Microlens Beam Combining for HDR Projection With Low Speckle
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Solution Overview
Problem
Conventional projectors face challenges in achieving high dynamic range (HDR) due to light leakage, inefficient light throughput, and speckle formation, particularly when combining light beams with different angular characteristics, leading to brightness and color artifacts, and laser safety hazards.
Innovation Solution
A system and method that combines a base illumination light beam with a collimated light beam using a micro-lens array and a transmissive-reflective means, such as a pinhole mirror, to control étendue, reduce vignetting, and introduce angular diversity, thereby minimizing speckle formation and laser safety risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a cascade of two light valves is used to reduce light leakage, then black level is improved, but peak brightness is reduced by up to 50%
Solution Approach 1:
The invention divides the light modulation function into two separate stages: a first light valve for binary amplitude modulation (blocking or passing light) and a second light valve for continuous amplitude modulation. This segmentation allows each component to perform its specialized function efficiently, avoiding the need for a cascade arrangement where both valves would block light sequentially.
Solution Approach 2:
The invention introduces an intermediate optical system between the two light valves that includes a beam splitter, a first imaging system, a second imaging system, and a combining beam splitter. This intermediary optical train redirects and combines light beams from the two different modulation stages, allowing the modulated light from the first valve to be properly integrated with the light from the second valve without direct cascading.
2Illumination intensity
If light steering is used to deliver darker black and lighter white, then contrast ratio is improved, but device complexity increases
Solution Approach 1:
The invention merges the light paths from two separate illumination sources (first and second light sources) through a combining beam splitter to create a single combined light beam that illuminates the second light valve. This combining approach allows the system to achieve HDR performance by integrating both direct light (for black levels) and steered light (for highlights) without requiring separate projection paths.
Solution Approach 2:
The first light valve serves multiple functions: it performs binary amplitude modulation to create dark regions (black levels) while also serving as a beam steering element that directs light to the intermediate optical system. This multi-functionality reduces the need for additional dedicated components for light steering, thereby managing device complexity.
3Illumination intensity
If dual projector systems are used to achieve HDR, then dynamic range is improved, but image alignment precision deteriorates
Solution Approach 1:
The invention merges the light paths from two separate illumination sources through a combining beam splitter to create a single combined light beam that illuminates the second light valve. This combining approach allows the system to achieve HDR performance by integrating both direct light (for black levels) and steered light (for highlights) without requiring separate projection paths.
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
The system effectively diffuses and blends the collimated beam with the illumination beam without expanding the étendue, reducing light losses and speckle, while maintaining precise alignment and modulation of both beams independently.
Implementation Method 1
A system and method that combines a base illumination light beam with a collimated light beam using a micro-lens array and a transmissive-reflective means
Implementation Method 2
combines a base illumination light beam with a collimated light beam using a micro-lens array and a transmissive-reflective means
Implementation Method 3
combines a base illumination light beam with a collimated light beam using a micro-lens array and a transmissive-reflective means
Implementation Method 4
An approach where the first modulator is based on a phase modulating LCOS device
Implementation Method 5
The first modulator can be based on a phase modulating LCOS device
Implementation Method 6
an analogue MEMS (Micro Electro Mechanical Systems) device is used as the first modulator
Data Source
Figure 1~2
Figure 3a~3b
Figure 4
AI summary
A system and method are described for projecting images comprising an illumination light beam (21, emitted by source 20) and a collimated light beam (36, emitted by laser source 35). The two light beams are combined into one light beam via a microlens array (30) combined with a pinhole matrix located in the focal plane of the micorlens array. The collimated beam is transmitted through this array and the base beam is reflected therefrom.