XR Iris Imaging Optics for Stray Light and Motion Blur
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Solution Overview
Problem
The integration of eye/iris imaging configuration in ultra-short focus optical paths for VR head-mounted displays is challenged by complex stray light interference, specular reflection from diopter glasses, and rapid eyeball rotation causing image blur, which affect image quality and recognition rates.
Innovation Solution
A biometric system for XR head-mounted displays is designed with an imaging optical unit, illumination optical unit, and control unit, utilizing angular conversion optical elements, metasurface lenses, and polarization control to optimize eye/iris imaging, improve image quality, and enhance recognition rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an ultra-short focus optical path is used in VR head-mounted display, then the device compactness is improved, but the integration of eye/iris imaging configuration becomes more difficult
Solution Approach 1:
The patent combines the eye/iris imaging optical system with the VR head-mounted display optical system into a unified integrated configuration. The imaging optical unit, illumination optical unit, and display optical unit share common optical paths and structural elements, allowing the biometric function to be embedded within the existing compact VR device architecture without requiring separate dedicated imaging systems.
Solution Approach 2:
The optical components in the system serve multiple functions simultaneously. The imaging optical unit captures both VR display content and eye/iris images through the same optical path. The illumination optical unit provides both display illumination and eye/iris imaging illumination. This multi-functionality reduces the overall component count and maintains compactness while enabling integrated biometric capabilities.
2Illumination intensity
If AR head-mounted form is used, then the transparency to exterior environment is improved, but the stray light interference in outdoor environment increases
Solution Approach 1:
The patent utilizes polarization properties of light to convert the harmful effect of stray light and specular reflections into useful information. By implementing polarization control in the imaging optical unit, the system can distinguish between desired eye/iris reflected light and unwanted stray light based on their different polarization states, thereby improving image quality in high-transparency AR configurations.
Solution Approach 2:
The system changes the polarization parameter of the illumination and imaging processes to optimize performance. By controlling the polarization state of the illumination light and matching it with polarization-sensitive detection in the imaging unit, the system enhances contrast and reduces the impact of unpolarized or differently polarized stray light from the outdoor environment.
3Ease of operation
If various optical power/diopter curved surface glasses are worn, then the user comfort is improved, but the specular reflection light interference on eye/iris image quality increases
Solution Approach 1:
The patent introduces polarization control as an intermediary mechanism between the illumination source and the imaging detector. The polarization controller acts as a selective filter that allows the desired eye/iris reflected light to pass through while blocking or attenuating the specular reflection light from external glasses. This intermediary polarization filtering preserves user comfort with corrective glasses while maintaining image quality for biometric authentication.
4Speed
If rapid eyeball rotation is captured, then the dynamic range is improved, but the eyeball movement blur affecting image quality increases
Solution Approach 1:
The system performs preliminary actions by pre-positioning the illumination optical unit and imaging optical unit to capture the eye/iris region before rapid movement occurs. The synchronized operation of illumination and imaging units ensures that light is already directed onto the target area and the sensor is ready to capture the image, minimizing motion blur during the actual rapid eyeball rotation event.
Solution Approach 2:
The patent implements periodic or pulsed illumination and imaging cycles that are synchronized with the expected timing of eye movements. By using brief, intense illumination pulses followed immediately by image capture, the system freezes the motion of rapidly moving eyeballs, reducing motion blur while still capturing the full dynamic range of eye movements for biometric analysis.
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 reduces interference from stray and specular reflections and blurs caused by rapid eyeball movement, achieving improved image quality and recognition rates for eye/iris imaging in challenging environments.
Implementation Method 1
an angular conversion optical element is configured to convert an angular range of incidence into a corresponding angular range of emergence within a predetermined imaging field of view
Implementation Method 2
an imaging optical unit, a illumination optical unit, and an imaging control unit, the imaging optical unit is configured to image near-infrared incident light of an eye/iris
Implementation Method 3
utilizing angular conversion optical elements, metasurface lenses, and polarization control to optimize eye/iris imaging
Data Source
AI summary
The biometric system for an extended reality head-mounted device, comprising: an imaging optical unit, a illumination optical unit, and an imaging control unit, the imaging optical unit is configured to image near-infrared incident light of an eye/iris, the illumination optical unit is configured to emit related near-infrared light for illuminating the eye/iris, and the imaging control unit is configured to control the eye/iris imaging optical unit and the near-infrared illumination optical unit to generate an eye/iris image in a joint imaging mode.