Precision Measurement—The “Eyes” of Scientific Exploration and the “Ruler” of High-End Manufacturing (Learning with Open Books)
The scientist Dmitri Mendeleev once said, “Science begins with measurement.” Lord Kelvin, the “Father of Modern Thermodynamics,” famously concluded, “If you cannot measure it, you cannot make it.” The revolutions in human scientific research and the iterative upgrades of industrial manufacturing both rely heavily on the advancement of measurement technology. In today’s scientific and industrial fields, high-level precision measurement techniques and the ability to manufacture precision instruments are key indicators of a country’s scientific research capabilities and overall industrial competitiveness. They are also indispensable for developing high-end manufacturing. As precision measurement technology continues to advance, it plays an increasingly important role in scientific research, engineering, modern industry, agriculture, healthcare, and environmental protection.
Precision Measurement: The Multiplier of Industrial Production
Precision measurement is a broad concept. Any measurement of high accuracy can be considered precision measurement. In the fields of precision and ultra-precision engineering, precision measurement has specific scales: measurements with accuracies from 1 micrometer to 0.1 micrometer are considered precision, while ultra-precision measurement refers to accuracies better than 100 nanometers—such as 10 nanometers, 1 nanometer, or even picometer (one-thousandth of a nanometer) levels.
Precision measurement emerged with industrial mass production. Large-scale production is a hallmark of modern industry, with increasingly detailed industrial division and specialization, widely distributed production, and globalized supply chains. A product may consist of hundreds or even thousands of components, which cannot all be manufactured by a single company, but instead require coordination among multiple specialized manufacturers around the world. For example, a smartphone contains over 1,600 parts and components sourced from more than 150 factories across more than 10 countries and regions. This approach enables large-scale standardized production with high efficiency, high quality, and lower costs, offering significant advantages. However, a technical challenge arises: if even one component or part fails to meet dimensional or other technical specifications, it cannot be integrated into the final product.
To address this challenge, the International Organization for Standardization (ISO) and the Bureau International des Poids et Mesures (BIPM) have established a series of standards and protocols. According to these standards, the BIPM transmits the internationally recognized standard values to each measuring instrument, ensuring global consistency. Manufacturers then use these instruments to precisely measure every technical parameter of each component and part. Only in this way can all measurement instruments yield accurate data, ensuring that thousands of parts are interchangeable. In simple terms, this guarantees that products from different manufacturers are all qualified and functional. As a result, precision measurement has emerged as a burgeoning discipline driving technological development.
Precision Instruments Enable Scientific Discovery
How is precision measurement performed? This requires the tools of precision measurement—precision instruments. Precision instruments include high-end measuring devices, analytical instruments, imaging instruments, diagnostic instruments, and various experimental apparatus. While ensuring industrial quality, precision instruments are also powerful tools for scientific research. Reviewing the history of technological development in various countries, it is evident that a strong scientific nation is necessarily a strong nation in basic research, and a strong basic research nation is always a leader in measurement and instrumentation. Most modern scientific discoveries and breakthroughs in fundamental research have been achieved through advanced precision measurement methods and cutting-edge instruments. Gravitational wave detection is a prime example.
Gravitational wave detection is an experiment that directly verifies Einstein’s general relativity and explores the origin and evolution of the universe, with enormous scientific value. However, gravitational wave signals are extremely weak and extremely difficult to detect, making ultra-high-resolution long-distance laser interferometry the most advantageous current technique. In other words, the accuracy of a laser interferometer directly determines the limits of gravitational wave detection. If the interferometer is established on Earth, its perpendicular laser arms must each be at least 4,000 meters long. Only under this condition can the minuscule changes in arm length caused by gravitational waves—less than one ten-thousandth of a proton diameter—be measured. To put it into perspective, this ultra-high-resolution measurement is equivalent to detecting a change no thicker than a human hair over a distance encircling the Earth 100 billion times. Through the joint efforts of scientists worldwide, humans successfully detected high-frequency gravitational waves directly in 2016, earning three related scientists the Nobel Prize in Physics.
From a research standpoint, even this is insufficient. Detecting low-frequency gravitational waves requires placing the interferometer in space, where perpendicular laser arms can reach hundreds of thousands to millions of kilometers, enabling measurement accuracies on the order of 1 picometer. The gravitational wave example vividly illustrates that the finer the measurement technology, the further scientific exploration can go.
Only Measured, Only Made
For a nation, precision measurement is closely linked to the level of equipment manufacturing. The key to advancing manufacturing toward mid-to-high-end production lies in improving manufacturing quality, and the key to improving quality is enhancing precision measurement capabilities. Only through precise measurement can one know where a product is defective; only by accumulating large volumes of measurement data can the root causes and patterns of defects be identified; and only by establishing systematic error compensation models based on this data can manufacturing accuracy and product performance be precisely controlled, allowing product quality to improve steadily.
The development of ultra-precision lithography machines exemplifies this principle. Known as the “Mount Everest of ultra-precision advanced equipment,” these machines challenge the limits of human ultra-precision manufacturing in terms of accuracy and performance. They integrate dozens of subsystems and tens of thousands of components in optics, mechanics, electronics, and control to operate in high-performance coordination. They rank among the most complex, technically demanding, and precise equipment ever made. Under high speed and acceleration, they achieve nanometer-level synchronization and alignment accuracy, requiring entirely different precision environments compared to traditional manufacturing. Manufacturing accuracy has approached the limits of current capabilities; even a small improvement requires several times more effort. For instance, a DUV lithography machine for 28-nanometer processes contains over 70,000 optical and mechanical parts, supplied by more than 5,000 upstream suppliers. All components demand extreme precision and stability; only by leveraging the technological advantages of all top-tier suppliers can the machine be successfully developed.
Even one defective component can cause failure. Take the laser mirror, a critical component: made of microcrystalline glass, it must meet 108 dimensional tolerances and 62 shape, position, and orientation tolerances, as well as internal stress requirements. Measuring such a complex component requires more than 20 specialized ultra-precision instruments. Among the 70,000 optical and mechanical parts in a lithography machine, over 80% are precision or ultra-precision grade, requiring more than 700 specialized measurement instruments. Without systematic ultra-precision measurement technologies and instruments, manufacturing accurate parts—and thus assembling a qualified machine—is impossible.
Precision measurement also drives countries to establish national measurement systems, effectively controlling industrial measurement networks, ensuring quality throughout manufacturing chains, and empowering high-tech industries to achieve high-quality development. For consumers, this translates into industrial products that are higher quality and more reliable. Industrialized countries’ products have generally evolved from low to high quality, supported by comprehensive precision measurement systems and world-leading ultra-precision instrument companies, which in turn enable high-end equipment manufacturing and internationally renowned brands.
China is advancing toward a world-leading scientific, manufacturing, and quality powerhouse. Building a next-generation national measurement system is a critical component of this goal. In January of this year, the State Council issued the Metrology Development Plan (2021–2035), explicitly calling for accelerating the construction of a modern advanced national measurement system and advancing metrology standardization. China’s precision measurement researchers continue to bear this responsibility, working with forward-looking vision, innovative courage, and unwavering determination to provide a “ruler” for Chinese manufacturing and to contribute to building a technology-strong nation.