Effective freeform TIR lens designed for LEDs with high angular color uniformity

Area of Science:

• Optics and Photonics
• Solid-state Lighting
• Optical Engineering

Background:

• Color nonuniformity in LED illumination fields degrades lighting quality.
• Existing LED systems often struggle with achieving uniform light output.
• Phosphor-converted LEDs and multicolor LED arrays are widely used but susceptible to uniformity issues.

Purpose of the Study:

• To propose and analyze a novel freeform total internal reflection (TIR) lens for enhancing LED lighting uniformity.
• To address the color nonuniformity problem in illumination fields.
• To improve the angular color uniformity (ACU) for both single and multiple LED sources.

Main Methods:

• Design of a novel TIR lens comprising a freeform panel and a collimator.
• Analysis based on light pattern overlap and energy mapping.
• Evaluation of angular color uniformity (ACU) using a phosphor-converted white LED model and simulation for multicolor LED arrays.

Main Results:

• The normalized standard deviation (NSD) for angular color uniformity (ACU) decreased from 0.792 to 0.232 when integrating the freeform TIR lens with a phosphor-converted white LED.
• Theoretical analysis and simulations confirmed the lens's effectiveness in enhancing ACU for multicolor LED arrays.
• The proposed TIR lens significantly improved light uniformity for both single and multiple LED sources.

Conclusions:

• The developed freeform TIR lens effectively mitigates color nonuniformity in LED illumination.
• This solution enhances lighting quality, making it suitable for demanding applications such as entertainment and architectural lighting.
• The proposed method offers a viable approach to improving LED source uniformity across various configurations.