CN111623960B - Method and device for measuring optical axis of structured light module - Google Patents
Method and device for measuring optical axis of structured light module Download PDFInfo
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Abstract
The invention provides a structured light module optical axis measuring method and device, and belongs to the technical field of three-dimensional modeling. The method comprises the following steps: adjusting the diffuse reflection flat plate or the structured light module so that the optical axis of the laser emission unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emission unit is incident to the diffuse reflection flat plate; calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the plate surface of the diffuse reflection flat plate; and calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit. The invention aims to provide a method and a device for measuring an optical axis of a structured optical module, which can simply and conveniently measure the optical axis of the structured optical module so as to clamp and control a product with poor assembly and improve the yield of the module.
Description
Technical Field
The invention relates to the technical field of three-dimensional modeling, in particular to a method and a device for measuring an optical axis of a structured light module.
Background
In recent years, 3D imaging has become more and more used in the field of consumer electronics, such as in the fields of 3D scanning, face payment, and scene modeling. The 3D imaging technique can not only image a target object but also acquire depth information of the target object. Structured light or tof (time of flight) depth cameras are the most widely used 3D imaging devices today. The structured light module is generally composed of a laser emitting unit, a laser receiving unit and a processing chip.
Wherein, in process of production, there is very high requirement to the equipment of structured light module, its reason lies in: in the matching calculation process, in order to reduce the time consumption of chip calculation and the power consumption of a module, generally, only the pixel points in the same line of the reference image and the scene image are searched and matched, if the deviation exists between the optical axes of the receiving unit and the laser transmitting unit, the cross-line search can cause that the calculated amount is multiplied, the hardware cost and the power consumption are greatly improved, and the real-time requirement of depth calculation is difficult to achieve in the algorithm. Therefore, the relative optical axis of the structural optical module (i.e. the consistency between the optical axis of the receiving unit and the optical axis of the laser emitting unit) needs to be measured, so as to facilitate the control of the products with poor assembly and improve the yield of the module. However, the measurement difficulty of the relative optical axis of the current structured light module is large, and the measurement efficiency is low.
Disclosure of Invention
The invention aims to provide a method and a device for measuring an optical axis of a structured optical module, which can simply and conveniently measure the optical axis of the structured optical module so as to clamp and control a product with poor assembly and improve the yield of the module.
The embodiment of the invention is realized by the following steps:
in one aspect of the embodiments of the present invention, a method for measuring an optical axis of a structured light module is provided, where the method is applied to an optical axis measuring apparatus of a structured light module, the apparatus includes a diffuse reflection plate, and the method includes:
adjusting the diffuse reflection flat plate or the structured light module so that the optical axis of the laser emission unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emission unit is incident to the diffuse reflection flat plate;
calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the plate surface of the diffuse reflection flat plate;
and calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit.
Optionally, calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image, which includes the pattern of the structured light, received by the receiving unit, includes:
acquiring an image received by a receiving unit;
calculating the distance between the optical axis point of the laser emission unit and the geometric center of the image in the image;
and calculating to obtain an included angle between the optical axis of the laser transmitting unit and the optical axis of the receiving unit according to the distance, the corresponding coefficient, the distance between the laser transmitting unit and the receiving unit and the distance between the structured light module and the diffuse reflection flat plate.
Optionally, the calculating an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image of the pattern containing the structured light received by the receiving unit includes:
acquiring an image received by a receiving unit;
calculating an included angle between a connecting line between a zero-order central point and a first diffraction order central point of the structured light pattern projected by the laser emission unit in the image and a connecting line between the zero-order central point and a geometric center of the image; the included angle is the optical axis rotation angle of the laser emitting unit.
Optionally, a scale is arranged on the surface of the diffuse reflection flat plate; calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate, comprising:
acquiring an image received by a receiving unit, wherein the image comprises an image of a graduated scale;
the corresponding coefficient is calculated from the image of the scale in the image.
Optionally, the corresponding coefficient is a number of pixels corresponding to a unit scale of the scale in the image of the scale.
Optionally, after calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image, which includes the pattern of the structured light, received by the receiving unit, the method further includes:
judging whether an included angle between an optical axis of the laser emitting unit and an optical axis of the receiving unit meets a preset range or not;
if not, adjusting the optical axis direction of the receiving unit or the optical axis direction of the laser emitting unit, and readjusting the diffuse reflection flat plate or the structured light module so that the optical axis of the laser emitting unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emitting unit is incident on the diffuse reflection flat plate.
