CN107765426A - Self-focusing laser scanning projection device based on symmetrical defocus double detector - Google Patents
Self-focusing laser scanning projection device based on symmetrical defocus double detector Download PDFInfo
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Abstract
基于对称离焦双探测器的自聚焦激光扫描投影装置属于先进加工制造技术领域。现有技术定焦准确度低，光强自动搜索扫描的横向分辨力低。本发明其特征在于，在1/4波片之后设置双轴扫描振镜；在偏振分光棱镜的标定反射光光路上设置对称离焦双探测器光强探测模块；在对称离焦双探测器光强探测模块中，在分光棱镜的透射、反射光路上各配备一组汇聚物镜、点探测针孔和光电探测器，点探测针孔位于汇聚物镜与光电探测器之间，两个光电探测器的感光面分别相对于各自对应的汇聚物镜离焦+ΔZ、‑ΔZ；两个光电探测器各自的光强电信号输出端分别连接到测量控制模块的两个光强模拟信号输入端；测量控制模块的调焦驱动信号输出端连接到动态自聚焦模块中的精密位移机构。
A self-focusing laser scanning projection device based on symmetrical defocused double detectors belongs to the field of advanced processing and manufacturing technology. In the prior art, the accuracy of focusing is low, and the horizontal resolution of automatic search and scanning of light intensity is low. The present invention is characterized in that a dual-axis scanning vibrating mirror is arranged after the 1/4 wave plate; a symmetrical defocused double detector light intensity detection module is arranged on the calibration reflected light optical path of the polarization beam splitter; In the strong detection module, a set of converging objective lenses, point detection pinholes and photodetectors are respectively equipped on the transmission and reflection light paths of the dichroic prism. The point detection pinholes are located between the converging objective lens and the photodetectors. The photosensitive surface is respectively defocused +ΔZ, -ΔZ relative to the corresponding converging objective lens; the light intensity electrical signal output terminals of the two photodetectors are respectively connected to the two light intensity analog signal input terminals of the measurement control module; the measurement control module The output end of the focus driving signal is connected to the precision displacement mechanism in the dynamic self-focus module.
Description
技术领域technical field
本发明涉及一种基于对称离焦双探测器的自聚焦激光扫描投影装置，在智能制造和装配过程中，用于各种零部件的激光辅助加工(如复合材料铺叠、蒙皮钻铆、焊接等)和指示定位装配，由扫描振镜实现激光循环扫描投影，将由三维CAD数模驱动的零部件三维外形轮廓激光线框准确投影显示在目标加工和装配区域，属于先进加工制造技术领域。The invention relates to a self-focusing laser scanning projection device based on symmetrical defocused dual detectors, which is used for laser-assisted processing of various parts (such as composite material laying, skin drilling and riveting, etc.) in the process of intelligent manufacturing and assembly. Welding, etc.) and instruction positioning assembly, the laser circular scanning projection is realized by the scanning galvanometer, and the laser line frame of the three-dimensional outline of the part driven by the three-dimensional CAD digital model is accurately projected and displayed in the target processing and assembly area, which belongs to the field of advanced processing and manufacturing technology.
背景技术Background technique
激光扫描投影装置是一种能够将待加工或者待装配的零部件，也就是待投影工件的三维外形轮廓以激光光线循环扫描投影的方式转换为激光线框并显示在目标加工和装配区域，该区域又称投影承接区域，从而实现各种零部件加工和装配辅助指示的精密光电仪器。The laser scanning projection device is a device that can convert the parts to be processed or assembled, that is, the three-dimensional outline of the workpiece to be projected, into a laser line frame and displayed in the target processing and assembly area in the way of circular scanning and projection of laser light. The area is also called the projection receiving area, so as to realize the precision photoelectric instruments for various parts processing and assembly auxiliary instructions.
在现有激光扫描投影装置中，如图1所示，激光器1、聚焦模块2、分光棱镜3依次同轴排列；在分光棱镜3的透射光光路上设置双轴扫描振镜4；在分光棱镜3的标定反射光光路上设置光强探测模块5；光强探测模块5的光强电信号输出端连接到测量控制模块6的模拟信号输入端；计算机7与测量控制模块6的通过USB端口连接；测量控制模块6的调焦驱动信号输出端连接到聚焦模块2中的精密位移机构8；测量控制模块6的扫描驱动信号输出端连接到双轴扫描振镜4中的精密转角机构9。所述测量控制模块6是一块多功能数据采集卡，能够采集、存储和处理数据，所述处理包括数模、模数转换。In the existing laser scanning projection device, as shown in Figure 1, the laser 1, the focusing module 2, and the beam splitting prism 3 are arranged coaxially in sequence; The light intensity detection module 5 is set on the demarcated reflected light optical path of 3; the light intensity electrical signal output end of the light intensity detection module 5 is connected to the analog signal input end of the measurement control module 6; the computer 7 is connected with the measurement control module 6 through the USB port ; The output terminal of the focusing drive signal of the measurement control module 6 is connected to the precision displacement mechanism 8 in the focusing module 2 ; The measurement control module 6 is a multifunctional data acquisition card capable of collecting, storing and processing data, and the processing includes digital-to-analog and analog-to-digital conversion.
