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Foreword: The Intelligent Revolution Starting from "Perception" When we talk about AI, the Internet of Things, and intelligent perception, we often focus on chips and algorithms. However, it is not the code that determines what a device "sees" and how much it perceives ", but the front end of the optical system. In the field of infrared perception, the seemingly inconspicuous but crucial plastic structure, the Fresnel Lens, has long been behind the evolution of a whole generation of security systems, automatic control devices, and intelligent spaces.

today, we take the Fresnel lens for PIR (passive infrared) sensing as the protagonist, and trace its technical route to explore how it completes the transition from" focused infrared "to" precise recognition "in the new era.

1. The birth of the PIR sensor and the first task of the Fresnel lens PIR (Passive Infrared) sensor principle relies on the pyroelectric material to respond to the infrared band (8-14 μm) released by the human body. However, this material itself has only a very narrow sensing area and a very weak electrical signal. Therefore, the addition of the Fresnel lens becomes crucial:

It focuses infrared signals over a wide range to the pyroelectric detector through a series of tiny concentric prism structures;

It constructs multiple "sensing windows" at the same time, allowing the sensor to "see" the target motion in multiple angles;

It is inexpensive and easy to mass-produce, making it ideal for embedded and micro-power devices.

in the 1990s, PIR lenses became an irreplaceable standard accessory in security alarms, automatic lighting, and corridor control systems.

2. From "seeing" to "recognizing": The awakening moment of PIR With the popularity of embedded processing capacity enhancement and AI edge computing, people have put forward higher requirements for PIR sensors:

is not just "someone walked by", but ** "Who is moving? In which direction? How far is the distance?"

This gave rise to algorithms such as single PIR direction and distance recognition (refer to Hirenkumar Gami, 2018) and analog signal regression modeling methods, driving PIR towards intelligence. The lens must therefore evolve:

Angle control is more accurate: avoid noise interference from heat sources and improve spatial resolution;

supports multi-focus aggregation design: adapt to the needs of machine learning signal input;

cooperates with signal algorithms: the lens pattern directly affects the recognition accuracy of neural networks.

Third, the rise of non-coaxial structures: make every corner "equal perception" The design of traditional Fresnel lenses adopts a coaxial focusing structure: that is, all infrared energy is concentrated in the center of focus. This results in strong sensing in the central area and weakened signal in the edge area - forming detection blind spots and uneven illumination problems.

recent years, a new design concept was born: non-coaxial structure (Non-coaxial Fresnel), such as the design of Vo Quang Sang team in 2024, the lens uses a rotating prism array, through asymmetric light convergence, so that the infrared energy is more uniform on the entire detection surface ssrn-5093890.

Light simulation results show:

Detection sensitivity remains uniform within 30;

Small viewing angle + short focal length + high gain The advantages are particularly prominent in the scene.

Fourth, Ober Observation: Lenses are no longer general-purpose parts, but "strategic design" Results In Aubor, we regard the design of PIR lenses as no longer a standard part selection, but a strategic process:

We believe that behind each lens, is the optimal solution of a set of objective functions.

Material selection Preferentially matches the infrared band transmittance (polymer infrared transmittance is greater than 85%);

Geometry is simulated by Zemax to ensure that the uniformity of the field of view is up to standard;

Each tooth depth and inclination are optimized for a specific band and focal length;

At the same time, according to the characteristics of the customer's perception algorithm, adjust the shape and response range of the light spot.

We never blindly use universal lenses, but design backwards with the final detection result as the goal.

About Aubor Optical Aubor Optical is a company specializing in the research and development and manufacturing of polymer optical components, specializing in small batch customization, fast iteration and high-precision simulation design. We have:

injection molding + single point diamond turning process to create free-form surfaces and microstructures;

Zemax + actual transmittance test platform, which allows simulation and actual measurement to fit together;

own mold workshop and coating production line to meet multi-band coating needs such as IR/ToF/LiDAR;

serves customers throughout Germany, Israel, North America, and has delivered more than 50 + PIR solutions.

At Ober, we believe that ** "perception ability" will be the standard of every equipment in the future **, and behind this, there are excellent lenses silently supporting