Optionally, after calculating the rotation angle of the optical axis of the laser emitting unit according to the corresponding coefficient and the image of the pattern containing the structured light received by the receiving unit, the method further includes:
judging whether the optical axis rotation angle of the laser emission unit meets a preset range or not;
if not, the optical axis of the receiving unit or the optical axis of the laser emitting unit is adjusted in a circumferential rotation mode, and the diffuse reflection flat plate or the structured light module is readjusted, so that the optical axis of the laser emitting unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emitting unit enters the diffuse reflection flat plate.
In another aspect of the embodiments of the present invention, an optical axis measuring apparatus for a structured light module is provided, including: fixing device and diffuse reflection flat board, fixing device are used for fixed structure optical module to make the optical axis of laser emission unit or the optical axis of receiving element perpendicular with the diffuse reflection flat board, the diffuse reflection flat board is used for receiving and the structure light that the laser emission unit of reflection structure optical module throws.
Optionally, the fixing means is a six-axis adjustment means.
Optionally, a scale is disposed on the surface of the diffuse reflection flat plate for receiving and reflecting the structured light.
The embodiment of the invention has the beneficial effects that:
according to the method for measuring the optical axis of the structured light module, provided by the embodiment of the invention, by using the diffuse reflection flat plate, the diffuse reflection flat plate or the structured light module can be firstly adjusted so that the optical axis of the laser emission unit or the optical axis of the receiving unit of the structured light module is vertical to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emission unit is incident on the diffuse reflection flat plate; then calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate; and then, calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which is received by the receiving unit and contains the pattern of the structured light. Since the relative positions between the optical axis point of the receiving unit and the optical axis point of the laser emitting unit can be obtained from the image containing the pattern of the structured light received by the receiving unit, the corresponding relation between the optical axis points of the receiving unit and the laser emitting unit on the diffuse reflection flat plate can be obtained according to the image containing the pattern of the structured light received by the receiving unit and the corresponding coefficient, and the included angle between the optical axes of the receiving unit and the laser emitting unit and the rotation angle of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit can be calculated. In conclusion, by the method, the relative relationship between the optical axis of the laser emitting unit and the optical axis of the receiving unit of the structured light module can be simply and conveniently measured and calculated, namely, the optical axis of the structured light module is measured. Therefore, the assembly of the defective products is convenient to clamp and control, and the yield of the module is improved.
The device for measuring the optical axis of the structured light module comprises a fixing device and a diffuse reflection flat plate, wherein the fixing device is used for fixing the structured light module so as to enable the optical axis of a laser emission unit or the optical axis of a receiving unit to be perpendicular to the diffuse reflection flat plate, and the diffuse reflection flat plate is used for receiving and reflecting structured light projected by the laser emission unit of the structured light module. In practical application, the structured light module can be fixed and adjusted through the fixing device, so that the optical axis of the laser emission unit or the optical axis of the receiving unit of the structured light module is perpendicular to the surface of the diffuse reflection flat plate, and the structured light projected by the laser emission unit is incident to the diffuse reflection flat plate; then calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate; and then, calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which is received by the receiving unit and contains the pattern of the structured light. In the image containing the pattern of the structured light received by the receiving unit, the relative position between the optical axis point of the receiving unit and the optical axis point of the laser emitting unit can be obtained, so that the corresponding relation between the optical axis points of the receiving unit and the laser emitting unit on the diffuse reflection flat plate respectively can be obtained according to the image containing the pattern of the structured light received by the receiving unit and the corresponding coefficient, and the included angle between the optical axes of the receiving unit and the laser emitting unit and the rotation angle of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit can be calculated. In conclusion, by the method, the relative relationship between the optical axis of the laser emitting unit and the optical axis of the receiving unit of the structured light module can be simply and conveniently measured and calculated, namely the optical axis of the structured light module is measured. Therefore, the assembly of the defective products is convenient to clamp and control, and the yield of the module is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a diagram illustrating triangulation of a structured light module according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a method for measuring an optical axis of a structured light module according to an embodiment of the present invention;
FIG. 3 is a second schematic flow chart of a method for measuring an optical axis of a structured light module according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an optical axis measuring device of a structured light module according to an embodiment of the present invention;
FIG. 5 is a third schematic flow chart of a method for measuring an optical axis of a structured light module according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating an image received by the receiving unit according to an embodiment of the present invention;
fig. 7 is a fourth flowchart of a structured light module optical axis measurement method according to an embodiment of the present invention.
