PAB-Lens System Expands Light Beam Angular Coverage

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Solution Overview

Problem

Existing non-mechanical beam steering technologies, such as those using spatial light modulators (SLMs) and phase-delay arrays (PDAs), are limited in their ability to steer a beam of light beyond a few degrees, making them inadequate for applications requiring larger angular deviations, such as free space optical telecommunications and LIDAR.

Innovation Solution

The implementation of a PAB-lens system, which combines a lens element with holographic layers on its optical surfaces, allows for the redirection of a collimated light beam by up to 4π steradians while maintaining collimation, using a phase-type scanning light modulator and strategically placing holographic layers to avoid total internal reflection and increase the diffraction angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spatial light modulator or phase-delay array is used for beam steering, then mechanical failure is avoided and the system is faster and more compact, but the maximum beam deviation angle is limited to about 5.5 degrees

Engineering Contradiction:

Improvemechanical failure resistanceVSAvoidbeam deviation angle range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The optical system is segmented into multiple functional components: a spatial light modulator for phase modulation, a lens for focusing, and a reflective surface (mirror or retroreflector) for angular amplification. Each component performs a specific function, and their combination enables beam deviation angles far exceeding the capabilities of any single component alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A lens is introduced as an intermediary element between the spatial light modulator and the reflective surface. This lens focuses the modulated beam onto the reflective surface, enabling the system to achieve large angular deviations while maintaining the non-mechanical advantages of the SLM. The lens acts as a mediator that transforms the small angular changes from the SLM into large angular deviations at the output.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If blazed gratings are used to increase diffraction efficiency, then the diffraction efficiency increases, but the spatial density of grating rulings must increase, reducing the diffraction angle

Engineering Contradiction:

Improvediffraction efficiencyVSAvoiddiffraction angle

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The beam steering function is segmented between the spatial light modulator (which provides phase modulation with high efficiency) and the reflective surface (which provides angular amplification). This segmentation allows each component to operate at its optimal performance point without the trade-off inherent in using blazed gratings alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical grating structure with a combination of phase modulation (electronic/optical control) and geometric reflection. This substitution eliminates the need for physical grating rulings and their associated trade-offs between efficiency and angle, allowing independent optimization of both parameters through electronic control of the SLM phase patterns.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively expands the angular coverage of beam steering beyond the limitations of traditional SLM/PDA systems, enabling the redirection of light beams by up to 4π steradians, thereby enhancing the applicability in advanced optical communication and LIDAR systems.

Implementation Method 1

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

using a phase-type scanning light modulator and strategically placing holographic layers to avoid total internal reflection and increase the diffraction angle

Methodology Applied

Scientific EffectPhase modulation: Phase Modulation

Implementation Method 4

using a phase-type scanning light modulator and strategically placing holographic layers to avoid total internal reflection and increase the diffraction angle

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS12044948B2Expansion of angular distribution of a light beam to cover a solid angle of up to 4pi steradians

Publication Date: 2024.07.23 THE ARIZONA BOARD OF REGENTS ON BEHALF OF THE UNIV OF ARIZONA

AI summary

A static optical system, for use with a phase modulator, configured to expand (at least up to 4π steradian) the solid angle range within which a light beam can propagate from and after interacting with the phase modulator. A specific embodiment includes a first holographic disperser (a layer with at least one hologram recorded therein, a lens element configured as a large spherical cap, and a second holographic disperser (a layer with at least one hologram in it) shaped as a shell against second optical surface of the lens element. Holographic dispersers carry/contain angularly-selective multiplexed volume holograms.