Central Field Of View Research Articles

Twisted clustered pinhole collimation for improved high-energy preclinical SPECT/PET

Objective.Advanced pinhole collimation geometries optimized for preclinical high-energyɣimaging facilitate applications such asɑandßemitter imaging, simultaneous multi-isotope PET and PET/SPECT, and positron range-free PET. These geometries replace each pinhole with a group of clustered pinholes (CPs) featuring smaller individual pinhole opening angles (POAs), enabling sub-mm resolution imaging up to ∼1 MeV. Further narrowing POAs while retaining field-of-view (FOV) may enhance high-energy imaging but faces geometrical constraints. Here, we detail how the novel twisted CPs (TCPs) address this challenge.Approach.We compared TCP and CP collimator sensitivity at equal system resolution (SR) and SR at matched sensitivity by tuning pinhole diameters for18F (511 keV) and89Zr (909 keV). Additionally, simulated Derenzo phantoms at low activity (LA: 12 MBq ml-1) and high activity (HA: 190 MBq ml-1) levels, along with uniformity images, were compared to assess image resolution and uniformity.Main results.At equal SR, TCP increased average central FOV sensitivity by 15.6% for18F and 29.4% for89Zr compared to CP. Image resolution was comparable, except for89Zr at LA, where TCP resolved 0.80 mm diameter rods compared to 0.90 mm for CP. Image uniformity was equivalent for18F, while for89Zr TCP granted a 10.4% improvement. For collimators with matched sensitivity, TCP improved SR by 6.6% for18F and 17.7% for89Zr while also enhancing image resolution; for18F, rods distinguished were 0.65 mm (CP) and 0.60 mm (TCP) for HA, and 0.70 mm (CP and TCP) for LA. For89Zr, image resolutions were 0.75 mm (CP) and 0.65 mm (TCP) for HA, and 0.90 mm (CP) and 0.80 mm (TCP) for LA. Image uniformity with TCP decreased by 18.3% for18F but improved by 20.1% for89Zr.Significance.This study suggests that the TCP design has potential to improve high-energyɣimaging.

Investigation of intra-fractionated range guided adaptive proton therapy: I. On-line PET imaging and range measurement

Objective. Develop a prototype on-line positron emission tomography (PET) scanner and evaluate its capability of on-line imaging and intra-fractionated proton-induced radioactivity range measurement. Approach. Each detector consists of 32 × 32 array of 2 × 2 × 30 mm3 Lutetium–Yttrium Oxyorthosilicate scintillators with single-scintillator-end readout through a 20 × 20 array of 3 × 3 mm2 Silicon Photomultipliers. The PET can be configurated with a full-ring of 20 detectors for conventional PET imaging or a partial-ring of 18 detectors for on-line imaging and range measurement. All detector-level readout and processing electronics are attached to the backside of the system gantry and their output signals are transferred to a field-programable-gate-array based system electronics and data acquisition that can be placed 2 m away from the gantry. The PET imaging performance and radioactivity range measurement capability were evaluated by both the offline study that placed a radioactive source with known intensity and distribution within a phantom and the online study that irradiated a phantom with proton beams under different radiation and imaging conditions. Main results. The PET has 32 cm diameter and 6.5 cm axial length field-of-view (FOV), ∼2.3–5.0 mm spatial resolution within FOV, 3% sensitivity at the FOV center, 18%–30% energy resolution, and ∼9 ns coincidence time resolution. The offline study shows the PET can determine the shift of distal falloff edge position of a known radioactivity distribution with the accuracy of 0.3 ± 0.3 mm even without attenuation and scatter corrections, and online study shows the PET can measure the shift of proton-induced positron radioactive range with the accuracy of 0.6 ± 0.3 mm from the data acquired with a short-acquisition (60 s) and low-dose (5 MU) proton radiation to a human head phantom. Significance. This study demonstrated the capability of intra-fractionated PET imaging and radioactivity range measurement and will enable the investigation on the feasibility of intra-fractionated, range-shift compensated adaptive proton therapy.

