Computer-Controlled Photometry And Large-Screen Display Resolution

A new method for measuring the resolution and contrast of calligraphic projection displays has been developed at NOSC (Naval Ocean Systems Center). The technique involves the use of a computer-controlled photometer and an X-Y plotter. The plotter is normally used to give hard copy records of the photometric data obtained from spectral or spatial scans and subsequently stored in the memory of the controlling computer. In this application the photo-metric sensor, a miniature integrating sphere with a slit aperture, is mounted on the X-Y plotter pen holder, which is in turn moved according to programmed instructions from the computer. With the X-Y plotter positioned vertically in front of a projection display, the projected brightness is measured and stored in the computer memory as a function of sensor position. The spatial displacement between measurements is under operator control and can be in increments as small as one-thousandth of an inch. After the data are stored in computer memory, they are made into hard copy with the X-Y plotter in one of several plotting modes. From this hard copy the display performance parameters of resolution and contrast can be extracted. The different plotting modes are used to enhance various differences when more scans than one are recorded on the same chart.