表面细节的快速和精确的非接触式 3D 测量——林肯先生会如何认为?

2023-07-03 18:02

Fast & precise non-contact 3D measurement of surface details – What would Mr. Lincoln say?

表面细节的快速和精确的非接触式 3D 测量——林肯先生会如何认为

Did you know that 3D measurement with interferometry can be highly precise AND crazy fast?

This dual capability is critical for in-line inspection in high-precision industries.

您是否知道使用干涉测量法进行的 3D 测量可以非常精确且速度极快?这种双重能力对于高精度行业的在线检测至关重要。

To illustrate this capability, we used Novacam SURFACEINSPECTTM
3D metrology system to scan a detail on a US penny.
Based on
low-coherence interferometry, the system measures with micron precision yet its typical measurement cycle is merely seconds, often satisfying challenging plant-floor applications.

为说明此功能,我们使用 Novacam SURFACEINSPECT
3D 计量系统扫描

Of course, the measurement cycle time will depend on two parameters: a) the size of the area measured and b) the required density of measurements. For this reason, we compare two measurement scenarios for the same area – one scenario with a high density and another with a lower density of 3D point measurements.

当然,测量周期时间将取决于两个参数:a) 测量区域的大小和 b) 所需的测量密度。出于这个原因,我们比较了同一区域的两种测量场景——一种场景具有高密度,另一种场景具有较低密度的 3D 点测量。

Enter Mr. Lincoln on the back of the US penny


The US one-cent coin is a familiar object in North America. The penny is ~21 mm wide and 1.52 mm thick.
The coin has a little-known detail on its back – a tiny figure that is interesting to measure.
Most people don’t ever notice it.

美国一美分硬币在北美是很常见的东西美分硬币宽约 21 毫米,厚 1.52 毫米。硬币的背面有一个鲜为人知的细节——一个测量起来很有趣的小数字。大多数人从来没有注意到这一点

To find the figure, look closely at the center of the Lincoln Monument pictured on the backside of the coin. Between the two central columns, you’ll see a tiny seated figure of Mr. Abraham Lincoln, America’s 16th president. We wanted to measure and visualize the smallest detail – Lincoln’s head, which is approximately 0.25 mm (250 µm) wide and 0.018 mm (18 µm) high.

要找到这个数字,请仔细观察硬币背面的林肯纪念碑中心。在两中央圆柱之间,您会看到美国第 16 任总统亚伯拉罕·林肯先生的小坐像。我们想要测量和可视化最小的细节——林肯的头部,大约0.25 毫米(250 微米)宽0.018 毫米(18 微米)高。

It has been measured before


Although a feature as small as Lincoln’s head is fast and easy to photograph, it is not easy to measure in 3D. A recent

small comparison study
illustrated this difficulty by comparing 3 optical measurement technologies:


a 3D laser line scanner,


a structured light system, and


a white-light interferometer.


Interestingly, from the 3 technologies compared in the study, only the white-light interferometry system provided the precision and accuracy that afforded a sharp and artifact-free visualization of the Lincoln figure.


Curiously however, the interferometry technology was judged as slow.
The cause of the slowness was the stitching required by the interferometry system used in that study.
In fact, this particular system required six (6) area measurements to cover the small surface of the coin!

然而奇怪的是,干涉测量技术被认为是缓慢的。缓慢的原因是该研究中使用的干涉测量系统所需的拼接。实际上,这个特殊的系统需要六 (6) 个面积测量来覆盖硬币的小表面!

But is this time-consuming stitching inevitable?
And is ‘slow’ a fair judgement of interferometry as measurement technology?


We would categorically say no.


Photo of the back of a US penny, a 21-mm diameter coin with an 18- micron-high relief of sitting Abraham Lincoln


Speeding up optical interferometry


Not all interferometry systems are equal in terms of system design. For example, NOVACAM 3D metrology systems, which use

low-coherence interferometry, achieve axial precision of <=1 µm, yet they measure much faster than the white-light interferometry system used in the study mentioned above. The speed advantage is due to system design. Since Novacam targets high-precision industrial applications, the company has pushed and progressively fine-tuned the performance of its systems to provide:

低相干干涉测量法的 NOVACAM 3D 计量系统可实现 <=1 µm 的轴向精度,但测量速度比上述研究中使用的白光干涉测量系统快得多。速度优势归功于系统设计。由于 Novacam 以高精度工业应用为目标,公司推动并逐步微调系统性能,以提供:

point-by-point surface acquisition at up to 100,000 3D points per second, and


the option of fast-scanning area probes, such as raster-scanning galvo scanners, with a field of view (FOV) of up to 84×84 mm (standard models). Larger FOVs are available in custom models.

可选择快速扫描区域探头,例如视场 (FOV) 高达 84×84 毫米(标准型号)的光栅扫描振镜扫描仪。自定义模型中提供更大的 FOV。

Within the galvo scanner FOV, the scanning beam traverses the surface extremely fast in a line-by-line raster pattern, rapidly providing a 3D point cloud for the specified area within the FOV. When the area to be measured fits within the FOV, stitching is not required. The measurement time then largely depends on the user-specified density of data points.

