Tilted Powered Microlens Array for Laser Scintillation Reduction
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Solution Overview
Problem
Optical systems, such as head-mounted displays and semi-active laser systems, face challenges in achieving precise focusing and reducing laser scintillation across a large field of view, leading to issues like requiring costly optics and scintillation problems.
Innovation Solution
The use of a microlens array with powered microlens elements that tilt and collimate light, allowing for individual adjustment of wavefronts to create a combined light spot with overlapping output from multiple microlens elements, which can be applied in displays and laser guidance systems to achieve desired focusing and reduce scintillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optics are used to direct and collimate light in head-mounted displays, then precise focusing is achieved, but the system becomes costly and complex
Solution Approach 1:
The patent divides the optical system into multiple microlens elements, each independently controlling light from specific light-emitting elements. This segmentation allows each microlens to be simple in design while the array collectively achieves precise focusing and collimation, reducing overall system complexity compared to a single complex optical train
Solution Approach 2:
Each microlens element is designed with specific optical properties tailored to its position in the array, allowing local optimization of light control. This enables precise focusing and collimation at each location without requiring the entire optical system to be complex, as each element performs its function independently
2Device complexity
If a single set of optics is used to image the entire display, then the system is simplified, but the ability to focus on both near and far-field objects is compromised
Solution Approach 1:
The microlens array enables dynamic control of light paths by adjusting the tilt and optical power of individual microlens elements. This allows the system to adaptively focus light from different light-emitting elements at different distances, enabling both near-field and far-field focusing without changing the physical optics, thus maintaining simplicity while achieving versatility
3Area of stationary object
If laser light is directed across a large field of view in semi-active laser systems, then coverage is improved, but laser scintillation increases
Solution Approach 1:
The patent segments the laser beam into multiple smaller beams by using an array of microlens elements. Each microlens creates a separate light path, which reduces the coherence effects that cause scintillation. This segmentation maintains the overall field of view coverage while distributing the laser energy across multiple independent paths, thereby reducing scintillation intensity
Solution Approach 2:
The microlens array changes the spatial distribution and coherence parameters of the laser beam. By controlling the tilt and optical power of each microlens, the system can adjust the beam characteristics to reduce scintillation while maintaining coverage, effectively changing the parameters of laser light propagation
4Object-generated harmful factors
If a diffuser is placed in front of the optical train to limit scintillation, then scintillation is reduced, but the optical system becomes more complex and less efficient
Solution Approach 1:
The patent extracts the scintillation-reducing function from a separate diffuser element and integrates it directly into the microlens array structure. The microlens elements themselves perform the function of breaking up coherent light paths, eliminating the need for a separate diffuser and reducing overall system complexity while maintaining scintillation reduction
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 enables users to focus on both near and far-field objects with a single eye focus, reduces scintillation in laser guidance systems, and provides an inexpensive method for displaying information in head-mounted displays, while maintaining clear and aberration-free images.
Implementation Method 1
a plurality of microlens elements having optical power, operatively coupled to the light-emitting device such that the microlens elements individually differently tilt wavefronts of light emitted by different of the light-emitting elements
Implementation Method 2
The microlens elements each tilt and shift focus of portions of the reflected light to produce a combined light spot with output light from the individual microlens elements overlapping
Data Source
AI summary
A microlens array includes plural powered microlenses or microlens elements for tilting different light-emitting elements or portions of a light-emitting device. Each microlens or microlens element both has optical power, and adjusts the tilt of the wavefront so that in combination the individual microlenses act like a more complex multiple-element optic where each element shifts light from only a portion of the light-emitting device. Such an optical device may be incorporated into eyewear for projecting subtitles or other information above or below a far-away image, such as on a movie screen. Another potential use of the microlens array is for use in a heads-up display. Still another potential use for the microlens array to provide soft focusing of emitted laser light to achieve a target light spot of a desired diameter.