Specially-designed lens option for near-eye display testing within augmented and virtual reality headsets
The Radiant Vision Systems AR/VR lens has a unique optical design specially engineered for measuring near-eye displays (NEDs), such as those integrated into virtual (VR), mixed (MR), and augmented reality (AR) headsets. The lens design simulates the size, position, and field of view of the human eye. Unlike alternative lens options, where the aperture is located inside the lens, the aperture of the AR/VR lens is located on the front of the lens, enabling positioning of the imaging system’s entrance pupil within NED headsets to view head-mounted displays (HMDs) at the same location as the human eye.
Evaluates the Full Display Field of View Experienced by Human Users
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Displays viewed near to the eye, such as those in AR/VR devices, create immersive virtual experiences. However, as display images are magnified to fill a user’s field of view, display defects are also magnified. Issues with uniformity of brightness and color, dead pixels, line defects, cloudiness, and image position become more evident to the user whose eyes are only centimeters away from display screens. In these cases, display quality testing is a critical step for product quality control. Test and measurement solutions for evaluation of NED quality include photometric imaging systems paired with software for luminance and chromaticity measurement and analysis. However, traditional optical components that measure displays like televisions and smartphones did not include design considerations for replicating the human eye’s view of visual input at the distances required for head-mounted display devices.
Specially-designed for display quality measurement in NED headsets, the Radiant Vision Systems AR/VR lens includes aperture characteristics that simulate the approximate size, position, and field of view of the human eye. With the aperture at the front of the lens, the connected imaging system can capture the full field of view (FOV) of the display (up to 120° horizontal, covering approximate human binocular FOV) without obstruction by the lens hardware. The aperture size of 3.6 mm also matches the size of a human entrance pupil, allowing displays to be measured under the same conditions as they are viewed by a human observer. This ensures that all aspects of the display visible to the user are comprehensively measured to ensure the intended experience.
Competitive measurement systems that use standard optical accessories (such as a 35mm lens) are unable to replicate the human observer’s visual experience because the aperture is integrated within the lens enclosure, limiting the full angular field of view of the display to be captured without occlusion by the NED headset hardware (frames of the eye lens). The effect is like viewing a scene through a knot hole in a fence – when the eye is position at the hole, the full field of view can be seen beyond the fence; as the eye moves away from the hole, the view becomes occluded by the edges of the fence.
Mount to ProMetric Photometers and Colorimeters
The AR/VR lens is an optional mounting accessory for Radiant’s ProMetric Y Imaging Photometer or ProMetric I Imaging Colorimeter, which attaches using a custom mounting bracket to ensure stability during movement or vibration. By mounting a lens directly to a ProMetric imaging photometer or colorimeter, the AR/VR lens offers the most efficient means of measuring NEDs as a turnkey, compact camera/lens solution that requires minimal setup and integration time, equipment, or expertise. The AR/VR lens can easily be removed and replaced with standard lenses for additional display measurement applications, such as testing displays outside of headset equipment or on the production line.
Complete Toolset for AR/VR Display Measurement
Paired with a Radiant ProMetric® 16- or 29-megapixel imaging photometer or colorimeter, the AR/VR lens captures high-resolution images of displays for pixel and sub-pixel measurements to detect defects and anomalies in LED, LCD, OLED, and projection displays. Radiant TrueTest™ Software provides the leading display test algorithms, with the capability to sequence tests for rapid evaluation of all relevant display characteristics in a matter of seconds, applying selected tests to a single image captured by the camera. Standard tests in TrueTest include luminance, chromaticity, contrast, uniformity, mura (blemishes), pixel and line defects, and more. Unique tests for AR/VR display analysis include:
- Modulation transfer function (MTF) to evaluate image clarity. Based on Slant Edge Contrast ISO 12233.
- Image Distortion (for distortion characterization)
- Image Retention/Sticking
- Factory distortion calibration of the lens solution to normalize wide field-of-view images for testing
- Spatial x,y position reported in degrees (°)
With this complete Radiant solution configured for exact application needs, manufacturers can realize an efficient measurement process with the benefit of a single provider with end-to-end support.
Wide-field-of-view images taken by a camera/lens solution before and after factory distortion calibration. Distortion calibration of each system ensures accurate spatial data is acquired by normalizing the lens effects in wide-field-of-view images.
AR/VR Lens Key Features and Highlights:
- Accurate, reliable measurement of display luminance and chromaticity
- Aperture positioned at front of lens to simulate human eye entrance pupil, capturing full field of view (FOV) of head-mounted display (HMD) projections through headset viewing lenses
- Aperture size (3.6 mm) simulates human eye pupil size
- FOV of lens (120° horizontal) covers approximate FOV of binocular human vision
- Designed to be positioned at the eye relief location
- Easily paired with ProMetric imaging colorimeters or photometers
- Combination of low cost, high performance, and flexibility, designed for R&D and quality assurance
- Easy-to-use measurement control and analysis software
All Radiant ProMetric camera solutions come with ProMetric Software, a powerful software suite that provides intuitive camera setup and control, data acquisition and image analysis. Extensive data analysis and display functions are also supported, including isometric plots, cross-section graphs, radar plots, bitmaps and CIE color plots. For additional measurement and test sequencing options, TrueTest Software offers the comprehensive range of Radiant display measurement capability.
The AR/VR lens is the first to enable evaluation of the entire display viewable to the human eye through AR/VR headsets. The camera/lens solution offers high-resolution imaging to address both off-line and in-line applications:
- Measurement of near-eye displays; ideal for augmented (AR), mixed (MR), and virtual reality (VR) headsets
- Test and measurement of luminance, chromaticity, contrast, modulation transfer function (MTF), image distortion, image retention/sticking, and x,y image position
- Characterization and quality control for devices in R&D and production