Icon: 410-a fixation device; 420-diffuse reflection flat plate; 430-structured light module; 431-a laser emitting unit; 432-receiving unit.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Although the 3D structured light scheme is well established, there are high requirements for the assembly of the structured light module during the production process. The structured light module generally includes a laser emitting unit for projecting structured light and a receiving unit for receiving the structured light reflected by the object. And then the processor performs matching calculation on the structured light pattern received by the receiving unit and the reference image to obtain the depth information of the measured object. In the matching calculation process, in order to reduce the time consumption of chip calculation and the power consumption of the module, the searching and matching are generally only performed on the pixel points in the same row of the reference image and the scene image.
The processor usually adopts triangulation method in the matching calculation, as shown in fig. 1, T represents the position of the laser emitting unit, and R represents the position of the receiving unitPosition, reference plane H, and module perpendicular distance D 0 When intersecting the optical axis of the laser emitting unit at point a, the perpendicular distance between the scene drawing plane M and the reference drawing plane H is D, and the perpendicular distance between the scene drawing plane M and the reference drawing plane H is B, it is obvious that the distance RT from the receiving unit to the laser emitting unit is equal to the baseline distance B (the distance between the receiving unit and the laser emitting unit). And setting the focal length of the receiving unit as f, taking the optical center O of the receiving unit as an origin, establishing a coordinate system parallel to the baseline direction, namely the RT direction as an x-axis, and setting P and Q as projections of two points A and B in the space under a camera coordinate system.
Let P point coordinate in xoy plane as (u) p ,v p ) And Q coordinate is (u) q ,v q ) From the geometric relationship Δ POR Δ ATR, Δ DOR Δ BTR of the following figures, one can deduce:
u p ＝c x +fb/D 0
v p ＝c y
u q ＝c x +fb/(D 0 +D)
v q ＝c y
when the object moves from point a to point B, the projected points inside the camera coordinate system are shifted along the direction parallel to the baseline RT, from point P to point Q. The relationship between the offset PQ and the distance variation D in the camera coordinate system is:
the area searched for when the images are matched is as follows:
v p -v q ＝c y -c y ＝0 (2)
wherein fb, D 0 The known quantity is adopted, so that the core of the depth map reconstruction is to search and match the pixel points in the same line of the reference map and the scene map, and the change D of the distance can be reversely deduced by solving the offset of the points in a camera coordinate system without searching across lines.
However, in the process of assembling the module, the rotation or inclination of the optical axis due to the assembling error is unavoidable, and here, taking the rotation around the z axis to form a new x 'oy' plane as an example, and assuming that the rotation angle is θ, the coordinates of the two points P and Q in the newly rotated camera coordinate system become:
the offset in the baseline direction at this time is:
the area searched for when the images are matched is as follows:
comparing the equations (1) and (2), (3) and (4), it can be seen that if there is a relative deflection between the optical axes of the laser transmitter and the receiver during the module assembling process, the following two serious problems are caused. First, the offset of the pixel is no longer
But instead become
The depth reconstruction results are biased. Secondly, when the images are matched, the searching area is not searched by the pixel points in the same line as the reference image, and the line-crossing searching is also needed, wherein the line-crossing size
That is, if there is a deviation between the optical axes of the receiving unit and the laser emitting unit, there will be a cross-line search that will result in a multiple increase in the calculated amount, the hardware cost and power consumption will be greatly increased, and the real-time requirement of depth calculation is difficult to achieve in the algorithm. Moreover, when the optical axes of the receiving unit and the laser emitting unit of the structured light module are not consistent, the image containing the structured light pattern received by the receiving unit and the reference image will deviate, so that the depth information of the object to be measured, which is finally calculated, is inaccurate.
Therefore, the relative optical axis of the structural optical module (i.e. the consistency between the optical axis of the receiving unit and the optical axis of the laser emitting unit) needs to be measured, so as to facilitate the control of the products with poor assembly and improve the yield of the module. However, the measurement difficulty of the relative optical axis of the current structured light module is large, and the measurement efficiency is low.