所述激光扫描投影装置在工作过程中，首先是扫描投影激光光斑的聚焦调整。激光器1出射的扫描投影激光先后通过聚焦模块2、分光棱镜3和双轴扫描振镜4投影到投影承接区域10，由操作人员人眼观察并判断投影承接区域10中的激光光斑的聚焦情况，通过键盘操作由测量控制模块6向聚焦模块2中的精密位移机构8发送控制信号，驱动精密位移机构8前后移动，直到观察到的激光光斑达到最小，最大程度地保证沿光轴方向的定焦准确度，完成扫描投影激光光斑的聚焦调整。During the working process of the laser scanning projection device, the first thing is to adjust the focus of the scanning and projection laser spot. The scanning projection laser emitted by the laser 1 is successively projected to the projection receiving area 10 through the focusing module 2, the beam splitting prism 3 and the biaxial scanning galvanometer 4, and the operator observes and judges the focusing of the laser spot in the projection receiving area 10, Through keyboard operation, the measurement control module 6 sends a control signal to the precision displacement mechanism 8 in the focusing module 2, and drives the precision displacement mechanism 8 to move back and forth until the observed laser spot reaches the minimum, ensuring the fixed focus along the optical axis to the greatest extent Accuracy, to complete the focus adjustment of the scanning projection laser spot.
可见，现有技术未能利用扫描投影激光的标定反射光的光路分布来自动反馈控制扫描投影激光光斑的聚焦调整，定焦准确度的提高十分有限。It can be seen that the existing technology fails to use the optical path distribution of the calibrated reflected light of the scanning projection laser to automatically feedback control the focus adjustment of the scanning projection laser spot, and the improvement of the focus accuracy is very limited.
其次是解算出双轴扫描振镜4的投影坐标系(P-XPYPZP)与待投影工件三维CAD数模的数模坐标系(O-XOYOZO)间的转换关系。The second is to solve the conversion relationship between the projection coordinate system (PX P Y P Z P ) of the biaxial scanning galvanometer 4 and the digital-analog coordinate system (OX O Y O Z O ) of the three-dimensional CAD digital model of the workpiece to be projected.
由于双轴扫描振镜4是精密转角器件，无法得知投影承接区域10的位置，无法确定反映待投影零部件三维外形轮廓特征的激光线框16应被扫描投影在哪里。这就需要确定投影承接区域10的位置，以及建立待投影工件三维CAD数模上任意点的三维坐标值与双轴扫描振镜4中的垂直扫描镜12和水平扫描镜13扫描角度值的对应关系，也就是建立双轴扫描振镜4的投影坐标系(P-XPYPZP)与待投影工件三维CAD数模的数模坐标系(O-XOYOZO)间的转换关系。Since the two-axis scanning galvanometer 4 is a precision corner device, it is impossible to know the position of the projection receiving area 10, and it is impossible to determine where the laser line frame 16 reflecting the three-dimensional outline characteristics of the parts to be projected should be scanned and projected. This just needs to determine the position of projection receiving area 10, and establish the correspondence between the three-dimensional coordinate value of any point on the three-dimensional CAD digital model of the workpiece to be projected and the scanning angle value of vertical scanning mirror 12 and horizontal scanning mirror 13 in biaxial scanning galvanometer 4 relationship, that is, to establish the conversion relationship between the projection coordinate system (PX P Y P Z P ) of the biaxial scanning galvanometer 4 and the digital-analog coordinate system (OX O Y O Z O ) of the three-dimensional CAD digital model of the workpiece to be projected.
