Variable Optical Attenuator Using Tunable Lenses
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Solution Overview
Problem
Conventional illumination control systems in display devices, such as head-mounted displays and heads-up displays, face limitations in dynamic range and contrast ratio when adjusting brightness and intensity in varying ambient light conditions, particularly failing to provide fine-grain control and maintaining spectral power distribution.
Innovation Solution
A variable optical attenuator system comprising a tunable aperture sandwiched between two coaxially aligned tunable lenses, which apply varying optical power to control light attenuation, allowing for dynamic adjustment of illumination intensity while maintaining collimated light characteristics, utilizing flexible glass membranes, liquid crystals, or immiscible fluids for optical surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional illumination control systems adjust brightness in varying ambient light conditions, then display brightness is maintained, but dynamic range and contrast ratio are limited
Solution Approach 1:
The patent employs two tunable lenses with variable optical power that can be dynamically adjusted to control light divergence and convergence. This dynamic adjustment enables continuous variation of attenuation levels, providing fine-grain control over illumination intensity and expanding the system's dynamic range across varying ambient light conditions.
Solution Approach 2:
The system changes the optical power parameter of the tunable lenses to control light attenuation. By varying the focal length and optical power of the lenses, the system achieves continuous adjustment of illumination intensity with high contrast ratio, overcoming the limited dynamic range of conventional fixed-parameter illumination control systems.
2Illumination intensity
If illumination intensity is adjusted in conventional systems, then brightness control is achieved, but fine-grain control and spectral power distribution are compromised
Solution Approach 1:
The tunable lenses provide continuous, dynamic adjustment of optical power rather than discrete steps, enabling fine-grain control of light attenuation. This continuous variability allows precise control of illumination intensity while maintaining spectral power distribution characteristics.
3Illumination intensity
If aperture is used for light attenuation, then intensity control is achieved, but contrast ratio and compact form factor are compromised
Solution Approach 1:
The system merges the aperture structure with two tunable lenses into a single integrated variable optical attenuator assembly. This combination achieves high contrast ratio through controlled light clipping while maintaining a compact form factor by eliminating the need for separate attenuation components.
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 provides high contrast ratio and fine-grain control over illumination intensity, enabling effective brightness adjustment in diverse ambient conditions while maintaining spectral integrity, thus enhancing user comfort and display intelligibility.
Implementation Method 1
The controller operates the first tunable lens to apply optical power to the light from the illumination source to cause it to be divergent at the aperture structure so that a portion of the light is clipped at the structure and not passed through the aperture
Implementation Method 2
The controller operates the second tunable lens to compensate for changes in light state at the first tunable lens. Thus, for example, the first and second tunable lenses can apply opposite optical power so that collimated light from the illumination source which enters the first tunable lens may exit the second tunable lens in the same collimated state
Implementation Method 3
The optical surfaces can comprise flexible glass membranes, liquid crystals, interfaces between immiscible fluids, or combinations thereof
Implementation Method 4
The optical surfaces can comprise flexible glass membranes, liquid crystals, interfaces between immiscible fluids, or combinations thereof
Data Source
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AI summary
Variable attenuation of an illumination source is provided by an aperture (i.e., an opening in a structure through which light passes) that is sandwiched between two tunable lenses that are configured to apply varying amounts of optical power. A controller operates the first tunable lens to apply optical power to the light to be divergent at the aperture structure so that a portion of the light is clipped. Varying the applied optical power at the first tunable lens can increase or decrease divergence at the aperture structure to thereby increase or decrease clipping and the attenuation of the light. The controller operates the second tunable lens to compensate for changes in light state at the first tunable lens by applying opposite optical power so that collimated light from the illumination source which enters the first tunable lens may exit the second tunable lens in the same collimated state.