about 2 times the Airy disk radius size, when the detection distance is in the range of 250-1200 mm, indicating that the imaging quality is good and the aberration correction is good. Referring to Figure 16 and Table 9, the MTF at the limit frequency is above 0.5 when the detection distance is in the range of 250-1200 mm, indicating that the imaging quality is good, the resolution of the imaging lens is higher than the resolution of the CCD, and the aberration correction is good.

[0179] Case 3 refers to Figures 17-20 Referring to Figure 17 Referring to Figure 18 Referring to

[0180] The parameters of Case 3 in the light path diagram of the software are shown in Table 10.

[0181] Table 10

[0182]

[0183] Referring to Figure 18 and Table 10, the slow axis size of the emitted light spot is adjusted to 320 um at a detection distance of 300 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (1.3468-1.3114) x 1000 / 7.8 = 4.5; the slow axis size of the emitted light spot is adjusted to 340 um at a detection distance of 400 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (0.0676-0.0337) x 1000 / 7.8 = 4.4; the slow axis size of the emitted light spot is adjusted to 465 um at a detection distance of 500 mm, and the pixel displacement amount mapped to the receiving system can be calculated as (0.7580-0.7238) x 1000 / 7.8 = 4.4. That is, when the detection distance changes in the range of 300-500 mm, the change range of the pixel displacement amount is 4.4-4.5, thereby maintaining a high theoretical resolution and a small pixel displacement amount when the detection distance span is large, thereby improving the calculation accuracy of the triangulation device.

[0184] Figure 19 The parameters of (a), (b) and (c) in the point graph of the software are shown in Table 11 below.

[0185] Table 11

[0186]

[0187] See Figure 19 As shown in Table 11, within the detection distance range of 300~500mm, the RMS radius of the dot pattern is within 4µm, approximately twice the size of the Airy disk radius, indicating good imaging quality and good aberration correction. (See also...) Figure 20 As shown, within the detection distance range of 300~500mm, the MTF at the limiting frequency is above 0.48, indicating good imaging quality, higher resolution of the imaging lens than that of the CCD, and good aberration correction.

[0188] See Case 4 Figures 21-24 As shown. See also Figure 21 As shown, the object movement y, which corresponds to the detection distance increasing from 300mm to 500mm, corresponds to an image movement x of 8.35mm. (See reference...) Figure 22 As shown, the detection distance ranges from a total of 334 pixels. The conversion relationship is 334 pixels × CCD pixel size 25um = image displacement x 8.35mm. Assuming that the software processing can resolve 0.03 pixels, the object displacement corresponding to the 334th pixel to the 333.97th pixel is 31.5um, which is the theoretical resolution at 500mm.

[0189] The parameters of the trace graph in Case 4 are shown in Table 12 below.

[0190] Table 12

[0191]

[0192] See Figure 22As shown in Table 12, the slow axis size of the emitted light spot is adjusted to 320 um at a detection distance of 300 mm, and the pixel displacement amount on the receiving system can be calculated as (5.5086-5.3571) x 1000 / 25 = 6.1; the slow axis size of the emitted light spot is adjusted to 340 um at a detection distance of 400 mm, and the pixel displacement amount on the receiving system can be calculated as (0.1887-0.0874) x 1000 / 25 = 4.1; the slow axis size of the emitted light spot is adjusted to 465 um at a detection distance of 500 mm, and the pixel displacement amount on the receiving system can be calculated as (2.9522-2.8545) x 1000 / 25 = 4. That is, when the detection distance changes in the range of 300 mm-500 mm, the pixel displacement amount changes in the range of 4-6.1, so that in the case of a large detection distance span, a high theoretical resolution is maintained, and the pixel displacement amount is small, so that the calculation accuracy of the triangulation device is improved.

[0193] Figure 23 The parameters of the point diagram of the software of (a), (b) and (c) are shown in Table 13.

[0194] Table 13

[0195]

[0196] Referring to Figure 23 As shown in Table 13, the point diagram RMS radius is within 6.5 um in the range of 300-500 mm, which is about 2 times the size of the Airy spot radius, indicating that the imaging quality is good and the aberration correction is good. Referring to Figure 24 As shown in Table 13, the MTF at the limit frequency is above 0.8 in the range of 300-500 mm, indicating that the imaging quality is good, the resolution of the imaging lens is higher than that of the CCD, and the aberration correction is good.

[0197] In a third aspect, the embodiments of the present application provide a use method of the triangulation device, comprising:

[0198] Switching from the first use state to the second use state:

[0199] Dismounting the first position sensor;

[0200] Adjusting the included angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device to a second included angle;

[0201] Adjusting the position of the second position sensor according to the second included angle and mounting the second position sensor;

[0202] Switching from the second use state to the first use state:

[0203] disassembling the second position sensor;

[0204] adjusting the included angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emitting device to be a first included angle;

[0205] adjusting the position of the first position sensor according to the first included angle and installing the first position sensor.

