Varifocal Optical System with Segmented Focus Tunable Lenses
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Solution Overview
Problem
Multi-focal display systems using focus tunable lenses suffer from artifacts related to lens inertia, such as oscillation, overshoot, and ringing, which limit the maximum frame rate achievable due to the inherent delay in reaching a steady-state optical response.
Innovation Solution
An optical system comprising multiple closely cascaded focus tunable lenses, where each lens is controlled with a specific periodic signal derived from Fourier decomposition of the desired optical step response, ensuring distinct optical responses that combine to minimize oscillation artifacts and reduce settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single focus tunable lens is used to rapidly switch focal planes, then the frame rate can be increased, but lens inertia causes oscillation artifacts and delays that limit the maximum achievable frame rate
Solution Approach 1:
The patent divides a single focus tunable lens into multiple smaller lens segments (e.g., 2x2, 3x3, or 4x4 arrays). Each segment can be independently controlled to adjust its focal length, allowing the system to achieve rapid focal plane switching while reducing the inertia-related oscillation artifacts that plague single large lenses. This segmentation enables faster response times and improved optical stability simultaneously.
Solution Approach 2:
The patent implements dynamic control of multiple lens segments where each segment's focal length can be independently and rapidly adjusted. This dynamic capability allows the system to achieve high frame rates by coordinating the focal adjustments across segments, while the distributed mass of multiple small segments reduces inertial oscillations compared to a single large lens.
2Speed
If the lens switching speed is increased to achieve higher frame rates, then productivity improves, but the oscillation artifacts and settling time increase due to lens inertia
Solution Approach 1:
By segmenting the lens into multiple smaller independently controllable units, the patent reduces the effective mass and moment of inertia of each individual lens element. This allows faster focal switching speeds while minimizing the oscillation artifacts that arise from inertial effects in larger, single-piece lenses.
Solution Approach 2:
The patent employs dynamic coordination of multiple lens segments to achieve rapid focal transitions. By controlling each segment's focal length independently and synchronizing their adjustments, the system achieves high switching speeds while the distributed segment architecture naturally dampens oscillation artifacts through reduced individual segment inertia.
Data Source
AI summary
A focus tunable optical system includes a lens assembly. The lens assembly includes: focus tunable lenses (FTLs) coaxially disposed along an optical axis, each FTL contributing to an optical power of the lens assembly; and a controller configured to control the optical power of the lens assembly by applying to each FTL a respective control signal, thereby generating a periodic optical response of the respective FTL. The optical response of each FTL is substantially different from the optical response of any other FTL of the plurality of FTLs.