Based on this, an embodiment of the present invention provides a structured light module optical axis measurement method, which is applied to a structured light module optical axis measurement apparatus, where the apparatus includes a diffuse reflection plate.
As shown in fig. 2, the method for measuring the optical axis of the structured light module may include:
s201: and adjusting the diffuse reflection flat plate or the structured light module to ensure that the optical axis of the laser emission unit or the optical axis of the receiving unit of the structured light module is vertical to the surface of the diffuse reflection flat plate, and the structured light projected by the laser emission unit is incident to the diffuse reflection flat plate.
S202: and calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the plate surface of the diffuse reflection flat plate.
S203: and calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit.
Wherein, to the adjustment of diffuse reflection dull and stereotyped or structured light module, can realize through corresponding adjustment support or adjusting device, for example, to the adjustment of structured light module, can adopt multiaxis adjusting device to go on, certainly, do not do the restriction here, as long as can realize adjusting diffuse reflection dull and stereotyped or structured light module.
In the method, a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate is calibrated, which may be measuring the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate, respectively, and then taking the ratio of the two as the corresponding coefficient. By this correspondence coefficient, the proportional relationship (similar to a scale) between the actual sizes of the length-sized subjects in the image to be obtained (captured) by the receiving unit can be characterized, and therefore, the sizes between the image and the actual subjects can be mutually converted by the scale coefficient.
For convenience of adjustment, when the diffuse reflection plate or the structured light module is generally adjusted, the optical axis of the laser emission unit is used as a reference, and finally the optical axis of the laser emission unit is perpendicular to the plate surface of the diffuse reflection plate. Of course, there is no limitation in the embodiment of the present invention.
Therefore, in the method for measuring the optical axis of the structured light module according to the embodiment of the present invention, the diffuse reflection plate or the structured light module may be adjusted by using the diffuse reflection plate, so that the optical axis of the laser emitting unit or the optical axis of the receiving unit of the structured light module is perpendicular to the surface of the diffuse reflection plate, and the structured light projected by the laser emitting unit is incident on the diffuse reflection plate; then calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate; and then calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit. Since the relative positions between the optical axis point of the receiving unit and the optical axis point of the laser emitting unit can be obtained from the image containing the pattern of the structured light received by the receiving unit, the corresponding relation between the optical axis points of the receiving unit and the laser emitting unit on the diffuse reflection flat plate can be obtained according to the image containing the pattern of the structured light received by the receiving unit and the corresponding coefficient, and the included angle between the optical axes of the receiving unit and the laser emitting unit and the rotation angle of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit can be calculated. In conclusion, by the method, the relative relationship between the optical axis of the laser emitting unit and the optical axis of the receiving unit of the structured light module can be simply and conveniently measured and calculated, namely the optical axis of the structured light module is measured. Therefore, the assembly of the defective products is convenient to clamp and control, and the yield of the module is improved.
Optionally, calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image of the pattern including the structured light received by the receiving unit, as shown in fig. 3, may include:
s301: the image received by the receiving unit is acquired.
S302: and calculating the distance between the optical axis point of the laser emission unit and the geometric center of the image in the image.
S303: and calculating to obtain an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the distance, the corresponding coefficient, the distance between the laser emitting unit and the receiving unit and the distance between the structured light module and the diffuse reflection flat plate.
It should be noted that, because the structured light projected by the laser emission unit diverges with the optical axis of the laser emission unit as the center, in the image containing the pattern of structured light received by the receiving unit, the geometric center of the pattern of structured light can be regarded as the optical axis point of the laser emission unit. Also, since the received (photographed) image of the receiving unit is generally centered on its optical axis, the geometric center of the image received by the receiving unit can be regarded as the optical axis point of the receiving unit.
