Single Pixel Retinal Imaging for HMD Eye Tracking
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Solution Overview
Problem
Conventional eye tracking systems for artificial reality devices face challenges due to the size and cost constraints of optical coherence tomography (OCT) devices, making it difficult to integrate them into head-mounted displays (HMDs) like AR glasses, which require low power consumption, high accuracy, and small size.
Innovation Solution
The use of compressive sensing technologies with a digital micro-mirror device (DMD) as a spatial light modulator and multiple single pixel detectors for 3D retinal imaging, allowing for 3D reconstruction of the retina and efficient eye tracking, reducing size and cost requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OCT devices are used for eye tracking, then measurement precision is improved, but device size increases and becomes difficult to integrate into HMDs
Solution Approach 1:
The conventional OCT device is segmented into its core functional components: a light source, a single-pixel detector, and a spatial light modulator (DMD). By separating these functions and reconfiguring them in a compact arrangement, the system achieves high measurement precision without requiring the bulk of a traditional OCT device, enabling integration into HMDs.
Solution Approach 2:
The patent transitions from conventional 2D retinal imaging to 3D retinal imaging by introducing temporal dimension through sequential projection of orthogonal sinusoidal patterns. This dimensional transformation enables precise depth measurement and gaze tracking while using a compact single-pixel detector setup instead of large-area cameras.
2Measurement precision
If conventional OCT devices are used for eye tracking, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent extracts only the essential components needed for OCT functionality: a low-cost LED light source, a single-pixel photodetector, and a DMD. By eliminating unnecessary components of conventional OCT devices and using commercially available off-the-shelf parts, the system achieves medical-grade measurement precision at a fraction of the cost.
Solution Approach 2:
The system uses inexpensive, readily available components such as LED light sources and standard DMDs that can be mass-produced. These components are designed for ease of manufacturing and integration, significantly reducing the overall system cost while maintaining high measurement precision for eye tracking applications.
3Ease of operation
If HMDs are designed with small size for wearability, then ease of operation is improved, but integration of eye tracking devices becomes difficult
Solution Approach 1:
The eye tracking system is merged with the existing HMD optical architecture by integrating the DMD into the display optics and positioning the single-pixel detector within the existing optical path. This consolidation eliminates the need for separate eye tracking modules, reducing overall device complexity while maintaining wearability.
Solution Approach 2:
The DMD serves multiple functions simultaneously: it displays visual content to the user and projects measurement patterns for retinal imaging. The single-pixel detector also contributes to both the display system and eye tracking measurements. This multi-functionality reduces the number of components needed, simplifying integration into compact HMDs.
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 approach enables accurate and efficient eye tracking in HMDs, allowing for precise gaze direction detection and movement analysis while minimizing the device's size and cost, thus addressing the limitations of conventional systems.
Implementation Method 1
Each of a plurality of single pixel detectors may capture a signal (e.g., light) of the rendered content on the user's retina
Data Source
AI summary
Systems and methods for eye tracking are disclosed. The system may emit, by a digital micro-mirror device(s) (DMD), light, including binary images or grayscale images, onto an eye(s) of a user. The system may determine, by single pixel detectors, a reflection of the light from the eye(s). The system may determine, by a first single pixel detector, a first signal associated with the reflection of the light from a retina of the eye(s). The system may determine, by a second single pixel detector, a second signal associated with the reflection of light from the retina of the eye(s). The system may perform, by the DMD(s), a transformation on the first and second signals to determine a grayscale image(s) of the retina. The system may determine, by the DMD(s), a 3D shape(s) of the retina based on performing a 3D reconstruction(s) associated with pixels of the grayscale image(s) of the retina.