Luminance spreading freeform lens arrays with accurate intensity control

Area of Science:

• Optics and Photonics
• Illumination Engineering
• Visual Comfort

Background:

• Glare and visual discomfort are critical in illumination design.
• Freeform lenses offer intensity control but lack near-field luminance management, leading to potential glare from high-brightness LEDs.
• Diffusing structures reduce glare but compromise the precise control offered by freeform lenses.

Purpose of the Study:

• To propose a novel method for designing luminance-spreading freeform lens arrays.
• To achieve precise control over the resulting intensity pattern while reducing peak luminance and glare.
• To address the limitations of conventional freeform lenses in managing near-field luminance.

Main Methods:

• Development of a non-invertible mapping technique for a 2D parameter space.
• Establishing a source-target mapping where multiple incoming ray directions converge to target distribution points.
• Discussion of both continuous and discontinuous mapping cases for lens array design.

Main Results:

• A novel method for designing freeform lens arrays with controlled luminance spreading was developed.
• The proposed method allows for perfect control over the outgoing intensity distribution, optimizing glare control.
• A 7x7 discontinuous freeform lens array was designed and experimentally validated, demonstrating the method's efficacy.

Conclusions:

• The proposed method effectively designs luminance-spreading freeform lens arrays, balancing glare reduction and intensity control.
• This approach overcomes the limitations of conventional freeform lenses and diffusing structures.
• The experimental validation confirms the potential for improved visual comfort and optical performance in LED illumination systems.