Therefore, when the optical axis of the laser emitting unit and the optical axis of the receiving unit are aligned, i.e., parallel to each other, the distance between the optical axis of the laser emitting unit and the geometric center of the image received by the receiving unit will be equal to the distance between the laser emitting unit and the receiving unit. Otherwise, because an included angle exists between the optical axes of the laser emitting unit and the receiving unit, a difference exists between the distance between the optical axis of the laser emitting unit and the geometric center of the image and the distance between the laser emitting unit and the receiving unit. Moreover, because the optical axis of one of the laser emitting unit and the receiving unit is perpendicular to the diffuse reflection plate, the difference value is in a right triangle surrounded by a line segment corresponding to the diffuse reflection plate and the optical axis perpendicular to the diffuse reflection plate, and an angle subtended by the line segment can be regarded as an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit. Therefore, in summary, the included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit can be calculated according to the corresponding coefficient, the distance between the laser emitting unit and the receiving unit, and the distance between the structured light module and the diffuse reflection plate. The distance between the structured light module and the diffuse reflection flat plate can be the distance between a unit (corresponding laser emitting unit or receiving unit) with an optical axis perpendicular to the diffuse reflection flat plate and the diffuse reflection flat plate.
Specifically, taking fig. 4 as an example, if there is no deviation between the optical axis of the laser emission unit 431 and the optical axis of the receiving unit 432, i.e., they are parallel to each other, the optical axis point of the laser emission unit 431 on the diffuse reflection plate 420 falls at B, and accordingly, the optical axis point of the receiving unit 432 on the diffuse reflection plate 420 falls at a. If the optical axis of the laser emitting unit 431 and the optical axis of the receiving unit 432 form an included angle, for example, the optical axis of the receiving unit 432 is set to be perpendicular to the diffuse reflection plate 420, the optical axis point of the laser emitting unit 431 falls at C, and thus the included angle α is the included angle between the optical axis of the receiving unit and the optical axis of the laser emitting unit. And the tangent value of the included angle alpha is equal to the ratio of a line segment BC (namely the difference between the distance AC between the optical axis point of the laser emitting unit and the geometric center of the image and the distance AB between the laser emitting unit and the receiving unit) and the distance between the structured light module and the diffuse reflection flat plate. When the optical axis of the laser emitting unit 431 is set to be perpendicular to the diffuse reflection plate 420, the included angle between the optical axis of the receiving unit 432 and the optical axis of the laser emitting unit 431 is the same as the above, and the description thereof is omitted here.
For example, the specific calculation of the step of calculating the included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit may be to convert the distance between the optical axis of the laser emitting unit and the geometric center of the image, the distance between the laser emitting unit and the receiving unit, and the distance between the structured light module and the diffuse reflection plate into values in the same reference system (taking the image or the actual structure received by the receiving unit as a reference system) according to the corresponding coefficients, for example, to convert the distance between the optical axis of the laser emitting unit and the geometric center of the image into corresponding values on the diffuse reflection plate, or to convert the distance between the laser emitting unit and the receiving unit, and the distance between the structured light module and the diffuse reflection plate into corresponding values respectively in a reference system taking the image of the receiving unit as a reference system. And then, calculating the difference between the distance between the optical axis of the laser emission unit and the geometric center of the image and the distance between the laser emission unit and the receiving unit according to the converted corresponding numerical value, calculating the ratio of the difference to the distance between the structured light module and the diffuse reflection flat plate, and calculating the ratio as an angle corresponding to a tangent value, wherein the angle is an included angle between the optical axis of the laser emission unit and the optical axis of the receiving unit. Wherein, the interval between laser emission unit and the receiving element is the fixed parameter of structured light module, and the interval between structured light module and the diffuse reflection flat board can be measured and confirm according to the relative position of structured light module and diffuse reflection flat board, and it is predetermined definite value.
Alternatively, calculating the rotation angle of the optical axis of the laser emitting unit according to the corresponding coefficient and the image of the pattern containing the structured light received by the receiving unit, as shown in fig. 5, may include:
s501: the image received by the receiving unit is acquired.
S502: and calculating an included angle between a connecting line between a zero-order central point and a first diffraction order central point of the structured light pattern projected by the laser emission unit in the image and a connecting line between the zero-order central point and the geometric center of the image. The included angle is the rotation angle of the optical axis of the laser emitting unit.
It should be noted that, since the laser emission unit usually diffracts the formed zero-order structured light by the optical diffraction element disposed therein and finally emits the light, the structured light pattern projected on the diffuse reflection plate includes at least a zero-order and a first diffraction order, and the diffraction orders of the structured light emitted by the optical diffraction element are usually arranged in sequence along a straight line perpendicular to the optical axis of the laser emission unit, and the central point of the zero-order structured light coincides with the optical axis point of the laser emission unit.
