Wavelength-Compensated Scanned Beam Source for Uniform Exit Pupil
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Solution Overview
Problem
Scanned beam displays face challenges in maintaining image uniformity across the exit pupil due to wavelength-dependent behavior of optical elements, leading to varying diffraction and refraction effects that affect the visibility of images, especially in applications with relative movement between the display and the viewer.
Innovation Solution
The solution involves combining beams of different wavelengths into a composite beam, which is then shaped and compensated using wavelength-dependent beam shaping optics and clipping apertures to ensure each wavelength component has proportional diameters and numerical apertures, thereby maintaining uniformity across the exit pupil by compensating for diffraction and refraction effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single composite beam is used for multiple wavelengths, then device complexity is reduced, but image uniformity deteriorates due to wavelength-dependent diffraction and refraction
Solution Approach 1:
The patent applies local quality by making the beam shaping optical element wavelength-dependent, where different regions of the optical element are designed to shape different wavelength components to specific diameters proportional to their wavelengths. This allows each wavelength to be locally optimized for uniform image quality across the exit pupil.
Solution Approach 2:
The patent changes the parameter of beam diameter for different wavelengths, setting the diameter of each wavelength component proportional to its wavelength (blue smallest, red largest). This parameter adjustment compensates for wavelength-dependent diffraction and refraction effects, maintaining image uniformity.
2Area of stationary object
If beam diameter is increased for all wavelengths, then exit pupil coverage is improved, but diffraction effects worsen and image uniformity deteriorates
Solution Approach 1:
Instead of uniformly increasing beam diameter, the patent applies local quality by setting different beam diameters for different wavelengths. Each wavelength component is shaped to a specific diameter proportional to its wavelength, optimizing both exit pupil coverage and minimizing diffraction effects for each wavelength.
Solution Approach 2:
The patent introduces asymmetry in beam dimensions by making beam diameter wavelength-dependent rather than uniform. This asymmetric approach, where blue light has smaller diameter and red light has larger diameter, compensates for wavelength-dependent optical effects and maintains image uniformity.
3Manufacturing precision
If wavelength-dependent beam shaping is applied, then image uniformity is improved, but device complexity increases due to additional optical elements
Solution Approach 1:
The patent applies universality by designing a single beam shaping optical element that performs multiple functions: it shapes all wavelength components simultaneously, compensates for wavelength-dependent effects, and maintains image uniformity across the entire visible spectrum, eliminating the need for separate optical paths for each wavelength.
Solution Approach 2:
The patent merges the shaping of multiple wavelength components into a single composite beam that passes through one beam shaping optical element. This combines what could be separate optical paths into a unified system, reducing overall device complexity while achieving wavelength-dependent beam shaping.
4Ease of operation
If relative movement between display and viewer is allowed, then ease of operation is improved, but image visibility deteriorates due to limited exit pupil
Solution Approach 1:
The patent applies segmentation by treating the composite beam as composed of distinct wavelength components (blue, green, red) that are shaped independently to different diameters. This segmentation allows each wavelength to be optimized for uniform distribution across the exit pupil, expanding the effective viewing region and maintaining image visibility with viewer movement.
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 approach ensures that the image uniformity is maintained across the viewing region, regardless of the viewer's position, by adjusting the beam diameters and numerical apertures of different wavelength components to achieve equal fill factors and reduce color fringing, resulting in a consistent and high-quality image projection.
Implementation Method 1
wavelength-dependent behavior of at least one other optical element... compensate for wavelength-dependent behavior... varying amounts of diffraction or refraction experienced by the wavelength components
Implementation Method 2
wavelength-dependent behavior of at least one other optical element... compensate for wavelength-dependent behavior... varying amounts of diffraction or refraction experienced by the wavelength components
Implementation Method 3
a wavelength-dependent clipping aperture may be formed from a polarization-dependent clipping aperture... The polarization dependency of the clipping aperture may be configured to provide differing diameters for the polarization states
Data Source
AI summary
According to embodiments, scanned beam source may include a first beam shaping optical element aligned to receive a composite beam of light carrying a plurality of wavelength components and a second beam shaping optical element aligned to receive the composite beam of light from the first beam shaping optical element and configured to modify the first plurality of wavelength components of the composite beam to a plurality of dimensions proportional to wavelength. The first beam shaping optic may be, for example, a top-hat converter. The second beam-shaping optic may be, for example, a polarization-sensitive clipping aperture, a wavelength-dependent clipping aperture, and/or an achromatic corrector.