Evaluation of Parameters Affecting Intrinsic Uniformity to Perform Best Optimum Daily QC

Nuclear Medicine plays a vital role in the diagnosis of benign and malignant cancer tissues. The quality assurance program of gamma cameras in nuclear medicine provides an artifact-free diagnosis. One of the most important quality control (QC) is to test the response of detectors to a uniform distributed source called as uniformity test. The QC of image uniformity test includes intrinsic uniformity (IU) and Differential uniformity (DU) of CFOV (Central Field of View) and UFOV (Useful Field of View). The purpose of this study is to evaluate the best value of parameters for getting the best uniformity results and set as a benchmark for checking the performance of gamma cameras in the future. It is analyzed that using an energy window placed at 140 KeV at 20%, with a matrix size of 256 x 256, acquiring 60 million counts and the source activity close to 500 µC obtained images are good and both uniformities are within the manufacturer’s requirements, however, increasing the number of acquired counts and by mounting a source at a distance larger than 2m, images become better.

Performance Characteristics of the NeuroEXPLORER, a Next-Generation Human Brain PET/CT Imager.

The collaboration of Yale, the University of California, Davis, and United Imaging Healthcare has successfully developed the NeuroEXPLORER, a dedicated human brain PET imager with high spatial resolution, high sensitivity, and a built-in 3-dimensional camera for markerless continuous motion tracking. It has high depth-of-interaction and time-of-flight resolutions, along with a 52.4-cm transverse field of view (FOV) and an extended axial FOV (49.5 cm) to enhance sensitivity. Here, we present the physical characterization, performance evaluation, and first human images of the NeuroEXPLORER. Methods: Measurements of spatial resolution, sensitivity, count rate performance, energy and timing resolution, and image quality were performed adhering to the National Electrical Manufacturers Association (NEMA) NU 2-2018 standard. The system's performance was demonstrated through imaging studies of the Hoffman 3-dimensional brain phantom and the mini-Derenzo phantom. Initial 18F-FDG images from a healthy volunteer are presented. Results: With filtered backprojection reconstruction, the radial and tangential spatial resolutions (full width at half maximum) averaged 1.64, 2.06, and 2.51 mm, with axial resolutions of 2.73, 2.89, and 2.93 mm for radial offsets of 1, 10, and 20 cm, respectively. The average time-of-flight resolution was 236 ps, and the energy resolution was 10.5%. NEMA sensitivities were 46.0 and 47.6 kcps/MBq at the center and 10-cm offset, respectively. A sensitivity of 11.8% was achieved at the FOV center. The peak noise-equivalent count rate was 1.31 Mcps at 58.0 kBq/mL, and the scatter fraction at 5.3 kBq/mL was 36.5%. The maximum count rate error at the peak noise-equivalent count rate was less than 5%. At 3 iterations, the NEMA image-quality contrast recovery coefficients varied from 74.5% (10-mm sphere) to 92.6% (37-mm sphere), and background variability ranged from 3.1% to 1.4% at a contrast of 4.0:1. An example human brain 18F-FDG image exhibited very high resolution, capturing intricate details in the cortex and subcortical structures. Conclusion: The NeuroEXPLORER offers high sensitivity and high spatial resolution. With its long axial length, it also enables high-quality spinal cord imaging and image-derived input functions from the carotid arteries. These performance enhancements will substantially broaden the range of human brain PET paradigms, protocols, and thereby clinical research applications.

Development of a four-color quasimonochromatic X-ray microscope for laser plasma research.

