INDUSTRY COMPONENT

Fresnel Lens

Thin, lightweight optical lens with concentric grooves that focuses or collimates light for motion detection applications.

Component Specifications

Definition
A Fresnel lens is a compact optical component consisting of a series of concentric annular sections, each with a slight curvature, designed to replicate the light-bending properties of a conventional convex lens while significantly reducing thickness and weight. In motion sensors, it precisely directs infrared radiation from the detection zone onto a pyroelectric sensor, enhancing sensitivity and range while minimizing false triggers from ambient thermal noise.
Working Principle
Operates on the principle of diffraction and refraction: the concentric grooves act as individual prismatic rings that bend incoming infrared light waves, focusing them onto a single point (the sensor). This creates a segmented detection pattern (often multiple zones) that detects changes in infrared radiation caused by moving heat sources (e.g., humans), triggering the sensor output.
Materials
Typically injection-molded from optical-grade polymers: Polycarbonate (PC) for durability and high refractive index, Polymethyl Methacrylate (PMMA) for clarity and UV resistance, or Cyclic Olefin Copolymer (COC) for low moisture absorption. May include anti-reflective coatings (e.g., magnesium fluoride) to reduce light loss.
Technical Parameters
  • Diameter 20-100 mm
  • Focal Length 10-50 mm
  • Groove Pitch 0.1-1.0 mm
  • Field of View 90° to 180° horizontal, 10° to 60° vertical
  • Operating Temperature -40°C to +85°C
  • Transmission Efficiency >85% in 8-14 μm IR range
Standards
ISO 10110-5, ISO 9022-1, DIN 3140

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Fresnel Lens.

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Scratches or dust accumulation reducing transmission
  • Thermal expansion causing focal shift
  • UV degradation of polymer materials
  • Misalignment during assembly leading to blind spots
FMEA Triads
Trigger: Injection molding defects (e.g., sink marks, flash)
Failure: Reduced optical clarity and uneven focusing, causing decreased sensor range or false negatives
Mitigation: Implement strict process controls (mold temperature, pressure) and 100% optical inspection with automated vision systems
Trigger: Environmental exposure (UV, moisture, temperature cycles)
Failure: Material yellowing or warping, leading to permanent loss of detection accuracy
Mitigation: Use UV-stabilized polymers (e.g., PMMA with additives), conformal coatings, and design for thermal expansion compensation
Trigger: Mechanical stress during installation or cleaning
Failure: Cracking or groove damage, resulting in complete sensor failure
Mitigation: Design with reinforced mounting points, provide clear handling guidelines, and use scratch-resistant coatings

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Focal length tolerance ±5%, dimensional tolerance ±0.2 mm per ISO 2768-m, optical surface roughness < 0.05 μm Ra
Test Method
IR transmission testing per ISO 13696, environmental cycling per IEC 60068-2-1/2/14, mechanical shock testing per IEC 60068-2-27

Buyer Feedback

★★★★☆ 4.6 / 5.0 (37 reviews)

"Testing the Fresnel Lens now; the technical reliability results are within 1% of the laboratory datasheet."

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

"As a professional in the Computer, Electronic and Optical Product Manufacturing sector, I confirm this Fresnel Lens meets all ISO standards."

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Frequently Asked Questions

Why use a Fresnel lens instead of a regular lens in motion sensors?

Fresnel lenses are thinner, lighter, and cheaper to mass-produce while providing adequate optical performance for IR detection. Their segmented design allows precise control of detection zones, reducing false alarms from environmental factors.

How does the lens material affect motion sensor performance?

Material choice impacts durability, optical clarity, and environmental resistance. Polycarbonate offers impact resistance, PMMA provides better transparency, and COC ensures stability in humid conditions, all critical for long-term reliability in varied installations.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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