From flash lenses in mobile phones to automotive LED lighting solutions, LED lenses at Shapeoptics are fully designed in-house. This article demonstrates how to design and construct a multi-cell LED lens using optical illumination design software.
Overview of the 7-Cell LED Lens
The LED lens presented here is designed to house seven LED light sources and generate a high-intensity illumination beam suitable for lighting small objects. The lens is molded from polycarbonate and is mounted directly above a 7-cell LED array.
Although the LED lens may appear complex at first glance, its geometry can be decomposed into several simple, well-defined elements:
- A primary rotationally symmetric lens body
- A central aperture removed from a lens-shaped volume
- A radial “flower” structure composed of six hexagonal cells
- Six compound parabolic concentrators (CPCs) intersecting the hexagonal cells, each with a lens-shaped aperture at the base
The overall profile indicates that the entire structure is derived from a single lens form, with additional material removed through Boolean operations.
Parametric Design Strategy
To ensure flexibility and scalability, the 7-cell LED lens is designed as a fully parametric model. Before starting, it is essential to identify which dimensions must be parameterized:
- Overall lens thickness
- Overall lens diameter
- Gap and cut dimensions defined using a constant ratio,
diamRatio
The diamRatio value is derived directly from the original optical and mechanical specifications. All subsequent geometry references these parameters, allowing the lens to be resized or optimized without redefining the geometry.
Step 1: Design the Main Lens
The main body of the LED lens is created first. After generating the primary lens surface, a secondary lens volume is created and subtracted to form the central aperture.
To accurately position this secondary lens relative to the curved front surface of the primary lens, the RAY command is used. This command calculates the intersection point of a ray with the lens surface, returning positional values that behave like variables. These values can be used directly in mathematical expressions to ensure precise alignment along the +Z axis—an operation that would otherwise require complex manual calculations.
Step 2: Design the Polygon (Honeycomb) Structure
The radial polygon structure consists of six hexagonal cells arranged in a honeycomb pattern. Each hexagon is defined using user-specified parameters, ensuring the geometry remains fully parametric.
To generate the honeycomb layout:
- A base hexagonal polygon is created and offset from the Z-axis.
- A RING command is applied to replicate the polygon around the optical axis.
- A copied polygon is positioned above the base geometry using offsets calculated via the RAY command.
- All polygon elements are merged using a UNION operation.
This approach ensures accurate placement and consistent geometry without manual trial-and-error.
Step 3: Design the CPC Array
The next stage is the creation of the 7-cell CPC array, which sits behind the polygon structure and shapes the emitted LED light.
Each CPC is:
- Defined parametrically using the same global parameters
- Drilled with a lens-shaped aperture at the rear surface
- Positioned using offsets derived from earlier RAY calculations
A single CPC object is duplicated, offset along the Y-axis, and then replicated using the RING command to form the full 7-cell array. The CPCs are then merged into a single structure for further Boolean operations.
Step 4: Finalize the LED Lens Array
In the final step, the polygon structure and CPC array are combined using Boolean overlap operations to create a single solid object, named finalLED.
The completed LED lens can be:
- Exported as CAD files (.IGS, .STEP, .STL, .SAT)
- Saved as .ZSO or .ZPO files for further ray-tracing optimization and illumination analysis
This enables seamless integration into both mechanical design workflows and optical performance validation.
Conclusion
By breaking a complex LED lens into simple, parametric components and leveraging ray-based positioning tools, highly sophisticated multi-cell LED optics can be designed efficiently, accurately, and repeatably. This approach significantly reduces development time while maintaining full control over optical performance.
Reference Source
- Zemax Optical Design Program User’s Guide, Zemax Development Corporation
- The design file used in this article is attached as shown. Design LED Lens Array