slower and sharper

two of my favorite diversions recently got a boost through new technologies: snowboarding and photography.

getting a grip
For skis, a network of electrodes embedded in each ski base will apply an electric field to the ski-ice or ski-snow interface. This low-frequency electric field will cause ice and snow to stick to the ski base, increasing friction and limiting the speed of the skier. If any skiers out there care to go faster, just increase the frequency. A high-frequency electric field applied at the ski base has an opposite effect as it melts snow and ice just enough to create the same thin, lubricating layer of water, but without the refreezing/sticking phenomenon.

depth of field

This is an image of inclined crayons from a traditional F/8 imaging system. The depth of field is less than one crayon width. The foreground and background are badly blurred due to misfocus.

After simple color and object independent image processing the final Wavefront Coded� image is formed. This image is sharp and clear over the entire image. Compare to the stopped down image from the traditional system. Wavefront Coding� allows a wide aperture system to deliver both light gathering power and a very large depth of field.

A Wavefront Coded� system differs from a classical digital imaging system in two fundamental ways. First, the light traveling through a Wavefront Coded� lens system does not focus on a specific focal plane. Because of a special surface that is placed in the lens system at the aperture stop, no points of the object are imaged as points on the focal plane. Rather, these points are uniformly blurred over an extended range about the focal plane. This situation is referred to as “encoding” the light passing through the lens system. Another way to describe this effect is to say that the special Wavefront Coded� surface in the lens system changes the ray paths such that each ray (except the axial ray) is deviated differently from the path that it would take in a classical, unaltered lens system and therefore they do not converge at the focal plane.

The second difference found in a Wavefront Coded� system is that the image detected at the detector is not sharp and clear, as discussed above, and thus must be “decoded” by a subsequent digital filtering operation. The image from the digital detector is filtered to produce an image that is sharp and clear, but has non-classical properties such as a depth of field (or depth of focus) that is much greater then that produced by an unaltered classical lens system of the same f number.