影像测量仪是一-种“基于成像在光电耦合器件上的光学影像系统(简称影像系统)，通过光电耦合器件采集,经过软件处理成像,显示在计算机屏幕上，利用测量软件进行几何运算得出最终结果的非接触式测量仪器”。测量软件通过数字图像处理技
术提取工件表面的坐标点,再利用坐标变换和数据处理技术转换成坐标测量空间中的各种几何要素，
从而得到被测工件几何尺寸和形位公差等参数。
1、影像测量仪发展概述
20世纪70年代后期，尤其是在DavidMar教授建立“计算视觉(Computational Vision)”理论框架以来,图像处理技术和图像传感器获得了快速发展。
随着坐标测量技术的日趋发展与成熟，在以光学比较为基础的光学测量领域里,坐标测量方法的发展应用有了更进一步的实质性进展。.
1977年,美国View Engineering 公司发明了世界上第一台由电机驱动XYZ轴的RB-1影像测量系统(见图1),它是一台控制终端整合了视频检测和软件测量的自动影像测量仪。此外, Mechanical Technology公司的Boice Vista 系统则充分借鉴了坐
标测量机的优势,在坐标测量机的测头上集成了一个视频图像测量系统,该系统可以将测量数据与预先编制好的标称尺寸和公差进行比较。
这两台仪器通过不同途径借鉴了坐标测量机的坐标测量原理,将被测量物体的图像投影到坐标系中。其测量平台继承了坐标测量机的形式，但其测头与光学投影仪相似。这些仪器的出现开辟了一个重要的测量仪器行业,即影像测量仪行业。上世纪80年代初,影像测量技术有了重要的发展。1981 年, ROI公司开发出光学影像探针(见图2),可以替代坐标测量机上的接触式探针进行非接触式测量,从此这个光学配件就成了影像设备的基.础部件之一。在80年代中期,市场上又出现了带高放大倍率显微镜目镜的影像测量仪。
进入上世纪90年代，随着CC)技术、计算机技术、数字图像处理技术LED照明技术.直流/交流伺服驱动技术的发展,影像测量仪产品获得了巨大的发展。更多的厂商进入到影像测量仪产品市场,共同推进了影像测量仪产品的发展。
2000年以后,我国在该领域的技术水平不断提高,有关影像测量技术研究的文献也不断出现;国内企业(如天准、智泰怡信、赛克数码、新天等公司)所开发的影像测量仪在生产规模、品种和质量上也不断有所提升和发展。2009年我国制定了国家标准
GB/T24762- 2009: 产品几何技术规范( GPS)影像测量仪的验收检测和复检检测,它适用于XY平面直角坐标系的影像测量仪，包括在垂直于平面直角坐标系Z方向上具有定位或测量功能的影像测量仪。
值得一.提的是天准精密技术有限公司,该公司由一批风华正茂、胸怀振兴我国精密测量行业壮志的学子们所创建,在学习借鉴国外优秀产品的基础上开发创新,形成了自身的特色和优势。经过多年不懈努力,天准公司于2007年在国内首次推出了具有完全自主知识产权的三维自动影像测量仪系列产品，填补了国内空白，在国产的影像测量仪中处于技术领先地位。
2影像测量仪 的评估
本文尝试从仪器结构、关键技术指标等方面对影像测量仪产品进行评价,由于笔者影像测头方面.的资料欠缺，故未与涉及。
(1)外观与结构
精密测量仪器类产品的外观与结构是用户选择的重要依据。好的产品外观与结构，给人以稳重、可e靠、精密的感觉,往往是决定一款产品在市场获得成败的重要因素。
目前影像测量仪的结构形式主要有立柱式结构、固定桥式结构与移动桥式结构。立柱式结构和固定桥式结构在小量程的影像测量仪中应用都很广泛,各有优势。移动桥式结构主要用在特大量程的影像测量仪中。立柱式结构的优势在于结构紧凑、
占用场地小、装取工件方便;固定桥式结构的特点是产品稳重、大气，但占用场地较大,装取工件不太方便;移动桥式结构则容易实现大量程测量,测量过程中工件固定不动。
(2)光源系统
光源系统在影像测量仪中起着至关重要的作用,直接决定着一-台影像仪性能的好坏、功能的强弱。好的光源系统可帮助影像测头获取清晰、锐利、均匀-致的正确图像,确保测量的精度与重复性。
为实现对不同材质、不同形状、不同种类的工件提供有效的照明,完成复杂的测量任务,影像测量仪通常都会提供三种照明光源:表面光源、轮廓光源、同轴光源。
表面光源为工件上表面的测量提供照明。好的表面光源，要能提供不同入射角度和不同入射方向的照明,确保不同的工件获得--致的照明效果。
轮廓光源为工件外轮廓、通孔等测量提供照明。轮廓光源通常安装在影像测量仪的底座上，在工作时,图像上被工件阻挡部分成像为黑色,无阻挡部分粕角帮助影像测头获得黑自分明、对比度高、边界清晰的工件图像。在轮廓光源照明下，仪器往往能达到最高的测量精度。
同轴光源沿着镜头光轴方向投射到工件表面,可为工件的高反射率表面和深孔部位的测量提供照明。
(3)多测头集成
影像测头在二维尺寸测量上具备无可比拟的速度优势,但影像测头也有其不擅长的地方,在三维测量中,测量效率不够高、工件侧面特征无法测量等。
由此就出现了多测头集成的需求,综合使用影像测头.接触式测头、激光测头和白光测头等,可针对不同的工件及不同的测量需求，选择最合适的测量方式，以便提供最佳的测量精度以及最好的测量效率。在二维尺寸的大批量检测时,可使用影像测
头;在测量复杂工件侧璧,而对效率要求又不高的情况下，可选择接触式测量;在复杂工件的三维测量中，如果对效率要求很高可使用白光测头或激光测头。
(4)测量性能