Generally, the direction of arrangement of each diffraction order of the structured light pattern projected by the laser emission unit needs to be parallel to a connecting line of the laser emission unit and the receiving unit on the structured light module, so as to meet the requirement that the structured light pattern received by the receiving unit is matched with a reference image.
Therefore, as shown in fig. 6, an angle between a connecting line DC between the zero-order center point and the first diffraction order center point of the structured light pattern projected by the laser emitting unit (i.e., the arrangement direction of the diffraction orders of the structured light pattern) and a connecting line AC between the zero-order center point and the geometric center of the image (i.e., the connecting line direction between the laser emitting unit and the receiving unit on the structured light module) can be regarded as an optical axis (relative to the optical axis of the receiving unit) rotation angle of the laser emitting unit.
Optionally, a scale is arranged on the surface of the diffuse reflection flat plate; calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate, as shown in fig. 7, may include:
s701: an image received by the receiving unit is acquired, wherein the image comprises an image of the scale.
S702: the corresponding coefficient is calculated from the image of the scale in the image.
The graduated scale arranged on the diffuse reflection flat plate can be a graduated scale attached to the surface of the diffuse reflection flat plate, and can also be a graduated scale pattern printed or drawn on the surface of the diffuse reflection flat plate.
For example, the corresponding coefficient may be a ratio between a scale length of the image of the scale in the image and a scale length of the actual scale on the diffuse reflection plate, of course, the corresponding coefficient may also be a corresponding relationship between a number of pixels in the image and a scale of the actual scale, for example, optionally, the corresponding coefficient is a number of pixels corresponding to a unit scale of the scale in the image of the scale, that is, the unit scale of the actual scale corresponds to a number of pixels in the image received by the receiving unit, for example, the corresponding coefficient may be a number of pixels corresponding to a unit scale of the actual scale of 1 mm, which may represent a number of pixels corresponding to a length of 1 mm in the actual space in the image received by the receiving unit, so that the corresponding coefficient may be used to convert the actual size and the size in the image received by the receiving unit into each other.
The calibration of the corresponding coefficient is realized through the steps, and compared with the method that the proportional relation is obtained after the size of the diffuse reflection flat plate and the size of the image received by the receiving unit are respectively measured, the calibration method is simpler, more convenient and faster, and more accurate.
It should be noted that, based on the above, when the included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and the rotation angle of the optical axis of the laser emitting unit both need to be calculated and obtained, the step of obtaining the image received by the receiving unit may be performed only once, and then the step of calculating the distance between the optical axis of the laser emitting unit and the geometric center of the image in the image is performed separately; calculating to obtain an included angle between an optical axis of the laser emitting unit and an optical axis of the receiving unit according to the distance, the corresponding coefficient, the distance between the laser emitting unit and the receiving unit and the distance between the structured light module and the diffuse reflection flat plate; and calculating an included angle between a connecting line between a zero-order central point and a first diffraction order central point of the structured light pattern projected by the laser emission unit in the image and a connecting line between the zero-order central point and a geometric center of the image. Moreover, the specific execution sequence is not limited to the above example, and may also be adjusted according to actual situations, so as to calculate the rotation angle of the optical axis of the laser emitting unit first, and then calculate the included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit, which is not limited here.
Optionally, after calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image of the pattern including the structured light received by the receiving unit, the method further includes:
and judging whether an included angle between the optical axis of the laser emission unit and the optical axis of the receiving unit meets a preset range or not.
If not, executing the following steps: the optical axis direction of the receiving unit or the optical axis direction of the laser emitting unit is adjusted. And returning to execute S201 until the calculated included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit satisfies the preset range.
The preset range can be set according to a deviation allowable range between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to design requirements, so that the optical axis of the receiving unit or the laser emitting unit is adjusted (generally, the setting angle of the corresponding unit on the structured light module is adjusted to change the course angle of the optical axis of the corresponding unit) according to the calculated included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit through the steps until the deviation between the optical axis of the laser emitting unit and the optical axis of the receiving unit meets the design requirements.
Optionally, after the optical axis rotation angle of the laser emitting unit is calculated according to the corresponding coefficient and the image containing the pattern of the structured light received by the receiving unit, the method further includes:
judging whether the optical axis rotation angle of the laser emission unit meets a preset range or not;
if not, executing the following steps: the circumferential rotation adjusts the optical axis of the receiving unit or the optical axis of the laser emitting unit. And returns to performing S201 until the calculated optical axis rotation angle of the laser emitting unit can satisfy the preset range.