根据多元方程解算的需要，在投影承接区域10内选取4至6个非规则分布的扫描标定位置，各个扫描标定位置在数模坐标系(O-XOYOZO)中的三维坐标是已知的。在所述各个扫描标定位置上各布置一个背向反射合作目标11，用于扫描标定。由测量控制模块6发送的扫描驱动信号通过驱动双轴扫描振镜4中的两个精密转角机构9分别驱动双轴扫描振镜4中的垂直扫描镜12和水平扫描镜13，扫描背向反射合作目标11的反光区，扫描投影激光的一部分被背向反射合作目标11反射，作为标定反射光沿原光路返回，由分光棱镜3全反射到光强探测模块5，在光强探测模块5中由汇聚物镜14汇聚到光电探测器15上，由光电探测器15进行光电转换得到光强电信号，并传送给测量控制模块6。测量控制模块6根据光强电信号值以及获得该光强电信号时的垂直扫描镜12和水平扫描镜13各自的偏转角度，探测到一个背向反射合作目标11的反光区的光强峰值区域，该区域中心点就是所述扫描标定位置，其三维坐标值与一对偏转角度值对应，完成一个背向反射合作目标11中心位置的高精度扫描定位。重复上述过程，逐一对每个背向反射合作目标11的反光区进行扫描，获取各组三维坐标值和偏转角度值，由此即可精确解算出双轴扫描振镜4的投影坐标系(P-XPYPZP)与待投影工件三维CAD数模的数模坐标系(O-XOYOZO)间的转换关系。According to the needs of solving multivariate equations, 4 to 6 irregularly distributed scanning calibration positions are selected in the projection receiving area 10, and the three-dimensional coordinates of each scanning calibration position in the digital-analog coordinate system (OX O Y O Z O ) are already Known. A back-reflection cooperation target 11 is arranged on each scanning calibration position for scanning calibration. The scanning drive signal sent by the measurement control module 6 respectively drives the vertical scanning mirror 12 and the horizontal scanning mirror 13 in the biaxial scanning vibrating mirror 4 by driving the two precision angle mechanisms 9 in the biaxial scanning vibrating mirror 4 to scan the back reflection In the reflective area of the cooperation target 11, a part of the scanning projection laser is reflected by the back reflection cooperation target 11, returns along the original optical path as the calibration reflected light, is totally reflected by the beam splitting prism 3 to the light intensity detection module 5, and in the light intensity detection module 5 Converging on the photodetector 15 by the converging objective lens 14 , the photoelectric conversion is carried out by the photodetector 15 to obtain an electric signal of light intensity, which is sent to the measurement control module 6 . The measurement control module 6 detects the light intensity peak area of the reflective area of the back-reflection cooperation target 11 according to the light intensity electric signal value and the respective deflection angles of the vertical scanning mirror 12 and the horizontal scanning mirror 13 when obtaining the light intensity electric signal , the center point of this area is the scanning calibration position, and its three-dimensional coordinate value corresponds to a pair of deflection angle values, so as to complete a high-precision scanning positioning of the center position of the back reflection cooperative target 11 . Repeat the above process, scan the reflective area of each back reflection cooperation target 11 one by one, and obtain the three-dimensional coordinate values and deflection angle values of each group, thus the projected coordinate system (PX P Y P Z P ) and the digital-analog coordinate system (OX O Y O Z O ) of the three-dimensional CAD digital model of the workpiece to be projected.
可见，如果能够增强激光扫描投影装置的光强自动搜索扫描的横向分辨力，将会更精确地解算出双轴扫描振镜4的投影坐标系(P-XPYPZP)与待投影工件三维CAD数模的数模坐标系(O-XOYOZO)间的转换关系。It can be seen that if the horizontal resolution of the automatic search and scan of the light intensity of the laser scanning projection device can be enhanced, the projection coordinate system (PX P Y P Z P ) of the biaxial scanning galvanometer 4 and the three-dimensional coordinate system of the workpiece to be projected will be solved more accurately. The conversion relationship between the digital-analog coordinate system (OX O Y O Z O ) of CAD digital model.
最后，完成待投影工件的三维外形轮廓在投影承接区域10的激光扫描投影。将待投影工件三维CAD数模导入到测量控制模块6中，根据待投影工件三维CAD数模中的位置、尺寸和形状等轮廓特征信息，驱动双轴扫描振镜4精确偏转和快速循环扫描，按三维CAD数模对待投影工件的位置、尺寸和形状等轮廓特征信息所做的定义，并按照所述两个坐标系的转换关系，将待投影工件的三维外形轮廓准确地循环显示在投影承接区域10中，形成激光线框16。Finally, the laser scanning projection of the three-dimensional outline of the workpiece to be projected on the projection receiving area 10 is completed. Import the three-dimensional CAD digital model of the workpiece to be projected into the measurement control module 6, and drive the two-axis scanning galvanometer 4 for precise deflection and fast cycle scanning according to the contour feature information in the three-dimensional CAD digital model of the workpiece to be projected, such as position, size and shape, According to the definition of the contour feature information such as the position, size and shape of the workpiece to be projected according to the three-dimensional CAD digital model, and according to the conversion relationship between the two coordinate systems, the three-dimensional contour of the workpiece to be projected is accurately and circularly displayed on the projection interface In the area 10, a laser line frame 16 is formed.