[0206] Exemplarily, the optical systems of case 1 and case 2 can be integrated in a triangulation device. The first included angle θ of case 1 is 10.2°, the second included angle θ of case 2 is 8.19°, the CCD pixel size in case 1, i.e. the pixel size of the first position sensor, is 12.5um, and the CCD pixel size in case 2, i.e. the pixel size of the second position sensor, is 14um.

[0207] Optionally, the first use state is a state in which the triangulation device uses the optical system of case 1, and the second use state is a state in which the triangulation device uses the optical system of case 2.

[0208] However, when the optical system of case 1 needs to be switched to the optical system of case 2, the first position sensor of case 1 is disassembled, the first included angle is adjusted to the second included angle, and the second position sensor is installed at a position corresponding to the second included angle, so that the optical system of case 1 for detecting a distance of 300-500mm is switched to the optical system of case 2 for detecting a distance of 250-1200mm.

[0209] The functions and effects of the technical features similar or related to the foregoing technical solutions in the technical solution are similar to those of the foregoing technical solutions. The inventive concept and beneficial effects of the technical solution are similar to those of the foregoing technical solutions, and thus are not described in detail.

[0210] In summary, by controlling the focal length and the CCD pixel size, adjusting the size of the light spot at the emitting end, and optimizing the imaging lens, the pixel displacement in the entire measurement range is uniformly kept within 8, and the situation that the pixel displacement is large at a short distance and small at a long distance does not occur. The pixel displacement in the entire measurement range can be kept basically consistent, which is beneficial to algorithm correction and can keep a high measurement accuracy.

[0211] The above are only preferred embodiments of the present application and are not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical system of a triangulation device, the optical system comprising a laser emitting device, an imaging lens and a position sensor; characterized in that: The ratio of the pixel size of the position sensor to the focal length of the imaging lens is 0.7-3.6; the ratio of the focal length of the imaging lens to the detection distance is 0.04-0.3; the pixel size is 7.8-25 microns; the detection distance refers to all detection distances of the measured object in the optical system of the triangulation distance measuring device; When the measured object is detected in the optical system of the triangulation distance measuring device, the detection distance changes in the range between the position closest to the distance reference line and the position farthest from the distance reference line; When the detection distance changes in the range of 300-500 mm, the pixel displacement changes in the range of 4-6.1; when the detection distance changes in the range of 250-1200 mm, the pixel displacement changes in the range of 6.2-7.

3.

2. The optical system of claim 1, wherein The imaging lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence in the reflection direction of the laser; the first lens has positive refractive power; the second lens has negative refractive power; the third lens has positive refractive power; and the fourth lens has positive refractive power.

3. The optical system of claim 2, wherein, The Abbe number of the first lens is 28-55; and / or, the refractive index of the second lens is 1.6-1.9; and / or, the refractive index of the third lens is 1.6-1.

8.

4. The optical system of claim 1, wherein, Further comprising a reflecting mirror; the reflecting mirror is used to reflect the laser emitted from the imaging lens to the position sensor.

5. The optical system according to any one of claims 1 to 4, wherein The position sensor is a charge coupled device; and / or, the emission lens of the laser emission device is an aspheric lens.

6. The optical system of claim 4, wherein, The angle between the reflecting mirror and the vertical direction is 5-80 degrees; and / or, the angle between the reflecting mirror and the vertical direction is 15-60 degrees.

7. A triangulation device, characterized in that The optical system comprises the optical system of any one of claims 1-6.

8. The triangulation device of claim 7, wherein, The number of position sensors is multiple; the position sensors comprise a first position sensor and a second position sensor; in the first use state, the optical system of the triangulation distance measuring device comprises a laser emission device, an imaging lens and the first position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emission device is adjusted to be a first angle; In the second use state, the optical system of the triangulation distance measuring device comprises a laser emission device, an imaging lens and the second position sensor; the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emission device is adjusted to be a second angle; The first angle and the second angle are the same or different.

9. The device of claim 8, wherein, Further comprising: A light blocking plate is arranged between the laser emission device and the imaging lens to block the laser emitted by the laser emission device from entering the position sensor.

10. A method of using the triangulation device of claim 8 or 9, characterized in that, Further comprising: Switching from the first use state to the second use state: Dismounting the first position sensor; Adjusting the angle between the optical axis of the imaging lens and the optical axis of the incident light generated by the laser emission device to be a second angle; Adjusting the position of the second position sensor according to the second angle and mounting the second position sensor; Switching from the second use state to the first use state: Dismounting the second position sensor; Adjusting an included angle between an optical axis of the imaging lens and an optical axis of incident light generated by the laser emitting device to be a first included angle; Adjusting a first position sensor position according to the first included angle and installing the first position sensor.

Images