HMD Optical Measurement Pupil Alignment and Dioptric Compensation
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Solution Overview
Problem
Head mounted display devices pose challenges in determining optical performance parameters due to their position sensitivity and complex configuration, which existing imaging photo-colorimeters struggle to accurately measure, especially when the position of the wearer's pupil is not accounted for.
Innovation Solution
A method that involves positioning the optical measurement device to align its entrance pupil with the wearer's pupil, using a pupil shift element to adjust the measurement device's position, and potentially employing a compensation optical element and immersion techniques to account for dioptric functions and refractive index differences, ensuring accurate optical performance parameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional imaging photo-colorimeter is used to measure head mounted display devices, then the measurement process is simple, but the measurement accuracy is poor due to position sensitivity and lack of pupil alignment
Solution Approach 1:
A pupil shift element is introduced as an intermediary component between the imaging photo-colorimeter and the head mounted display device. This element shifts the entrance pupil of the measurement device to align with the wearer's pupil position, enabling accurate optical performance measurements while maintaining a relatively simple overall system architecture.
Solution Approach 2:
The measurement system incorporates positional alignment in the pupillary dimension, shifting the entrance pupil along the optical axis to match the wearer's pupil position. This dimensional adjustment resolves the position sensitivity issue without requiring complete system redesign.
2Measurement precision
If the entrance pupil of the measurement device is shifted to align with the wearer's pupil, then measurement accuracy improves, but the positioning and configuration becomes more complex
Solution Approach 1:
The pupil shift element is designed to automatically shift the entrance pupil to the correct position based on the optical configuration of the head mounted display device. This self-adjusting mechanism reduces the need for manual positioning and complex alignment procedures, improving ease of operation while maintaining measurement precision.
3Measurement precision
If dioptric compensation elements and immersion techniques are used, then optical performance measurement accuracy is significantly improved, but the measurement process and device complexity increase
Solution Approach 1:
Dioptric compensation elements are pre-positioned in the optical path before measurement begins, and immersion media are pre-applied to optical surfaces. These preliminary actions prepare the optical system in advance, reducing the time required during actual measurement while ensuring high accuracy through proper dioptric compensation.
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 method significantly increases the accuracy of optical performance measurements by aligning the measurement device with the wearer's pupil and compensating for dioptric functions, allowing for precise characterization of head mounted display devices.
Implementation Method 1
a pupil shift element configured to shift the entrance pupil of the optical measurement device
Implementation Method 2
the optical element having a dioptric function is immerged in a medium having a refractive index deferring by less than 0.05, for example less than 0.01, from the refractive index of the optical lens having a dioptric function
Data Source
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AI summary
Method for determining an optical performance parameter of a head mounted display device adapted for a wearer, the method comprising at least: - a head mounted display device providing step, during which a head mounted display device adapted for a wearer is provided, - an optical measurement device providing step, during which an optical measurement device is provided, the optical measurement device comprises at least an entrance pupil and a sensor receiving light through the entrance pupil, - a positioning step, during which the optical measurement device and the head mounted display device are positioned so that the position of the entrance pupil of the optical measurement device corresponds to the position of the pupil of the wearer when wearing the head mounted display device, - an optical performance parameter determining step during which at least one optical performance parameter of the head mounted see-through display device is determined based on the data measured by the optical measurement device.