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What is a line-confocal 3D measurement sensor?
Release time:
2024-12-17
The line-confocal 3D measurement sensor, often referred to as "line confocal," originated from point confocal technology.
Point-spectrum confocal displacement sensor Born at the end of the 20th century, point-spectrum confocal displacement sensors gradually began to be widely adopted in certain high-precision measurement fields in Western industries from 2000 to 2010. From 2010 to 2020, driven by domestic brands such as THINKFOCUS, these sensors started to see widespread adoption in China’s industrial high-precision measurement sector.
Line confocal Born in the early 21st century, the technology saw virtually no large-scale industrial adoption from 2000 to 2010. From 2010 to 2020, it gradually began to find applications in high-precision industrial measurement, though at that time there were relatively few brands involved—just a total of 2.5 companies: Germany’s Precitec, France’s STIL, and Finland’s Focalspec. Initially, all three companies’ products had significant limitations. The German and French firms both featured extremely narrow measurement ranges, with only 800 points per line, resulting in very low lateral resolution. Moreover, the French company STIL’s structural design was non-standard and inherently fragile, making it completely unsuitable for industrial use. Although Finland’s Focalspec broke through by expanding its measurement range and improving lateral resolution, its high price rendered it impractical for industrial applications, leading to persistently poor business performance and eventually prompting its acquisition by Canada’s LMI.
Domestic confocal Also largely based on point-of-focus technology, various manufacturers are diligently working on R&D. In reality, only one or two manufacturers have successfully commercialized such products, and among them, only THINKFOCUS is truly capable of competing with—and even surpassing—the performance of foreign brands.
Laser confocal principle
A line-shaped light source emits broad-spectrum white light. This light passes through a spectroscopic prism and then through an apochromatic lens, which disperses the broad-spectrum white light into monochromatic lights of different wavelengths, forming a line-shaped light strip with a certain depth of focus along the Z-axis within the measurement range. Each wavelength corresponds to a specific Z-distance value. When the measuring light is reflected off the surface of an object, it passes through the spectroscopic prism and is captured by the spectral detection system. Only the light that satisfies the confocal condition can pass through the slit and be detected by the camera on the spectrometer. By analyzing the wavelength of the light focused at the sensor, we can calculate and convert it into the corresponding Z-axis distance value and X-axis position value.
Features
Laser confocal microscopy is particularly well-suited for measuring samples with high surface reflectivity, tiny measurement areas, and high requirements for accuracy and resolution. Examples include wafers, semiconductor devices, microelectronic components, optical communication devices, miniature components in the 3C industry, surface scratches, and the thickness of transparent materials.
A line laser sensor is similar to a line confocal sensor. However, the two sensors differ significantly in their optical principles, which also give rise to their distinct characteristics. In a line confocal sensor, the light beam from the source converges toward the measurement point; whereas in a line laser sensor, the light beam diverges and then focuses at the measurement point. Because of this convergence, the line confocal sensor offers higher measurement accuracy and can measure surfaces with high specular reflection—but its measurement range is relatively limited. On the other hand, due to the divergence of its light beam, the line laser sensor generally has lower measurement accuracy, but it can measure surfaces with diffuse reflection and boasts an exceptionally large measurement range.
Application:
Wafers, semiconductor devices, microelectronic devices, optical communication components, tiny components in the 3C industry, surface scratches, thickness of transparent materials, and more.
Technical Parameters ：
The key parameters to focus on are: X-axis range, X-axis resolution, Z-axis range, Z-axis resolution, Z-axis accuracy, and sampling rate.
Taking the domestically produced THINKFOCUS line confocal parameters as an example,
| Model | CCL-5040 |
|---|---|
| Points | 2000 |
| X-axis range | 4mm |
| X-direction resolution | 2.1 μm |
| Z-axis range | 1.5mm |
| Z-axis accuracy | 0.5 μm |
| Sampling rate (full scale) | 0.5kHz-7kHz |
Precautions ：
Line-confocal systems generally have larger volumes and higher costs, and are primarily designed for high-end measurement applications.
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