Varifocal Optical Element for High-Resolution Projection
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Solution Overview
Problem
Image display devices face challenges in maintaining high-resolution images across an entire screen due to variations in optical path length and beam waist position, leading to decreased resolution at certain angles, and existing varifocal lenses are large and power-intensive, making them difficult to miniaturize while maintaining image quality.
Innovation Solution
A varifocal optical element comprising a first and second lens with parallel optical axes, a reflector to direct the light beam between them, and an actuator to adjust the focal length based on scanning angles, allowing precise control of the beam waist position and reducing actuator displacement requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a varifocal lens is used to maintain beam waist position at projection surface for all scanning angles, then image resolution is improved across the entire screen, but device size and power consumption increase
Solution Approach 1:
The varifocal lens is divided into two separate lenses (first lens and second lens) with parallel optical axes arranged side by side. This segmentation allows each lens to handle specific portions of the beam path, reducing the complexity and size requirements compared to a single monolithic varifocal lens while maintaining the ability to adjust focal length for different scanning angles.
Solution Approach 2:
The patent introduces a reflector that directs the light beam between the two lenses, adding a spatial dimension to the optical path. This dimensional arrangement allows the system to achieve variable focal length functionality through geometric configuration rather than requiring a complex single-lens mechanism, thereby reducing overall device volume.
2Manufacturing precision
If a varifocal lens is used to maintain beam waist position at projection surface for all scanning angles, then image resolution is improved across the entire screen, but power consumption increases
Solution Approach 1:
By segmenting the varifocal lens into two separate lenses with parallel optical axes, the system reduces the total number of moving parts and the complexity of the focusing mechanism. This segmentation leads to lower power consumption while maintaining the capability to adjust focal length for different scanning angles, as each lens can be independently optimized with reduced actuator requirements.
3Area of stationary object
If scanning angle increases, then coverage area is improved, but beam diameter increases causing resolution decrease
Solution Approach 1:
The patent implements a dynamic focusing system where the focal length of the optical element is adjusted based on the scanning angle. As the scanning angle changes, the system dynamically modifies the beam waist position to maintain optimal focus at the projection surface. This dynamic adjustment prevents beam diameter expansion at high scanning angles, thereby maintaining image resolution across the entire screen coverage area.
Solution Approach 2:
The system incorporates feedback control where the scanning angle information is used to adjust the focal length of the optical element. This feedback mechanism ensures that as the scanning angle increases to cover more area, the system automatically compensates by adjusting focus to maintain consistent beam diameter and resolution across all scanned positions.
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 high-resolution and high-quality image display on the entire screen while minimizing the size and power consumption of the image display device by accurately positioning the beam waist and reducing actuator displacement, thus improving response performance and image quality.
Implementation Method 1
condenser lens 122 that condenses a laser beam emitted from light source 121 on projection surface 124
Implementation Method 2
scanning mirror 123 that scans projection surface 124 with the laser beam condensed by condenser lens 122
Implementation Method 3
if a varifocal lens is used as condenser lens 122 and the focal length of the varifocal lens is controlled based on scanning angle θ such that the beam waist is positioned at projection surface 124
Data Source
AI summary
An image display device may include a varifocal optical element that condenses a light beam emitted from a light source and scans a projection surface with the light beam from the varifocal optical element. The varifocal optical element may include lenses located side by side in a direction orthogonal to their optical axes that are in parallel with each other; an orthogonal plane mirror that reflects the beam that passes through one of the lens to the other lens; and an actuator that moves the orthogonal plane mirror in parallel along the optical axes of the lenses. The displacement of the actuator may be controlled based on the scanning angle.