精度是测量仪器的根本,精度是用户选择仪器的最重要指标之一。影像测量仪的测量精度主要取决于影像测头的质量.照明光源系统性能、仪器运动及定位精度,数据处理测量软、硬件的质量和水平也是极其重要的影响因素。
作为自动化测量仪器,影像测量仪的测量效率是客户最为看重的要素之一。高测量效率可以减少设备投入、提高生产效率、降低人工费用等。
(5)测量功能
影像测量仪的基本测量功能通常包括:点线、圆、弧等多种基本几何量的测量,在测量方式上，提供多种提取及构建方式;提供多种形状公差和位置公差的测量;提供多种坐标系建立方式;提供手动测量与自动批量测量;批量测量程序可记录测量基元、提取方式、机台操控、光源控制、自动聚焦等过程;可导入导出CAD图纸;测量数据输出到指定格式的报表中。
除了这些基本测量功能外,仪器厂商通常还会提供SPC、图纸比对、离线编程、定制输出报表等扩展功能。部分厂商还会针对特定用户行业的测量需求,开发相应的专用软件或硬件,增加仪器测量功能,如小模数齿轮测量、试验筛校准等。
(6)其他方面
产品易用性、对环境的适应性、操作界面是否人性化等方面，也是判别仪器性能的重要因素。是否能方便建立测量任务、制定及输出报表、机台操控等,影响用户对仪器的接受程度。仪器的长期稳定性,测量方案的提供,客户服务的响应速度。交货周期、定制化开发能力等等,都是影响客户选择影像测量仪产品的重要因素。
3、国内外典型产品的点评
影像测:量仪可天致分为科学级和工业级两大类。科学级产品精度非常高对工作环境和操作人员要求也非常高,目前世界上只有少数厂家有这类产品,其市场容量很小。
工业级产品占据了市场最大份额。在工业级产品中，精度高、性能稳定.效率高、功能丰富的一线品牌主要有国外的蔡司、三丰、尼康、0GP、海克斯康及国内的天准精密技术等公司。它们各自开发的具有三维影像测量功能的品牌产品代表了当今工业级影像测量仪的先进水平，本文拟以这些公司相同规格的一个主导产品作为对象,进行概略的介绍比较。
其他常见的进口品牌及绝大部分国产品牌的产品，总体水平质量上相比来看，还存在一些差距。
(1)蔡司
德国蔡司公司是工业测量领域的著名企业，具有丰富的产品线,其CMM更曾是高端CMM的代名词。蔡司旗下最有代表性的影像测量仪产品为0-NSPECT(见图3)。0- NSPECT 采用固定桥式结构,产品美观、稳重,具备影像式测头和接触式测头、
两种检测手段。
(2)三丰
日本三丰公司作为泄界著名的精密测量仪器制造商,其影像测量仪产品线广。 型号齐全,图4为其代表性产品QV- ELF202PRO。 该产品采用固定桥式结构。产品外观稳重,太气。
(3)天准
中国苏州的天准精密技术有限公司多年来专注于精密测量仪器的研发,是中国技术领先的影像测量仪品牌,两项国家校准规范的起草单位。其代表性产品VMU322具有测量精度高、测量速度快、功能丰富等优点(见图5)。
(4)尼康
日本尼康在光学测量仪器领域技术实力雄厚、产品众多。其典型产品VMR3020产品美观、精致,测量精度高,功能全面，如图6所示。
(5)0GP
美国0GP公司一直致力于影像测量仪产品的开发、生产与销售,拥有影像测量仪的多项核心技术,其典型产品ZIP250如图7所示。它采用了固立柱式结构,仪器技术水平较高。
( 6)海克斯康
瑞典的海克斯康是全球知名的长度测量仪器厂商,2010年初推出了Optive系列影像测量仪,其中的Peformance222是其代表性产品(见图8)。该产品源自Mahr技术,采用立柱式结构,结构稳定、精度高,是一款优秀的影像测量仪产品。
英斯特力仪器是一家集研发、生产及销售于一体的 影像测量仪，拉力试验机, 硬度计 ,探伤仪, 粗糙度仪, 测厚仪, 金相设备厂家, 致力于为客户提供更好的检测仪器。
Image measuring instrument is a - "based on imaging optical image system on the optocoupler (referred to as the image system), through the optocoupler acquisition, after software processing imaging, displayed on the computer screen, using the measurement software geometric operation to obtain the final result of the non-contact measuring instrument". Measurement software through digital image processing technology
The coordinate points on the workpiece surface are extracted and converted into various geometric elements in the coordinate measurement space by coordinate transformation and data processing technology.
The parameters such as geometric dimension and shape and position tolerance are obtained.
1. Overview of image measuring instrument development