The preset range can be set according to the allowable range of the circumferential rotation angle deviation of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit, which meets the design requirement, so that the circumferential rotation adjustment of the optical axis of the receiving unit or the laser emitting unit is realized according to the calculated optical axis rotation angle of the laser emitting unit through the steps (generally, the corresponding unit is rotated circumferentially on the structured light module so that the optical axis of the corresponding unit is rotated and changed circumferentially) until the circumferential rotation angle deviation of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit meets the design requirement.
It should be noted that, based on the above, when the included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit and the rotation angle of the optical axis of the laser emitting unit need to be calculated and obtained, the receiving unit and/or the laser emitting unit can be respectively adjusted according to the above steps, so that the deviation between the optical axis of the laser emitting unit and the optical axis of the receiving unit and the circumferential rotation angle deviation of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit can both meet the design requirement. And the execution sequence between the relevant steps of adjusting the laser emitting unit or the receiving unit to make the deviation between the optical axes of the laser emitting unit and the receiving unit meet the requirement and the relevant steps of adjusting the laser emitting unit or the receiving unit to make the deviation of the circumferential rotation angle of the optical axis of the laser emitting unit relative to the optical axis of the receiving unit meet the requirement can be determined according to the actual requirement, and the implementation sequence is not limited herein.
Based on the foregoing method, another aspect of the embodiments of the present invention provides an optical axis measuring apparatus of a structured light module, as shown in fig. 4, the apparatus may include: the fixing device 410 is used for fixing the structured light module 430, so that an optical axis of the laser emitting unit 431 or an optical axis of the receiving unit 432 is perpendicular to the diffuse reflection flat plate 420, and the diffuse reflection flat plate 420 is used for receiving and reflecting the structured light projected by the laser emitting unit 431 of the structured light module 430.
Through the optical axis measuring device of the structured light module 430, the structured light module 430 can be fixed and adjusted by the fixing device 410, so that the optical axis of the laser emitting unit 431 or the optical axis of the receiving unit 432 of the structured light module 430 is perpendicular to the plate surface of the diffuse reflection plate 420, and the structured light projected by the laser emitting unit 431 is incident to the diffuse reflection plate 420; then, calibrating a corresponding coefficient between the size of the image received by the receiving unit 432 and the actual size of the corresponding image on the surface of the diffuse reflection flat plate 420; then, an angle between the optical axis of the laser emitting unit 431 and the optical axis of the receiving unit 432, and/or an optical axis rotation angle of the laser emitting unit 431 is calculated according to the corresponding coefficient and the image of the pattern containing the structured light received by the receiving unit 432. Since the relative positions between the optical axis point of the receiving unit 432 and the optical axis point of the laser emitting unit 431 can be obtained from the image containing the pattern of the structured light received by the receiving unit 432, the corresponding relationship between the optical axis points of the receiving unit 432 and the laser emitting unit 431 on the diffuse reflection flat plate 420 can be obtained according to the image containing the pattern of the structured light received by the receiving unit 432 and the corresponding coefficient, and the included angle between the optical axes of the receiving unit 432 and the laser emitting unit 431 and the rotation angle of the optical axis of the laser emitting unit 431 relative to the optical axis of the receiving unit 432 can be calculated. In summary, with this method, the relative relationship between the optical axis of the laser emitting unit 431 and the optical axis of the receiving unit 432 of the structured light module 430, that is, the optical axis of the structured light module 430 can be simply and conveniently measured and calculated. Therefore, the assembly of the defective products is convenient to clamp and control, and the yield of the module is improved.
Optionally, the fixture 410 is a six-axis adjustment device.
Through setting up fixing device 410 as six adjusting device, can adjust structured light module 430 convenient and fast more to improve this structured light module 430 optical axis measuring device's measurement of efficiency.
Optionally, a scale (not shown in fig. 4) is disposed on the surface of the diffuse reflection plate 420 that receives and reflects the structured light.
