Characteristics of flight simulator visual systems

The physical parameters of the flight simulator visual system that characterize the system and determine its fidelity are identified and defined. The characteristics of visual simulation systems are discussed in terms of the basic categories of spatial, energy, and temporal properties corresponding to the three fundamental quantities of length, mass, and time. Each of these parameters are further addressed in relation to its effect, its appropriate units or descriptors, methods of measurement, and its use or importance to image quality

Medical Grade Displays in Radiation Oncology

In modern day medicine medical images are an integral part of clinical care. They are used in almost every clinical department from diagnosis to treatment and beyond. Medical images are viewed using electronic displays of various sizes, shapes, hardware, and software. Some clinical departments, like diagnostic radiology, require electronic displays with a large dynamic range, high contrast and high resolution. Other departments do not have any requirements and will use any commercially available display in their clinical workflow. Viewing the same medical image on different electronic displays with different hardware, software or calibration setup could influence how observers perceive and analyze these images. This occurs often when a patient is referred from diagnostic radiology to another clinical specialty department such as radiation oncology. In this case, the patient’s tumor would be diagnosed using a high-performance display while their treatment will be planned and delivered using a commercially available display. In this dissertation, at first, an experiment was design to examine and verify the visual contrast sensitivity of observers using the two types of displays used in the clinic. Observers were tasked with detecting a modulating bar pattern using each display under different background luminance levels and ambient room illumination. The luminance response of each display was also measured for proper comparison. Second, a set of visual experiments compared the image quality of both displays in the different sections of the radiation oncology workflow. Observers were tasked with comparing medical images viewed on both displays and ranking them on a rating scale. As part of the workflow, the observers used both displays to contour tumor and healthy tissue volumes, analyze and fuse two sets of images, verify and adjust patient’s treatment position in three degrees of motion. The results show a clear presence for the high-performance display over the commercial grade display in every step of the radiation oncology workflow. It was shown that better visualization of medical images can improve the accuracy and precision of treatment plan and treatment delivery of radiation oncology patients

Human Factors Compatibility Concerns in the Selection of Display Technologies for Computer and Data Terminals

Human factors considerations are often overlooked in the selection of electronic computer displays. When cost is used as the only determining factor, the resulting product may not be commercially successful because of an inadequate display. To help avoid this situation, designers and users should be aware of the various factors involved in proper display selection. These factors were developed by a synthesis of existing scientific and industrial literature on the subject and are explained in this paper. The first factor is a basic knowledge of the structure, characteristics, and function of the human visual system. The theory of sight, anatomy of the eye, visual perception, and photometric and nonphotometric parameters are covered. The human factors elements of visual response comprise the second factor. The adverse effects of display use as well as ergonomic standards, fonts, color, modes, and the use of status indicators are discussed. The last factor concerns displays. The various available and projected technologies along with comparisons, and applications are presented. Display evaluation criteria are listed to provide guidelines for proper selection

Adaptive Optical Devices in Vision Science

In this thesis we investigate the use of adaptive optical devices in three different areas of vision science. These areas are defocus perception, retinal imaging and severe vision loss. Birefringent material has been utilised to produce optical components that can control the angle of refraction of incident light. Using a ferroelectric liquid crystal (FLC) the orientation of linear polarised light can be controlled. This provides us with the ability to switch between the two refractive indices of birefringent materials at very high speeds. A focus switchable lens (FSL) has been made from barium borate (BBO), and a ferroelectric liquid crystal to switch between equal and opposite defocus levels to determine the optimum focus correction by making use of the human eye's sensitivity to flicker. Flicker simulation result indicate that there is a high dependence of flicker sensitivity to the flicker frequency. High spatial frequencies also increased the ability to perceive small defocus shifts. Promising results have been obtained showing a person is able to find a point of equal defocus using flicker more accurately than they would be able to find perfect focus. The same focus switching lens system has the ability to produce fast focus switching cameras. Its potential has been analysed for the use in retinal cameras to ease the process of obtaining good quality images of the optic nerve and providing such cameras with the ability to switch focus within the depth of the optic nerve head at high speeds. Simulation results showed that two FSLs positioned within the zoom system of the imaging arm are able to create focal point shifts of very small amounts. Finally, collaborative research has been conducted in the use of a birefringent prism in conjunction with an FLC to create image jitter that can enhance visual performance in people with severe visual impairment. Image jitter created on-screen and via an optical system was tested. Patients were able to increase their reading speed and improve their ability to discriminate between happy and sad faces