X-ray multicolor imaging diagnosis obtains the spatial distribution of the imploding core during laser inertial confinement fusion. We propose a four-color quasimonochromatic X-ray microscope based on the Kirkpatrick-Baez microscope configuration, covering the medium-to-high-energy X-ray range. Composed of single-layer film mirrors and periodic multilayer film mirrors, the microscope features high spatial resolution and spectral resolution. Furthermore, zoned coating technology achieves common field-of-view (FOV) imaging at four energy points: 4.51, 6.4, 8.4, and 9.67 keV. When assembled and calibrated in the laboratory, the microscope achieved central FOV spatial resolutions of 3.9, 3.7, 4.0, and 4.1 µm at 4.51, 6.4, 8.04, and 9.67 keV, respectively. Finally, a spectral calibration experiment confirmed spectral selectivity at the four energy points.

Room corners and how they influence the memory of visual information arranged on walls

In formal and informal learning settings corresponding information units are often arranged in the space around the viewer. For example, teachers pin task relevant information on classroom walls, or museum curators arrange exhibits in museum halls. Often learners and visitors are expected to see meaningful relationships between these information units. Theoretically, Gestalt Psychology has been examining the effects of connecting and separating elements in visual information displays, leading to the question of whether these findings also hold in three-dimensional environments. Does the mostly rectangular form of our rooms also either highlight or downplay relations between information dispersed across a room? Three experiments using virtual rooms showed that the matching pairs of pictures were memorized better if both pictures were arranged on the same wall instead of across two adjacent walls: that is, the presence of a room corner between matching pairs decreased memory (Experiments 1–3). Additionally, the findings showed that the participants’ orientation of their central field of view during learning influenced the effect of corners on memory. When initially looking around in rooms, participants most often oriented the center of their field of view toward the middle of a wall (Experiments 1 and 2); however, if they were restricted to orienting their field of view toward corners, the corner effect on memory vanished (Experiment 3). These findings suggest that room characteristics influence the exploratory behavior of viewers, thereby also affecting their memories of the presented information.

The Effects of Eye Illuminance Distribution in the Horizontal Field of View on Human Performance in a Home Paper-Based Learning Situation

Previous studies have focused on task/ambient illumination for visual effects and eye illumination for non-visual effects. In this context, eye illumination within the non-visual realm was defined as vertical non-visual eye illuminance. Considering the functional specificity of central vision and peripheral vision, this study aims to explore whether the distribution of eye illuminance in the horizontal field of view (FOV) affects human performance in home paper-based learning settings. In this study, a within-subject design was used to investigate the effects of eye illuminance distribution on mental perception, task performance, and physiological health while maintaining constant task illuminance and correlated color temperature (CCT). The findings revealed that eye illuminance and its distribution in the horizontal FOV had complex effects on visual fatigue, Landolt ring performance, heart rate variability, and luminous environment appraisal. A relatively optimal lighting configuration was suggested—Scene 4, which was characterized by an eye illuminance level in central FOV of 186 lx and an “m” shaped eye illuminance distribution pattern. This indicates the importance of considering eye illuminance distribution in the horizontal FOV, rather than solely focusing on vertical eye illuminance.

Construction and initial performance evaluation of a newly developed plant PET system

In plant research, positron emission tomography (PET) is occasionally employed for physiological studies, offering valuable insights. However, the generally high cost of PET systems and their suboptimal design for plant research pose challenges to their application in this field. To address these issues, we have developed a new PET system optimized specifically for plant research. The PET detector ring was positioned vertically to enable measurements of plants in their normal upright position. The developed plant PET system features a transaxial field of view (FOV) of approximately 12 cm and an axial FOV slightly larger than 9 cm, allowing for the imaging of relatively small-sized plants. To facilitate imaging of taller plants, the PET system can expand the axial FOV by changing the subject height using a lab jack, enabling the imaging of taller plant species. The measured spatial resolution at the central FOV was 3.3 mm FWHM, and the sensitivity was 3.7%. The timing resolution was 6.78 ns FWHM with a lower energy threshold set to 350 keV. Phantom images simulating plants were successfully measured using the developed plant PET system. We conclude that the developed plant PET system holds promise for effective plant imaging.

Wide Field of View Under-Panel Optical Lens Design for Fingerprint Recognition of Smartphone.