在振镜扫描仪 FOV 内,扫描光束以逐行光栅模式极快地穿过表面,为FOV内的指定区域快速提供3D点云。当要测量的区域适合视场时,不需要拼接。测量时间很大程度上取决于用户指定的数据点密度。

The galvo scanner acquires 3D surfaces in an efficient raster pattern. Standoff distance is up to 215 mm. Standard FOV options range up to 84×84 mm.

振镜扫描仪以高效的光栅模式获取3D表面。间距可达 215 毫米。标准 FOV 选项范围高达 84×84 毫米

To show the relationship between the data point density and the resulting scan time, we ran a couple of scan scenarios.


Cycle time scenarios


Let’s get back to Mr. Lincoln on the US penny. To measure the backside of the coin, we used the
SURFACEINSPECT 3D metrology system
with a lens FOV of 54 x 54 mm, a working distance (standoff) of 125 mm, and a spot size of 6 µm (FHM).

让我们回到美分硬币的林肯先生雕像。为了测量硬币的背面,我们使用了SURFACEINSPECT 3D 测量系统,其镜头视场为 54 x 54 mm,工作距离(间距)为 125 mm,光斑尺寸为 6 µm (FHM)。

We scanned the coin twice: once at a high density and once at a lower density. The table here shows the results associated with the two scans.


Scan 1: high-density scan
Scan 2: low-density scan
Area scanned
25 x 25 mm
25 x 25 毫米

125 mm
125 毫米

Point density in X&Y
6 µm
6 微米
37.5 µm
37.5 微米
# of data points per scan line
# 每条扫描线的数据点个数
Total # of data points
17,363, 889
Cycle time
5.8 min
5.8 分钟
9 sec

As shown in the table:


Scan 1, a high-density scan, involved acquiring a 3D point measurement every 6 microns. It provided over 17 million data points and took several minutes. To note, very few of our industrial clients require this many measurements.

扫描 1 是高密度扫描,涉及每 6 微米获取一个 3D 点测量。它提供了超过 1700 万个数据点耗时几分钟。需要注意的是,我们的工业客户很少需要这么多测量。

Scan 2, a lower-density scan, involved acquiring a measurement every 37.5 microns. It
provided close to 1/2 million data points in 9 seconds. This scan represents a more typical density of points required by our industrial clients. Even much lower density than this one often suffices for 3D geometry analysis.

扫描 2 是一种低密度扫描,每 37.5 微米进行一次测量。它在 9 秒内提供了近 1/2 百万个数据点。这种扫描代表我们的工业客户所需的更典型的点密度。即使比这低得多的密度通常也足以进行 3D 几何分析。

To be sure, with NOVACAM 3D metrology systems, users may experiment with and select the acquisition point density that meets their needs.
In general,

可以肯定的是,使用 NOVACAM 3D 量系统,用户可以试验并选择满足他们需求的采集点密度。一般来说,

Geometry measurements require low-density 3D point clouds, while

几何测量需要低密度 3D 点云,而

Identifying and measuring the smallest of defects requires the highest density 3D point clouds.

识别和测量最小的缺陷需要最高密度的 3D 点云。

Analysis and visualization of the 3D data


Following an area scan, the SURFACEINSPECT system users may view the 3D data in 3 different ways.

在区域扫描之后,SURFACEINSPECT 系统用户可以通过 3 种不同的方式查看 3D 数据。

As a 3D point cloud


The 3D point cloud provides the basis for either interactive or automated 3D geometry analysis with 3D GD&T software. If the point density is high enough, the 3D point cloud can be also used to identify and measure defects.

3D 点云为使用 3D GD&T 软件进行交互式或自动 3D 几何分析提供了基础。如果点密度足够高,3D点云也可以用来识别和测量缺陷。

Use arrows to zoom into the 3D point cloud of the penny.

使用箭头放大硬币的 3D 点云。


3D point cloud of the US penny viewed as colour deviation map

美分硬币的 3D 点云视为彩色偏差图

Novacam provides PolyWorks Inspector software for 3D GD&T analysis as an option with its 3D metrology systems.

Novacam 提供用于 3D GD&T 分析的 PolyWorks Inspector 软件,作为其 3D 计量系统的选项。

As a Light intensity map


The light intensity map from a high-density scan is equivalent to a photo obtained by a vision system. Though it does not contain data, the light intensity map is a helpful visual reference, particularly for identifying defects.


Click for close-up


As one of 3 types of output data, an intensity map of the back of the coin gives a photo-like image.

作为 3 种输出数据之一,硬币背面的强度图给出了类似照片的图像。

Click for close-up


Close-up zoom on Abraham Lincoln


As a Height map


The height map represents the micron-precision height value of each measured point of the surface. This format of the 3D data can be interesting for both interactive or automated analysis of surface features or defects. For example, as shown, a linear profile (indicated by a yellow line) on the penny surface height map
provides the exact measurements of the height of Lincoln’s head and the columns on either side.