可见，在实际应用中将由三维CAD数模驱动的零部件三维外形轮廓激光线框准确投影显示在目标加工和装配区域，影响扫描投影定位准确度的本质因素是扫描投影激光的调焦，其对扫描投影定位准确度的影响表现有以下两方面：It can be seen that in practical applications, the laser line frame of the three-dimensional outline of the part driven by the three-dimensional CAD digital model is accurately projected and displayed in the target processing and assembly area. The essential factor affecting the positioning accuracy of the scanning projection is the focusing of the scanning projection laser. The influence of scanning projection positioning accuracy has the following two aspects:
一是激光扫描投影出的激光线框16的线宽，即在投影承接区域10中进行扫描投影时，激光光斑所能达到的最小尺寸。扫描投影激光经聚焦模块2在投影承接区域10中沿光轴方向的定焦准确度越高，激光光斑的尺寸就越小，激光光斑循环扫描投影的激光线框16的线宽就越窄，越能精确地辅助加工和指示装配；One is the line width of the laser line frame 16 projected by laser scanning, that is, the minimum size of the laser spot that can be achieved when performing scanning projection in the projection receiving area 10 . The higher the focusing accuracy of the scanning projection laser along the optical axis direction in the projection receiving area 10 through the focusing module 2, the smaller the size of the laser spot, and the narrower the line width of the laser line frame 16 that is cyclically scanned and projected by the laser spot. The more accurately it can assist in processing and instructing assembly;
二是双轴扫描振镜4对背向反射合作目标11中心位置的扫描定位精度。当激光光斑尺寸越小，激光光斑在背向反射合作目标11上进行光强自动搜索扫描时的横向分辨力就越强，双轴扫描振镜4就能够以更小的扫描间隔进行更细致的扫描，同时，光强探测模块5也能够获取更多扫描标定位置的标定反射光的光强信息，也就能够更准确地获得与背向反射合作目标11中心位置对应的一对偏转角度值，进而解算出更准确的坐标系转换关系。The second is the scanning positioning accuracy of the center position of the back reflection cooperation target 11 by the biaxial scanning galvanometer 4 . When the size of the laser spot is smaller, the lateral resolution of the laser spot is stronger when performing light intensity automatic search and scanning on the back-reflection cooperative target 11, and the biaxial scanning galvanometer 4 can perform more detailed scanning with a smaller scanning interval. Scanning, at the same time, the light intensity detection module 5 can also obtain more light intensity information of the calibration reflected light at the scanning calibration position, and can more accurately obtain a pair of deflection angle values corresponding to the center position of the back reflection cooperation target 11, Then solve the more accurate coordinate system conversion relationship.
所述现有激光扫描投影装置中的激光器1出射的激光波长为532nm，背向反射合作目标11的反光区直径为6mm，反光材料为玻璃微珠，最佳激光扫描投影定位距离为3～5m，在5m距离时的激光扫描设计线宽为0.5mm，激光扫描投影定位准确度定义为激光光线的半线宽，定位准确度为0.25mm。The laser wavelength emitted by the laser 1 in the existing laser scanning projection device is 532nm, the diameter of the reflective area of the back reflection cooperative target 11 is 6mm, the reflective material is glass beads, and the optimal laser scanning projection positioning distance is 3-5m , the laser scanning design line width at a distance of 5m is 0.5mm, the laser scanning projection positioning accuracy is defined as the half line width of the laser light, and the positioning accuracy is 0.25mm.
发明内容Contents of the invention
本发明的目的在于，在双轴扫描振镜4的扫描精度和测量控制模块6的控制精度确定的前提下，进一步提高激光器1出射的扫描投影激光沿光轴方向的定焦准确度，获得尺寸最小的激光光斑，以及提高光强自动搜索扫描的横向分辨力，为此，我们发明了一种基于对称离焦双探测器的自聚焦激光扫描投影装置。由于激光扫描投影的定位准确度以激光半线宽定义，因此，所述定焦准确度的提高直接决定了激光扫描投影的定位准确度的提高；由于光强自动搜索扫描的横向分辨力直接关系到投影坐标系(P-XPYPZP)与数模坐标系(O-XOYOZO)转换关系的解算精确度，因此，横向分辨力的提高同样也直接决定了激光扫描投影的定位准确度的提高。The object of the present invention is to further improve the focusing accuracy of the scanning projection laser light emitted by the laser 1 along the optical axis direction under the premise that the scanning accuracy of the biaxial scanning galvanometer 4 and the control accuracy of the measurement control module 6 are determined, and obtain a dimension The smallest laser spot, and the horizontal resolution of automatic search and scan with improved light intensity, for this reason, we invented a self-focusing laser scanning projection device based on symmetrical defocused dual detectors. Because the positioning accuracy of the laser scanning projection is defined with the laser half line width, therefore, the improvement of the fixed focus accuracy directly determines the improvement of the positioning accuracy of the laser scanning projection; The calculation accuracy of the conversion relationship between the projected coordinate system (PX P Y P Z P ) and the digital-analog coordinate system (OX O Y O Z O ), therefore, the improvement of the lateral resolution also directly determines the positioning of the laser scanning projection Increased accuracy.
