UNDERSTANDING SURFACE FIGURE ACCURACY IN LASER COLLIMATING AND FRESNEL LENSES
Fresnel lens for infrared sensing and illumination, the key to achieving stable and predictable optical performance lies in one subtle yet decisive parameter — surface figure accuracy.
Introduction
In precision optics, every micron matters. Whether designing a laser collimating lens for high-energy beam shaping or a Fresnel lens for infrared sensing and illumination, the key to achieving stable and predictable optical performance lies in one subtle yet decisive parameter — surface figure accuracy.
What Is Surface Figure Accuracy?
Surface Figure Accuracy describes how closely a manufactured optical surface matches its ideal theoretical shape.
It directly affects how light travels, focuses, and diverges after interacting with the lens.
For laser collimating lenses, even a slight deviation in curvature can cause the beam to lose parallelism, leading to spot enlargement or energy drift over distance.
For Fresnel lenses, excessive figure error may distort the designed focusing pattern, resulting in reduced detection sensitivity or uneven illumination.
Surface figure accuracy is typically expressed as:
λ/4 to λ/10 (in optical wavelength terms) for imaging and collimation optics.
Micron-level tolerance for non-imaging optics like PIR Fresnel lenses.
Laser Collimating Lenses: Where Precision Defines Performance
A laser collimating lens converts divergent light from a point or fiber source into a parallel beam.
This process requires perfect control of:
Curvature radius, ensuring uniform beam divergence.
Surface figure, ensuring wavefront remains planar.
Even a 50-nm deviation in surface figure can introduce measurable wavefront aberration — unacceptable in fiber-coupling or laser measurement systems.
At Aubor, polymer lenses are manufactured with sub-micron surface form accuracy using single-point diamond turning (SPDT) and precision injection molding, ensuring every optical surface maintains excellent consistency across production batches.
Fresnel Lenses: Balancing Cost, Function, and Form
Unlike traditional imaging lenses, Fresnel lenses achieve light focusing through a series of concentric grooves, significantly reducing thickness and cost.
However, this design amplifies the importance of groove precision and surface figure uniformity:
Too large a figure deviation: focusing angle shifts, detection blind zones appear.
Too rough a surface: infrared transmittance drops, signal sensitivity decreases.
Aubor’s PIR Fresnel lenses maintain groove height errors within ±10 μm and use high-transmission optical polymers to preserve signal integrity even at 12 m ceiling-mounted detection distances.
How Surface Figure Connects Laser and Fresnel Design
Though the two lens types serve different purposes, they share a common foundation — controlling light propagation through precise surface geometry.
| Parameter | Laser Collimating Lens | Fresnel Lens |
|---|---|---|
| Function | Beam collimation / focusing | Infrared focusing / detection |
| Surface Figure Tolerance | λ/10 or better | ±10 μm typical |
| Material | Optical-grade PMMA / COC / PC | IR-transmitting PMMA / HDPE |
| Process | SPDT + ultra-precision molding | Precision injection molding |
| Key Performance Metric | Wavefront error | Detection uniformity |
The tighter the surface figure, the more predictable the optical path.
In both applications, it determines whether a system performs as designed — whether a laser beam remains crisp at 10 m, or an infrared sensor detects motion precisely at 12 m height.
We Help You Achieve Surface Precision
At Aubor Optoelectronics, surface figure control isn’t a single process — it’s a system:
Design simulation: Optical modeling via CODE V and LightTools to predict wavefront sensitivity.
SPDT mold fabrication: Nanometric form accuracy on master tools.
Injection molding optimization: Real-time cavity temperature and pressure control to minimize deformation.
Interferometric inspection: Verifying each surface meets figure tolerance before coating.
Through this workflow, Aubor achieves the rare combination of mass-production efficiency and precision-optics-level accuracy — enabling polymer lenses to enter domains once dominated by glass.
Conclusion
Whether it’s the clean parallelism of a laser beam or the reliable infrared capture of a Fresnel array, surface figure accuracy is the invisible boundary between a functional lens and a truly engineered optical component.
Aubor’s precision polymer optics redefine what’s possible — delivering performance once reserved for glass, with the flexibility and scalability demanded by next-generation sensors and laser systems.
