Proc. SPIE 4442, New paradigm for head-mounted display technology: application to medical visualization and remote collaborative environments, 0000 (10 December 2001); https://doi.org/10.1117/12.449956
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.
We investigate aspects of the design of a large area display based on seamless tiling of Photoluminescent LCD (PL-LCD) panels. This paper discusses and illustrates the design methodology involved in optically tiling PL-LCD panels to make arbitrarily large displays. Suitable magnification, image quality and throw were achieved through optimization of the front-face optical system. In addition, active and passive-matrix drive schemes were investigated with regard to the throughput, contrast-ratio and video-rate performance.
A potential application for ferroelectric thin films is micro positioning and actuation, as in MEMS devices. The amount of actuation possible is determined by a number of factors: the piezoelectric coefficient d31, geometric factors and the compliance of both the actuator and cantilever and the electric field across the film. It is important for their realization as devices in applications that these micro-actuators are characterized. One such means is to use optical beam deflection (OBD). However, whilst extremely simple to implement, optical beam deflection does not provide an absolute measure of displacement. For absolute displacement measurement, with directional determination, a dual-beam normal incidence polarization interferometer is required. Based upon an interferometer developed in our laboratory to measure the flying height or head-disk spacing in a hard disk drive, an optical system is proposed which enables both an OBD and a polarization interferometer to be combined in one compact system. Details of both systems and are presented and the combined system described.
We present a method for designing and testing a null corrector for use with scatterplate interferometry on a large conic mirror. The null corrector in a scatterplate interferometer must maintain OPD of less than 1/2 wave over a finite field size for optimal fringe visibility. Our design uses an aspheric diamond-turned mirror (DTM) to exactly cancel out the spherical aberration of the surface under test. The DTM has the additional benefit of being useable in other types of interferometers for testing of the conic surface in a null condition. Low power refractive elements correct field aberrations over the finite aperture of the scatterplate. The null corrector can be certified using another smaller DTM or a computer generated hologram (CGH). This design has the advantages of being small in size, less expensive than designs using spherical surfaces (due to the small size of the null-correcting mirror), useable with other interferometers, and easy to align.
As improving manufacturing techniques drive down the expense of imaging detector arrays, the total costs of future thermal imaging systems will become increasingly dominated by the manufacturing costs of the complex lens systems that are necessary for athermalization and achromatization. The concept of wavefront encoding combined with post-detection digital decoding has previously been shown to produce systems that are insensitive to thermal and chromatic defocus in slow imaging systems. In this paper we describe the application of the wavefront coding technique to thermal imaging systems with particular emphasis on the specific difficulties encountered. These difficulties include the use and effects of fast optics (~f/1), wide fields of view and noise amplification in low-contrast thermal images. Modeling results will be presented using diffraction models. We will describe the optimization of the wavefront encoding technique with a specific aim to reduce weight, size, and cost whilst maintaining acceptable imaging performance.
The general problem to find the shape of a refractive surface such as to produce a desired brightness distribution on a given target surface from a known point source leads to a boundary value problem with an elliptic partial differential equation of the Monge-Ampere type. This equation has been described and analyzed in the literature. The purpose of our contribution is to present a venue for a numerical solution as well as several solved examples. The essence of our algorithm for a numerical solution appears to be the explicit incorporation of the condition for the existence of a pseudopotential for a normal vector field.
We investigate unobstructed plane-symmetric imaging systems of two spherical mirrors having three- or four-reflections. Geometry constraints are used to ensure that the odd numbered reflections occur on one spherical mirror, and that even numbered reflections occur on a separate spherical mirror. Imaging constraints are used to ensure appropriate first-order behavior. These geometry and imaging constraints eliminate degrees of freedom from the configuration space, thereby simplifying the design process. For the three-reflection systems, the available degrees of freedom are reduced to four, and for four-reflection systems, they are reduced to five. An alternate method using pickup constraints is discussed. Global optimization using simulated annealing is performed, and example systems are presented.
All optical design and analysis software computer codes possess some form of ray tracing capability. Optical design software computer codes have made do with sequential ray tracing algorithms for the past 40 to 50 years. In developing a general non-sequential ray trace tool at TRW, a new paradigm had to be adopted in order to make this new software tool completely general and flexible. This paper compares and contrasts existing sequential ray tracing algorithms and then describes how we went about crafting our own solution to the general non-sequential ray tracing problem
It is the aim of this paper to call attention to and to suggest practical applications in imaging of the long known but neglected skeew invariant. For a ray passing through a rotationally symmetric optical system whose axis is the z- axis of a Cartesian coordinate system, the quantity S=n((beta) x-ay) where n is the refractive index and ((alpha) ,(beta) ) are direction cosines, is constant. Despite the generality of this result and the strength of the constrain that it expresses, this result is little used by optical designers, except with non-imaging systems. The skew invariant precludes perfect imaging of more than one object plane (except for the well-known special case of afocal system). With one perfect imaging plane, the skew invariant limits the quality possible on another plane. For a lens that images one plane the upper limits of imaging at another are restrained by the invariant. Similar restraints exist with two imperfectly images planes. Additional applications are speculated upon.
