Announcement of the Results

Our "Guangheng" series of remote housings specifically designed for high-end visual endoscopes have successfully pushed the installation and alignment accuracy of optical components to the nanometer scale. Through two core technologies, "nanometer precision reference surface processing" and "in-situ optical alignment auxiliary structure," this product ensures that the relative position tolerance between the camera sensor, optical lens, and illumination window is stable within ±3 micrometers, eliminating image distortion, chromatic aberration, and illumination dark areas from the mechanical root cause. This product has become an indispensable core component for 4K/8K ultra-high-definition endoscopes, 3D stereoscopic vision endoscopes, and fluorescence imaging endoscopes.

Research and Development Background Challenges

The quality of endoscopic images serves as the "eyes" for diagnosis and surgery, and its core bottleneck often lies in the optical alignment at the distal end. In traditional shell manufacturing, key reference planes such as the camera installation surface, lens retaining ring surface, and light fiber exit surface are processed by different processes separately, and cumulative errors can easily lead to optical axis deviation, sensor tilt, or objective lens defocus. Even a small deviation (such as a 0.02 millimeter sensor tilt) will, after optical magnification, cause obvious image trapezoidal distortion, edge blurring, or uneven illumination. Moreover, the shrinkage of adhesives and stress release during the assembly process will further introduce uncontrollable alignment errors. In clinical settings, problems such as "edge softening" of images, "dark shadows at the corners," or "vergence disorder" in 3D vision caused by poor optical alignment seriously affect the accuracy of doctors' observation and operation, and are also the key factors contributing to the differences in performance and experience of endoscopic products.

Core Technological Innovation

• Multi-benchmark surface one-time forming process: Breaking the traditional step-by-step processing mode, we have developed an ultra-precision processing solution of "one-time clamping, full feature forming." On the ultra-high rigidity 5-axis micro-processing center, through the self-developed "thermal-thermal coupling error compensation" algorithm, all key optical benchmark surfaces, lens barrel cavity, optical fiber socket, and channel can be continuously processed in a single clamping. This eliminates the benchmark conversion error caused by repeated clamping and reduces the parallelism, perpendicularity, and position error between each optical benchmark surface by more than 80%, achieving the manufacturing concept of "design alignment."
• In-situ calibration mark and measurement feature integrated design: In the non-functional area of the shell, innovative micro-v-shaped grooves, cross lines, or hemispherical depressions are processed as in-situ calibration marks. These marks can serve as high-precision reference benchmarks for the machine vision system in the subsequent active alignment (AA) process of the optical components, greatly improving the alignment efficiency and accuracy. At the same time, a dedicated micro-measurement plane is designed on the shell, allowing laser interferometers or confocal sensors to be used for in-situ measurement during assembly, real-time monitoring of key dimensions, forming a manufacturing-assembly-testing closed loop.
• Low stress and high stability connection interface treatment: For the bonding area of the optical components, a special micro-textured surface treatment technology was developed. Through laser surface texturing, a regular distribution of micro-cone arrays is formed on the bonding surface, which not only significantly increases the effective bonding area and mechanical interlocking force, but also provides a stable flow and curing space for the adhesive, reducing the component tilt stress caused by uneven adhesive layer shrinkage by 70%. Combined with medical-grade epoxy glue with low shrinkage rate and high thermal conductivity, the long-term positional stability of the optical components under temperature cycling from -40°C to 135°C and repeated sterilization is ensured.

Mechanism of Action

The core function of the "Guangheng" series housing is to establish a "zero-drift mechanical coordinate system" for complex optical systems. Every feature serving the optical components within the housing has undergone strict kinematic constraint analysis and optimization. For instance, the mounting surface of the camera sensor is designed with a "six-point positioning" structure that ensures precise flatness and verticality, thereby limiting the six degrees of freedom of movement and ensuring that the sensor cannot undergo any micro-movements after being fixed. The introduction channel of the illumination fiber and the exit end face have been precisely controlled for concentricity and angle, ensuring that the emitted light cone can uniformly cover the field of view of the camera and maintain a preset angle with the optical axis, avoiding direct glare from the lens. For 3D endoscopes, the two independent cavities used for installing the left and right camera modules have their optical axis spacing, convergence angle, and the coplanarity of the sensor planes all processed to sub-micron precision. This is the physical basis for achieving natural and non-fatiguing stereoscopic vision. These precise mechanical relationships constitute the "invisible skeleton" of high-quality optical imaging.

Efficacy Verification

The endoscopic module equipped with the "light balance" housing performs exceptionally well on the professional optical testing platform: in the standard grid projection test, the geometric distortion rate within the full field of view is less than 1.5% (the industry's top standard is typically <3%); in the uniformity lighting test, the illumination uniformity within the field of view is greater than 90%; in the modulation transfer function (MTF) test, at the Nyquist frequency, the ratio of MTF values at the center and the edge is greater than 0.8, demonstrating excellent off-axis imaging performance. In the thermal stability test, during the temperature change from 10°C to 50°C, the image center drift is less than 2 pixels. The customer's complete machine test report shows that after using this housing, the 4K endoscope's geometric correction parameters at the factory are almost not requiring personalized adjustment, significantly simplifying the production process and improving the yield rate. In clinical simulations, the doctors' depth perception score for the 3D images using this housing significantly improved.

Research and Development Strategy and Philosophy

Our strategy is "to define mechanical accuracy based on optical performance." We are at the forefront of endoscope optical design and have established deep cooperation with the world's leading optical design companies and image sensor manufacturers. We not only understand mechanical drawings, but also have a thorough knowledge of optical modulation functions, aberration theory, and illumination optics. Our design inputs are not only CAD models and tolerance bands, but also the modulation transfer function (MTF) curves, relative illumination (RI) diagrams, and distortion grids of the customer's optical system. We convert these optical performance indicators through sensitivity analysis into quantifiable and measurable mechanical tolerance requirements for each relevant feature of the housing. Our philosophy is: a perfect remote housing should enable the perfect design of optical engineers to be presented without loss in the real world. We are the "realizers" of optical dreams.

Future Outlook

In the future, optical alignment will be deeply integrated with intelligent compensation. We are developing an "active optical alignment housing," which integrates micro piezoelectric actuators inside. Before production or during use, it can perform nanometer-level fine-tuning of the position of the camera or lens components based on the detected image signals to compensate for minor drift caused by long-term use or extreme environments, achieving "lifelong accuracy." At the same time, we are exploring and integrating with computational imaging to develop housing structures specifically optimized for new imaging technologies such as "no-lens imaging" or "light field imaging." These technologies may have different requirements for mechanical precision from traditional optics. The grander vision is to participate in the research and development of "chip-level endoscopes," integrating CMOS sensors and micro optical components at the wafer level. Our role will be to manufacture the ultimate microstructure base with atomic-level flatness and thermal matching that carries this "optical chip," driving endoscopes into the "system-on-a-chip" era.