Femtoprojector Optical System with Nested Mirrors
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Solution Overview
Problem
Current femtoprojector optical systems face challenges in fitting inside contact lenses while providing appropriate magnification and maintaining good image quality due to size constraints and the need for realistic manufacturing processes.
Innovation Solution
The design of femtoprojector optical systems involves a compact configuration with a solid transparent substrate, a concave primary mirror, and a convex secondary mirror, along with a light baffle system using an obscuration and sidewalls to manage stray rays, optimizing parameters like mirror size, obscuration placement, and refractive indices to achieve efficient optical throughput and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical system is made compact to fit inside a contact lens, then the device size is reduced, but image quality and magnification capability deteriorate
Solution Approach 1:
The patent implements a nested mirror configuration where a secondary convex mirror is positioned within the focal length of a primary concave mirror. This nesting arrangement allows both mirrors to occupy a compact volume while maintaining their optical functions, enabling the optical system to fit inside a contact lens without sacrificing image quality or magnification capability
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning the image source, primary mirror, and secondary mirror in specific three-dimensional coordinates. The mirrors are arranged with specific curvature radii and distances that optimize the optical path within the constrained volume, transforming the problem from a two-dimensional layout to a three-dimensional optimization that achieves both compactness and image quality
2Volume of moving object
If the optical system components are miniaturized to fit in contact lens dimensions, then device size is reduced, but optical throughput and light gathering capability worsen
Solution Approach 1:
The patent optimizes critical optical parameters including mirror curvature radii (R1 for primary, R2 for secondary), mirror distances (d1 from image source to primary, d2 from primary to secondary), and aperture sizes. By carefully selecting these parameters within the miniaturized geometry, the system maximizes optical throughput and light gathering capability despite the reduced scale, ensuring sufficient brightness and image quality on the retina
3Volume of moving object
If the optical path is shortened to reduce device size, then the device becomes more compact, but depth of focus and image sharpness deteriorate
Solution Approach 1:
The patent employs curved mirror surfaces with specific radii of curvature (R1 for the primary concave mirror, R2 for the secondary convex mirror) to focus light effectively within the shortened optical path. The curvature of these mirrors compensates for the reduced path length, maintaining the ability to form sharp, focused images on the retina despite the compact dimensions of the contact lens-mounted system
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 solution enables femtoprojector optical systems to project high-quality images on the retina within the constraints of a contact lens, offering adjustable design priorities such as optical throughput, depth of focus, and reduced stray light, thus addressing the size and manufacturing challenges.
Implementation Method 1
a concave primary mirror and a convex secondary mirror
Implementation Method 2
a concave primary mirror and a convex secondary mirror
Implementation Method 3
a solid transparent substrate, a concave primary mirror
Data Source
AI summary
A variety of femtoprojector optical systems are described. Each of them can be made small enough to fit in a contact lens using plastic injection molding, diamond turning, photolithography and etching, or other techniques. Most, but not all, of the systems include a solid cylindrical transparent substrate with a curved primary mirror formed on one end and a secondary mirror formed on the other end. Any of the designs may use light blocking, light-redirecting, absorbing coatings or other types of baffle structures as needed to reduce stray light.