This paper presents the use of optics as it relates to the various forms of illusions and magic, and we will present many of the best optical illusions to demonstrate the use of optics. In magic and visual illusions, objects are made to appear different from how we expect them to appear. Performing such illusions show us things that are impossible based on our preconceived knowledge base. This includes levitation, sawing a lady in half, or creating other similar effects. Optical illusions often take the form of illusions of relative size, shifting perception of items, and other ways of fooling the eye, the mind and the brain. These effects are all highly deceiving to the viewer. In addition to optical illusions, there is close up, parlor and stage magic. These would include classical effects as well as contemporary effects with items such as cards, coins, rings, etc. Here too the goal of the magician is to totally mystify the audience. Another topic of the paper is
The state of the art conformal optics is described. Conformal optics refers to the design, fabrication and use of optical windows and domes that are neither flat nor a section of a sphere. The challenges and solutions to overcome the challenges associated with developing the tools and techniques that enable the use of conformal optics is described. A demonstration of the utility of conformal optics is presented.
Thefirst birefringent optical element was the calcite trilobite eye, 540,000,000 years ago. One type was a hexagonal array of from one to several thousand lenslets of calcite crystals, oriented to produce no double images. At each molt new eyes were grown. Some trilobite eyes were calcite with spherical aberration correction resulting from a gradient index. (Some trilobites were blind.) Reference: Richard Fortey, Trilobite!, Knoff, New York, 2000
A new paradigm and methods for special effects in images were recently proposed by artist and movie producer Steven Hylen. Based on these methods, images resembling painting may be formed using optical phase plates. The role of the mathematical and optical properties of the phase plates is studied in the development of these new art forms. Results of custom software as well as ASAP simulations are presented.
Binary optics has been interested widely in recent years, where the optical element can be fabricated on a thin glass plate with micro-ion-etching film layer. A novel optical scanning system for gene disease diagnostics is developed in this paper, where four kinds optical devices are used, such as beam arrays splitter, arrays lens, filter arrays element and detection arrays. A soft for binary device designing with iterative method is programmed. Two beam arrays splitters are designed and fabricated, where one devices can divide a beam into the 9x9 arrays , the other will divide a beam into the 13x13 arrays. The beam arrays splitter has a good diffraction efficiency >70%, and an even energy distribution. The gene disease diagnostics system is portable by biochip and binary optics technology.
One of the most critical and effective parameters in increasing areal density is the flying height or spacing between the read-write head and the recording disk medium. As the flying height reduces to near contact, the head flies around 5 nm about the disk surface. To date, optical interferometry has been the major means for the characterization of this parameter. However, it is difficult to use it directly to measure the flying height on a sealed drive. To circumvent this limitation, a system based upon CD-ROM optics has been designed. The results from the system are correlated to measurements of suspension arm movement and disk flutter using poly-vinylidine-flouride (PVdF) strain sensors. A CD-ROM drive utilizes a laser with photodiodes to read data from the disk. The photo detector output responds linearly to changes in the lens-disk separation. In our system two CD-ROM heads are located within a rig that allows independent positioning in all three planes. The optics are configured to reflect off of a typical hard disk drive disk and the slider. To validate its performance a thin (110 micron) sheet of poly vinylidine flouride (PVdF) piezoelectric material is bonded to the suspension arm to measure the average induced strain. A further PVdF sensor was used to measure the edge displacement of the disk due to disk bending. The sensor used was in a cantilever configuration, with one end rigidly bonded to the drive chassis in a manner that pre-tensions the cantilever against the disk. Any movement of the disk would change the strain induced in the cantilever.
A simple and direct method using these equations to correct real aberrations and to find the minimum aberration of the system has been suggested. The calculated third-order aberration can exactly meet the target values at each stage by means of the damped least-squares method. The spherical aberration is first targeted to get the minimal value of an on-axis aberration corresponding to the real aberration. Similarly, the coma and astigmatism target values are adjusted to force off-axis real aberrations at the 1.0 field angle down to the minimum. Finally, the minimum aberration at the field angle of 0.7 is fulfilled by the manual variation of the lens thickness and lens spacing. Two examples of triplet designs are presented.
We presented an efficient method to achieve the optimized design of a doublet lens. Using the third-order aberrations to obtain directly a minimal area from the ray-fan diagram was suggested. We took the specification of F/#=3.333 and a half field of view 1 degree(s) as the design example. The optimization technique was utilized to control the third order aberrations such as spherical aberration and coma, and used the third-order spherical and coma aberrations to correct directly the on-axis aberrations. In order to minimize increasing the tendency of the off-axis aberration at the 1.0 field angle, during the correction of the on-axis aberration a small value, then had a tendency to increase. Our solution is taking the RMS value of spot diagram less than the diffraction limited value of point spread function (PSF) as an evaluated criterion for the on-axis aberrations. Finally, the optimized value of the system design is obtained by adjusting lens thickness and lens spacing. Two design examples of the doublet, one glass lens and one plastic lens, are well presented in this article.