Fingerprint recognition is a widely used biometric authentication method in LED-backlight smartphones. Due to the increasing demand for full-screen smartphones, under-display fingerprint recognition has become a popular trend. In this paper, we propose a design of an optical fingerprint recognition lens for under-display smartphones. The lens is composed of three plastic aspheric lenses, with an effective focal length (EFL) of 0.61 mm, a field of view (FOV) of 126°, and a total track length (TTL) of 2.54 mm. The image quality of the lens meets the target specifications, with MTF over 80% in the center FOV and over 70% in the 0.7 FOV, distortion less than 8% at an image height of 1.0 mm, and relative illumination (RI) greater than 25% at an image height of 1.0 mm. The lens also meets the current industry standards in terms of tolerance sensitivity and Monte Carlo analysis.

Visual Servo Control for Workspace Navigation of Nanorobot End-Effector Inside SEM

Despite of the promising advancements in the last decade, the majority of scanning electron microscope (SEM)-based nanomanipulation tasks remain manually performed. Even in automated tasks, human intervention is required, at least during the task preparatory stage, where both the object of interest and robot end-effector are adequately enclosed in the field of view (FOV) of SEM at moderate magnification. This paper proposes a fully automated visual servo control method for workspace navigation of nanorobot end-effector that actively maintains the end-effector position offset from the center of FOV during passive working scene zooming and translation operations. We also propose using the scaling image Jacobian matrix theory to adaptively establish the hand-eye relationship of the nanorobotic system at uncalibrated magnifications, without the need for hardware regulation. This proposed method for workspace navigation is applicable to almost all commercial nanomanipulation systems. To the authors’ best knowledge, there has been no dedicated research on this problem in the literature. Experiments show that the proposed method significantly improves workspace navigation efficiency by about two-thirds, even for a skilled operator. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Workspace navigation refers to the process of moving the FOV to visually enclose the object or feature of interest at a moderate magnification, which is prerequisite for initializing either an automated or manual nanomanipulation task. This process involves consecutive zooming of the SEM in and out, as well as translating the sample stage, which can cause the end-effector to move out of the FOV. Therefore, it is necessary to move the robot end-effector with visual assistance along workspace navigation to avoid unexpected collisions. Typically, skilled operators perform this process manually in almost all nanomanipulation tasks, which is tedious and time-consuming. Therefore, developing an automated visual servo control method for workspace navigation of end-effector will significantly contribute to the nanomanipulation community.

An On-Orbit Relative Sensor Normalization for Unbalance Images from the Ice Pathfinder Satellite (BNU-1)

The Ice Pathfinder satellite (code: BNU-1) is the first Chinese microsatellite, designed for monitoring polar climate and environmental changes. The major payload of BNU-1 is the wide-field camera which provides multispectral satellite images with a 73.69 m spatial resolution and a 739 km swath width. However, the color misrepresentation issue can be observed as the BUN-1 image appears yellowish as it gets farther towards the center field of view (FOV). The blue band of the image appears to be higher near the center FOV and declines generously towards both the edge areas of the image, which may cause the color misrepresentation issue. In this study, we develop a relative sensor normalization method to reduce the radiance errors of the blue band of BNU-1 images. This method uses the radiometric probability density distribution of the BNU-1 panchromatic band as a reference, correcting the probability density distribution of the blue band radiance first. Then, the mean adjustment is used to correct the mean of the blue band radiance after probability density function (PDF) correction, obtaining the corrected radiance in the blue band. Comparisons with the ground measurements and the Landsat8 image reveal the following: (1) The radiances of snow surfaces also have good consistency with ground observations and Landsat-8 images in the red, green, and blue bands. (2) The radiance errors of the uncorrected BNU-1 images are eliminated. The RMSE decreases from 80.30 to 32.54 W/m2/μm/sr. All these results indicate that the on-orbit relative correction method proposed in this study can effectively reduce the radiance errors of the BNU-1 images.