如图2所示，本发明之基于对称离焦双探测器的自聚焦激光扫描投影装置其组成部分包括，激光器1、双轴扫描振镜4、测量控制模块6、计算机7，计算机7与测量控制模块6连接；测量控制模块6的扫描驱动信号输出端连接到双轴扫描振镜4中的精密转角机构9，所述测量控制模块6是一块多功能数据采集卡；其特征在于，激光器1、扩束准直镜组17、动态自聚焦模块18、偏振分光棱镜19、1/4波片20依次同轴排列；在偏振分光棱镜19的扫描透射光光路上，且在1/4波片20之后设置双轴扫描振镜4；在偏振分光棱镜19的标定反射光光路上设置对称离焦双探测器光强探测模块21；在对称离焦双探测器光强探测模块21中，在分光棱镜22的透射、反射光路上各配备一组汇聚物镜14、点探测针孔23和光电探测器15，点探测针孔23位于汇聚物镜14与光电探测器15之间，两个光电探测器15的感光面分别相对于各自对应的汇聚物镜14离焦+ΔZ、-ΔZ；两个光电探测器15各自的光强电信号输出端分别连接到测量控制模块6的两个光强模拟信号输入端；测量控制模块6的调焦驱动信号输出端连接到动态自聚焦模块18中的精密位移机构8。As shown in Figure 2, the components of the self-focusing laser scanning projection device based on symmetrical defocused dual detectors of the present invention include laser 1, biaxial scanning galvanometer 4, measurement control module 6, computer 7, computer 7 and measurement The control module 6 is connected; the scanning drive signal output end of the measurement control module 6 is connected to the precision angle mechanism 9 in the biaxial scanning vibrating mirror 4, and the measurement control module 6 is a multifunctional data acquisition card; it is characterized in that the laser 1 , beam expander collimating mirror group 17, dynamic self-focusing module 18, polarization beam splitter 19, 1/4 wave plate 20 are arranged coaxially in sequence; After 20, the biaxial scanning galvanometer 4 is set; the symmetrical defocused double detector light intensity detection module 21 is set on the demarcated reflected light optical path of the polarization beam splitter prism 19; in the symmetrical defocused double detector light intensity detection module 21, the A set of converging objective lens 14, point detection pinhole 23 and photodetector 15 are respectively equipped on the transmission and reflection optical paths of prism 22, and point detection pinhole 23 is located between converging objective lens 14 and photodetector 15, and two photodetectors 15 The photosensitive surfaces of the two photodetectors 15 are respectively defocused with respect to the corresponding converging objective lens 14 +ΔZ, -ΔZ; the respective light intensity electrical signal output terminals of the two photodetectors 15 are respectively connected to the two light intensity analog signal input terminals of the measurement control module 6 ; The output end of the focusing drive signal of the measurement control module 6 is connected to the precision displacement mechanism 8 in the dynamic self-focusing module 18 .
若两个光电探测器15中的任何一个位于像方焦点处，探测到的轴向光强响应曲线为像方焦点处的轴向光强响应曲线，即图3中的曲线0；实际上两个光电探测器15分别探测到轴向光强响应曲线为偏离像方焦点-ΔZ处和偏离像方焦点+ΔZ处的轴向光强响应曲线，即图3中的曲线1和曲线2。此时来看，同在零点O，曲线1和曲线2的光强值仅相当于曲线0光强值的约0.707倍，而标定反射光的光强原本就维持在数十皮瓦(pW)的极微弱量级，看似本发明之效果适得其反，然而，在此条件下，能够以差分和加和的方式进行控制，从而获得预期效果。If any one of the two photodetectors 15 is located at the focal point of the image, the detected axial light intensity response curve is the axial light intensity response curve at the focal point of the image, that is, the curve 0 in Fig. 3; The axial light intensity response curves detected by each photodetector 15 are the axial light intensity response curves at -ΔZ away from the image focus and +ΔZ away from the image focus, namely curve 1 and curve 2 in FIG. 3 . At this point, at zero point O, the light intensity values of curves 1 and 2 are only about 0.707 times the light intensity value of curve 0, while the light intensity of the calibrated reflected light is originally maintained at tens of picowatts (pW) It seems that the effect of the present invention is counterproductive. However, under this condition, it can be controlled in a differential and summative manner to obtain the desired effect.