Image processing techniques and image sensors have advanced rapidly since the late 1970s, especially since professor DavidMar established the theoretical framework "Computational Vision".
With the development and maturity of coordinate measurement technology, the development and application of coordinate measurement method has made further substantial progress in optical measurement field based on optical comparison. .
In 1977, American View Engineering company invented the world's first RB-1 image measurement system driven by a motor XYZ axis (see Figure 1). It is an automatic image measuring instrument with a control terminal integrating video detection and software measurement. Mechanical Technology's Boice Vista, meanwhile, borrows heavily from sitting
The advantage of the scale measuring machine is that a video image measuring system is integrated into the measuring head of the coordinate measuring machine, which can compare the measured data with pre-programmed nominal dimensions and tolerances.
These two instruments refer to the coordinate measuring principle of CMM in different ways and project the image of the measured object into the coordinate system. Its measuring platform inherits the form of coordinate measuring machine, but its probe is similar to the optical projector. The emergence of these instruments opened up an important measuring instrument industry, that is, image measuring instrument industry. In the early 1980s, there were important developments in image measurement technology. In 1981, ROI developed an optical imaging probe (figure 2) that could replace the contact probe on a CMM for non-contact measurements, and this optical accessory has been the basis of imaging equipment ever since. One of the base components. In the mid-1980s, image-measuring instruments with high magnification microscope eyepieces appeared on the market.
In the 1990s, with CC technology, computer technology, digital image processing technology, LED lighting technology. With the development of DC/AC servo drive technology, image measuring instrument products have achieved great development. More manufacturers enter the image measuring instrument product market, and jointly promote the development of image measuring instrument products.
