59.5L: Late‐News Paper: Evaluation of a Prototype Grating‐Light‐Valve Laser Projector for Flight Simulation Applications

Abstract

An evaluation of a prototype grating light valve laser projector indicates it has properties well-suited to flight-simulation applications. Full-field luminance and contrast, spatial resolution, temporal resolution, and color stability were equal to or better than those of CRT projectors typically used in flight-simulator applications. In addition, this projector is capable of providing refresh rates greater than 60 Hz. The higher refresh rates eliminate perceived flicker, and greatly reduce (120 Hz) or eliminate (240 Hz) motion artifacts over the range of target speeds tested. IntroductionDigital projectors, such as LCD, LCoS, and DLP projectors, typically provide better spatial resolution than CRT projectors. However, tracking blur, which occurs when an observer tracks moving imagery, is greater for most digital projectors due to a longer within-frame hold-time than that of CRTs [6,7]. Digital projectors can be relatively easily modified to reduce their holdtime, and we have previously evaluated several such projectors for possible use in flight-simulator applications [12,13]. Those evaluations verified the high contrast and spatial resolution of digital projectors, and also indicated that tracking blur could be reduced sufficiently for use in many simulator applications.The potential benefits of laser-projector technology are generally well-known [11], and include high-pixel count, short hold-time, and expanded color gamut. However the development of a such a projector has, to date, proved problematic. Sony Corporation has recently developed a prototype laser projector: the GxL (G-by-L), which may be sufficiently stable to provide high-resolution images suitable for flight-simulator applications. In addition, the projector can provide refresh rates of 60 Hz, 120 Hz, and 240 Hz, by effectively exchanging spatial and temporal resolution. Based on previous studies [5, 10] we expected that high frame/refresh rates would reduce or eliminate many motion artifacts. Additionally, increasing refresh rate can produce the added benefit of increasing luminance and contrast [8].We describe here an evaluation of the GxL prototype laser projector and discuss implications for flight simulation. The evaluation included instrument measurements of display luminance, contrast, spatial resolution, temporal characteristics, and color stability. In addition, psychophysical experiments were performed to assess the effects of higher spatial resolution on aircraft-orientation discrimination, and the effects of higher temporal resolution on perceived tracking blur, image flicker, and motion fidelity. MethodsThe GxL prototype laser projector evaluated here is based on grating light valve technology, and can produce images of 7680 × 1080 pixels at 60 Hz, 3840 × 1080 pixels at 120 Hz, or 1920 × 1080 pixels at 240 Hz (additional details on the GxL can be found in Kikuchi, et al., in press [4]). Although the GxL is typically demonstrated in curved (60 Hz) and flat (120 Hz and 240 Hz) front projection configurations, the current evaluation wa...

Effects of Visual Spatio-Temporal Aliasing on Pilot Performance in Active Control Tasks

“…In previous experiments, the perception of spatio-temporal aliasing artifacts was studied in passive tasks. [3][4][5] These studies indicate that at higher image resolutions (for a given refresh rate), the visibility of spatio-temporal aliasing artifacts will occur at lower image velocities. Increasing the refresh rate of the display device reduces the visibility of these artifacts.…”

High‐pixel‐rate grating‐light‐valve laser projector

“…11 Perceptual tests of the temporal response of our 240-Hz frame-rate prototype laser projector were conducted by the U.S. Air Force Research Laboratory and NASA. 12 These tests were conducted to evaluate the feasibility of the 240-Hz GLV laser projector for flight-simulator applications. According to their report, the very short hold-time of the GLV projector (~2 µsec) eliminates tracking blur.…”

Perceptual assessment of laser‐speckle contrast

“…[1][2][3] They can also provide a sufficiently high temporal response to significantly reduce motion-blur artifacts. 4 However, laser displays also produce laser speckle that can degrade displayed imagery, and thus affect both machine [5][6][7] and human [8][9][10][11][12][13] vision. There have been relatively few studies of the effects of laser speckle on visual tasks.…”