由测量控制模块6将曲线1和曲线2的光强信号逐点相减，获得差分轴向光强响应曲线，即图3中的曲线3，曲线3在零点O与曲线0峰值点P精确对应。曲线0在P点附近的斜率接近于零，也就是光强值的变化对精密位移机构8的位移量的变化不敏感，即使由测量控制模块6根据曲线0向动态自聚焦模块18发送反馈控制信号，控制其中的精密位移机构8实现扫描投影激光光斑的轴向自聚焦，而非人眼观察手动调焦，扫描投影激光沿光轴方向的定焦准确度依旧难以提高。尽管曲线3在零点O的光强为零，但是，曲线3在零点O的斜率最大，也就是说此处随轴向位移光强变化最大，至此可见，利用曲线3与曲线0的这种特定关系，由测量控制模块6向动态自聚焦模块18发送反馈控制信号，控制其中的精密位移机构8实现扫描投影激光光斑的轴向自聚焦，不仅能够取代现有人眼观察手动调焦方式，而且轴向聚焦精度能够得到明显提高。The light intensity signals of curve 1 and curve 2 are subtracted point by point by the measurement control module 6 to obtain the differential axial light intensity response curve, that is, curve 3 in Figure 3, and the zero point O of curve 3 corresponds exactly to the peak point P of curve 0 . The slope of curve 0 near point P is close to zero, that is, the change of the light intensity value is not sensitive to the change of the displacement of the precision displacement mechanism 8, even if the measurement control module 6 sends feedback control to the dynamic self-focusing module 18 according to the curve 0 Signal, control the precision displacement mechanism 8 to realize the axial self-focusing of the scanning projection laser spot, instead of manual focusing by human eye observation, the focusing accuracy of the scanning projection laser along the optical axis direction is still difficult to improve. Although the light intensity of curve 3 at zero point O is zero, the slope of curve 3 at zero point O is the largest, that is to say, the change of light intensity with axial displacement is the largest here. relationship, the measurement control module 6 sends a feedback control signal to the dynamic self-focusing module 18, and controls the precision displacement mechanism 8 to realize the axial self-focusing of the scanning projection laser spot, which can not only replace the existing manual focusing method of human eye observation, but also the axis Focusing accuracy can be significantly improved.
由测量控制模块6将曲线1和曲线2的光强信号逐点相加，获得加和轴向光强响应曲线，即图3中的曲线4；曲线4峰值点P″与曲线0的峰值点P相对应，且曲线4峰值约为曲线0峰值的1.414倍，因此，相比于现有单探测器激光扫描投影装置和方法，本发明能够对背向反射合作目标11进行高精度的横向扫描定位，从而能够更灵敏、更准确地建立投影坐标系(P-XPYPZP)与数模坐标系(O-XOYOZO)间的转换关系。The light intensity signals of curve 1 and curve 2 are added point by point by the measurement control module 6 to obtain the summed axial light intensity response curve, that is, curve 4 in Fig. 3; the peak point P" of curve 4 and the peak point of curve 0 P is corresponding, and the peak value of curve 4 is about 1.414 times of the peak value of curve 0. Therefore, compared with the existing single-detector laser scanning projection device and method, the present invention can perform high-precision lateral scanning of the back-reflecting cooperation target 11 Positioning, so that the conversion relationship between the projected coordinate system (PX P Y P Z P ) and the digital-analog coordinate system (OX O Y O Z O ) can be established more sensitively and accurately.
可见，本发明将差分式光强探测方法与加和式光强探测方法相结合，兼顾提高激光扫描投影装置的轴向定焦能力和横向扫描分辨能力。It can be seen that the present invention combines the differential light intensity detection method with the additive light intensity detection method, taking into account the improvement of the axial focusing ability and lateral scanning resolution ability of the laser scanning projection device.