Effect of depth of interaction resolution on the spatial resolution of SIAT aPET

Objective. Spatial resolution is a crucial parameter for a positron emission tomography (PET) scanner. The spatial resolution of a high-resolution small animal PET scanner is significantly influenced by the effect of depth of interaction (DOI) uncertainty. The aim of this work is to investigate the impact of DOI resolution on the spatial resolution of a small animal PET scanner called SIAT aPET and determine the required DOI resolution to achieve nearly uniform spatial resolution within the field of view (FOV). Approach. The SIAT aPET detectors utilize 1.0 × 1.0 × 20 mm3 crystals, with an average DOI resolution of ∼2 mm. A default number of 16 DOI bins are used during data acquisition. First, a Na-22 point source was scanned in the center of the axial FOV with different radial offsets. Then, a Derenzo phantom was scanned at radial offsets of 0 and 15 mm in the center axial FOV. The measured DOI information was rebinned to 1, 2, 4 and 8 DOI bins to mimic different DOI resolutions of the detectors during image reconstruction. Main results. Significant artifacts were observed in images obtained from both the point source and Derenzo phantom when using only one DOI bin. When accurate measurement of DOI is not achieved, degradation in spatial resolution is more pronounced in the radial direction compared to tangential and axial directions for large radial offsets. The radial spatial resolutions at a 30 mm radial offset are 5.05, 2.62, 1.24, 0.86 and 0.78 mm when using 1, 2, 4, 8, or 16 DOI bins, respectively. The axial spatial resolution improved from ∼1.3 to 0.7 mm as the number of DOI bins increased from 1 to 16 at radial offsets from 0 to 25 mm. Two DOI bins are required to obtain images without significant artifacts. The required DOI resolution is about three times the crystal width of SIAT aPET to achieve a uniform submillimeter spatial resolution within the central 60 mm FOV and resolve the 1 mm rods of the Derenzo phantom at both positions.

Development and performance of SIAT bPET: a high-resolution and high-sensitivity MR-compatible brain PET scanner using dual-ended readout detectors.

Positron emission tomography/magnetic resonance imaging (PET/MRI) is a powerful tool for brain imaging, but the spatial resolution of the PET scanners currently used for brain imaging can be further improved to enhance the quantitative accuracy of brain PET imaging. The purpose of this study is to develop an MR-compatible brain PET scanner that can simultaneously achieve a uniform high spatial resolution and high sensitivity by using dual-ended readout depth encoding detectors. The MR-compatible brain PET scanner, named SIAT bPET, consists of 224 dual-ended readout detectors. Each detector contains a 26 × 26 lutetium yttrium oxyorthosilicate (LYSO) crystal array of 1.4 × 1.4 × 20 mm3 crystal size read out by two 10 × 10 silicon photomultiplier (SiPM) arrays from both ends. The scanner has a detector ring diameter of 376.8mm and an axial field of view (FOV) of 329mm. The performance of the scanner including spatial resolution, sensitivity, count rate, scatter fraction, and image quality was measured. Imaging studies of phantoms and the brain of a volunteer were performed. The mutual interferences of the PET insert and the uMR790 3T MRI scanner were measured, and simultaneous PET/MRI imaging of the brain of a volunteer was performed. A spatial resolution of better than 1.5mm with an average of 1.2mm within the whole FOV was obtained. A sensitivity of 11.0% was achieved at the center FOV for an energy window of 350-750keV. Except for the dedicated RF coil, which caused a ~ 30% reduction of the sensitivity of the PET scanner, the MRI sequences running had a negligible effect on the performance of the PET scanner. The reduction of the SNR and homogeneity of the MRI images was less than 2% as the PET scanner was inserted to the MRI scanner and powered-on. High quality PET and MRI images of a human brain were obtained from simultaneous PET/MRI scans. The SIAT bPET scanner achieved a spatial resolution and sensitivity better than all MR-compatible brain PET scanners developed up to date. It can be used either as a standalone brain PET scanner or a PET insert placed inside a commercial whole-body MRI scanner to perform simultaneous PET/MRI imaging.

