We have implemented a variation of the classical Hartmann test on a commercial lens bench. We use a single motorized aperture for scanning in X,Y, an image analysis microscope with CCD detector, and image processing software. In a short time, it is possible to measure and plot the wavefront tilt at hundreds of points across the entrance pupil. The technique combines both high sensitivity and large dynamic range. For example, is possible to measure wavefront tilt to 1/200 wave across a 1.5 mm sampling aperture. The high dynamic range allows useful measurement of poorly molded plastic lenses whose surface figure would not yield useable fringes on an interferometer.
Virtual displays have tremendous potential in entertainment applications such as video games, head mount displays for personal computers, and mobile World Wide Web viewers. These consumer applications require high quality virtual displays at a cost below $40 per eye. This combination of performance and cost is not realizable with virtual displays based on LCDs or CRTs. However, low cost, high quality virtual displays can be achieved using patented scanned linear array technology and red, green and blue monolithic LED arrays. A 384 by 224 full color virtual display prototype has been built using this approach. The prototype delivers 4-bits of grayscale per color and flicker-free performance at a 60 Hz frame refresh rate. This paper discuses details of our LED based full color virtual display prototype; development of red, green and blue monolithic LED arrays; and work-in- progress to miniaturize the display and scale the resolution to full VGA.
A virtual display with 1120 X 900 pixel resolution has been constructed using a high density LED array and scanning optics. The display has a field of view of 25 degree(s) X 20 degree(s). The display is small, light weight, and suitable for hand-held or head-mounted use. Pixels appear red on a jet black background. Individual pixel size is 1.3 arc minutes, which is near the resolution limit of the human eye. Pixels appear crisp and sharply defined. Contrast ratio is over 500:1. The paper describes operation of the display in detail, and discusses design tradeoffs encountered in the development of high resolution virtual displays. Extension of this design to other resolutions and field of views is also explored.