设置扩束准直镜组17能够提高动态自聚焦模块18中的聚焦镜组的数值孔径3至5倍。根据汇聚物镜成像理论，其光斑直径d由下式得出：Setting the beam expander and collimating lens group 17 can increase the numerical aperture of the focusing lens group in the dynamic self-focusing module 18 by 3 to 5 times. According to the imaging theory of converging objective lens, the spot diameter d is obtained by the following formula:
式中：λ为激光波长，n·sinα为汇聚镜组的数值孔径。可见，增大汇聚镜组的数值孔径，可以减小汇聚光斑的理论直径。当激光波长λ为532nm，汇聚镜组的工作距离为4600mm时，汇聚镜组组合焦距约为2500mm左右，激光入射在汇聚镜组上的有效口径为12mm，可计算获得艾里斑的理论直径约为0.27mm，意味着理论定位准确度提高到0.135mm。压缩扫描投影激光光斑尺寸，提高扫描投影激光光斑汇聚质量的附带的效果是，扫描投影激光光斑尺寸越小，可以随之减小所述背向反射合作目标11中的反光区的尺寸，如减小至4～5mm，这就意味着能够在更紧凑、更窄小的投影承接区域10进行精确的激光扫描投影，并因此而能够扩展本发明的应用领域。In the formula: λ is the laser wavelength, and n·sinα is the numerical aperture of the converging lens group. It can be seen that increasing the numerical aperture of the converging lens group can reduce the theoretical diameter of the converging spot. When the laser wavelength λ is 532nm and the working distance of the converging mirror group is 4600mm, the combined focal length of the converging mirror group is about 2500mm, and the effective aperture of the laser incident on the converging mirror group is 12mm. The theoretical diameter of the Airy disk can be calculated to be about It is 0.27mm, which means that the theoretical positioning accuracy is increased to 0.135mm. The incidental effect of compressing the laser spot size of the scanning projection and improving the convergence quality of the scanning projection laser spot is that the smaller the scanning projection laser spot size is, the size of the reflective area in the back reflection cooperation target 11 can be reduced accordingly, such as reducing As small as 4-5mm, this means that accurate laser scanning projection can be performed in a more compact and narrower projection receiving area 10, and thus the application field of the present invention can be expanded.
附图说明Description of drawings
图1为现有激光扫描投影装置的结构示意图。FIG. 1 is a schematic structural diagram of a conventional laser scanning projection device.
图2为本发明之基于对称离焦双探测器的自聚焦激光扫描投影装置结构示意图。FIG. 2 is a schematic structural diagram of a self-focusing laser scanning projection device based on symmetrical defocused dual detectors of the present invention.
图3为采用本发明之基于对称离焦双探测器的自聚焦激光扫描投影装置获得的轴向光强响应曲线图，竖轴为光强I，横轴为轴向归一化坐标u，图中：Fig. 3 is the axial light intensity response curve obtained by the self-focusing laser scanning projection device based on symmetrical defocused dual detectors of the present invention, the vertical axis is the light intensity I, and the horizontal axis is the axial normalized coordinate u, Fig. middle:
曲线0为探测器位于像方焦点处的轴向光强响应曲线；Curve 0 is the axial light intensity response curve of the detector at the focus of the image space;
曲线1为探测器位于偏离像方焦点-ΔZ处的轴向光强响应曲线；Curve 1 is the axial light intensity response curve of the detector located away from the focal point of the image space -ΔZ;
曲线2为探测器位于偏离像方焦点+ΔZ处的轴向光强响应曲线；Curve 2 is the axial light intensity response curve of the detector at the position away from the focal point of the image space + ΔZ;
曲线3为差分轴向光强响应曲线；Curve 3 is the differential axial light intensity response curve;
曲线4为加和轴向光强响应曲线。Curve 4 is the summed axial light intensity response curve.
具体实施方式Detailed ways
如图2所示，本发明之基于对称离焦双探测器的自聚焦激光扫描投影装置其组成部分包括，激光器1、双轴扫描振镜4、测量控制模块6、计算机7，计算机7与测量控制模块6连接；测量控制模块6的扫描驱动信号输出端连接到双轴扫描振镜4中的精密转角机构9，所述测量控制模块6是一块多功能数据采集卡。As shown in Figure 2, the components of the self-focusing laser scanning projection device based on symmetrical defocused dual detectors of the present invention include laser 1, biaxial scanning galvanometer 4, measurement control module 6, computer 7, computer 7 and measurement The control module 6 is connected; the scanning drive signal output end of the measurement control module 6 is connected to the precision angle mechanism 9 in the biaxial scanning galvanometer 4, and the measurement control module 6 is a multifunctional data acquisition card.
激光器1、扩束准直镜组17、动态自聚焦模块18、偏振分光棱镜19、1/4波片20依次同轴排列。Laser 1, beam expander and collimator lens group 17, dynamic self-focusing module 18, polarization beam splitter prism 19, and 1/4 wave plate 20 are arranged coaxially in sequence.
