Folded Optical Path Fundus Imaging for Compact VR Headsets
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Solution Overview
Problem
Conventional VR devices are unable to capture retinal images due to the large size and weight of an ophthalmoscope, which compromises the compactness and lightweight requirements, and the addition of a fundus imaging system would further increase the size and reduce the field of view.
Innovation Solution
A fundus imaging system utilizing an optical path folding lens set, visible light fixation lamps, an illumination module, and an image sensor, which shares an optical path folding lens set to minimize the volume and weight by folding the optical path, allowing for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an ophthalmoscope is added into the limited space of a VR device without changing the original optical path design, then fundus imaging capability is achieved, but the device size becomes too large
Solution Approach 1:
The patent merges the ophthalmoscope functionality with the existing VR display optical path by positioning the image sensor at the location of the display device's optical imaging element. This integration allows the VR device to capture retinal images without adding a separate, bulky ophthalmoscope component, thus achieving fundus imaging capability while maintaining compact device size.
Solution Approach 2:
The optical path folding lens set serves multiple functions: it folds the optical path for the display device while simultaneously enabling the image sensor to capture retinal images. This multi-functionality allows a single optical component to fulfill both display and imaging purposes, reducing the need for additional dedicated imaging hardware and minimizing device volume.
2Volume of moving object
If the volume of the ophthalmoscope is reduced, then device compactness is improved, but the field of view is sacrificed
Solution Approach 1:
The patent employs an optical path folding lens set that introduces dimensional complexity to the optical path, allowing light to traverse a longer effective path length within a compact physical space. This enables the image sensor to capture a wide field of view (200 degrees) while maintaining a small ophthalmoscope volume, as the folding lens set effectively extends the optical path in multiple dimensions rather than requiring linear space expansion.
3Length of stationary object
If the distance between the lens and the screen is reduced in a VR device, then device compactness is improved, but the ophthalmoscope size becomes too large
Solution Approach 1:
The patent combines the ophthalmoscope optical path with the VR display optical path by positioning components at the same spatial locations. The image sensor is placed at the display device's optical imaging element location, and both systems share the same optical path folding lens set. This merging allows the ophthalmoscope to function within the reduced distance constraints of the VR device without requiring a separate, larger ophthalmoscope structure.
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 effectively captures full-fundus images without significantly increasing the volume or weight of the VR device, enabling compact and lightweight design while maintaining the field of view.
Implementation Method 1
The folding optical path not only is an important innovation of the optical system but also provides more space for the head-mounted VR devices. The folding optical path element can reduce the distance between the lens and the screen from 40-50 mm to 15-20 mm.
Implementation Method 2
The virtual reality display is used to project an imaging light through the optical path folding lens set onto the human eye to form an image on a retina of a fundus of the human eye.
Implementation Method 3
While the visible light fixation lamp is turned on, the illumination module emits an illumination light to light up the retina through the optical path folding lens set.
Implementation Method 4
The retina reflects the illumination light to form a fundus light.
Implementation Method 5
The image sensor is disposed at the first side, receiving the fundus light through the optical path folding lens set to form a sub-fundus image.
Data Source
AI summary
The invention discloses a fundus imaging system, which includes an optical path folding lens set, a virtual reality display, visible light fixation lamps, an illumination module, an image sensor, and a processor. The virtual reality display and the human eye are located on different sides of the optical path folding lens set. The virtual reality display forms images on the retina of the fundus of the human eye through the optical path folding lens set. The visible light fixation lamps are sequentially turned on to guide the eyeball of the human eye to rotate. When the visible light fixation lamp is turned on, the illumination module emits illumination light through the optical path folding lens set to illuminate the retina. The retina reflects the illumination light to form fundus light. The image sensor receives fundus light through the optical path folding lens set to form a sub-fundus image. The processor stitches all sub-fundus images into a full-fundus image and drives the virtual reality display to display the full fundus image.