Since 2000, the technical level in this field has been continuously improved in Our country. The image measuring instrument developed by domestic enterprises (such as Tianjun, Zhitai Yixin, Secco Digital, Xintian etc.) has also been improved and developed in terms of production scale, variety and quality. China set a national standard in 2009
GB/ T24762-2009: Acceptance inspection and reinspection inspection of PRODUCT Geometric Technical Specification (GPS) image measuring instruments, which are suitable for image measuring instruments in XY plane rectangular coordinate system, including image measuring instruments with positioning or measurement function perpendicular to the plane rectangular coordinate system in the Z direction.
It is worth mentioning that Tianzhun Precision Technology Co., LTD., which was founded by a group of young students with the ambition to revitalize China's precision measurement industry, developed and innovated on the basis of learning from foreign excellent products and formed its own characteristics and advantages. After years of unremitting efforts, Tianzhon company launched in 2007 for the first time in China with fully independent intellectual property rights of 3d automatic image measuring instrument series products, to fill the domestic gap, in the domestic image measuring instrument technology leading position.
2. Evaluation of image measuring instrument
This paper attempts to evaluate the image measuring instrument products from the instrument structure, key technical indicators and other aspects, due to the author's image probe. Is not covered because of lack of information.
(1) Appearance and structure
The appearance and structure of precision measuring instruments are the important basis for users to choose. Good product appearance and structure, give people a stable, reliable, precise feeling, is often an important factor to determine the success or failure of a product in the market.
At present, the structure of image measuring instrument mainly includes column structure, fixed bridge structure and moving bridge structure. Both the column structure and the fixed bridge structure are widely used in the small range image measuring instrument, each has its own advantages. The moving bridge structure is mainly used in the image measuring instrument with large range. The advantage of the column structure lies in its compact structure,
Small occupation site, easy to install the workpiece; Fixed bridge structure is characterized by stable, atmospheric products, but occupy a large site, installation of the workpiece is not very convenient; Moving bridge structure is easy to achieve large range measurement, the workpiece is fixed during the measurement process.
(2) Light source system
Light source system plays an important role in image measuring instrument, which directly determines the performance and function of an image measuring instrument. Good light source system can help image probe to obtain clear, sharp, uniform - correct image, ensure the accuracy and repeatability of measurement.
In order to achieve the realization of different materials, different shapes, different types of workpiece to provide effective lighting, complete complex measurement tasks, image measuring instrument usually provides three lighting sources: surface light source, contour light source, coaxial light source.
The surface light source provides illumination for measuring the upper surface of the workpiece. A good surface light source should be able to provide illumination from different incident angles and different incident directions to ensure that different workpieces get the lighting effect.
Contour light source provides illumination for measuring workpiece contour and through hole. Contour light source is usually installed on the base of the image measuring instrument, at work, the image is blocked by the part of the workpiece imaging black, no blocking part of the workpiece Angle to help the image probe to obtain black from clear, high contrast, clear boundary of the workpiece image. The instrument usually achieves the highest measurement accuracy under the illumination of contour light source.
The coaxial light source is projected to the workpiece surface along the optical axis of the lens, which can provide illumination for the measurement of the high reflectivity surface and deep hole parts of the workpiece.
(3) Multi-probe integration
The image probe has incomparable speed advantage in two-dimensional size measurement, but the image probe also has its disadvantages, in three-dimensional measurement, the measurement efficiency is not high enough, the side features of the workpiece can not be measured.
Therefore, there is a need for multi-probe integration, integrated use of image probe. Contact probe, laser probe and white light probe can select the most suitable measurement method for different workpiece and different measurement requirements, in order to provide the best measurement accuracy and the best measurement efficiency. Image measurement can be used for mass inspection of two-dimensional dimensions
Head; In the case of measuring the side wall of complex workpiece, but the efficiency requirement is not high, contact measurement can be selected; In 3d measurement of complex workpiece, white light probe or laser probe can be used if high efficiency is required.
(4) Measurement performance
Precision is the fundamental of measuring instrument, precision is one of the most important indicators for users to choose instruments. The measuring precision of image measuring instrument mainly depends on the quality of image probe. The performance of lighting source system, the precision of instrument motion and positioning, and the quality and level of data processing and measurement software and hardware are also very important factors.
