In the modern aerospace field, infrared optical systems are the "eyes" of specialized satellite payloads. Especially with the surge in commercial space constellation deployments and deep space exploration missions, the delivery quality of high-performance infrared payloads has become a key measure of technological strength. However, the research and development and production of infrared lenses have always faced two major challenges: the alignment difficulties caused by the invisibility of infrared light, and the quality uncertainties caused by the inherent characteristics of infrared materials. 1. Core Mission: Why are we so focused on "transmitted wavefront" testing? In the visible light domain, meeting surface shape and size standards usually guarantees optical performance.
But in the infrared domain (especially when using materials such as germanium and silicon), this is far from sufficient. Zhixing Optics' customers are mainly concentrated in the commercial satellite payload and high-end optoelectronic system fields. Faced with these high-reliability missions, why do we emphasize the necessity of testing the transmitted wavefront?
◆ The "Hidden Trap" of Refractive Index: Unlike traditional optical glass, the refractive index (n) stability of infrared materials is greatly affected by the growth process. Even if the surface shape accuracy of the processed components is extremely high, if there is refractive index inhomogeneity within the material, it will still introduce serious system aberrations.
◆Comprehensive Performance Evaluation: Merely detecting surface shape only reveals the "surface." By testing the transmitted wavefront, we can comprehensively evaluate the refractive index fluctuations, internal stress, and surface shape errors within the material. This is a core scientific method to ensure the final wavefront performance of individual infrared components and even the assembled system.
◆Ensuring On-Orbit Reliability of Payloads: For infrared payloads operating in space, even minute wavefront distortions can lead to blurred recognition of distant targets. Transmitted wavefront detection is the last line of quality defense to ensure that payloads are "clearly visible and accurately measured" in complex environments. 2. Core Bottlenecks: The "Visual Blind Spot" in Infrared Detection Although transmitted wavefront detection is crucial, there are insurmountable obstacles in actual operation: "Blackout Operation" is Inefficient: Due to the invisible working wavelength, there is a lack of intuitive guidance when adjusting the interferometer focus and the coordinates of the measured object, resulting in extremely long setup and adjustment cycles and seriously affecting delivery schedules. Sensitivity Loss Due to Long Wavelength: This is a physical limitation of infrared detection. Infrared interferometers have long wavelengths, and the sensitivity of the optical path to pose changes is much lower than that of visible light. This means that the accuracy of position and attitude locking is naturally limited in the infrared band. This inaccurate attitude locking due to wavelength characteristics will produce significant misalignment errors that will be carried over into the final surface data, leading to deviations in measurement results and an inability to accurately reproduce the true physical properties of the raw materials. 3. Zhixing Solution: Dual-wavelength CGH Integration Technology – Visible Guidance, Infrared Measurement To meet the stringent requirements of customers with high-precision loads, Zhixing Optics has developed a cross-band dual-wavelength CGH solution. We make visible light (632.8nm) a "digital guide" for infrared light, making transmission wavefront detection intuitive and efficient.
◆ Physical-level "One Image, Two Waves" Design: On a single high-purity quartz substrate, through precise phase encoding, we simultaneously implant a visible light alignment area and an infrared zero-position compensation area.
Infrared-visible shared CGH layout diagram
◆Phase 1: Rapid Visible Light Reference Locking. Using a naked-eye visible red interferometer, the CGH and the infrared element under test are rapidly adjusted to a sub-micron level coaxial orientation. This step eliminates interference from geometric misalignment, providing accurate spatial orientation for subsequent evaluation of material homogeneity.
Visible light alignment optical path diagram
◆Second Stage: Seamless Infrared Wavefront Measurement. Since the visible and infrared regions share the same set of micro/nano pattern geometric centers, the system automatically achieves ideal alignment after switching to the infrared interferometer. The transmitted wavefront data captured at this stage can accurately and objectively reflect the comprehensive physical characteristics of the component.
Infrared optical path diagram
4. Cross-Band Precision Transfer: Endorsing High-Reliability Loads
Our independently developed cross-wavelength alignment method ensures the spatial alignment of the red light alignment axis and the infrared testing axis. This "reference relay" not only shortens alignment time by more than 80%, but more importantly, it provides a true, closed-loop "wavefront health check report" for the quality assessment of high-end loads.
Leap in Efficiency:
◆Efficiency Improvement: Alignment time has been reduced from "hours" to "minutes".
◆Quality Closed-Loop: Truly achieves full-dimensional assessment of surface shape, dimensions, and material refractive index uniformity, significantly reducing system integration risks.
Conclusion
ZhiXing Optics deeply understands the pursuit of ultimate precision for high-reliability loads. We illuminate the infrared "blind spot" through visualization technology and use high-precision transmission wavefront detection solutions to shield you from material risks and protect every core wavefront.