高度图表示表面每个测量点的微米精度高度值。这种 3D 数据格式对于表面特征或缺陷的交互式或自动分析都很有趣。例如,如图所示,美分表面高度图上的线性轮廓(用黄线表示)提供了林肯头部和两侧柱子高度的精确测量值。

Click for close-up


A height map contains the 3D micron-precision height data. Here, a linear profile across Lincoln’s head is extracted for analysis.

高度图包含 3D 微米精度的高度数据。在这里,提取了林肯头部的线性轮廓以供分析。

Is one penny enough? How about more?


The galvo scanner FOV is selected based on the application need. For example, with an adequate FOV, the SURFACEINSPECT system may scan several pennies in one pass as shown below.

根据应用需要选择振镜扫描仪 FOV。例如,在足够的 FOV 下,SURFACEINSPECT 系统可以一次扫描数个硬币,如下所示。

The NOVACAM SURFACEINSPECT system with a 54×54 FOV easily scans 4 pennies in one go.

具有 54×54 视场的 NOVACAM SURFACEINSPECT 系统可一次轻松扫描4枚硬币

Intensity image from a scan of 4 pennies – acquired in one continuous scan, no stitching required

扫描 4 便士的强度图像 – 在一次连续扫描中获取,无需拼接

Where are high-precision and high speed needed?


The combination of measurement precision and speed is required by many manufacturers in high-precision industries.
In many of these industries, NOVACAM 3D metrology systems (including the SURFACEINSPECT and EDGEINSPECT, for example) measure
geometry, defects, and even
of semi-transparent materials.

高精度行业的许多制造商要求测量精度和速度的结合。在许多此类行业中,NOVACAM 3D 测量系统(例如包括 SURFACEINSPECT 和 EDGEINSPECT)测量半透明材料的几何形状、缺陷甚至厚度。

Here are a few typical industrial applications:


Semiconductors – wafers,
CMP pads

半导体 – 晶圆、CMP 垫

Aerospace – aircraft rivet
countersinks, airfoils, jet engine turbine blades, cooling holes

航空航天 - 飞机铆钉埋头孔、机翼、喷气发动机涡轮叶片、冷却孔

Automotive – fuel injector seats,
valve bodies

汽车 – 喷油器座、阀体

Glass industry – multi-layer thickness measurement, smartphone glass


Ophthalmology – regular or intraocular lenses

眼科 - 常规或人工晶状体

Plastics –
extruded fibers or tubing


Bio-medical – tissue thickness, surface-finish or thickness of implants (e.g., catheters)


Nuclear – nuclear fuel rods


Metallurgy – weld inspection.


Automated 3D wafer metrology and defect measurement with NOVACAM EDGEINSPECT system

使用 NOVACAM EDGEINSPECT 系统进行自动化 3D 晶圆计量和缺陷测量

More than speed & precision


In addition to speed & precision, Novacam SUFACEINSPECT & EDGEINSPECT galvo scanning systems offer unique capabilities such as:

除了速度和精度之外,Novacam SUFACEINSPECT 和 EDGEINSPECT 振镜扫描系统还提供独特的功能,例如:

Ability to acquire dimensions, defects and thickness with the same instrument


Standoff distance (up to 215 mm) and FOV that enable industrial deployment (unlike microscopes)


Ability to measure blind hole bottoms (such as injector seat measurements) or hard-to-reach areas (with mirrors, for example)


Area or strip scanning even in hard-to-reach spaces such as bores and cylinders with new periscope-like galvo scanners


Ability to perform continuous (long strip) scanning by combining the galvo scanner with a motion stage


Measurement in
hostile environments
involving extreme temperatures, extreme pressures, or radioactivity.


With NOVACAM 3D metrology systems, scan definitions can be optimized to meet each application’s measurement and cycle time requirements.
Also, scan definitions, which include measurement sequences and data analysis, are user-customizable. Moreover, NOVACAM systems support full
of the inspection-analysis cycle.

使用 NOVACAM 3D 计量系统,可以优化扫描定义以满足每个应用程序的测量和周期时间要求。此外,扫描定义(包括测量序列和数据分析)是用户可定制的。此外,NOVACAM 系统支持全自动化的检测分析周期

Read about other advantages of NOVACAM technology

在此处了解 NOVACAM 技术的其他优势。

What would Lincoln say?


Of course, we don’t know what Mr. Lincoln would say. But we can speculate that, as a strong proponent of constant learning, he would also approve of pursuing technological advancements that improve the capabilities of the day’s manufacturers. NOVACAM systems, which offer non-contact high-precision 3D
measurements combined with high-speed acquisition, strive to do just that.

当然,我们不知道林肯先生会如何认为。但我们可以推测,作为一个不断学习的坚定支持者,他也赞成追求技术进步以提高当今制造商的能力。NOVACAM 系统提供非接触式高精度 3D 测量和高速采集,力求做到这一点。


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