Three-Lens Projection Optics for Compact Bright Imaging
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Solution Overview
Problem
Existing projection optical systems for compact optical devices, such as portable projectors and 3D measuring devices, struggle to achieve a compact form factor while maintaining bright lens performance and high resolution.
Innovation Solution
A projection optical system comprising an aperture stop followed by three lenses with positive refractive powers, including a third lens with a convex surface closer to the projection surface, adhering to specific conditional expressions to correct aberrations and reduce system length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a projection optical system is designed to be compact with shorter total length, then the device size is reduced and portability is improved, but the lens performance becomes dimmer and resolution decreases
Solution Approach 1:
The projection optical system is divided into multiple lens units (first through fourth lens units) with different functions. The first lens unit has positive refractive power for light convergence, the second has negative refractive power for beam expansion, the third has positive refractive power for focusing, and the fourth has negative refractive power for final beam shaping. This segmentation allows each unit to be optimized for its specific function, achieving compact overall length while maintaining bright lens performance and high resolution through coordinated operation of the divided optical system.
2Length of moving object
If a projection optical system is designed to be compact with shorter total length, then the device size is reduced and portability is improved, but the resolution decreases
Solution Approach 1:
Different regions of the optical system are assigned different optical properties to optimize local functions. The first lens unit uses positive refractive power for strong light convergence, the second uses negative refractive power for beam expansion, the third uses positive refractive power for precise focusing, and the fourth uses negative refractive power for final beam shaping. This local optimization of optical quality in different system regions enables the compact design to achieve high resolution by ensuring each local region contributes optimally to the overall image quality.
3Illumination intensity
If high-luminance backlight with high power consumption is used in image display elements, then the luminance is increased, but the power consumption increases and image quality decreases
Solution Approach 1:
The patent replaces the traditional high-power backlight illumination system with self-luminous micro-LED pixel elements. Instead of using a high-luminance backlight that requires significant power consumption, each pixel is formed by individual micro-LED elements that generate their own light. This substitution of the illumination mechanism eliminates the need for high-power backlights, achieving high luminance with lower power consumption and improved image quality through direct light emission from the display elements themselves.
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 system achieves a compact design with brighter lens performance and higher resolution, effectively correcting spherical aberration, coma aberration, and distortion.
Implementation Method 1
a first lens L1 with a positive refractive power, a second lens L2 with a positive refractive power, and a third lens L3 with a positive refractive power
Data Source
AI summary
A projection optical system includes, in sequence from a projection surface: an aperture stop; a first lens with a positive refractive power; a second lens with a positive refractive power; and a third lens with a positive refractive power. The third lens have a convex surface closer to the projection surface. The projection system satisfies: 1.0<f/EPD<1.35, 1.0<(r2+r1)/(r2−r1)<1.45, and 0.2<d2/f<0.45, where f is a focal length of the overall projection optical system, EPD is an entrance pupil diameter, r1 is a radius of curvature of a surface of the first lens closer to the projection surface, r2 is a radius of curvature of a surface of the first lens closer to the image display element, and d2 is an air spacing between the first lens and the second lens on an optical axis.