We present the first-order design details and preliminary lens design and performance analysis of a compact optical system that can achieve mutual occlusions. Mutual occlusion is the ability of real objects to occlude virtual objects and virtual objects to occlude real objects. Mutual occlusion is a desirable attribute for a certain class of augmented reality applications where realistic overlays based on the depth cue is important. Compactness is achieved through the use of polarization optics. First order layout of the system is similar to that of a Keplerian telescope operating at finite conjugates. Additionally, we require the image to lie on the plane of the object with unit magnification. We show that the same lens can be used as the objective and the eyepiece. The system is capable of having very close to zero distortion.
This paper proposes a new method to design an optically-fabricated holographic element, where the construction optical system and the playback system can be optimized jointly. The method was driven by the use of a new holographic recording material - the photo-thermo-refractive (PTR) glass - that can only be written at 325nm, while its playback takes place in the visible part of the spectrum. Applying the method proposed, a single holographic element head-mounted display (HMD) was modeled. Results show that a single holographic element may be constructed at 325 nm, and inserted in a playback optical system operating at 633nm, with a MTF of over 80% across a 40 degree field of view at 37cycles/mm.
The projection based head-mounted display (HMD) constitutes a new paradigm in the field of wearable computers. Expanding on our previous projection based HMD, we developed a wearable computer consisting of a pair of miniature projection lenses combined with a beam splitter and miniature displays. Such wearable computer utilizes a novel conceptual design encompassing the integration of phase conjugate material (PCM) packaged inside the HMD. Some of the applications benefiting from this innovative wearable HMD are for government agencies and consumers requiring mobility with a large field-of-view (FOV), and an ultra-light weight headset. The key contribution of this paper is the compact design and mechanical assembly of the mobile HMD.
In this paper, we investigate the design and fabrication of ultra-light weight projection lenses for color wearable displays. Driven by field of view requirements from 40 degree to 90 degrees, we employed the combination of plastic, glass, and diffractive optics to yield less than 10g optics per eye. The approach centers on the use of projection optics instead of eyepiece optics to yield most compact and high image quality designs. The implementation of the fabricated 52 degrees lens in a teleportal head-mounted display and remote collaborative environment is demonstrated. We also present the design results for a 70 degrees design.
Common techniques of lens design lead to image quality assessment in the plane of the miniature display of a head-mounted display (HMD) instead of image quality in visual space as expected from a usability point of view. In this paper, we present an analysis of HMD performance in visual space including MTF, accommodation, astigmatism, and transverse color smear.
In this paper, we shall present an overview of research in augmented reality technology and applications conducted in collaboration with the 3DVIS Lab and the MIND Lab. We present research in the technology of head-mounted projective displays and tracking probes. We then review mathematical methods developed for augmented reality. Finally we discuss applications in medical augmented reality and point to current developments in distributed 3d collaborative environments.
Visualizing information in three dimensions provides an increased understanding of the data presented. Furthermore, the ability to manipulate or interact with data visualized in three dimensions is superior. Within the medical community, augmented reality is being used for interactive, three-dimensional (3D) visualization. This type of visualization, which enhances the real world with computer generated information, requires a display device, a computer to generate the 3D data, and a system to track the user. In addition to these requirements, however, the hardware must be properly integrated to insure correct visualization. To this end, we present components of an integrated augmented reality system consisting of a novel head-mounted projective display, a Linux-based PC, and a commercially available optical tracking system. We demonstrate the system with the visualization of anatomical airways superimposed on a human patient simulator.
Today advanced 3D virtual environments are mostly based on either a technology known as the cave or head-mounted displays. A new type of head-mounted display, which consists of a pair of miniature projection lenses and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment, has been proposed as an alternative to eyepiece optics types of displays. The novel concept and properties of the head- mounted projective display (HMPD) suggests solutions to part of the problems of state-of-art visualization devices and make it extremely suitable for multiple-user collaborative environments. In this paper, we first review the concept of the HMPD and present the latest prototype developed. We then discuss its application to medical visualization and remote collaborative environments.
A Zernike polynomial can be used to describe not only the phase of a wavefront, but also its entire complex amplitude. For the latter case, a diffractive optical element (DOE) is proposed to decompose the incident wavefront into a set of diffraction orders with their amplitudes proportional to the coefficients of the Zernike polynomial. A 25-channel Zernike decomposer is designed by means of an iterative method, and its operation simulated. When the amplitude distribution of the incident wavefront is known, its shape can be uniquely determined from the intensity measured on the output plane of the DOE. An exemplary algorithm for the phase retrieval is also presented. Such a DOE can be very useful in the rapid analysis of wavefronts.