Impact of the maximum ring difference on image quality and noise characteristics of a total-body PET/CT scanner

The sensitivity of a PET system highly depends on the axial acceptance angle or maximum ring difference (MRD), which can be particularly high for total-body scanners due to their larger axial field of views (aFOVs). This study aims to evaluate the impact on image quality (IQ) and noise performance when MRD85 (18°), the current standard for clinical use, is increased to MRD322 (52°) for the Biograph Vision Quadra (Siemens Healthineers). MethodsStudies with a cylindrical phantom covering the 106 cm aFOV and an IEC phantom filled with 18F, 68Ga and 89Zr were performed for acquisition times from 60 to 1800 s and activity concentrations from 0.4 to 3 kBq/ml to assess uniformity, contrast recovery coefficients (CRCs) and to characterize noise by coefficient of variation (CV). Spatial resolution was compared for both MRDs by sampling a quadrant of the FOV with a point source. Further IQ, CV, liver SUVmean and SUVmax were compared for a cohort of 5 patients scanned with [18F]FDG (3 MBq/kg, 1 h p.i.) from 30 to 300 s. ResultsCV was improved by a factor of up to 1.49 and is highest for short acquisition times, peaks at the center field of view and mitigates parabolic in axial direction with no difference to MRD85 beyond the central 80 cm. No substantial differences between the two evaluated MRDs in regards to uniformity, SUVmean or CRC for the different isotopes were observed. A degradation of the average spatial resolution of 0.9 ± 0.2 mm in the central 40 cm FOV was determined with MRD322. Depending on the acquisition time MRD322 resulted in a decrease of SUVmax between 23.8% (30 s) and 9.0% (300 s). ConclusionPatient and phantom studies revealed that scan time could be lowered by approximately a factor of two with MRD322 while maintaining similar noise performance. The moderate degradation in spatial resolution for MRD322 is worth to exploit the full potential of the Quadra by either shorten scan times or leverage noise performance in particular for low count scenarios such as ultra-late imaging or dynamic studies with high temporal resolution.

Vehicle-mounted imaging lidar with nonuniform distribution of instantaneous field of view

Imaging lidar is an important sensor for use in vehicle environment perception systems, and its field of view (FOV) and instantaneous field of view (IFOV) determine the system’s spatial coverage and the spatial resolution of detection, respectively. A smaller IFOV indicates that lidar can recognize a target over a greater distance. The FOV and the IFOV of conventional array-type lidar systems are constrained by the detector and cannot increase their target recognition distance while maintaining the same spatial coverage. To solve this problem, an imaging vehicle-mounted lidar system with a nonuniform IFOV distribution is proposed. By reducing the central IFOV while maintaining the same detection space, the system effectively doubles the available range for target discovery and recognition. Simultaneously, the central FOV has a larger entrance pupil, which matches the characteristic required to allow the central FOV to detect targets at greater distances. The proposed lidar system can recognize vehicle information at a longer range than conventional systems, and can play an important role in the 3D environmental perception field for intelligent vehicles.

Study on full-aperture intensity response measurement for x-ray Kirkpatrick–Baez microscope

The diagnostic demand of hot-spot intensity distribution in laser inertial confinement fusion experiment has motivated quantitative measurement experiment to give the response efficiency of grazing incidence system to improve the accuracy of the diagnosis. In our study, a full-aperture intensity response measurement method is proposed, which is based on pinhole-scanning field of view (FOV) to obtain the response efficiency of grazing incidence system. The method is highly repeatable and enables response efficiency measurements over the full FOV with acceptable accuracy. A silicon positive-intrinsic-negative detector with an energy response range of 1.5 to 30 keV is used to directly detect the input and output spectrum. The response efficiency of a single-channel aspheric Kirkpatrick–Baez (KB) microscope coated with W/Si is obtained under the FOV of ±150 μm. The response efficiency of center FOV of the KB system is measured to be 2.52E-7 sr. The value is promising, as it shows a 6.6% maximum deviation from the theoretical value at center FOV, with a global uncertainty of 7.4%.

