When we think of CNC machine tools, lithography machines, CT scanners, and coordinate measuring machines, they often seem like distant, cutting-edge technologies. Yet few realize that achieving their remarkable precision relies on an unassuming yet critical component: the linear encoder. Acting as the equipment’s built-in “super‑scale” and “keen eye,” it can detect minute displacements down to the micrometer and even nanometer levels, while continuously monitoring every movement of the machine. From chip manufacturing and component quality inspection to medical radiotherapy and high‑precision metrology, its indispensable support is found everywhere.

I. Basic Structure: Two Major Core Components Each Perform Their Respective Functions

Don’t be fooled by the grating scale’s high precision—its structure is anything but complicated; it essentially consists of… Ruler grating and Readhead With two parts working in coordinated synergy, displacement measurement can be taken to the ultimate level.

Ruler grating It serves as the “reference scale surface” of the linear encoder, firmly mounted on the machine’s stationary base. Typically fabricated with a glass or metal substrate, it is engraved with closely spaced, fine grating lines using precision manufacturing techniques. The pitch of these grating lines directly determines the measurement accuracy: the smaller the pitch, the higher the resolution. Based on optical principles, glass‑substrate gratings are transmissive, while metal‑substrate gratings are reflective, allowing them to meet the diverse installation and operational requirements of different machines.

Readhead It serves as the “signal translator” for the grating scale, mounted on the machine’s moving components and housing a light source, an index grating, optical elements, and a photodetector. As the machine moves, the readhead slides relative to the scale grating; when the grating lines overlap, alternating bright and dark patterns are produced. The readhead converts these optically encoded signals—imperceptible to the naked eye—into electrical signals that the machine can interpret, accurately determining the distance of travel and transmitting this information in real time to the machine controller, enabling the system to adjust its position accordingly.

II. The Function of the Grating Scale

Setting aside the complex optical principles, a grating scale is essentially the device’s “close‑quarters supervisor.” It continuously monitors moving components such as the scanner’s stage and the radiotherapy treatment head, detecting even the tiniest positional deviations. It then converts these mechanical displacements into electrical signals and feeds them back to the system’s “brain” in real time.

If the actual travel distance deviates from the set value, it immediately alerts the system to correct the error, preventing even small deviations from accumulating and ensuring that every operation is precisely executed. In short, without an optical grating scale, even the most advanced equipment cannot perform tasks with micrometer- or nanometer-level precision.

III. Key Application Scenarios

1. The “Precision Gatekeeper” of High-End Manufacturing

In CNC machine tools, lithography machines, and chip‑processing equipment, whether cutting a micron‑scale precision part or etching fine circuits on a chip, once the operator sets the parameters, the grating scale continuously monitors the travel of the tool and the worktable. Even deviations as small as 0.001 millimeter are accurately detected, enabling the system to make timely adjustments and ensuring that the manufactured parts meet tolerances with pinpoint accuracy—fully satisfying the exacting demands of high‑end manufacturing.

Chip manufacturing equipment

2. The “Iron-Faced Judge” of Precision Quality Inspection

In quality‑inspection equipment such as coordinate measuring machines and precision gauges, the grating scale is universally recognized as the “standard ruler.” With exceptionally high intrinsic accuracy, it delivers objective and reliable measurement data—enabling precise assessment of part dimensions and geometric tolerances to determine product compliance—as well as calibration of other measuring instruments. It truly serves as the “impartial arbiter” in industrial quality‑control processes.

Precision testing instrument

3. The “Precision Driver” of Medical Equipment

When it comes to medical equipment such as CT scanners and radiotherapy machines, linear encoders shoulder the critical responsibility of safeguarding patient safety. Take radiotherapy, for instance: the treatment head must be precisely aligned with the tumor target—any deviation of even a millimeter could damage healthy tissue. Linear encoders reliably monitor and control the head’s position, achieving millimeter‑level or even sub‑millimeter‑level accuracy, ensuring that the radiation beam is delivered solely to the lesion while sparing surrounding healthy tissues. This approach not only maximizes therapeutic efficacy but also provides the highest possible level of patient safety.

Radiotherapy equipment

4. The “Multi-Dimensional Positioning Marvel” of Astronomy and Aerospace

Except for one-dimensional linear scales, which can only measure displacement in a single direction, Two-dimensional grating scale Even more impressive ！ It can simultaneously monitor motion in both the X and Y directions, and even compensate for angular deviations, making it an indispensable core component in fields such as astronomical observation and satellite‑borne applications, where multidimensional precision is of paramount importance.

In the field of astronomical observation, large telescopes and spectrographs must capture signals from distant celestial objects with pinpoint precision, requiring that the orientation of their mirrors and detectors remain absolutely stable. Two-dimensional grating scales serve as the telescope’s “precision positioning system,” continuously monitoring the fine adjustments of the mirrors and the rotational movements of the mount, correcting even the tiniest deviations to ensure the telescope remains locked onto its target. This enables clear acquisition of galactic spectra and deep‑space signals, helping scientists unravel the mysteries of the universe.

Astronomical observation

When applied to satellites and aerospace systems, two-dimensional grating scales play an even more critical role. Satellite antennas and solar array panels must deploy with precision and adjust their attitude in real time under space‑environment conditions, compensating for the minute deformations caused by weightlessness and thermal cycling. Similarly, spacecraft docking and the positioning of onboard high‑precision sensing instruments require multi‑axis displacement monitoring. Leveraging their strong anti‑interference capability, high accuracy, and compact form factor, two-dimensional grating scales provide continuous control over component motion in two dimensions, ensuring stable antenna signal transmission and reception, precise spacecraft docking, and the successful execution of space exploration, satellite navigation, and other missions.

Satellite navigation

IV. Core Technology: Nanoimprinting Enables High-Precision Mass Production

To produce grating scales with ultra‑fine lines and maximum precision—especially high‑end, nanometer‑level products—ordinary manufacturing processes simply won’t suffice. Nanoimprint lithography It is the core game-changer for the mass production of high-precision grating scales.

When fabricating ultra‑fine grating lines using conventional lithography, not only is the precision limited, but costs are high and mass production proves challenging. Nanoimprint lithography, by contrast, effectively overcomes these obstacles. The process begins with creating a high‑precision master grating, which is then transferred—via mechanical imprinting combined with curing—to substrates such as glass or metal, accurately replicating the nanoscale grating pattern. This approach ensures uniform grating pitch and well‑defined groove profiles, achieving nanometer‑level measurement accuracy while significantly boosting production efficiency and reducing costs. As a result, high‑precision grating scales can be manufactured at scale, supporting precision upgrades in fields like advanced manufacturing and precision medicine.

SEM image of the grating scale

Though compact in size, the linear encoder is the “precision heart” of high-end, precision equipment. From basic displacement measurement to nanometer‑level fine control, and even the nanoimprint technology that underpins mass production, this cascade of extreme precision quietly fuels high‑quality advancements across industries such as industrial manufacturing, medical diagnostics, and aerospace. It is precisely this relentless pursuit of excellence that gives Chinese manufacturing an unshakable confidence and enables humanity to push the frontiers of exploration ever further into the future.