As an automatic measuring instrument, the measurement efficiency of image measuring instrument is one of the most important factors for customers. High measurement efficiency can reduce equipment input, improve production efficiency, reduce labor costs, etc.
(5) Measurement function
The basic measurement function of the image measuring instrument usually includes: point line, circle, arc and other basic geometric measurement, in the measurement method, provide a variety of extraction and construction methods; Provide a variety of shape tolerance and position tolerance measurement; Provide a variety of coordinate system establishment methods; Provide manual measurement and automatic batch measurement; The batch measurement program can record the measurement elements, extraction methods, machine control, light source control, automatic focusing and other processes; Can import and export CAD drawings; The measurement data is output to a report in the specified format.
In addition to these basic measurement functions, instrument manufacturers often provide extended functions such as SPC, drawing comparison, off-line programming, and customized output reports. Some manufacturers will also develop corresponding special software or hardware for the measurement needs of specific user industries, and increase instrument measurement functions, such as small module gear measurement, test screen calibration, etc.
(6) Other aspects
The usability of the product, adaptability to the environment and humanization of the operating interface are also important factors to judge the performance of the instrument. Whether it is convenient to establish measurement tasks, formulate and output statements, machine control, etc., will affect users' acceptance of the instrument. Long-term instrument stability, measurement solution delivery, customer service response speed. Delivery cycle, customized development ability and so on are important factors that affect customers' choice of image measuring instrument products.
3. Comments on typical products at home and abroad
Image measurement: measuring instrument can be divided into scientific and industrial two categories. Scientific products have very high precision and very high requirements for the working environment and operators. At present, only a few manufacturers in the world have such products, and their market capacity is very small.
Industrial grade products occupy the largest share of the market. In industrial grade products, high precision, stable performance. The first-line brands with high efficiency and rich functions mainly include foreign Zeiss, Santoyo, Nikon, 0GP, Hexagon and domestic Tianjun Precision Technology companies. The brand products with 3d image measurement function developed by each of them represent the advanced level of industrial image measurement instrument. This paper intends to take a leading product of the same specification of these companies as the object to make a brief introduction and comparison.
Compared with other common imported brands and most domestic brands, there are still some gaps in overall quality.
(1) the Zeiss
Zeiss is a famous company in the field of industrial measurement, with a rich product line, and its CMM was once synonymous with high-end CMM. The most representative Zeiss imaging instrument is 0-NSPECT(see Figure 3). 0-NSPECT adopts fixed bridge structure, the product is beautiful and stable, with image probe and contact probe,
Two methods of detection.
(2) sanfeng
As a famous manufacturer of precision measuring instruments, Santoyo has a wide product line of image measuring instruments. Various models are available. Figure 4 shows its representative product QV-ELF202Pro. The product adopts fixed bridge structure. Product appearance is stable, too gas.
(3) days
Suzhou Tianzhon Precision Technology Co., Ltd. has been focusing on the research and development of precision measuring instruments for many years. It is the leading image measuring instrument brand in China and the drafting unit of two national calibration specifications. Its representative product VMU322 has the advantages of high measurement accuracy, fast measurement speed and rich functions (see Figure 5).
(4) the nikon
Nikon has strong technical strength and numerous products in the field of optical measurement instruments. Its typical product, VMR3020, is beautiful and delicate, with high measurement accuracy and comprehensive functions, as shown in FIG. 6.
(5)0GP
American 0GP Company has been committed to the development, production and sales of image measuring instrument products. It owns a number of core technologies of image measuring instrument, and its typical product ZIP250 is shown in Figure 7. It adopts a fixed column structure and has a high level of instrument technology.
(6) Hex
Sweden hexcom is a world-renowned manufacturer of length measuring instruments. At the beginning of 2010, it launched Optive series of image measuring instruments, among which Peformance222 is its representative product (see figure 8). This product is derived from Mahr technology, using column structure, stable structure, high precision, is an excellent image measuring instrument products.
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