By arranging the scale on the surface of the diffuse reflection flat plate 420, the scale and the scale image in the image received by the receiving unit 432 of the structured light module 430 can be conveniently and quickly calibrated to obtain the corresponding coefficient between the size of the image received by the receiving unit 432 and the actual size of the corresponding image on the surface of the diffuse reflection flat plate 420.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process of the apparatus described above may refer to the corresponding process of the method in the foregoing method embodiment, and is not described in detail herein.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A method for measuring an optical axis of a structured light module, the method being applied to a structured light module optical axis measuring apparatus, the apparatus comprising a diffusely reflecting plate, the method comprising:
adjusting a diffuse reflection flat plate or a structured light module so that an optical axis of a laser emission unit of the structured light module or an optical axis of a receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and structured light projected by the laser emission unit is incident on the diffuse reflection flat plate;
calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate;
calculating an included angle between an optical axis of the laser emitting unit and an optical axis of the receiving unit and/or an optical axis rotation angle of the laser emitting unit according to the corresponding coefficient and the image which is received by the receiving unit and contains the pattern of the structured light;
the calculating an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit includes:
acquiring the image received by the receiving unit;
calculating the distance between the optical axis point of the laser emission unit and the geometric center of the image in the image;
calculating to obtain an included angle between an optical axis of the laser emission unit and an optical axis of the receiving unit according to the distance, the corresponding coefficient, the distance between the laser emission unit and the receiving unit and the distance between the structured light module and the diffuse reflection flat plate;
the calculating the rotation angle of the optical axis of the laser emitting unit according to the corresponding coefficient and the image which contains the pattern of the structured light and is received by the receiving unit includes:
acquiring the image received by the receiving unit;
calculating an included angle between a connecting line between a zero-order central point and a first diffraction order central point of the structured light pattern projected by the laser emission unit in the image and a connecting line between the zero-order central point and a geometric center of the image; the included angle is the optical axis rotation angle of the laser emission unit.
2. The method according to claim 1, wherein the plate surface of the diffuse reflection plate is provided with a graduated scale; the calibrating a corresponding coefficient between the size of the image received by the receiving unit and the actual size of the corresponding image on the surface of the diffuse reflection flat plate comprises the following steps:
acquiring an image received by the receiving unit, wherein the image comprises an image of the graduated scale;
and calculating the corresponding coefficient according to the image of the graduated scale in the image.
3. A method according to claim 2 wherein the correspondence coefficient is the number of pixels in the image of the scale to which a unit scale of the scale corresponds.
4. The method according to claim 1, wherein after calculating an angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit according to the corresponding coefficient and the image of the pattern containing the structured light received by the receiving unit, the method further comprises:
judging whether an included angle between the optical axis of the laser emitting unit and the optical axis of the receiving unit meets a preset range or not;
if not, adjusting the optical axis direction of the receiving unit or the optical axis direction of the laser emitting unit, and readjusting the diffuse reflection flat plate or the structured light module so that the optical axis of the laser emitting unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and the structured light projected by the laser emitting unit is incident on the diffuse reflection flat plate.
5. The method according to claim 1, wherein after calculating the rotation angle of the optical axis of the laser emitting unit according to the corresponding coefficient and the image containing the pattern of the structured light received by the receiving unit, the method further comprises:
judging whether the optical axis rotation angle of the laser emission unit meets a preset range or not;
if not, the optical axis of the receiving unit or the optical axis of the laser emitting unit is adjusted in a circumferential rotation mode, and the diffuse reflection flat plate or the structured light module is readjusted, so that the optical axis of the laser emitting unit or the optical axis of the receiving unit of the structured light module is perpendicular to the plate surface of the diffuse reflection flat plate, and structured light projected by the laser emitting unit enters the diffuse reflection flat plate.
6. A structured light module optical axis measurement apparatus, for performing measurement using the structured light module optical axis measurement method of any of claims 1 to 5, the structured light module optical axis measurement apparatus comprising: the structure light module comprises a fixing device and a diffuse reflection flat plate, wherein the fixing device is used for fixing the structure light module so that an optical axis of a laser emission unit of the structure light module or an optical axis of a receiving unit of the structure light module is perpendicular to the diffuse reflection flat plate, and the diffuse reflection flat plate is used for receiving and reflecting structure light projected by the laser emission unit of the structure light module.
7. The device of claim 6, wherein the securing device is a six-axis adjustment device.
8. The apparatus according to claim 6 or 7, wherein a scale is disposed on the surface of the diffuse flat plate receiving and reflecting the structured light.
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