扩束准直镜组17能够压缩来自于激光器1的扫描投影激光的发散角，并扩束至接近动态自聚焦模块18中的汇聚镜组满瞳的状态，增大了动态自聚焦模块18中的汇聚镜组的数值孔径，进而压缩扫描投影激光照射到投影承接区域10上的光斑尺寸。在扩束准直镜组17中设置照明针孔24，使得激光器1发出的激光以点照明的方式工作，同时消除杂散光干扰，提高光束质量，进一步减小光斑尺寸，在投影承接区域10中获得更理想的汇聚光斑。在动态自聚焦模块18中，调焦透镜25安装于精密位移机构8上，实现扫描投影激光光斑的轴向自聚焦。动态自聚焦模块18中的聚焦镜组为反远距型镜组，使得激光扫描投影定位距离范围达到1～10m，但是，这会导致聚焦镜组的数值孔径减小，约为10-3，不过，由于扩束准直镜组17的存在能够予以弥补。Beam expander collimating mirror group 17 can compress the divergence angle of the scanning projection laser light from laser 1, and expand beam to the state that the converging mirror group in the dynamic self-focusing module 18 is close to full pupil, has increased in the dynamic self-focusing module 18 The numerical aperture of the converging lens group can further compress the spot size of the scanning projection laser irradiating onto the projection receiving area 10 . The illumination pinhole 24 is set in the beam expander and collimator lens group 17, so that the laser light emitted by the laser 1 works in the manner of point illumination, and at the same time eliminates stray light interference, improves the beam quality, and further reduces the spot size. In the projection receiving area 10 Obtain a more ideal convergent spot. In the dynamic self-focusing module 18, the focusing lens 25 is installed on the precision displacement mechanism 8 to realize axial self-focusing of the scanning projection laser spot. The focusing lens group in the dynamic self-focusing module 18 is an anti-telephoto lens group, so that the laser scanning projection positioning distance ranges from 1 to 10 m, but this will lead to a decrease in the numerical aperture of the focusing lens group, which is about 10 −3 , However, due to the existence of the beam expander and collimator lens group 17, it can be compensated.
在偏振分光棱镜19的扫描透射光光路上，且在1/4波片20之后设置双轴扫描振镜4。在偏振分光棱镜19的标定反射光光路上设置对称离焦双探测器光强探测模块21。在与偏振分光棱镜19标定反射光光路相反的光路上设置陷波汇聚物镜26和陷波滤波器27，用于消除杂散光干扰。在对称离焦双探测器光强探测模块21中，在分光棱镜22的透射、反射光路上各配备一组汇聚物镜14、点探测针孔23和光电探测器15，点探测针孔23位于汇聚物镜14与光电探测器15之间，两个光电探测器15的感光面分别相对于各自对应的汇聚物镜14离焦+ΔZ、-ΔZ；两个光电探测器15各自的光强电信号输出端分别连接到测量控制模块6的两个光强模拟信号输入端。测量控制模块6的调焦驱动信号输出端连接到动态自聚焦模块18中的精密位移机构8。On the optical path of the scanning transmitted light of the polarization splitter prism 19 and behind the 1/4 wave plate 20, a biaxial scanning galvanometer 4 is arranged. A symmetrical defocused double-detector light intensity detection module 21 is arranged on the standard reflected light optical path of the polarization beam splitter prism 19 . A notch converging objective lens 26 and a notch filter 27 are arranged on the optical path opposite to the optical path of the calibrated reflected light of the polarization beam splitter prism 19 to eliminate stray light interference. In the symmetrical defocus double-detector light intensity detection module 21, a group of converging objective lenses 14, point detection pinholes 23 and photodetectors 15 are respectively equipped on the transmission and reflection optical paths of the dichroic prism 22, and the point detection pinholes 23 are located at the converging Between the objective lens 14 and the photodetector 15, the photosensitive surfaces of the two photodetectors 15 are respectively defocused with respect to the respective converging objective lenses 14 +ΔZ, -ΔZ; the respective light intensity electrical signal output terminals of the two photodetectors 15 They are respectively connected to the two light intensity analog signal input ends of the measurement control module 6 . The focus drive signal output end of the measurement control module 6 is connected to the precision displacement mechanism 8 in the dynamic self-focus module 18 .
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| TWI700544B (en) * | 2018-03-28 | 2020-08-01 | 宏達國際電子股份有限公司 | Projection apparatus |
| CN110448266A (en) * | 2018-12-29 | 2019-11-15 | 中国科学院宁波工业技术研究院慈溪生物医学工程研究所 | Random Laser is copolymerized focal line and scans three-dimensional ophthalmoscope and imaging method |
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| CN111412835B (en) * | 2020-04-14 | 2021-04-30 | 长春理工大学 | Novel laser scanning projection method |
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| CN113787722A (en) * | 2021-07-21 | 2021-12-14 | 武汉锐科光纤激光技术股份有限公司 | Packaging device and packaging method |
| CN113917651A (en) * | 2021-09-29 | 2022-01-11 | 中国科学院西安光学精密机械研究所 | Focusing device of low-temperature optical system |
| CN113917651B (en) * | 2021-09-29 | 2022-10-04 | 中国科学院西安光学精密机械研究所 | A low temperature optical system focusing device |
| CN119140982A (en) * | 2024-11-13 | 2024-12-17 | 华中科技大学 | Laser three-dimensional automatic focus-following scanning processing optical system |
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