Flat-field correction (FFC) is essential for addressing relative illuminance roll-off in optical imaging systems, a calibration process that requires capturing an image of a uniform light source. In imaging systems capable of mimicking or measuring SPH, CYL, AXIS, such as those used for eye prescriptions, the number of images required to collect for FFC increases with each lens adjustment. We propose a numerical method that uses a few core images to synthesize FFC images for various configurations, reducing data requirements substantially. This method was validated on two imaging systems with differing optical alignment quality, achieving relative illuminance falloff of less than 2% with only 5% the amount of the original data.
This paper discusses a methodology based on the free space depth measurement scheme facilitating the allocation of the real optical axis relative to the newly established datum resulting from the presence of a mechanical attachment. The methodology only requires depth data in one direction and the DUT does not need to be perfectly aligned with the sensor. This, in turn, enables an in-situ optical alignment capability in the mass-production environment, where position accuracy and repeatability are critical.
This paper discusses a high sensitivity quantitative method to efficiently detect the defect existence and allocate the impurity down to single micron level. This methodology by nature only enhances the defects within the signal path no matter on the optics surface, in the coating or inside the glass material, which fundamentally helps on high contrast optics like the AR/VR metrology lens which mimics human eye’s sensitivity, or deep space observation optics or biology imaging system.
This paper reviews an inspiration model for young talents in MLOptic corp.’s industrial education outreach program. With proper mindset training to focus on the end delivery through milestone-based essential necessaries allocation, proactively self-learning and logistic thinking capabilities can be greatly magnified independent of education level and age, significantly boosts the courage to explore unknown technical or non-technical challenges, promotes confidence and desires to self-grow into a technical expert. The logic to get things done naturally plants the seed of leadership and grows efficiently through more teamwork practice. An example was described to support this model.
This paper first reviews the practical optical calibration constrains of the optical metrology equipment Periscope, which measures AR/VR glass’s binocular disparity by providing the numerical measurement of non-parallelism between two eyes’ optical axes. A self-adaptive calibration methodology with close loop feedback to track on the calibration tool’s accuracy is proposed to precisely calibrate the parallelism of the periscope’s two optical sensing channels and efficiently verify this parameter periodically with consistency over time or instruments. A few implementation schemes, including a passive target, an active selfreferenced target, and two different sensitivity enhanced targets are discussed in depth to compare the performance contributors: accuracy, repeatability, and system complexity, which leads to the recommendations for different application scenarios. Beyond the AR/VR disparity measurement a potential application based on the same methodology is introduced to evaluate the precision motion system’s accuracy and tolerance.
MTF tests, one of the most important optical metrology tasks for AR/MR glasses, analyze the DUT’s (Device Under Test) optical resolution to provide quantitative feedback for design verification and manufacturing process control. Due to the immaturity of the whole design/fabrication technical chain, current diffractive AR glasses show strong angular resolution non-uniformity across the FOV, and the measurement’s angular accuracy and consistency significantly impact the test repeatability and reproducibility. This paper presents a novel optical calibration apparatus to enable absolute angular alignment/verification, which can be implemented with a small volume and easily fit into the metrology equipment.
To achieve user immersion experience and wearing comfort, AR/VR glass designer targeting general consumer market strives hard for larger FOV and smaller form factor. These ultimate goals cause challenges for mass production metrology due to geometrical conflicts and test cost inefficiency. Two imaging system designs are reviewed in this paper. Both resolve above practical issues of AR/VR glass optical resolution test by shifting the complexity of the lens design to a novel optical coupler. This coupler smartly remaps discrete angular field points onto a detector with minimum spatial gap. Proposed methodologies significantly decrease the metrology equipment cost for mass production.
Optical metrology provides direct feedback for AR/VR/MR design verification and manufacturability evaluation by imitating the human eye’s optical properties of resolution, color sensitivity and uniformity over large FOVs, self-adaption to focus location, brightness and contrast. This paper defines a generic, standardized optical metrology platform to efficiently integrate various optical metrology instruments into the platform’s global coordinate system by utilizing a specially designed active-optical calibration target to precisely map the optical entrance pupil of any optical metrology instrument and device under test (DUT) to a common reference point, providing effective data correlation. The platform can easily accommodate common AR/VR/MR optical metrology equipment for measurements of: MTF/contrast, color and brightness, virtual distance, angular FOV, and binocular alignment error; to provide a unified metrology platform for optical measurements.
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