Freeform Surface Error Compensation Technology

Ensuring Precision and Yield in Freeform Optics

Manufacturing freeform optical components is far more complex than producing spherical or aspheric lenses. Even with nanometer-level machining tools, small deviations accumulate from multiple sources: tool wear, thermal drift, spindle dynamics, and especially material shrinkage in injection molding. Without correction, these factors lead to form errors, inconsistent slope performance, and reduced optical quality.

At Yighen Ultra Precision, we have developed proprietary Freeform Surface Error Compensation Technology to eliminate these inconsistencies. By embedding compensation maps into our freeform optics machining and manufacturing workflow, we ensure that both prototypes and mass-produced optics consistently achieve design specifications.

🔍 Why Error Compensation Is Critical

Injection Molding Shrinkage
Plastics such as PMMA, PC, or ZEONEX undergo shrinkage and warpage during cooling. Without correction, lenses suffer from form deviations >0.5 µm PV, reducing system performance.
Machining Dynamics
Even state-of-the-art SPDT and 5-axis machines experience tool deflection, vibration, and thermal expansion. These introduce slope errors that can exceed tolerance budgets for AR/VR or LiDAR optics.
Batch-to-Batch Consistency
In volume production, maintaining Cp/Cpk >1.33 is critical. Error compensation transforms process variation into predictable, correctable data, enabling stable production quality.

This is why error compensation is not optional—it is the backbone of successful freeform optics manufacturing at scale.

⚙️ How Yighen’s Error Compensation Works

Surface Measurement
Each prototype or molding test piece is scanned via interferometry or profilometry to create a detailed error map.
Error Modeling
Deviations are classified into toolpath errors, thermal drift, and molding deformation. Statistical analysis identifies recurring patterns.
Compensation Algorithm
Customized correction maps are generated and applied to machine toolpaths or mold insert designs.
Closed-Loop Verification
The compensated surface is re-measured. Iteration continues until PV, RMS, and slope values meet design tolerances.
Mass Production Integration
Once validated, compensation curves are built into molding SOPs, ensuring that every batch meets spec without repeated manual adjustment.

This closed-loop method links design, machining, metrology, and production—a key differentiator of Yighen’s approach to freeform optics machining.

📊 Typical Improvements with Compensation

Form accuracy improved from 0.5 µm → ≤0.2 µm PV in injection-molded freeform optics
Surface slope error reduced by 30–50% compared to uncompensated machining
Yield rate increased by 15–25% across large production batches
Consistency across 10k+ molded lenses with Cp/Cpk ≥1.33

These measurable results highlight why our compensation technology is a decisive advantage for customers in AR/VR, automotive HUD, LiDAR, and medical optics.

📚 Application Scenarios

AR/VR Displays

In AR waveguides and pancake optics, pixel-to-optics alignment is extremely sensitive. Without error compensation, slope deviations lead to blur at the edge of the eyebox and color fringes across the display. By integrating freeform optics error compensation into prototyping and molding, Yighen ensures consistent resolution at >200 lp/mm—matching micro-OLED pixel density.

Automotive HUD

HUD optics require wide FOV projection with minimal distortion on the windshield. Injection-molded freeform lenses, if left uncompensated, show warpage after cooling. Yighen’s compensation workflow corrects this deformation, producing stable PV ≤0.25 µm and high image clarity even under temperature fluctuations.

LiDAR Beam Shaping

LiDAR requires high-power, high-uniformity beams. Freeform diffusers and collimators without compensation suffer from uneven beam patterns. With Yighen’s closed-loop correction, uniformity across the beam footprint improves by over 20%, enhancing sensing accuracy.

⚖️ With vs. Without Error Compensation

Parameter	Without Compensation	With Yighen Compensation
Form Accuracy (PV)	0.5–1.0 µm deviation typical	≤0.2 µm PV after correction
Surface Roughness (Ra)	Ra 5–10 nm but slope deviations persist	Ra 5 nm with corrected slopes
Injection Molding Yield	70–80% (significant rejects)	≥95% consistent yield
Cp/Cpk (Process Capability)	<1.0 (unreliable)	≥1.33 (stable production)
Optical Performance	Distortion, edge blur, reduced MTF	High MTF, uniform FOV, consistent beam quality

This comparison shows why error compensation is inseparable from freeform optics manufacturing if precision and yield are priorities.

🚀 From Prototype to Mass Production

Error compensation is not just a prototyping tool—it is the bridge that guarantees consistency as designs scale.

Prototype phase: Early deviation mapping prevents iteration waste.
Tooling phase: Mold inserts designed with shrinkage compensation reduce trial-and-error costs.
Mass production: Compensation curves integrated into SOPs ensure thousands of freeform optics maintain stable quality.

This ensures that every project at Yighen transitions smoothly from concept validation to stable, large-scale delivery.

📞 Partner with Yighen

Yighen’s proprietary Freeform Surface Error Compensation Technology is trusted by customers in AR/VR, automotive, sensing, and medical industries to deliver optics that are not only precise but also mass-producible.

👉 Contact Us | Download Freeform Optics Whitepaper
Or explore our Freeform Optics Machining & Manufacturing Services for a complete design-to-production solution.

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Yighen Ultra Precision- Optical Design & Machining ꄲ Optical Machining & Production ꄲ Freeform Surface Error Compensation