Development of vertical edge Thomson scattering diagnostic on HL-2M Tokamak

A vertical edge Thomson scattering diagnostic system on HL-2 M Tokamak has been developed recently. A Nd: YAG laser (1064 nm, 0.6–2.0 J, 30 Hz, 15 ns) is used as the probe beam. The laser beam propagates vertically through the plasma region and the scattered light is observed horizontally. The combination of a half-wave plate and a polarized beam splitter is used for stray light suppression. A group of in-vacuum collection lens is designed to image the 400 mm scattered region onto the rectangular fiber arrays. The laser beam waist and vertical spatial resolution are 2 mm and 10 mm, respectively. Scattered light is imaged on the 2.20 × 2.86 mm (10 × 13) fiber optic bundle. The development of collection optics with a special designed safety shutter ensures a reliable scattered signal, where the solid angle at central field of view (FOV) is 0.018 sr. A compact polychromator is developed to measure the scattered light. Relative calibration of the filter response (1060 nm, 1052 nm, 1029 nm and 982 nm) and absolute calibration by nitrogen Raman scattering have been completed. In the 2022 plasma campaign of HL-2M, the scattering signal is measured at E0 = 1.2 J, confirming the capability of the system for pedestal measurement in the future H-mode campaign.

Suppressing the polarization aberrations by combining reflection and refraction optical groups.

Polarization remote sensing technology expands the dimensions of the target and enriches its basic information over traditional remote sensing methods. During the imaging process, polarization imaging changes the polarization information of the target by the modulation of the optical system, affecting the detection accuracy. We term the modulation of the polarization state of light by an optical system as polarization aberration, and we found that a lens group combined with mirrors is beneficial in suppressing polarization aberrations. This study analyzed the principles of suppression and the polarization aberration of the optical system before and after suppression. Simulation results show that the diattenuation's average value is reduced by 51.1% and the retardance's average value is reduced by 26.3% after suppression. The corrected polarization cross-coupled energy is reduced by 73.18% in the central field of view and by 69.80% in the fringe field of view. Adding a lens group also effectively suppresses traditional aberrations and expands the field of view.

Visual Search in Augmented Reality: Effect of Target Cue Type and Location

The current experiment examined the relative benefit of different cueing aids during a visual target search task, and the tradeoff between reduced information access effort and increased overlay clutter. Using an augmented reality head-mounted display (AR-HMD), participants completed a 180-degree visual search task with three different cue types (world-referenced arrow, screen-referenced icon target image, and screen-referenced minimap) compared to a control condition (no cueing aid). Target cues differed in terms of display proximity and where they were presented on the AR-HMD (the central field of view or approximately 15 degrees downward from the center). We found an overall performance benefit when searching for an object in the far domain with a target cue compared to searching with no cue, and the arrow cue (highest display proximity) showed the greatest overall benefit. We also found a performance benefit for cues located at the center of the AR-HMD compared to the downward location, but this benefit was offset by the higher clutter of the icon image and the minimap. These findings suggest that target cues with higher display proximity that also reduce information access effort (scanning) may be more suitable cueing aids when searching for an object in the far domain.

Information Access Effort: Are Head Movements “Cheap” or Even “Free”?

Augmented reality head-mounted displays (AR-HMDs) can present information at the center field of view (FOV) to 360° around the user. Deciding where to place virtual content when using an AR-HMD could directly impact the effort required to access information for different tasks. The current paradigm investigated the cost of information access effort for two different tasks presented on a virtual display using an AR-HMD. Participants made comparison judgments for two types of tasks (focused attention and computation integration) based on information presented at increasing lateral distances from the left side of the virtual display. Results showed no loss in performance as predicted by the Information Access Effort function. However, results show that evoking head movements played a significant role in restoring and preserving accuracy at greater visual eccentricities without hindering response time.