AR Optical Lens Layout for High-Throughput Compact Imaging
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Solution Overview
Problem
The challenge in developing augmented reality devices is to create optical systems that offer high resolution, large relative aperture, and miniaturization.
Innovation Solution
An optical system comprising a stop, a lens group with specific focal powers, and a display unit, where the lens group consists of four lenses: a first lens with positive focal power, a second lens with positive focal power, a third lens with negative focal power, and a fourth lens with positive focal power, with the display unit having a maximum imaging circle diameter less than the diameter of the stop, optimizing focal lengths and air gaps to enhance light throughput and reduce system weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the optical system uses a conventional lens configuration, then the structure is simple, but the light throughput is insufficient and image resolution is poor
Solution Approach 1:
The optical system divides the lens group into four distinct lenses (first lens with positive focal power, second lens with positive focal power, third lens with negative focal power, and fourth lens with positive focal power) arranged in sequence. This segmentation allows each lens to contribute differently to light manipulation, collectively achieving high light throughput and image resolution while managing system complexity through modular design
Solution Approach 2:
Each lens in the group is assigned specific focal power characteristics (positive or negative) to optimize local optical functions. The first and second lenses have positive focal power for converging light, the third lens has negative focal power for diverging light to correct aberrations, and the fourth lens has positive focal power for final focusing. This local differentiation of optical properties enables the system to achieve superior light throughput and image resolution
2Measurement precision
If the optical system is designed for high resolution and large relative aperture, then image quality improves, but the system weight and volume increase
Solution Approach 1:
The optical system optimizes specific parameters including the focal powers of individual lenses, the spacing between lenses (with the air gap between third and fourth lenses accounting for 23% to 25% of total optical length), and the relationship between display unit imaging circle diameter and stop diameter. These parameter optimizations enable high image resolution and large relative aperture while controlling system weight through efficient optical design
3Area of stationary object
If the display unit imaging circle diameter is increased, then the field of view expands, but the light throughput decreases
Solution Approach 1:
Instead of increasing the imaging circle diameter to expand field of view (which would reduce light throughput), the patent inverts the approach by making the stop diameter larger than the maximum imaging circle diameter of the display unit. This reversal of the conventional design relationship allows the stop to be the limiting factor rather than the imaging circle, thereby maintaining large light throughput while achieving adequate field of view through the optimized lens group configuration
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 enhances light throughput, improves image resolution, and reduces the weight and volume of the optical system, thereby enhancing the user experience of augmented reality devices.
Implementation Method 1
a lens group, and a display unit; the lens group sequentially includes from the object side to the image side: a first lens, a second lens, a third lens, and a fourth lens; wherein the first lens, the second lens and the fourth lens have positive focal power, and the third lens has negative focal power
Data Source
AI summary
Disclosed are an optical system and an augmented reality device. The optical system comprises sequentially from an object side to an image side: a stop, a lens group, and a display unit; the lens group comprises sequentially from the object side to the image side: a first lens, a second lens, a third lens, and a fourth lens; wherein each of the first lens, the second lens and the fourth lens has positive focal power, and the third lens has negative focal power; wherein the display unit has a maximum imaging circle diameter less than a diameter of the stop.