Helmet-Mounted Displays: - USAARL - The - U.S. Army

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Clarence E. Rash, John C. Mora, and Melissa H. Ledford
Testing for most, if not all, systems and subsystems can be performed
in a laboratory environment. Such testing allows for controlled conditions
and produces the most repeatable data. The basic Army HMD design
consists of three sections: Image source, relay optics and tracker. While
all three sections are required, it can be argued that the image source is the
most critical section. For image source evaluation, CRT techniques are
well established and can be found in a number of sources (Verona, 1992;
Anstey and Dore, 1980; Verona et al., 1979; Task and Verona, 1976).
Task (1979) identified a large number of CRT performance FOMs. They
were divided into three categories: Geometric, electronic, and photometric
(Table 10.1).
Table 10.1.
CRT display FOMs.
Geometric Electronic Photometric
Viewing distance
Display size
Aspect ratio
Number of scan lines
Interlace ratio
Scan line spacing
Linearity
Bandwidth
Dynamic range
Signal/noise ratio
Frame rate
Field rate
Luminance
Grey shades
Contrast ratio
Halation
Ambient illuminance
Color
Resolution
Spot size and shape
Modulation transfer
function
Luminance uniformity
Gamma
Quast and Marticello (1996) have developed a test and evaluation plan
for flat panel displays intended for military applications. This plan
emphasizes the need for continuous testing, identifies test categories (Table
10.2), and suggests appropriate test equipment and facilities.
Rash et al. (1996) present an extensive assessment methodology for
testing rotary-wing HMDs. It provides recommended test parameters (at
Table 10.2.
Recommended FPD image source evaluation program.